Thread: Still having complications

Tweet

you have way less then 9.1 if the heads are not milled less then 108.cc and the deck is at stock deck your about 8.1 with a 4.310 bore .not much cam in this one

is 108 the ccs on a 291 rectangle port head?

Originally Posted by Cooter1989

is 108 the ccs on a 291 rectangle port head?

about that.. the older O ports are less cc.your never going to get to 9.5 with the stuff you have less its not what you have with them heads a 4.530 bore x 4.250 crank your about 10to1.you have no crank stroke to build CR

o port heads? im confused. the heads i have are 3964291 they are gm's hi-perf rectangle port closed chambers

yes i know them heads i had them and used them in builds . i telling you that the old O port you would have a hard time getting to9.1 not 9.5 with a flat top and a 3.765 crank

what are you meaning by o port?

Originally Posted by Cooter1989

what are you meaning by o port?

older O port has smaller chamber size less cc =more CR then them heads on a 427 with flat tops are not much good if it has any size cam

sooooo---what did you drop the pressure to??? do you have pressure guage where you can see it while driving?? why no answers to my questions??
Where is Sapulpa?

this may clear things up for you not trying be hard on you just can not see why you went to flat tops ? is this a tall deck bottom end ? are you sure you have a 427 and not a454? the O port heads i am talking about is the head we used with a flat top 454 engine to get around 9to1 that head was a 215 101cc.or 206 97cc. now if you have a 3.765 crank with the heads you have on there now your lucky to be at 8.5 but if it was a 454 with flat tops at would be 9.1 as it has a4.000 crank now the same build in a 496 would be 9.5 as the crank is now 4.250 .same crank 4.250 as the 496 in a 548 with bigger bore4.530 now is at 10.3 .volume in bore and storke make bigger engines and the CR will go up if the head CC in the chamber is the constant

ok got cha. im not sure on the cam size but like you say i imagine its to big for no more motor than i have. i really need to pull the heads and find out exactly what piston i have the guy that the motor came from was trying to tell me it has 12-1 domes in it but from what i can see from the plug hole doesnt look like a dome piston and it doesnt ping with 91 oct and alot of timing. ive ran a compression check on it i dunno if it means much for the comp ratio but it has 175psi cranking. here is a link to a video of it running the dominator and intake have been replaced with the demon and an air gap.
‪79 trans am‬‏ - YouTube

Originally Posted by jerry clayton

sooooo---what did you drop the pressure to??? do you have pressure guage where you can see it while driving?? why no answers to my questions??
Where is Sapulpa?

hey i give you the answer .... hi jerry .... if this thing under 8.5 cr with any cam fuel is running out his tail pipes at idle

sorry jerry i missed that post. i dropped it down to 5 last night and checked the power valve it already has a 3.5 in it but didnt get a chance to drive it. sapulpa is in oklahoma. Pat i didnt build this motor so im learning about it as i go but it is a 427. im not 100% sure it has flat tops in it but with it liking alot of timing and runs with no detonation on 91 octane im assuming its a lower comp engine. so if it does have flot tops and with the heads being a 109cc it would still struggle to get 9-1 compression?

there is many things that can add or sub on CR hard to say if the heads have been cut down like .050 off then? is the block @ O deck ? what head gasket was used ? 4.370 fire ring or a 1017 fel pro with a 4.540 fire ring bigger and thicker head gasket= l less cr . the best you could hope for with the heads at 108 and O deck would be a round 8.5 like i posted on here many times

i know none of the above lol. surely it has more compression that that, i need to find a borea scope and see if i can tell if it has domes or not. did you watch the video?

no i did not look at the video.. but if its a flat top with stock un cut heads and stock deck height on block its less then that i been at this for some time on BBC .far from my first time at the Rodeo thats the carb you have on there NOW?? thats a very very old 4500 holley