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Discussion Starter #21
My small class engines were 305 ci, but I used t love the way the 288s revved up. and I wanted to build one... With the 23 degree deal it is hard to get the comp anywhere near decent, hence plenty of angle mill and dome,,, finding it needed or wanted a fair amount of advance, but I never got to the 50* plus you did Randy... some seem surprised wen they hear of the advance used,,, Aluminum heads, seem to like less, but I just wonder how much chamber shape and design has to do with this
 

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My 548 BBC 13.5 CR Brodix -2 heads C12 fuel like 40 deg fixed at crank trigger with 38 in high gear with a high gear -2 retard chip. Never dyno'd it, just that's was it best ETs at. Probably likes a lot of timing due to large chamber and not so efficient cam. If I upped the compression, smaller chamber, better cam, C14+ I'd guess I'd be around 36 deg as a starting point.
 

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My small class engines were 305 ci, but I used t love the way the 288s revved up. and I wanted to build one... With the 23 degree deal it is hard to get the comp anywhere near decent, hence plenty of angle mill and dome,,, finding it needed or wanted a fair amount of advance, but I never got to the 50* plus you did Randy... some seem surprised wen they hear of the advance used,,, Aluminum heads, seem to like less, but I just wonder how much chamber shape and design has to do with this
Along with stroke and rod/piston length, piston speed would change timing requirements I assume. What I don't get is why chev (old stuff) seemed to like more timing than ford, or at least more than my quench cleveland chambers. I was around 34 when it was stock 351 (358) rotating assembly, with the 4" stroke it went to 30-31 degrees. But my brothers ford 302 seemed to like advance. One other variable is timing tabs, I always zero mine at TDC when degreeing the cam.
 

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My small class engines were 305 ci, but I used t love the way the 288s revved up. and I wanted to build one... With the 23 degree deal it is hard to get the comp anywhere near decent, hence plenty of angle mill and dome,,, finding it needed or wanted a fair amount of advance, but I never got to the 50* plus you did Randy... some seem surprised wen they hear of the advance used,,, Aluminum heads, seem to like less, but I just wonder how much chamber shape and design has to do with this
Only 50 plus on 2 engines in my whole life. Most liked 48, one loved 44. Anymore, and it slowed down. Any less, same. I think everything has to do with timing needs. Chamber, dome, rod length, stroke, and maybe even cam.
 

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Only 50 plus on 2 engines in my whole life. Most liked 48, one loved 44. Anymore, and it slowed down. Any less, same. I think everything has to do with timing needs. Chamber, dome, rod length, stroke, and maybe even cam.
It seems that as we got better at cyl heads it took less cam to get a good fill which led to being able to run less timing.

All I know for sure is I keep running less cam & timing & keep making more power
 
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Discussion Starter #27
Along with stroke and rod/piston length, piston speed would change timing requirements I assume. What I don't get is why chev (old stuff) seemed to like more timing than ford, or at least more than my quench cleveland chambers. I was around 34 when it was stock 351 (358) rotating assembly, with the 4" stroke it went to 30-31 degrees. But my brothers ford 302 seemed to like advance. One other variable is timing tabs, I always zero mine at TDC when degreeing the cam.
I tried t rule out the many variables that will effect this in the original post, and only tried to nail down to an identical engine with ONLY a compression increase hard/impossible to do I know, but I was, and am curious what you guys all think in regards this topic.
 

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Discussion Starter #28
Only 50 plus on 2 engines in my whole life. Most liked 48, one loved 44. Anymore, and it slowed down. Any less, same. I think everything has to do with timing needs. Chamber, dome, rod length, stroke, and maybe even cam.
What fuel were you running, I was on Methanol and mid 40s for timing.. And absolutely as much comp as I could make at the time
 

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I tried t rule out the many variables that will effect this in the original post, and only tried to nail down to an identical engine with ONLY a compression increase hard/impossible to do I know, but I was, and am curious what you guys all think in regards this topic.
I know. We kinda derailed your posts.
 

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Only 50 plus on 2 engines in my whole life. Most liked 48, one loved 44. Anymore, and it slowed down. Any less, same. I think everything has to do with timing needs. Chamber, dome, rod length, stroke, and maybe even cam.
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.
 

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I tried t rule out the many variables that will effect this in the original post, and only tried to nail down to an identical engine with ONLY a compression increase hard/impossible to do I know, but I was, and am curious what you guys all think in regards this topic.
Right, I forgot that. Compression is all I wanted to change but to do that I went to a 4" stroke kit with 6.2" rod and light pistons compared to a stock 30 over 351c rotating assembly. But that is all I changed, same cam, heads, intake, carb etc. Compression went from 9.5ish to 12.8:1 (pump fuel build). Cubes went from 358 up to 409, power went from 454hp to 583hp, torque from 400 ft/lbs up to 503 ft/lbs. Timing went from 35 down to 31. Also made power at about 750 less rpm.
 

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Wow 28 to 36, that is quite some difference. Oval chevy iron or alloy heads? assuming iron ,, but you know!! The engine that provoked the thought for this thread is on a run stand at present, has alloy heads and is sitting at 35* locked out
Desoto these were a chi 4v Cleveland head. The a3 style head with little bigger chamber wanted around 34.
 

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Desoto these were a chi 4v Cleveland head. The a3 style head with little bigger chamber wanted around 34.
Those A3'S on a 408?
So me with same heads never liked more than 31-32* , on the dyno. Timing tab difference or engine combination, who knows.
 

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Tb1 the 438 is the one that liked 28*. Sometimes at track we will see some engines like more timing than found on Dyno. Im thinking the advanced timing helps more in first stages of track. 60ft especially.
 
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