Thread: 402 internals

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My question is, how strong are the internals of a 1972 big block 402? im kind of hoping i can reuse the cast iron crank and connecting rods. I have heard the connecting rods are pretty good from a 72 402 truck. I want about 500 hp b/c its gonna be a street/ import killer. ill probally be looking at the rpm package through edelbrock. 454 oval heads, and all the good stuff to make that set up work. Money dont grow on trees so thats why im interested on reusing as many parts as i can without worrying about giant holes in my block from throwing a rod or something.

"DON'T bother arguin' with TROLLS & IDIOTS "
-Okay I won't.

Dowierj, Im sorry,You ask a reasonable question. You deserve a reason able answer. I dont know if you can build 500 horsepower out of your 402 but you can build quite a nice motor on a budget, I have some good articles on this. I would be glad to forward them to You. If I were You I would go to Your local speed shop or book store a buy a book on rebuilding big blocks. It should have a section on 396--402. If you look through old Hot Rod and Super Chevy magazines you should find some good articles. I guess I was lucky when I first came on line.I was treated a little better. Senior Members,This is what I see happening here. A new member comes on ,(this one 7 post) is made to feel like crap and they never come come back. Is this what You want??????
I know You are not that kind of person.

I used that same motor and made the convert to a 454, while doing a rebuild its not that much more money to get the cubes. Heads may be the "unshrouded open chambered" that could put your existing compression at about 8.5 to1. I had the block sonicly meassured and the machine shop made small adjustments to the bore to keep even wall thickness, again not alot more money than a standard rebuild, but with whats left I think I can "a-bore no more".With good bolt ons and in good tune im guessing 400-425 streetable HP. No blower or nos and I keep under 6000 rpm
paul

Thanks to You, Tech. You show good judgement and guidance to all of us. For that we are grateful.

Thanks to those who acually replied to me. Its kinda frustrating when a person wants to ask questions and all the "know it all" ppl just shut you down or look at you like they were born with the knowledge. Doing some listening and research I think im gonna replace the pistons, buy a nice steel crank and as long as the connecting rods are good reuse them. Ive heard lots of ppl reuse them b/c there build tough. not as tough as racing rods, but im not gonna be at more than 450 hp so they should stand up. My new question is regarding heads, the heads right now are cast iron, the heads i want are 454 aluminum ones. Would i be better of buying those, or saving my money and rebuilding the iron heads with roller rockers. How much hp would i lose going that route and saving like 1000 bucks.

If you plan on the 500 horse, you better go to the aluminum. Thats not saying you can't make that kind of hp with iron. You will spend most of your budget repairing the iron heads. That same money will buy you new parts and heads that flow very well out of the box.

As for boring the motor to 4 1/4" and making a 427-454 out of it. I don't recommend it. As the post said. THIN walls. The old Super Stock class racers used to say that a 402 block bored .060 was not as good as a .030 one. Too much wall flex in most blocks. These guys were looking for every horse they could, while running stock carb and heads.

Tho the 402 is kind of an orphan, there are plenty of goodies for it. Keith Black/Silvolite lists good pistons for the motor and even a set for a 454 crank in that block. Stock rods will do the trick. Have them magged and replace the bolts and re-sized. They will last as long as you don't like to hit the rev limiter at 7600 or so. The cast crank will also do. Have it checked. Ground and polished. Tell the machinist that you want it right in the middle of specs on the rods. Mains can be a bit loose.

A good cam(Big blocks like lots of lift),Pistons, Appropriate carb and intake and a good set of 2" headers and you will be in the ballpark.