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Randy were those alloy heads? What size chamber and piston type. I know some of the bbc Oc style heads like more timing as well as the oc ford. Most of the cc heads ive dynoed fell off after 36*. That said these were 7000-7500 rpm engines. Not sure if higher would require more.
The 2 that liked 53 degrees, were aluminum heads. The Dart/Buick liked 40 with C-25, and 44 with C-14. The others were all 23 degree on C-12. One, with iron bow ties, liked 44 with C-12. Most wanted 48. Who knows? Above my pay grade.
 

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I know alot of the chevy motors i seen like more. However never seen to much over 40. What kind of rpm?Im just wondering if rpm plays a role. I know some two stroke snowmobile engines actually retard timing automatically on upper end. But i think its more for detonation reasons.
 

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I know alot of the chevy motors i seen like more. However never seen to much over 40. What kind of rpm?Im just wondering if rpm plays a role. I know some two stroke snowmobile engines actually retard timing automatically on upper end. But i think its more for detonation reasons.
Most were 10,000, and above. I know it sounds extreme, but it was, what it was. The stroke seems to have something to do with it also. Cause 355” engines seemed happy with 38 to 40, 327” and 307” liked 39 to 42, a couple with 3.160 strokes liked 44, and the 2.750, to 3.013 liked 53 and down to 44. The ones that actually liked the 53 degrees were both 2.80 and 2.75 stroke. But, both also had exact same piston, and chamber design. And rod length ranged from 5.485, to 6” with every conceivable length in between.
 

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Wow you guys were winging on them. Could be. Ive never seen that before. But never seen 10g rpm before. Except pro stock guys. Thats cool stuff.
 

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Wow you guys were winging on them. Could be. Ive never seen that before. But never seen 10g rpm before. Except pro stock guys. Thats cool stuff.
Not really. Most Modified Eliminator, and Comp engines exceed that by quite a bit. Up to 12,500. And some legal Super Stock engines do. Not 12,000, but 10,000 and above.
 

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Most were 10,000, and above. I know it sounds extreme, but it was, what it was. The stroke seems to have something to do with it also. Cause 355” engines seemed happy with 38 to 40, 327” and 307” liked 39 to 42, a couple with 3.160 strokes liked 44, and the 2.750, to 3.013 liked 53 and down to 44. The ones that actually liked the 53 degrees were both 2.80 and 2.75 stroke. But, both also had exact same piston, and chamber design. And rod length ranged from 5.485, to 6” with every conceivable length in between.
That makes sense, with less stroke you'd have slower piston speed and need more advance?
 

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What I am trying to figure out is if you did a real slow pull if you would need less timing. Or steady state at say 6000rpm
I assume it would be relative to the engine rpm, not the time taken to make the pull. Are you thinking along the lines of how timing can be taken out in hi gear. Like pulling in 1st gear compared to 4th?
 

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I assume it would be relative to the engine rpm, not the time taken to make the pull. Are you thinking along the lines of how timing can be taken out in hi gear. Like pulling in 1st gear compared to 4th?
I actually have done a few boat motors on my dyno where it made best power with timing but was not going to live. The spark plugs where overheated and detonation could see with microscope. If I did a fast pull spark plugs would not look as bad. You tune the timing to max hp? Sorry still learning.
 

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I actually have done a few boat motors on my dyno where it made best power with timing but was not going to live. The spark plugs where overheated and detonation could see with microscope. If I did a fast pull spark plugs would not look as bad. You tune the timing to max hp? Sorry still learning.
Lol, me too. Im not sure but id think the overheating and detonation may be plug (heat range) and fuel related but tuning on the dyno usually isnt the same as at the track, or lake I guess. I think most tune for highest mph at the track. I tuned for best power on the dyno but also went by heat on the ground strap.
Were your quick pulls on the dyno with less load?
 

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So shorter stroke motors want more advance.? I always thought it was combustion chamber design ?
I think it’s a combination of a lot of things. That engine I had with a short stroke, only wanted 44. And that one was a 2.85 stroke. Different pistons, and chamber, so who knows. Ran best rich.
 

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So shorter stroke motors want more advance.? I always thought it was combustion chamber design ?
I don't think its stamped in stone but makes sense. Slower piston speed and less dwell time at TDC with shorter stroke/rod combo. Roll that 4.35 stroke over and watch how fast the piston comes up compared to a 3.5 stroke. I think combustion chamber plays a big role as well. Like Randy said, a lot of factors. Then add weight of car and tranny and rear end gearing.
 

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Lol, me too. Im not sure but id think the overheating and detonation may be plug (heat range) and fuel related but tuning on the dyno usually isnt the same as at the track, or lake I guess. I think most tune for highest mph at the track. I tuned for best power on the dyno but also went by heat on the ground strap.
Were your quick pulls on the dyno with less load?
Yes I was also setting timing of ground strap. Plugs where 9 ngk heads around 100* and pull was 100 rpm a second and pump gas 93. Plugs didn’t look good till around 27* they are supercharged around 1050hp
 

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Yes I was also setting timing of ground strap. Plugs where 9 ngk heads around 100* and pull was 100 rpm a second and pump gas 93. Plugs didn’t look good till around 27* they are supercharged around 1050hp
Yes I was also setting timing of ground strap. Plugs where 9 ngk heads around 100* and pull was 100 rpm a second and pump gas 93. Plugs didn’t look good till around 27* they are supercharged around 1050hp
Ok, I've never been around anything supercharged or 1050 hp, lol, but there's been good discussions on heat range and reading plugs on here before. Maybe start a thread on it, lots of serious engine builders on here
 

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Ok, I've never been around anything supercharged or 1050 hp, lol, but there's been good discussions on heat range and reading plugs on here before. Maybe start a thread on it, lots of serious engine builders on here
Ya I am still learning but now have a little idea what I am looking at. Just want to see how everyone else does it.
 

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Are you sure the 93 is ok, how much boost?
Yes it was good. Under 8lbs on the supercharged motor. The twin turbo motor I did same thing. But he flew a tuner in from California they where tuning it for peek power I said plugs don’t look good. Thats when I bought bought microscope and wow what you can see than.
 
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