Originally Posted by Tod74
Thanks for the reply guys..I never really thought it would go 5's just by changing heads...only reason I ask is I see other people on here with motors similar to mine with good heads running much faster ..plus,like I said only made 4 passes, So have not done any playing with timing and so forth. The car leaves hard and pulls hard the first half of the track but it really seemed to nose over on top when I took it to 6800...I have been told I am running too much timing for a big block (38 total distributor locked out). I just thought it was nosing over because it has stock factory heads on a relatively large engine(compared to the factory BBC).
I haven't decided for sure which heads to get...as far as intake port size. The cost difference between the various AFR heads is trivial. On one hand I think I should get the 345 or 357 but on the other hand I am afraid I will go too big and hurt the short times too much. I don't want to take this thing past 6800 or so .I will also change the intake to a Dart or a Super Victor and I am not against a camshaft swap if I thought it would pick it up some.
I haven't checked the stall..to be honest I actually forgot to look.I do leave flat against the converter with the trans brake...but I don't mash the throttle until just before I release it because this is a bottom bulb car with no delay box.The converter is an 8" Coan that I had built for a 14.1 454 that I had in the car with the same heads and intake. Cam was a .714 lift Comp cams roller with dur @ .050 262/ 272 with a 108 LSA. I did dead head the converter with that engine one time and it stalled at 5200 with the transbrake. I called Coan before I put it behind this engine to see if the converter could be modified for this combonation..I gave them my engine specs.He told me to try it as is and see how it did. The car ran 6.50's with the old engine and the 60' were always around 1.43 - 1.46 and MPH was 104....I thought that 80 more cubic inches would have picked it up more than 3 tenths.
You've touched upon several things here that would cause your problems. Back when I first built my 496 and was running on gas, I set the timing to 35 initially just to be safe until I got the thing on a dyno. Once on the dyno we picked up 35 hp just by advancing the timing from 35 to 38. Later on I played with 39 and then 40 and got a little detonation at 40 so backed it down to 38 and had no other problems. Now that I'm running alky I run 37* with no problems.
You'll be surprised at how much you will pick up with good heads and you'll be surprised again at how much you pick up my having those good heads ported by someone who knows what they're doing. I had Curtis Boggs do my Bodix 2X heads and at the same time I installed a vacuum pump. The best I can figure I gained a total of 90 hp with those 2 changes and allowing maybe 20 hp from the vacuum pump that means 70 hp or more just from porting the heads.
I think you are suffering from 2 major items. I think you have the wrong cam and your heads don't flow enough to support the power level you want. I don't think that motor will have the ummff to work well with a 114 LSA. I would think something on a 110 or 112 LSA. Even if you keep your current cam I would retard it a few degrees from the 5 degrees advance you have now. Maybe install it on a 112 or 111 ICL which should give you a little more top end. As far as the intake, there's no sense in changing it until you get better heads. Going with a larger intake now will just make the problem worse.
I think some well researched dollars in heads, intake and cam will get you where you want to be. Give Curtis a call. You'll be glad you did.
George