hink

Back then they were not at the power level that are today

I972Nova

we had a stock 2 bolt main 400 block and put the splayed caps and bored / stroked it out to 434 cubes. Block half filled...

It ran 9.60's in a 3100 pound car for 4 seasons (about 800-900 passes)

All we did was freshen it with new rings and bearings every winter. After we ran it we sold it and the guy is still running it now onto his 3rd season.

This is shifting at 6800 and going through just under 7000.

I would build another one in a heartbeat, but there must be a difference in my drag cars from the roundy rounders.

Tod74

I bet for every 1 block like yours there are a hole bunch more that didn't live .

modracer64

I would be willing to bet the concrete in the block helped it stay together with the splayed caps not to mention your peak rpm of 7000.
I don't know being an ex drag racer myself I would've never believed a dirt track car would be so hard on parts until I heard some of the horror stories and saw some really well built stuff come apart. Part of it might be the fact that in drag racing you tune the car to peak power (shift point and rpm at the end of the track) so the motor rarely sees rpm past the power peak. Circle track cars see rpm past peak power every lap because every track usually has a pretty big swing over the course of a night between high traction and no traction so the car has to be able to pull hard when the traction is there and yet not be prone to blowing the tires off when the traction goes away.
I would say that if I was buiding a motor to put in a drag car i wouldn't be nearly as scared to build it using the block I have unless I was going to be putting a lot of spray to it.

edvancedengines

If It was mine I would use it. Fact is I still buy 400 blocks when I find a good one that is a straight casting. I also buy 400 factory crankshafts if in good shape and are cheap enough. Why? most of my SB customers just will not buy an aftermarket block. WE do a lot of prep on them and have really had good sucess at lower than 700 hp with them. We did have one that at a shade above 800 experienced the main caps moving around. Actually we saw some funny things with oil pressures so tore it down and found the main caps were moving on the block. So now I tell my guys to keep them below 750 hp even with nitrous.

Several of the factory blocks doing 530 to 570 hp in street use in poor boy strokers.

I am not arguing with Carl or disagreeing. He is correct.

Ed

Racefab57

You should have em sonic tested,lots of variations in wall thickness. Find a good one and with 4 bolt mains, maybe a short fill and limit hp and your ok! A friend of mine built a 377 years ago ( drag car) and its still running fine!!! David.

modracer64

Aside from sonic testing is there anyway to tell visually whether a block is a "good" block or not?

Darren

hink

It will let you know when you max out the HP limit!

jmarksdragster

Look for core shift around the machined holes, lifter bores, freeze plugs, etc.

hink

We have not found that not to be very accurate compared to a sonic test.