Visit The Dirt Forum for More Information

Author Topic:   400 Blocks??
dirtracer14
Dirt Freak

Total posts: 499
posted January 19, 2003 06:15 PM UIN: 23443678
Has anyone had good luck with the 4 bolt 400 blocks? What combo were you using with sucess and what kinda comp. Thanks

dirtracer14
Dirt Freak

Total posts: 499
posted January 21, 2003 11:58 PM UIN: 23443678
Come on..........

ZIGGY
Dirt Roller

Total posts: 25
posted January 22, 2003 12:50 PM
The 400 4-bolt are even weaker in the webs than the 2 bolts. Like Hendrens and the other pro's say, if you're going to run a stock block 400, stay under 500hp and even then they get tired. My personal experience says they're right.

DMS CEO
Dirt Freak

Total posts: 212
posted January 22, 2003 01:07 PM
The key to the life of those is not hanging alot of gear on them. They make torque not big end hp. Keep them under 7000 and they will live.

dirtracer14
Dirt Freak

Total posts: 499
posted January 22, 2003 07:59 PM UIN: 23443678
We started this with 13.5 to 1 with zero deck...didnt last so we just squared the block and dropped it to around 12to1 for some added help im going to add about 4" of block sealer to the bottom to help keep flex down and tapping intake for extra water....i just was wondering if anyone had any other secrets besides crossed fingers???

ZIGGY
Dirt Roller

Total posts: 25
posted January 23, 2003 10:20 AM
My further two cents: I've run the **** things about every way you can think of including billet caps, rock-bloc, you name it. I've also geared 'em high and I've geared 'em low. I built a Vortec-headed baby that had torque numbers like a big block. Ran as high as a 4.71 on a short half mile track (try slowing the car down with that). Conclusion: A stock block is not something you want to use for a serious motor. If you've got good parts (not some Chinese stuff) in your engine now, I'd move them to an aftermarket block. If it's claimer or Eagle or whatever, let it rip - because it likely will. I'm not trying to be a smartass know-it-all, but I've been there with these things. Best of luck to you.
P.S. - I've heard somebody's making a girdle for 400's. I don't think it would work but that's one thing I haven't tried. You might go looking for one but the question is, why not put the money towards a good aftermarket block.

dirtracer14
Dirt Freak

Total posts: 499
posted January 23, 2003 02:59 PM UIN: 23443678
The motor is pretty close to what whould be a claimer....i dont put alot of $$ in motors but i have all the parts already including machined block....but got scared of it so pulled it out after 10 laps....the crank was a new scat, srp pistons, and eagle rods so i have a little $$ in the rotating i just dont feel its enough to spend $2500 on a block by the time its ready to go. I am just tring to get what i can out of what i have, i am not putting the scat back in i went with a steel gm crank instead. I have heard tons of stories about how bad the 400 blocks are and was looking at anything i could do to help get atleast 1 year out of the motor. The other reason i didnt go with aftermarket block was the pistons are .40 over...didnt make sence to get a new block at .40 allready or spend another $700 on pistons and rings.

66jj
Dirt Freak

Total posts: 352
posted January 23, 2003 04:54 PM
Are you talking about a 377??

i know plenty of guys rinning 2 bolt 400s all day long at 6800 or so, with average parts..

only thing they ever say is head studs are a must to prevent gaskets from burning thru.

ive never heard anything good whatsoever about hard block in a circle track motor.

ZIGGY
Dirt Roller

Total posts: 25
posted January 23, 2003 06:24 PM
dirtracer14: Based on what you've said, I'd run it as is and say a prayer. Better have a wet mag handy for regular use. I've run all stock bottom 377's, twisting them to 7300 or more and had them live for 30 nights but not with serious compression and/or really hooked up a lot. The vortec engine I mentioned was all done at 6200 and geared accordingly. But it was a TRUE 14:1plus and the main caps walked all over the place. Cure that and the webs will give up.

Head gaskets s/b no problem on any properly machined & assembled 400 unless you're using some third world gasket. And hard block down below the core plugs doesn't hurt anything but your weight. Guess I'm up to three cents worth now.

hamer36
Dirt Full Roller

Total posts: 61
posted January 23, 2003 09:39 PM
Use a good 4340 crank, balanced, and a good distributor and it'll last. Preignition will break the web on any block using any cap.Even with alky I never go over 36* timing and on a dry slick I'll pull it back to 28*...hows that for traction control?

dirtracer14
Dirt Freak

Total posts: 499
posted January 23, 2003 10:42 PM UIN: 23443678
I have run the most nights on a motor with hard block in it....the mains are only 20 to 25 laps with a few 40 lappers Of wich that motor had over 30 races befor freshin. Plus running allky the motor tends to not get as hot as gas.....i have heard a guy try it on pavement(yakima) and smoked the bottom end.The last motor we did it to was all the way up to allmost the top of the block...to seal cracks from freezing... This is a 377 motor and i am gearing and caming it to keep it under 7000 and keeping the comp down as well.....and i have been saying prayers for years

Oh and if i remember right the weight of the sealer is about the same as water

ZIGGY
Dirt Roller

Total posts: 25
posted January 24, 2003 07:18 AM
hamer36: My vortec 400 was tuned on a dyno which had detonation sensors. Timing (using accurately established TDC marks and a quality light) was 30 degrees - typical of flattop vortecs. There's a lot I don't know and I always want to learn more 'cause ignorance is expensive. But I don't think detonation is the reason 400 blocks so often fail. Ask the pro's.

hamer36
Dirt Full Roller

Total posts: 61
posted January 24, 2003 08:48 PM
Ziggy
I didn't say preignition was THE reason they fail. A friend had a splayed nodular capped block with a 4340 eagle crank and broke 2 caps. He had a home made HEI and had put the weights in the distributor upside down so that it just continued to advance as rpm went up. Give me a 400 4bolt and a good USA 4340 and I'll run it until the pistons give out...been there

rico 08
Dirt Freak

Total posts: 372
posted January 25, 2003 12:52 PM
400's are all smog motors(1970 on) and they almost all have core shift. 350's are cast a lot better it seems,this is why blocks fail they we're never up to par to begin with.

Back to the Archives