[Doc Willis]

I recently purchased a '70 Chevelle 396SS with a 454 engine (taken from a '77 GMC pickup - the original unmounted 396 engine was included in the sale as the rest of the car is in an original condition). I admittedly have a lot to learn about automotives and I hope to learn by working on
this car. I would appreciate any advice from you pros here at Team Chevelle about the engines. I want to improve the engine performance. The 454 in my car doesn't move like I think it should. I know nothing about the motor (except it has headers and an Edelbrock carburetor) and I have no idea what kind of horsepower it pulls. My friends who know more than I say it might pull less than 300 HP. The original 396 engine is a L-34 350HP 396 (actually a 402 ci). Should I put my effort and dollars into improving the 454's performance or rebuild the original 396 and put it back under the hood? If it makes any difference, I'm not planning to resell this vehicle any time soon, and I want to keep the car "streetable" though I am entertaining the idea of bracket racing). Please share with me your opinions.

 

[Brian n az]

If this doesn't open pandora's box, nothing will.
Its all up to you. I have friends with 454's that feel sluggish to my 402. The best thing about your delima is that alot of the parts you will need will work on either engine. How fast do you want to go? Speed costs money. Most of the "stock" Chevelles on this page can run in the low 13's, a good, respectful time. To get into the 12's
you will spend 1.5x over the normal build. To go faster, increase that by 2-2.5x. It's fairly simple, big cubic inches make big horsepower. In summary, you will get more horses and torque from the 454 for less $ than the 402 . Keep the 402 for selling the car (if you ever need to) and build the 454.

Brian

 

[Joe Y]

If you're going to keep the car around for a long time, I would rebuild the 454, keep the 396 and rebuild it if and when you decide to make the car original. Just don't go too radical on the cam and either engine can be streetable althogh your not really going to see a big difference in gas mileage between the two. I would say however, if your interested in braket racing, use the 454 because you will get more power easier with more cubes. I assume you'll be running pump gas with iron heads so keep compression down to 9.0 to 1. have fun!

 

[Hot66ss]

bang fo the buck go 454.
Run 10:1 compreshion and use an MSD 6a box...
with the box and 10:1 you will have to run 92 octane but worth the extra power...


Just my .02

Hot66

 

[GaryR]

Doc:
I'll go along with the other advice posted ahead of me. If you don't care about keeping it original go with the 454 and save the 402 incase you change your mind later or want to sell the car.
Before you start on the 454 check out the casting numbers on the heads. If the engine came out of a truck, depending on the year of the truck, it may have the peanut port heads. The intake ports are only about 2/3 the size of the ports on your 402. Good for a truck to make pulling torque but bad for a high performance car.
You could use the 402 heads on the 454 if the 454 heads are the small ones.
GaryR

 

[Joe Harrison]

As Gary stated if you can use (and have)the 402 heads use them it will bump up the compression and will have bigger ports> Most later modle 454's from trucks do indeed have the peanut port heads, these heads work fine for a truck but not a chevelle. One more thing if you plan on racing , plan on braking it some time and if racing is in your future I wouls not use the origal 402 heads go with a world products Merlin or edlbrock aluminum heads. Like every one has said it's up to you and it's your checkbook and only you know the balance.

 

[Steve S]

I guess I will chime in here since this car was in my driveway while I helped a friend complete the interior and do some wiring work. The 454 probably does not have the peanut heads based on what I felt when I drove it. One problem that we never got around to fixing was the kickdown for the turbo 400. I noticed that the wire was not hooked up but we never got to it. The 454 felt like it pulled pretty good to me but you have to manually shift it. The first thing I would do is replace the intake with a good high rise aluminum then the carb. Have the iginition checked for timing and advance. While you have the intake off you might want to upgrade the cam. The one in there now is pretty mild based on the rock solid smooth idle. Like the others who have replied I would definately go with the 454 and save the original 402. It is pretty rare to find a matching number 70SS anymore.

 

[Doc Willis]

Fellas, I sincerely appreciate your advice. Hello again to Steve in Dallas. I've loved every minute of the 16 days and 22 hours that I've owned this car - my ol' lady is beginning to get real jealous.

I spoke yesterday to the other Steve (in South Texas) who owned the car for several years. He said the performance markedly improved when he took the current heads off the 454 and replaced them with the heads from the 396 (presumably demonstrating that the 454 heads are of the "peanut-port" variety.) The original heads are now back on the 454.

Thanks for the input and I'll be working on the 454, saving the 396 for another day.