Experiences buying 400 blocks for high performance builds?

[adam83]

About to start my engine build, and Im trying to find a good 400 block to start with. From what I've been reading, only about 1 in 4 blocks is good for a high performance build (600-900hp). I wish I had a sonic tester to make things easier in finding a good block, but I dont. I've found multiple blocks for $50, some are complete engines that supposedly were running when pulled but who knows. Even if they were runners that doesnt automatically make them good candidates. I can measure bore size and see how far they've been bored, or if they've even been bored, but that still wont tell me the cylinder wall thickness, which can vary a lot. I'll call my local shop tomorrow and see how much sonic testing costs. At $50 bucks, I could probably get my money back if I dont use the block, unless its cracked. What has been ya'lls experience with used blocks? any tips you can give me on bad signs to look for?

 

[RustyRatRod]

I have a friend who races. When he finds a 400 he gets it. Period. End of discussion. Over and out. Roger wilco. IMO, most any of them will go to the 600 HP range. Get in the racers forum and ask around. womanator would be a good one to talk to.

 

[rsd859]

Would you have to stroke it to get to the 600 horse range? I would be happy to get 400 horses out of mine.

 

[RustyRatRod]

If 400 HP will make you happy, Keith Black makes some nice pistons that'll get compression up in the 400 and fill that bill easily, or you could use a 440 crank and build a 451. It's basically a 440 in a 400 package, but the rod to stroke ratio is better. Some people swear by that stuff, but I don't think it's a huge deal. Either way, the 451 is a nice package and can easily see 600 HP with the right heads.

 

[Garys1969RR]

I have bought 3-complete 400 engines. The first one from Ne, for $300, and used it to build my 451 which is running great! It was stock bore size, and cleaned up fine. The next one I paid $225 for, found locally. Bought that one for a spare, and because it had a Holley Street dominator intake on it, and elec ign dist. The last one was $175, came with an extra set of 516 heads, and a Holley 650 dbl pumper! The carb alone was worth that! So now I have 2 spare motors. One has a steel crankshaft. I like to buy the motor complete, and assembled, as its usually in better condition. The best (and hardest to find) block is the one with the casting number 3614230. These were built in 1972 and have the strongest main journal webs. The 3698630 blocks are next best, and were built in 1973. Those are what I have. The last ones were4006530. 76-78.

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Look on the 440 source website, and they explain on there what to look for.

 

[RustyRatRod]

Thanks Gary. I couldn't remember which was which. The early block like you said have the thicker main webbing but the later ones have thicker cylinder walls. I didn't want to say because I couldn't remember and I wouldda got it backwards.

 

[Cranky]

Just had one sonic tested and it was 80 bucks....and if you're looking for 900 hp, I'd recommend you look at an aftermarket block.

 

[moparmarks]

The best blocks are the 230 blocks cast up to 10/17/71. Super thick webs. The strongest factory wedge block made. The 230 blocks cast after 10/17/71 are not the same as the early ones.
440Source has some good block info.

 

[rsd859]

So by just simply swapping cranks and new KB pistons I would see a substantial ammount of horses? I better start saving my scheckels. Nothing wrong with my motor now, doesnt even smoke and runs like a champ. But when its time to refresh I want to do it right.

 

[Garys1969RR]

So by just simply swapping cranks and new KB pistons I would see a substantial ammount of horses? I better start saving my scheckels. Nothing wrong with my motor now, doesnt even smoke and runs like a champ. But when its time to refresh I want to do it right.

That will help you get a reliable base for a high horse power engine. On my 451, (400 block, 440 crankshaft) I used Ross 14 cc dome pistons, 509 cam, and 906 heads with mild porting. That got me into the 13s at the mile high track called Bandimere. I just installed 915 fully ported heads and headers on the same motor. Now that thing is a feal screamer! Fries the tires in 2nd gear, and runs awesome! Hope to get into the 12s this season. Alot harder to do at 5000 feet than at sea level. A good flowing cyl head is key to making high horse power. And I like alot of compression. But that also means high octane fuel is required. Plan on spending 4 to 5 thousand dollars to get a good motor. And read up on how to build a high perf big block. Good luck.

 

[RustyRatRod]

Gary you got me curious now. What's your car weigh?

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So by just simply swapping cranks and new KB pistons I would see a substantial ammount of horses? I better start saving my scheckels. Nothing wrong with my motor now, doesnt even smoke and runs like a champ. But when its time to refresh I want to do it right.

Purdy much. You'd be goin from a 3.375" stroke to a 3.750" stroke. When you increase the stroke, you increase the amount of leverage the engine has. It's much the same as using a longer wrench on a nut or bolt. ........and as Gary mentioned, there are other piston manufacturers. Keep that in mind if you planon really beatin on it racing or want to run nitrous. A forged piston would probably be a better choice there.

 

[Garys1969RR]

Hey Rusty, fully equipped 69 RR, title says 3600 lbs. Prob closer to 3800 with driver and fuel.

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Just looked at the title and registration, they both say CWT 25. That means curb weight 2500 lbs, but I dont think thats right. Those cars were closer to 3500, correct?

 

[RustyRatRod]

Yeah, somebody got that wrong. I have a 63 Dart 2 door and it's probably heavier than 2500 pounds......but not by much. I think 3600-3800 is close. That's impressive ET and speed at your altitude, Gary. Nuthin to be shamed about at all. Let us know how the new heads do.

 

[rsd859]

12's in the 1/4? Thats really good for as much as the older cars weigh. Thanks for all of the info even tho this isnt my thread! I may be running on the strip this summer on test and tune nights just to see where Im at and I will be posting times when this happens.

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Rusty, here is another question for ya, Can I take my stock cast intake and have the plenum notched out like the eddy performer rpm?

 

[Garys1969RR]

Sounds good, 859. My thinking on high output big blocks is alot of compression, and alot of airflow. With a reliable bottom end of course. I know IQ 52 gets alot of power with C/R as low as 9.5 to 1. But he has cyl head airflow down to a science. I haven't got there yet. All the big blocks I've built needed at least 12 to 1 C/R. And 13 to 1 works even better. May be due to the thin air up here in Colorado, although I Q 52 in Idaho is around the same elevation. Is that a early 70s charger you have?

 

[moparmarks]

So by just simply swapping cranks and new KB pistons I would see a substantial ammount of horses? I better start saving my scheckels. Nothing wrong with my motor now, doesnt even smoke and runs like a champ. But when its time to refresh I want to do it right.

Abit of machine work is involved. 440's crank 2.750 journals have to be cut down to the 400's 2.625 size. 400 block need alittle clearance work done too. Right??????

 

[RustyRatRod]

No, no block work is necessary, but the counterweights on the 440 crank have to be turned down 1/4" to fit the 400 block.

 

[rsd859]

I have a 73 RR Gary.

 

[Garys1969RR]

400 block

No, no block work is necessary, but the counterweights on the 440 crank have to be turned down 1/4" to fit the 400 block.

Thats right, Rusty. And that also makes the crankshaft counter weights close to proper balance weight with 550 gram pistons. My crank grinder took mine an extra 1/4 inch too far. To 7 " radius rather than 7 1/4 ". So the balancer had to add mallory metal to the counter weights to make it balance. But it sure revs quick with that relatively light reciprocating weight!