what is the maximum rpms i would want to take a balanced 455 pontiac to? it would be a 2 bolt with a stock bottom end, maybe forged or hyper pistons and probably have ARP rod bolts and main studs.

i am thinking about a comp XE274H cam with 230/236 duration at .050 and over .500 lift with 1.65 rocker arms. in car craft the 455 they built with this cam, headers, intake, and stock heads/compression made about 350hp at 4500. if i could rev it to about 5500 i would probably go with the next one up and a little higher stall. what do you think? i also have 6X heads that don't flow very well but i'm cleaning them up, do you think they could handle a bigger cam like the XE284H?

 

You might want to post such a question on the forum on the Performance Years website...there is some incredible Pontiac knowledge on that forum.

 

I'd stick to about 6000 rpm or less... the stroke on that 455 is really long anyway compared to the bore, so i doubt it would breathe well enough to make good power over 6000 rpms. It basically the same problem the 305 chevy has, just on a bigger engine.

 

5500 would be no prob, just don't skimp when it comes to having your rods recon'd, and be sure to use arp bolts. Even better pick up a set of pro-torque h-beam rods for $399.

 

455s can rev up to 5800 but cross yyyyyyour fingers after that. The weak link are the rods. By the time you put all the time and money into resizing rods , ballancing, polishing beams, and shot peening to make them stronger , you can buy a set of H-Beam rods that will withstand 700 HP. they are under $400.00 now. What heads are you running and what is your compression.

 

hell, the cool thing about pontiacs is that you dont have to rev them very high to get them to move, just get GOOD heads, a good cam, and BIG exhaust.

seems to be the formula for pontiac motors to run hard.



adam

 

I have a 400 Pontiac running mid 12s. 12.6 and soon to be 12.5- secs . It is a stock rebuild except TRW forged pistons and cam. Heads are non ported #16s and the engine was built in 1991 by NAPA for $999.00 Gotta love that torque. This car runs and races on ARCO gas, 92 octane. It never overheats in traffic and the best thing ,it gets the best gas milage. LOL! Not!!!!!! 8-10 MPG. Oh well it hauls *** and was cheap. 12 years of abuse and still pulling strong.http://groups.msn.com/SixtyEightFire...ox.msnw?Page=1
There are 5 pages, I believe the 3rd page has the car I currently race. And yes I raced the convert 68 and totally stock with a 2:78 non posi ,It pulled a 13.89 at 100 with a 0-60FT time of 2.0secs.

 

sixt8bird, where did you get those heads and how much were they? i'l be running lightly ported 6X heads but 16s would be better.

 

You will not be able to run #16s on any pump gas with 455. Your heads will flow very well if ported out right 250 cfm intake 200 exhaust. They also have a high floor which helps the short turn radius. Dont take any off floor and smooth out short turn radius. Are your 6Xs #4 or # 8s . Your compression will be 9.2 or 9.6 to1 depending which heads, the 16s would put you at 11.25-11.75 way too much . You can dish the pistons but the 6 X heads are the way to go. Check out www.classicalpontiac.com or "street performance pontiac" or www.performanceyears.com forum. Lots of great info Type in 6x heads on classical pontiacs and you will be lambasted with info. You may even see alot of my posts. #16scame on 1968 and 1969 Performance 400s and go for around $200-$250 and then will need a valve grind. But again the 6 Xs flow great. SD Performance is very well known for his great port work.This link is for Street Performance Pontiac. http://members.boardhost.com/boylewo...tml?1032402509 This link will bring you directly to Performance years forum http://forums.performanceyears.com/6/ubb.x

 

Funny nobody mentioned oiling.

I had an Army buddy in the late '70's who ruined three 455 cores before he did something to improve oiling. All he did was a mild cam upgrade that raised the power band by about 500 RPMs, and he kept spinning bearings. As I recall, cross-drilling, chamfering, and high volume oil pump solved the problem.

Perhaps that's just standard practice now, so nobody thought it worth mentioning.