Regardless of what this video tells you - subscribe as it has good content. David vizard

Man oh man! You’re explaining a lesson I wished that I had learned the easy way. Close to 20 years ago I built a SBC for a 1969 SS Camaro convertible. Very nice restoration. Engine had to be built to look exactly like it was off of the show room. So no HEI conversion. What the customer elected to do was a Pertronics conversion in a dual point housing. The distributor was a “rebuilt” brand from a popular parts store here in the U.S. The conversion kit was straight forward and looked very clean. Where I got into trouble as the engine builder….. When I built the engine, degreeing the cam off of top dead center from the positive stop method, I noticed that the timing reference on the balancer was off near 45 degrees from the factory timing pointer. The harmonic balancer was brand new but some stock form of aftermarket. I did not purchase this for the build it was supplied with the rest of the parts. I’ll further explain that it’s been my long term policy to lock the crankshaft down after the cam is degreed in and verified. Then I will close everything up around the front cover and install the balancer and verify timing reference. Just for this reason. Ensuring proper ignition timing. So in this case. I taped the balancer to paint a mark in line with the timing pointer and painted a nice bright white stripe on the balancer to correct. Big mistake!! So the engine is fired up. Brand new transmission from a reputable transmission shop that supplied everything surrounding. When we filled the transmission with fluid. A very loud noise began. It was the flex plate being pushed into the transmission inspection cover and the shift linkage had issues to be worked out. The car owner was standing right there and elected to take the car to the transmission shop right then and there. We managed to set timing and check for leaks but the engine did not get much running time. Maybe 5 minutes and I was not comfortable with the situation either way. A few days later I get a call at work from “the transmission guru”. He just wanted to tell me that my timing mark was off about 15 degrees. So he fixed that for me. I was busy with work and didn’t really have time to realize just what had been done. When it gets out of the shop the car owner called me to inform me that the engine was running hot. No problem, I’ll set the timing and check everything out. When time comes to set timing and I’m looking for my painted timing mark, it’s gone. That transmission guy took it upon himself to strip the painted timing reference off of the balancer and repaint the balancer. He then hastily remarked the balancer with a piece of chalk you could barely see. The explanation on how transmission guru determined top dead center??? Not worth mention the guy was screwed up in the head and just screwed me over big time. So now I’m trying to set timing based roughly off of feeling for compression and doing my best to get a mark on the balancer. It was mess everything in the way. All culminated into uncertainty. When I tried to set timing the initial was set around 8 degrees and when I looked at the total timing I was well passed 45 degrees. I thought the vacuum advance was still hooked up. It wasn’t. Where is all of this advance coming from? I was in a hand wringing situation. The car owner was very understanding. They could see and knew enough about the situation to realize that we were out in left field for referencing. They took the car home with them with the plans to disassemble the front end of the engine and reestablish TDC reference later. I took my problems to work and explained them to my boss. A very wise engine builder. He immediately asks me why I didn’t use the mill or something else to make a permanent mark on the balancer. I had the tools available to do so and didn’t. But where was all of this extra advance coming from. It’s all brand new store bought rebuilt?? The answer came a few weeks later on the engine dyno at work. Another engine. This time a 327. Same popular parts store “rebuild” dual point with an electronic conversion kit. This time the timing marks were right and not tampered with. This engine was hitting near 52 degrees with no vacuum advance. Mr. Boyd calls me into the dyno room and asks me if this is what I was seeing with my project?? Exactly. Same brand distributor from the same parts store doing the same thing. So he has me pull this distributor and he goes at disassembly. The mechanical advance plates!!! The stop pins had deep wear grooves. The plates the stop pins were mating to, worn out! He calls popular parts store and explains. Their response….. No way! For sure for certain. It was. It was the same on the distributor that had plagued me with issues. Moral of the story. Permanently mark your timing references. The uncertainty that little detail created was more than I want to ever deal with again. For those that set timing by ear. It isn’t happening when your mechanical advance is in this condition. You’re flat lost with a slow boiler that will never cool down. My apologies for the long winded this one I felt was just too important.

Great explanation! Thank you Mr. Gold for the walk-through on vacuum advance with the visuals (excellent graph.) Side note for anyone interested: David Vizard has a very recent video that touches on the ignition subject and expands on a couple points, (manifold vacuum for the win). Again, thank you for helping us less experienced guys.

Congratulations on the 10K subs, it is all a testament to your great content!! Back in the 80's I worked at The Carb Shop here in BC. As such, I have a Sun distributor machine as well as a Sun osilliscope/gas analyzer too!

Thanks for the follow up on this subject. Congrats on 10K subscribers.

Great timing curve, mechanical and vacuum advance tutorial. I was a tune up mechanic in my youth and quickly learned to move vacuum advance from ported to manifold. The smog laws in 1966 in California moved them back to ported to lower emissions. Engines ran hotter and got poor mileage and had sluggish street performance. I've converted several friends' engines to manifold vacuum advance with great results. Some are harder to start when warm since there's more advance while cranking. Opening the throttle stops that. Street driving with this makes for cooler running and better MPG. Last note: I lived in Denver for a decade, and we could run nearly 40 degrees total there with no detonation. Higher altitude makes the difference. I'm in Texas now at 700 ft and 35 degrees is my maximum total now. Thans for the fine video.

You’re a very good instructor and do a great job explaining the details.

Congratz on 10k subs! Great content as always. Another video idea would be to going into points and HEI details.

Excellent video AG. Thank you. 👍

Excellent video and a fantastic explanation, Allan. Thanks!

I really like the lock washer lesson! I fully agree! I think those were designed back when harmonics were not fully understood or there was a knowledge deficit on how to mitigate certain applications where harmonics came into play.” So just add a spring into the equation and maybe that bolt won’t back out because of harmonic resonance.” That’s all I can reasonably figure on.

Liked the video. I'm somewhat passionate about ignition timing and have studied it extensively over the years. FTR, I've a manifold vacuum preference too. The ported vacuum as you know was a crutch used in the early smog days and was a way to try and clean up emissions. I noticed the engines you referenced with your "good book" were all pre-smog examples. Keep up the good work.

Great helpful content.....Thx for Detailed explanation on the "Ported" vacuum advance issue...

Congratulations on 10K👍

I agree about using the knowledge from the past. If you're building a regular production engine, naturally aspirated, someone in the past already designed one, all you have to do is follow their blueprint. I remember the old "Chevy Bible" and the Chevrolet interchange manuals, they were worth their weight in gold......no pun intended.

great video, ported vs manifold each have their place depending on what your timing curve needs.

Congrats on reaching 10k subs 👍👍👍

Wow! Congratulations great channel! Take care

Love your content so glad I found this channel.

It’s great when you go into detail. I really learned something on that youtube about bolts. Not sure if you done one yet! But a you tube on decreeing a cam

Thank you so much sir. I just found your channel and I'm subscribed. Great explanation on the vacuum advance question. 👍

Congratulations on reaching 10K subs! I knew that this channel would grow if you kept up the interesting content that really isn't explained elsewhere on YT.

Very good, very interesting. I assumed you were going to discuss whether ported or manifold vacuum is correct.I have seen the issue argued in both directions.the one thing I might add is when you are at steady cruise, manifold vacuum will be a fuel milage improvement.

Thank you for explaining the vacuum advance ported manifold vacuum an how it works with mechanical advance

TIMING AND VACUUM ADVANCE 101 by GM Engineer. The most important concept to understand is that lean mixtures, such as at idle and steady highway cruise, take longer to burn than rich mixtures; idle in particular, as idle mixture is affected by exhaust gas dilution. This requires that lean mixtures have "the fire lit" earlier in the compression cycle (spark timing advanced), allowing more burn time so that peak cylinder pressure is reached just after TDC for peak efficiency and reduced exhaust gas temperature (wasted combustion energy). Rich mixtures, on the other hand, burn faster than lean mixtures, so they need to have "the fire lit" later in the compression cycle (spark timing retarded slightly) so maximum cylinder pressure is still achieved at the same point after TDC as with the lean mixture, for maximum efficiency. The centrifugal advance system in a distributor advances spark timing purely as a function of engine rpm (irrespective of engine load or operating conditions), with the amount of advance and the rate at which it comes in determined by the weights and springs on top of the autocam mechanism. The amount of advance added by the distributor, combined with initial static timing, is "total timing" (i.e., the 34-36 degrees at high rpm that most SBC's like). Vacuum advance has absolutely nothing to do with total timing or performance, as when the throttle is opened, manifold vacuum drops essentially to zero, and the vacuum advance drops out entirely; it has no part in the "total timing" equation. At idle, the engine needs additional spark advance in order to fire that lean, diluted mixture earlier in order to develop maximum cylinder pressure at the proper point, so the vacuum advance can (connected to manifold vacuum, not "ported" vacuum - more on that aberration later) is activated by the high manifold vacuum, and adds about 15 degrees of spark advance, on top of the initial static timing setting (i.e., if your static timing is at 10 degrees, at idle it's actually around 25 degrees with the vacuum advance connected). The same thing occurs at steady-state highway cruise; the mixture is lean, takes longer to burn, the load on the engine is low, the manifold vacuum is high, so the vacuum advance is again deployed, and if you had a timing light set up so you could see the balancer as you were going down the highway, you'd see about 50 degrees advance (10 degrees initial, 20-25 degrees from the centrifugal advance, and 15 degrees from the vacuum advance) at steady-state cruise (it only takes about 40 horsepower to cruise at 50mph). When you accelerate, the mixture is instantly enriched (by the accelerator pump, power valve, etc.), burns faster, doesn't need the additional spark advance, and when the throttle plates open, manifold vacuum drops, and the vacuum advance can returns to zero, retarding the spark timing back to what is provided by the initial static timing plus the centrifugal advance provided by the distributor at that engine rpm; the vacuum advance doesn't come back into play until you back off the gas and manifold vacuum increases again as you return to steady-state cruise, when the mixture again becomes lean. The key difference is that centrifugal advance (in the distributor autocam via weights and springs) is purely rpm-sensitive; nothing changes it except changes in rpm. Vacuum advance, on the other hand, responds to engine load and rapidly-changing operating conditions, providing the correct degree of spark advance at any point in time based on engine load, to deal with both lean and rich mixture conditions. By today's terms, this was a relatively crude mechanical system, but it did a good job of optimizing engine efficiency, throttle response, fuel economy, and idle cooling, with absolutely ZERO effect on wide-open throttle performance, as vacuum advance is inoperative under wide-open throttle conditions. In modern cars with computerized engine controllers, all those sensors and the controller change both mixture and spark timing 50 to 100 times per second, and we don't even HAVE a distributor any more - it's all electronic. Now, to the widely-misunderstood manifold-vs.-ported vacuum aberration. After 30-40 years of controlling vacuum advance with full manifold vacuum, along came emissions requirements, years before catalytic converter technology had been developed, and all manner of crude band-aid systems were developed to try and reduce hydrocarbons and oxides of nitrogen in the exhaust stream. One of these band-aids was "ported spark", which moved the vacuum pickup orifice in the carburetor venturi from below the throttle plate (where it was exposed to full manifold vacuum at idle) to above the throttle plate, where it saw no manifold vacuum at all at idle. This meant the vacuum advance was inoperative at idle (retarding spark timing from its optimum value), and these applications also had VERY low initial static timing (usually 4 degrees or less, and some actually were set at 2 degrees AFTER TDC). This was done in order to increase exhaust gas temperature (due to "lighting the fire late") to improve the effectiveness of the "afterburning" of hydrocarbons by the air injected into the exhaust manifolds by the A.I.R. system; as a result, these engines ran like crap, and an enormous amount of wasted heat energy was transferred through the exhaust port walls into the coolant, causing them to run hot at idle - cylinder pressure fell off, engine temperatures went up, combustion efficiency went down the drain, and fuel economy went down with it. If you look at the centrifugal advance calibrations for these "ported spark, late-timed" engines, you'll see that instead of having 20 degrees of advance, they had up to 34 degrees of advance in the distributor, in order to get back to the 34-36 degrees "total timing" at high rpm wide-open throttle to get some of the performance back. The vacuum advance still worked at steady-state highway cruise (lean mixture = low emissions), but it was inoperative at idle, which caused all manner of problems - "ported vacuum" was strictly an early, pre-converter crude emissions strategy, and nothing more. What about the Harry high-school non-vacuum advance polished billet "whizbang" distributors you see in the Summit and Jeg's catalogs? They're JUNK on a street-driven car, but some people keep buying them because they're "race car" parts, so they must be "good for my car" - they're NOT. "Race cars" run at wide-open throttle, rich mixture, full load, and high rpm all the time, so they don't need a system (vacuum advance) to deal with the full range of driving conditions encountered in street operation. Anyone driving a street-driven car without manifold-connected vacuum advance is sacrificing idle cooling, throttle response, engine efficiency, and fuel economy, probably because they don't understand what vacuum advance is, how it works, and what it's for - there are lots of long-time experienced "mechanics" who don't understand the principles and operation of vacuum advance either, so they're not alone. Vacuum advance calibrations are different between stock engines and modified engines, especially if you have a lot of cam and have relatively low manifold vacuum at idle. Most stock vacuum advance cans aren’t fully-deployed until they see about 15” Hg. Manifold vacuum, so those cans don’t work very well on a modified engine; with less than 15” Hg. at a rough idle, the stock can will “dither” in and out in response to the rapidly-changing manifold vacuum, constantly varying the amount of vacuum advance, which creates an unstable idle. Modified engines with more cam that generate less than 15” Hg. of vacuum at idle need a vacuum advance can that’s fully-deployed at least 1”, preferably 2” of vacuum less than idle vacuum level so idle advance is solid and stable; the Echlin #VC-1810 advance can (about $10 at NAPA) provides the same amount of advance as the stock can (15 degrees), but is fully-deployed at only 8” of vacuum, so there is no variation in idle timing even with a stout cam. For peak engine performance, driveability, idle cooling and efficiency in a street-driven car, you need vacuum advance, connected to full manifold vacuum. Absolutely. Positively.

30+ years in heavy industrial transportation and you are 100% correct on split washers👍

The vacuum advance really is important in a street vehicle, they spend most of their time at something less than half throttle and at a steady state like highway use may be considerably less. People need to realize this and be truthful with themselves and the actual application of their engine. A part throttle dyno run may show the benefits of layering more vacuum advance on top of the total mechanical in such cases, there may be free torque and fuel economy to be had and better driveability. You did hint at this, but there are numbers to be had. In modern engines there are ECUs, multiple sensors, and advance tables that play the game, but really it's not that much more functionally advanced than the good old distributor. Anyway thanks for another interesting video and congratulations on breaking the magic 10k subscribers, it must feel good for you and your team.

Excellent...agreed on manifold vacuum source...working a 67 Ford 289....question...if running manifold vacuum source, do I still need to disconnect and plug vacuum source to set initial timing?...thank you in advance.

Nice lesson... My experience with vac advance has been that connecting to manifold provides great cruise efficiency and smoothness, but the vac cannister cannot respond quickly enough to throttle input. It fails to pull timing out quickly enough under load. You get a brief moment of spark knock while the advance plate moves back. Connected to ported vac doesn't give such issues. I have since gone to MSD programmable, which uses a GM MAP sensor and has a fully programmable curve in addition to the run curve ie: "mechanical". My 302C has about 45 degrees total dialled in at cruise, and around 25 at idle. It's a happy engine.

Not to go too far off topic but this got me thinking about the other parts of the ignition system; plug wires, distributor cap, rotor, spark plugs. Recurving the distributor would be good too. Heat range of spark plugs and adjustable vacuum diaphragm. Maybe with an engine on the test stand or dyno.

The distributor on my 67 gto had a single advance stop on the underside of the weight plate and the weights had a different shape. For some reason the gto had a rubber bushing on the stop. Aftermarket timing kits supplied a steel bushing. Chevys that I saw had the same type. Your chart shows the total timing graphed at 35 degrees not 30. In the late 60's and early 70's the recommended total timing on both small and big block Chevys was 38-42 as I remember.......

from kuwait and soo happy to follow and here you sir and Mr Vizard

Awesome channel Alan

On another note, I never knew the factory Chevy timing curves were ridiculously slow and had too much mechanical advance and not enough initial advance. I didn't know that they were this bad until you showed the factory specs. Modifying it like you have makes a big difference in getting off the line 💪

Good points whether you use ported or manifold vacuum for advancing, I found for my 340 that initial set at 22 degrees allowed the max advance go to 34 and using the manifold vacuum stalls the engine when I stomp it from stop. If I move it to ported, no more falling flat, trouble is that my centrifugal needs to advance quicker like about 1800 rpm. Can turning the set screw in the vacuum pot do that or what will it take?

I added an aluminum plate to the arm of my vacuum can limiting the vacuum advance to 8 degrees. I think it originally was s 22ish degrees. With my throttle plate virtually closed, my idle was slways higher than i wanted. I was finally able to get a lower idle by redicing my vacuum advance. I think it was actually too low after the mod, so i actually opened my throttle plates slightly. I ran 13 to 14 advance, 34 total and using the stock GM weights. I used a Mr Gadket or Accell spring kit. I had heavily modified some new World Products heads, installed a mild Edelbrock performer cam and manifold. To make it pretty, i added some cast iron Sanderson block hugger manifolds and 2 1/2 dual exhaust. I spent months playing with and learning to get the timing curve right. Yup, manifold vacuum is the right way.... I don't care what other internet professionals say. It may be devicive, but it really doesnt bother me if they do it the wrong way. 😁 I had this 350 in a 73 Chevy stepside. I had it bored 30 over. I dont recall my time slips best et, but i managed 76mph in the 8th with some TA50 tires. Those didnt grip well and my converter grabbed pretty early. With so little weight in the back, this combo was so hard to launch without smoking the tires. From my et and online calcuulators, i think it was 294 HP. No race truck for sure. I never built it to race, just took it out to the track twice for curiosity. I miss my old truck. It never let me down. Did I mention happy 10,000? Yeah, but ill do it again. 😁 🎉🎉🎉🎉🎉🎉🎉🎉🎉🎉

We have had great luck with tool bags, much like Paul has. From bikes to sleds to all offroad toys except we put the bags inside amo cans.

Awsome explanation

You are 100% correct on vacuum advance. It was changed to ported for emissions purposes only. It is interesting that a more efficient engine doesn't always produce the "cleanest" emissions. The only difference between manifold and ported is at idle and deceleration. At cruise they are about the same. It is alarming how many guys don't understand how vacuum advance works or why we use it.

! u r right about the washers. I wondrd y they went out of shape and found loose, later. Thank you. Now, I need to go back and get rid of a few... Ha! Cheers!

So, the vacuum advance, when manifold vacuum, actually allows the engine to act much like it has a race distributor locked at 34 degrees, but without the hard starting issue because before it fires its at 4 degrees, after it starts its at 30 and the time between the drop in pressure from WOT until max mechanical advance is about a second or two at most?

Good tip I've been throwing lock washers away for years, 30 years ago my boces teacher told me the same thing, friction holds bolts tight, and there not used in engines and those bolts will stay tight forever.

I've, always hooked my distriburor vacuum hose, to the base of the carburetor.

THANK YOU VERY VERY MUCH FOR THIS VIDEO ❤🔥💪👌👍🏻

Alan, I noticed that you use generic branded Bravex HEI distributors, my question is do you find that the curve is right on the money for your builds? Thanks and keep up the good informative videos. :)

I love this subject, nobody ever mentions the vacuum canisters are calibrated differently, for the application. Optimum peak combustion chamber pressure occurs at 14 degrees atdc.

I didn't know factory HEI ignitions had way more than 20 degrees of mechanical advance built into them, the aftermarket HEI ignitions on the market seem to have only 20 or so, I THINK! I have had a hard time getting info on built in mechanical advance on anything. I have been using manifold vacuum advance on my mild GM performance 350, and it been working out great, but I need access to a distributor machine for the remainder. Good video.

I have old massey ferguson tractors from the 50s and 60s. They have lock washers on 1/2" bolts. And smaller.

Even emissions engines that utilize “ported” vacuum also utilize “manifold” vacuum. A thermal switch plumbed into engine coolant switches between the two depending on engine temperature. If the engine starts running hot it switches to manifold vacuum because the engine runs more efficient therefore cooler...

Hmm,I'm running a stock l31 motor with a Eddy carb. I locked the mechanical advance to keep the timing down to 36 and hooked the vacuum advance up to ported. It feels like it's got a flat spot around 40 to 50. And I can't rev past 4000.

Your example for vacuum can had about 16 degree of advance. I think my can had more. My car had a misfire at cruise with the can hooked up. My whole curve may have been quicker. Where do you find specs for the different cans? My 68 has a Q-jet. A lot of HEI's have a lot of advance due to EGR.

Your right on about lock washers, the guys at work look at me like I got two heads when I talk about lock washers

Could that lock washer explanation be the same as a crush washer (I.e. Honda recommends on oil drain plug)?

Thanks You Very Much Sir❤

I haven't ever seen a reason to lockout a distributor the total advance is the only thing to worry about always has a better response from idle starts easier and still holds accurate timing at full throttle

New to your channel, but you should do a video on vacuum secondaries and how many people think if they dont feel their secondaries opening up it means its not working

I recurved a lot of distributors from 73 to 94. One thing nit mentioned is the huge variety of vacuum cans uu

Will a motor need more initial timing for a intake leak? Mine seems to need quite a bit of timing to start and idle.

I agree with lock washers in most cases if you get the bolt or nut tight it wont come loose anyway.

Im s newbie...do you set your timing with the vacuum advance hooked up or disconnected with the manifold port capped?

Good tip on so called lock washers. When these things spread open [as they like to do], surface area under the bolt head begins to disappear and trouble has arrived. .

Didn't GMC put lock washers on there engines? I've done thousands of bolt ups in the oil patch and we don't even use flat washers unless the engineering tells us. Lock washers are a waste of time and sometimes we have to use them. I've flattened so many out. Good knowledge.

We have to find for you some better audio settings. The Mic is actually shutting off as you come to the end of a word.I don't know if it's the noise blanking or the hands free activation..love the videos and the subjects. Thanks.

I’m a 73 year old drag racer and have not been able to find a vacuum advance diaphragm that will last very long on my HEI distributor. I’m about to ready to order a HEI distributor from Progression Ignition that features the ability to program everything with your phone app.

I have a rebuilt 350 engine and im trying to install the distributor in place but even after i macht the oil pump drive with the distributor one still have a 1/4 inch gap for some reason the distributor doesn't want to drop down all the way in????

My car with a 4:11 gears runs 3K RPM @ 55 MPH at part throttle crusing on the highway. How would that work with a vacuum advance? I have 17 initial advance with 18 Mechanical all in by 3K. What would your advice be?

So a normal engine always works better with more than initial timing? Does that mean that initial timing alone is only good for starting a cold engine ?

Great info 👍 msd instructions say to put the vacuum on a ported source. But the video says manifold. Even theyre confused

the problem I have noticed with manifold vacuum is during tip in the timing gets retarded,throttle response seems better with ported vacuum but not every engine responds the same

With regard to split type lockwashers; you don't see them used with connecting rod fasteners or main cap fasteners which should tell you something.

I have been told that under part throttle high vac you could have over 40 degrees advance at the higher RPM because of the vac advance.

12:24 You're one of the few that say "flame propagation" or a burn rate. So many people believe the combustion mixture explodes. As a side note: engine "ping" is a shock wave in the cylinder bouncing back and forth at the speed of sound.

Thank you for your knowledge and video's USA 🇺🇸 USA 🇺🇸

A sbc 350 can make 400 hp. But a 383 can make 400 hp with more idle vacuum, and because of the increased stroke, make more low end torque. So if you're not limited by any racing rules, and you're changing the crank and pistons anyways, I would go with a 383, unless I already had the parts to do a 350.

How about if you have a little bit bigger cam and your vacuum is all over the place at idle and vacuum advance is hooked up to manifold kind of means the timing is jumping all over the place at idle, ported vacuum in my experience keeps the timing the same at idle!! This is confusing

I have always been a full port vacuum guy. I’ve worked on Small Block Chevy’s for 40 years now. The advantage is at idle. Engines will always idle better regardless of the cam with the distributor connected to the manifold vacuum on the carb. At WOT who cares neither port is worth a darn. At half throttle or cruise mode both ports will be putting out some vacuum so we are now back to the whole advantage of manifold port vacuum, idle. The tuned port was designed for emission compliance and hoping to get better gas mileage. That is it. Most of us are building street and muscle cars so this is really irrelevant. Go manifold vacuum port and your engine will idle so much better and be happier.

The ported vacume goes away with throttle opening just like manifold vacume. The only thing different between the two is the ported vacume is zero at idle

I recently saw Junkerup's video about this. I have nothing to add on the subject, but it's funny to see people rehash things like this and argue in the comments

I thought the vacuum adds to the total bringing it to 40 and 50 degree total.

A great wife, is key!

10K 🎉🎉🎉🎉🎉🎉🎉🎉🎉

400hp comes at lower revs and has a smoother idle on a bigger motor so it's a how high a rpm do you want your 400hp question.

They sell them split washers in grade 8, don't buy the cheap ones did not realize that until recently so will keep throwing them away unless I know they are grade 8.

I work in industry...Nord-locks are the gold standard.

I do not agree with the lock washer episode I learned a lot about lock washers from motorcycle mechanics aluminum parts versus steel parts. Nowadays most lock washers are very cheap.

34 degrees... Is that with manifold vacuum disconnected?

If you are going with 350 then why don't you go with a factory roller cam block with factory lifters ect! you could save 400+ dollars than using a link roller lifters and special front timing cover and that money saved can be for upgrading the crank for 383 or better heads.. Over achieve is never a bad thing!

Vacuum advance is primarily to fire lean stretched out molecules at steady state light part throttle . The fuel mixture is lean and needs more time to fire the fuel This benefits fuel economy . Where does light throttle occur typically 37mph to 55mph approx Vacuum needs to be measured and known at every 5mph How much advance , manifold vacuum at mph and get the highest reading u can ,at approx 14.5--15:1 air fuel ratio . Primarily vac advance manifold or ported can also depend on auto or manual g/box . The auto can have more vac adv because of the stall in the convertor ie helps engine thru stall and engine detonation is less likely . VS a manual =ported Is there some emissions reduced on deceleration using manifold connection ?? Many emissions distributors have both advance and retard cans

I THROW MY TIMING LIGHT IN THE BUSHES MR G MY VACUUM OFF MY LAUNCH STRAIGHT TO THE PING OF MY GAS. THAT'S HOW I GET YA W/ THE POSI AND THE GEARS . DIAL IN MY STREET 60' // I STOP LOSING PARTS 😎 🤙

I stopped this right off the bat.I have never disagreed with anything you have said. A lot of people have this wrong.

You are 100% INCORRECT about vacuum advance…Ported vacuum does NOT add ANY timing when it is at WOT because at WOT there is NO vacuum at either port UNLESS the carb is too small in which case it creates a restriction and can pull in a little timing with PORTED and MANIFOLD vacuum…and there are times when a motor idles better with PORTED vacuum… Having said that, YES, the engineers working on STOCK motors know more than you do, but they weren’t making distributors with curves for motors with as much camshaft as we run now, so you CAN’T use a 1960’s book for tuning a 2020’s motor combo. 🤦‍♂️ You have to be smart enough to let the motor tell you what it wants and then make the curve do that.

The smart guys in the '70s wanted it ported

Vacuum advance is an economy advance.... that's it... that's all.

So don't try to out smart the engineers that designed the engines. But you modify the centrifugal advance that they designed. 🙄🙄 But, your design is an improvement. 👍

Just keep ur vids honest, and SMART, like the one i just had to UN-sub from, cuz the solution for the issue was to CUT POLY LOCKS DOWN!!!...........WHAT????....DONT MAKE A SPACER TO CLEAR THE POLYS if u want stack valve covers, CUT THE POLY LOCKS.....i mean REALLY????....THIS IS UR SOLUTION???....NO!!...i had to un-sub, as i WONT participate in AWFUL band aids!!

ZzzZZZzzzz.....

30+ years in heavy industrial transportation and you are 100% correct on split washers👍