[steve25]

Here's some plug reading help.

[PontiacJim1959]

I may have missed it, but don't see what carb/intake system you are using.

My opinion is you are running lean - which could be cylinder over scavenging. I have not run aluminum heads, but my opinion is that 28 total at 3,000 RPM's is a bit on the low side. With iron heads and 10.0 compression, you would want 32-34 degrees @ 2,800-3,000 RPM' BUT, you would also need high octane gas.

Rather than lower the timing, I would bump it up to around 34-36 @ 2,800-3,000 RPM's and run a higher octane or octane booster. And I would fatten up the carb with bigger jets. If the exhaust is over scavenging, try 1.5 rockers on the exhaust only and check results. With your combo, you may need a bigger CFM carb if you are using the Q-jet. Again, my opinion.

[BLK/RD462TA]

Well, I guess my hearing and vision up close isn't as good as it used to be. Upon further investigation most of my spark plugs have faint aluminum specs on them. I also realized i'm using aftermarket silver springs with stock hei pontiac dizzy weights. Its supposed to cool down over weekend and will put new plugs in and factory stiffer springs. Gonna run some more tests check existing dist curve. Im realizing from other posts about short seat timing that im not needing much total advance with Edelbrock dports fast burn chamber. I was running a 750 holley vac originally and put a new quickfuel 830 DP on a RPM intake and that made little difference. I also made the mistake midstream of changing double roller summit timing chain to a cloyes without degreeing it.When I first put the new 73cc e dports on crank pressure was 205. installed straight up at 112 icl. That was with a 15cc dish so went to 20cc dish to help the compession. Car has 1 3/4 headers and 3 exhaust. According to Butlers flow chart intake to ex ratio around 84 to 82 % up to 600 lift if that helps. Thanks

[Dragncar]

Get your distributor on a Sun distributor machine and end all the wondering. It will tell you exactly what is going on.

[steve25]

Yes, 205 cranking compression was too high for a street motor that you would like to be able to run on no more the 92 octane.
With Aluminum heads I consider 190 about the limit , but that can at times be tempered by the stroke your running,

[Jay S]

Most guys running 200-210 cranking pressure are running 93 octane. I would put the stiffer advance spring in and pull the timing back to 28 total. Then check the plugs again. If you thought it ran good before and it had some preignition going on you may find it runs better yet with less timing. Get the coolant leaks cured and look at the plugs again. Pull a little timing out just to be safe starting out.

I don’t think over scavenging would be an issue when the cam timing is straight up on 112. That cam was likely designed to be installed on 108. Retarding the timing generally promotes less scavenging, at least until the engine gets to the upper rpms. By then preignition should not be a issue anyway.

[lust4speed]

If I'm getting kickback with 8° initial I'm going to doubt that it is really only at 8°. Considering your other problems it sure points to the marks being off. You won't know for sure until you verify TDC with a degree wheel and then slip the balancer back in place and see if it aligns with the timing cover.

A simple test for total timing is to remove both springs from the distributor and fire up the engine and read the results at idle. Lot less stressful than having your head under the hood at high RPM's. Keep in mind that if your marks are off then this result will also be off but at least you have another data point logged and know if the distributor is sneaking in additional timing at high RPM.

[BLK/RD462TA]

To be honest, my back has been going through chiropractic care for months so I have limited underhood time. So I have to chose my battles. I would have liked to confirm TDC with timing cover but as Elarson said, "aluminum on porcelain is bad" So what I did today was change was change spectre silver springs to original gm pontiac hei springs with original weights which were already changed back. I previously installed a console pod and a aem a/f gauge and summit oil and temp backup gauges. I think I found the problem! I ordered wrong temp sender from summit but finally got that resolved. Turns out with a 180 thermostat that my 16" single pro form rad fan isn't keeping up! It crept up to 216 in driveway idling in no time! Ive suspected old factory gauge was off cause it reads kinda low. Gauge now is led digital. Who knows what the temp was when I put it to the floor! Tachometer does weird stuff too! I have a electronic timing light that shows idle sometimes 200 off. I have a jegs aftermarket radiator with a single proform 2100 cfm fan. I did see a dual 2800 combo that would cover rad area better. Or Jegs sells a shroud for that radiator? I did check timing and its steady at 8 initial and 28 total up to 4000. Thanks again

[BLK/RD462TA]

pic of fan