hello, I'm new

[Speedracer]

Whatever combo you choose,you will need a good acid man.

[J/SA Grand Prix]

from looking on the NHRA website, it seems that 72' only had a 300 horse 455. Why are you saying that the 455 is a better combo when you can't turn as many rpms safely as a 400? Just trying to figure out what combo will go best in my grand prix. I have heard about acid etching from a few stock racers around here but you can't do it a very big amount because NHRA is cracking down on etchers now. Please let me know on any 400/455 combo's that any of you have built and what would be the way to go. I appreciate all your replies.

[Harry 6674]

The 455 is a good low rpm torque motor and I think thats what it will take to move that much weight at the start. Big rpms are hard on parts ia an engine that wasn't designed for it. Use the 455s big torque it will be cheaper and its been proven competitive.

[J/SA Grand Prix]

would NHRA let me put a 455 crank in a 400? it would be basically the same thing just smaller main bearings? I have a 4.21 stroke crank with the 3 inch mains for the 400 i currently have in the car. If anyone has some 66 cast heads for sale let me know. I didn't see the 315 horse 455 on the engine blue print on the NHRA website. What does this motor call for as far as heads intake and carb? I could build the 325 horse 455 that would be an I or H/SA i believe is what it comes out too. this is for the 71' motor.

[Don Himes]

Jake, let's slow down a little bit. First off, You must not be looking at the NHRA classification guide correctly. In 1971, the 400 cube engine is factored from 300 to 320 h.p. and the 455 is at 325 h.p.Now in 1972 the 400 is factored to 310 h.p. and the 455 is factored to 315 h.p. Now you can clearly see that the 455 is a much better deal. Now if you get the '71-455 engine defactored to 315, its all even! BUT, if you don't get it defactored, your better off getting the '72 parts and calling your car a '72. Do you follow me so far?

[Jack Matyas]

Jake---You're off to a great start my boy ------ "Etchers" --- that sounds so much better than just plain cheaters . Dave is right - that Pontiac is very different than Fords and Chevy's --- loads of torque at lower RPM's . As for your 7500 RPM--that's about a thousand or so too high for most Pontiac engines . Good luck and have a great time...........


PS--Don--you're starting to sound like a used car salesman (it takes one to know one) . If - come - maybe-etc.

[Don Himes]

Jake, here's some info on parts: for the heads (7M5) call Automotive Recyclers in Rochester, Minn. @1-800-657-4403- no stock # listed, and for the intake call All-American Classics, in Vancouver, Washington @ 1-800-955-4999. They both list above parts in stock.

Jack, hope your feeling well........I'm too old to build one for myself (thank God for Billy) but I'm moist with antisipation for a younger fellow to find out what we've always known-----PONTIACS KICK BUTT

[Mark Ruset]

Don are we going to see you at Moroso this weekend?

[J/SA Grand Prix]

Great, after talking to you all, my dad and I have decided on the 71 or 72 455, it seems that the 72 parts are in more supply and basically the same motor, just with different part numbers. Don, I appreciate all your research for me and all the numbers. What duration cam would you suggest and as far as converter and rear gear ( as a fellow post says 4.56 or 4.33 ). After talking to Hefler he says A1 or Munsinger makes a great high stall converter. What stall would you guys recommend for my torq machine? Don, I am with you 100% and appreciate all the great feedback!

[Mark Yacavone]

Stall for the 455 would be in the low to mid 4000 range. 400 a little higher
It's not legal to use a 3" main crank to make a 455. I won't say it hasn't been done though.
Listen to these guys .There's about 200 years of experience here, now that Jack is onboard.

Mark

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