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Hey guys, so I'm having a couple of issues. Or it may be 1 I'm really not sure. The 428 was running good but the vacuum was lower than what I thought it should be 7-8 in park and 4-5 in drive. I do have a small cam but I wouldn't think it should effect it that much. So I tried retuning the carb (edelbrock 1411 750cfm) to get more vacuum. was able to get as high as 8 in park, 5 in drive. Also I had issues with the motor holding prime. When its was running it was fine. When you shut it off you can see the fuel slowly creeping back down the fuel line and big air bubbles coming up it. Oh I put on a clear fuel line for now so I could as what was going on. No wet spots on the driveway either. So I figured that was a problem with the pump. 2 Days ago I replaced the pump, still doing the same thing. Yesterday I went out to give it another try. I use starting fluid to get the engine turning enough to pull fuel up and got it to the carb but she wouldn't run on her own. As soon as you take your foot of the pedal she dies. I forgot to mention, when she was running I had to set the RPM's between 1100- 1200 in park and in gear they would drop to 450- 550 RPM's. If I set it as say 800RPM's in park she would try to die when shifting to drive or reverse. The carb was rebuilt last year and everything on the car has been rebuilt or is new. Any thoughts?

Thank you

Edited by Wrongway
Added the RPM section
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It's very common for your 60 year old harmonic balancer to be off due to slippage and the old rubber.  But doesn't rule out timing gear/chain probs. Too much slack will alter timing and may not have j

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Ok Kiwi. Wasn't able to do anything on her today. Still putting the shop back in order after emptying it out yesterday. Hopefully get it finished tomorrow so get back to her.

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Doesn't look like I can get maniseal around here Kiwi. Not sure if you can even get it in the states bro. I found some on eBay for $12.00 and $67.00 USD shipping lol. Guess I'll go back to using Indian head, but thank you bro.

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All good Mate, hay how are you getting on with your steering Wheel ?🙄

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Its going good bro. A lot better then I thought it would. lol. I'll post pics as soon as I get it finished.

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Awesome. Thanks Bear

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Well, the holes in the valve covers didn't line up. I reached out to the company I got them from and was told that I should drill them out to fit. Thinking that this was kind of an odd response I did just that, and yes I did order the valve covers for my engine. So I drilled the holes out from 5/16 to 7/16. They still didn't line up so I sent them back this morning. I could've went a bit bigger but I was afraid of leaks.

Valve cover 1.jpg

Valve cover 2.jpg

Valve cover 3.jpg

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So with the old valve covers back on I let the engine run for a while to play with the settings today. Remember I was only 6-8 on the vacuum gauge and crazy high timing before all the issues. So I've got her running 900-950 RPM @ 10.2 degrees of timing and 12lb on the vacuum gauge. But knowing NOTHING about Pontiac engines before this car and engine (and proving that in the past lol) I thought I should ask If that sounds right or does anybody have a timing number that I should start at or a goal to shoot for? What's a good idle speed for these engines? Vacuum? 1421445700_Camcard.thumb.jpg.67385a3547e84cb6cab8582fdaef8fe1.jpgs the cam card again so nobody has to go back and find it.

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Ok I will do that tomorrow and report back with the numbers bud. This is the timing light I bought when we started all of this and I've been using. https://www.summitracing.com/parts/anm-cp7529?seid=srese2&utm_source=bing&utm_medium=cpc&utm_campaign=Brands+|+A&utm_term=4582214710510654&utm_content=GSAPI+5ba0fb3fb7fce

Will this be ok or is there a reason to buy the one from O'reillys? Just not sure what I'm missing bro?

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Yeah, that looks exactly like the one I have.  Oughta work just fine.

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Ok great. Thx bro. I'll let you know how tomorrow goes.

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bear is bang on Wrong way 👍

what i could add is if you cant find the correct timing tape, just measure your balancers diameter, divide by 360 and that gives you 1 degree increments... i mark my balancer at 36 degress for chevs, and 35 sound right too me for a ponti ( i use a white permanent marker):dancingpontiac:

dont go over 35-36 or you will break shit 🙈Hahaha

 

Edited by 64 kiwi boni
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i found this via nastyz28 and its from hot rod forum. enjoy the read....:cheers:

 

 

This is a great article!!!!I had my vacuum advance hooked up to the ported vacuum port after reading this article I hooked it up to full manifold vacuum adjusted the idle rpm.The car has so much more power now.



As many of you are aware, timing and vacuum advance is one of my favorite subjects, as I was involved in the development of some of those systems in my GM days and I understand it. Many people don't, as there has been very little written about it anywhere that makes sense, and as a result, a lot of folks are under the misunderstanding that vacuum advance somehow compromises performance. Nothing could be further from the truth. I finally sat down the other day and wrote up a primer on the subject, with the objective of helping more folks to understand vacuum advance and how it works together with initial timing and centrifugal advance to optimize all-around operation and performance. I have this as a Word document if anyone wants it sent to them - I've cut-and-pasted it here; it's long, but hopefully it's also informative.

TIMING AND VACUUM ADVANCE 101

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. Don't ask Summit or Jeg's about it – they don’t understand it, they're on commission, and they want to sell "race car" parts.

Edited by 64 kiwi boni
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5 hours ago, Wrongway said:

RPM @ 10.2 degrees of timing and 12lb on the vacuum gauge.

10.2 is pretty high mate and i think you mean 12 inches of vacuum 

i would be happy back at 6-8 degrees of initial. at idle with like bear said,( vacuum plugged to the dizy mate.)

do what Bear said and just dont go over 36 when your up there at 2500 rpm.

if you find that your starter kicks back when you try to start her, move your initial timing back 2 degrees and start again.

 AND try it when your engine is cold, then again when its HOT... it can make a :cheers:

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Ok that makes sense. I am running an after market distributor also. I'm getting ready to go play with her. I'll let you know how it goes. 

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