Hi, Im not an expert but this could be a fuel supply problem, maybe you need a bigger fuel line and high volume fuel pump? uzzled: Christian
I agree that it seems like a fuel issue however he is running a electric pump and claims to have good pressure at full throttle... We suggested that before when he was running poorly.
I will tell you what the problem is just from reading through the thread and looking back at your build. You need to order shorter pushrods. Your rods are too deep in the cup and you are laying over at high rpm's.
ok. did a little work out in the lab. vacuum is at 16 inches. as far as carb goes, it is set up so that there is NO vacuum secondaries any more. primaries have been drilled an opened up from before, different metering rods in secondaires, an are adjusted to open right now. when car is warm, response is great. you can really feel it kick!! comprsion test showed 210-215 across the board. seems pretty good. fuel pressure stays at 7 pounds.this pushrod idea makes sence. they were new with the build, an ive ALWAYS had a top end issue. hmmmmm. how much shorter would i really need?? the head were decked 20 thousandths, so 20 thousandths shorter than stock? i had a freind with a 455 poncho go though this. but his engine is a monster!!
That won't work with a spreadbore carb and a spreadbore intake.. I have the only system that I know of that will work that way.
It sure does work great on a spreadbore it just needs a spreadbore to squarebore adapter, I ran this on a 350 with both stock intake and Poston intake worked great with a 150 shot.
What he is saying is that if his block was decked and his heads rebuilt the stock pushrods will not be optimum for the current combination. A further issue is that the base circle on some of the cams are different then stock. An adjustable pushrod should be used to measure what each pushrod needs to be for length then custom pushrods ordered... Or you can run adjustable pushrods adjusted properly. Here is some info: http://www.compcams.com/information/Products/Pushrods/ http://www.carcraft.com/techarticles/116_0401_setting_pushrod_length/index1.html
ok, but my block wasnt decked, heads were. i have NO CLUE what im looking for..... when i ordered the cam from comps, i talked to a rep an he said i am good to go with the stock stuff, being the cam was so mild.
i plan to. read up on it, sounds awsome!!! but whats got me wondering is the pushrod length. could that be my cause for laying over at top end?? an if so, when i put an even more agressive cam in, same issues?? if that really is an issue. like i stated, comps rep said everything was good to run stock valve train.:shock: :shock:
Since you only removed 20 thou from the heads it is most likely not enough to cause an issue with the stock rods, BUT the stock rods may not have been the correct length in the first place. too add to this some of the comp cams have a different base circle measurement which further complicates the issue. Yes too long of pushrods will hurt performance. I suggest getting an adjustable pushrod checker, measuring what you need then ordering a set if the stock ones are not optimum. Get the new cam first then check the pushrod length and go from there. Or just run a full set of adjustable pushrods.
OK. Let me splain the pushrod issue. Normal or stock preload on hyd. lifters is .030 inch. Acceptable range is .020 - .060 inch. Stock engine - no machine work. ANY changes to the valvetrain will effect this preload. You had the heads milled .020 inch. Your preload is now at .050 inch. Almost maxed out. You would notice this most on a completely stock engine because it would run rough at idle. Wind through the gears at WOT and you would REALLY see the effects above 4500 rpm. You would think the engine was coming apart. You cannot see the effects because you have a mild cam in there now. Preload for an engine that will see over 5K should be at .020-.025 inch. You need pushrods .020-.025 shorter than you have now. Like Sean said, get a pushrod measuring tool and measure a few lifters while on the base of the cam. measure to 0 lash and add .020 - .025 inch and that is the length you need. I'll say with certainty that this alone will get you 14's. PS. This is one of the most overlooked changes that is needed whenever ANY adjustments are made to the valvetrain or deck height.
ok. pulled intake an had scorling racing's engine guy come over an check my pushrods. everything is well within specs. he said i have plenty of preload left on my lifters, an that i run a bigger cam. such as the lunati cam the sean spec'ed for me. he feels strongly that this comps cam just doesnt have the top performance in it. said it is a early 80s grind, which i knew,an to grow a set an put in the 3500 converter, the lunati cam, an 4.10s!! as far as porting goes, he said dont, cause its not an never will be a rpm motor. 100 shot of juice, with the combo listed above, should net me mid to high 13s.or better, if tuned correctly.:grin: p :3gears: :3gears: so bottom line im keepin the ole 350.
''cause its not an never will be a rpm motor.'' i take it he is another brand engine guy. i also take it he has no clue that the 350 will go 7500 (sometimes more:eek2 rpm. the rest of his input is good.
I think Margel's engine would have hit 8000rpm no sweat if the rods would hold it when he ran my X-Factor!
