Topic: Pontiac 455 and Ram Air IV heads

[jjrrose20]

I hope someone here can answer a question i have had for over 20 years. When I was back in high school I had a 78 ta that I had a engine built for it replace the 400 that had some rods knocking in it. I had a 1970 455 block out of a gto, ram air IV 614 casting heads, and a custom comp cam installed. The problem i had was after two or three hundred miles the motor would start missing. My mechanic would pull the valve covers off to find that the motor had broken one or more push rods and find some of the stamped rocker arms pushed off of the screwed in studs. This happen more than once. The guy that built the engine had a lot of experience with ford and Chevy motors but not Pontiac's. He thought that it might be the heads so he pulled them off and put on some 6x heads. The question that has bugged me for the last 23 years what did he do wrong. After reading some of posts on engine builds here i know I've found the right place to get the answer. thanks for any answers or suggestions anybody comes up with.

[kjkjkcjkcj]

weclome to the site.  Do you still have the car?

As for your problem you did one major thing wrong.   and you may think im saying this but you had a chevy guy build a pontiac.  They are two totally different animals which have different power ranges.  What size cam did you have in the motor.  perhaps he put a  cam in that was WAY too big and the stock rockers couldn't take it.

[jjrrose20]

Thanks for the welcome to the site. Unfortunately I sold the car after he installed the other set of heads. If i remember right it was a street cam from comp cams the cam card said it made power from 1500 rpm to 5500 rpm. I told him that i didn't want to have a race car but a car to drive on the street 99% of the time. The car did have a lot of power. it was no problem to spin the tires from a stop light or driving on the highway. It's funny I found this site while looking to find a good 78 ta to replace the one i had. If i do find one i would like to recreate the motor from the before but without the problems.

[kjkjkcjkcj]

do you know any other info about the cam.  the lift is the more important number

[jjrrose20]

Sorry can't come up anything else. All the info for the engine went with the car when i sold it. So your saying that the cam lift was to big for the valve train? Was there any special valve train for the ram air heads? 

[brian c]

Sounds to me like he got the pushrod length wrong. That and probably too high compression with the RA IV heads on a 455 so it was probably detonating/pinging to death.

I'm running a 1970 455 in my TA with 6x-4 heads, custom ground cam, edelbrock performer RPM intake, etc. Stock valve train other than the Comp Cams roller tip 1.52:1 rockers.

Runs like a bat out of hell with 3.42:1 gearing out back. Really haven't tried roasting the tires because, quite frankly, I spent WAY too much getting the car on the road to lose it doing something incredibly stupid.

[kjkjkcjkcj]

Sounds to me like he got the pushrod length wrong. That and probably too high compression with the RA IV heads on a 455 so it was probably detonating/pinging to death.

I'm running a 1970 455 in my TA with 6x-4 heads, custom ground cam, edelbrock performer RPM intake, etc. Stock valve train other than the Comp Cams roller tip 1.52:1 rockers.

Runs like a bat out of hell with 3.42:1 gearing out back. Really haven't tried roasting the tires because, quite frankly, I spent WAY too much getting the car on the road to lose it doing something incredibly stupid.

Brian has a point on the pushrods, that was my second guess, i just know with chevy guys they throw ridiculously big lift cams in chevys and pontiacs cant take without some new parts.

[jjrrose20]

yep push rods were just factory ones. I would hate to think that all i needed to do was to get shorter after market push rods and would have fixed the problem. As far as pinging the only way i was able to run that combo was to fill half of the gas tank with union 76 racing gas and then top it off with 91 octane unleaded. The guy that built the engine felt it was putting out 500 to 525 hp. I don't if he was right but I can tell u that there was a huge difference in how quick it was after he changed to the 6x heads. Brian c you own it to your self to open your car up and hang on for the ride. it's what you built it to do.

[brian c]

Yeah he changed the compression ratio - severely. It went from 11.3 (roughly) to 9 (roughly). You can check out the info here:

http://www.wallaceracing.com/cratio0001.htm

Here's the various cc's of the heads:

http://www.wallaceracing.com/head1.htm

Generally accepted rule of thumb is to keep the engine compression around 9 to survive on pump gas.


As for opening my car up, no thanks. I've had it up once around 90 and it got squirrelly. Like I said, I spent WAY too much on my resto to turn it into a new Honda doing something incredibly stupid. Or lose my license. Or hit someone while showing off. Too many variables and I'm too old to cuddle up with Bubba in a 6x6 jail cell.

[RainMan]

As for opening my car up, no thanks. I've had it up once around 90 and it got squirrelly. Like I said, I spent WAY too much on my resto to turn it into a new Honda doing something incredibly stupid. Or lose my license. Or hit someone while showing off. Too many variables and I'm too old to cuddle up with Bubba in a 6x6 jail cell.

Gee Brian you sure live life on the edge , I guess we won't be seeing you on Fear Factor any time soon ?

[jjrrose20]

Thanks for all the info. I wish i had u guys back in 1988 when i was trying to get this engine straightened out. It would have made it a lot easier to fix.

[kjkjkcjkcj]

gotta love the world wide web.  idk how you guys survived without Google.  haha  i kinda wish i lived in that era.  things were way more simple i'll be honest im scared to see what things will be like in 30 years.

[brian c]

Gee Brian you sure live life on the edge , I guess we won't be seeing you on Fear Factor any time soon ?

Actually last summer, about 10 miles from my house, a Mustang was toying with an import. The Mustang missed a shift, rocked violently, and then slammed into a telephone pole. Killed the passenger instantly. Car was cut in 2 pieces by the pole so you know he was really moving. I can't remember but I think the Mustang driver also lost his life. The import guy turned himself into police, was arrested, tried, and convicted, and is currently enjoying Erie County (NY) finest quisine - behind bars.

Hits a little too close to home.

[kjkjkcjkcj]

i would agree i use to drive dumb now the only time im driving fast is if its a straight line.  all my friends try gettin me to hit it and i just say nope cuz of stories like that.  do you know how long the guy is behind bars for.

[RainMan]

I was gving you a hard time Brian . I don't believe in racing but I can't see the harm in laying a patch once in a while .
I know I'm not going to build a stroker just to say I have one