Help!!!
Thread Starter
Racer
Joined: Oct 2010
Posts: 474
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From: Bishop CA
Help!!!
I just installed a set of Aluminum heads on my 1975 small block. The motor is slightly built with a moderate cam, headers, high rise and 650 cfm carb. I was told I should expect a 50 hp increase from the heads. I don't seem to hardly notice any difference at all. My timing is at 8 which makes my total advance at 36. I was told to go to 10 on the initial but I'm afraid that will take the full advance above 36. I was told that I shouldn't exceed 36 total. I live at 4600 ft elevation and am running 87 octane. Any suggestions on the timing or fuel or anything. Thanks in advance.
Thread Starter
Racer
Joined: Oct 2010
Posts: 474
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From: Bishop CA
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Thread Starter
Racer
Joined: Oct 2010
Posts: 474
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From: Bishop CA
Melting Slicks
Joined: May 2009
Posts: 3,079
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2024 C3 of the Year Finalist - Unmodified
I run my BB at 34 and my initial falls in at 15, stock points distributor. I've run the engine at 38 and it wants more, but that fits neither my style nor my pocketbook. Why don't you try adding one degree at a time until you hear a rattle under load with your 87 octane? Then back it down one degree...or try 93 octane. Your engine will tell you the best timing setting, regardless of the digital number.
Thread Starter
Racer
Joined: Oct 2010
Posts: 474
Likes: 0
From: Bishop CA
I run my BB at 34 and my initial falls in at 15, stock points distributor. I've run the engine at 38 and it wants more, but that fits neither my style nor my pocketbook. Why don't you try adding one degree at a time until you hear a rattle under load with your 87 octane? Then back it down one degree...or try 93 octane. Your engine will tell you the best timing setting, regardless of the digital number.
Pro
Joined: Oct 2006
Posts: 734
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From: Bryan Texas
My mistake, mechanical advance should be about 24. So, you are little over. Perhaps something is worn in the distributor. Yes, timing should be at 36 with base and mechanical advance with the engine revved to make sure all the mechanical advance is in. With the vac, it should not exceed 52.
Thread Starter
Racer
Joined: Oct 2010
Posts: 474
Likes: 0
From: Bishop CA
My mistake, mechanical advance should be about 24. So, you are little over. Perhaps something is worn in the distributor. Yes, timing should be at 36 with base and mechanical advance with the engine revved to make sure all the mechanical advance is in. With the vac, it should not exceed 52.
Melting Slicks
Joined: May 2009
Posts: 3,079
Likes: 314
2024 C3 of the Year Finalist - Unmodified
You won't see 52 total with the vacuum advance connected. It is just a theoretical number. Vacuum advance decreases as the engine speed is increased from idle, which adds centrifugal advance. They work together to optimize engine performance thru out the rpm range. By 3000 rpm you should have all centrifugal plus initial, but no vacuum. A lack of WOT performance is not a vacuum advance issue. The L88 did not even have a functioning vacuum advance canister and can run as much as 42 degrees total timing...just not on 87 or 93 octane with 10% corn juice.
Make sure you have no centrifugal at idle. I tried changing my springs but all 3 sizes in the Mr. Gasket curve kit allowed the weights to move out at idle. Ended up putting the original factory springs back in.