Just got a 72 impala conv starting talikng the engine apart for a performance rebuild then out of curiosty i took down the casting number to find out what im working to find out that its a 4 bolt main should i scrao it or should i try to find something thatll work with it
03-14-2006 02:11 PM
how much power are you looking to build
400 have some problems
and are you driving it on the street
03-14-2006 02:13 PM
yes but looking to gain about 420 horse power
03-14-2006 02:13 PM
By your post and it being a 400, I say you got a "511" block. There is nothing wrong with a "511" block being used for performance. That is what I have in mine and if you want to get rid of it, I will gladly take it off your hands if you want to scrap it.
03-14-2006 02:18 PM
i hear you but i called up gm performance and they told me i was better off scraping it and going with a 350 my casting number is 3951511
03-14-2006 02:24 PM
I don't know who you talked to, but he's correct and you should definitely scrap that block. I don't know where "mtl" is, but I'll be there in the morning to take the 400 block off your hands. LOL
03-14-2006 02:30 PM
Good one i think i just stick with my 400 i begining to think it was good then and its still good now . what can i do to reach the maxium performance of that motor
03-14-2006 04:19 PM
420hp is pretty easy in a 400. 400's love air and 200cc heads are perfect for street 400's. Give it around a 280 duration cam, good hi-rise dual plane intake, 750 carb and 1 5/8" headers and you are there. Keep compression to about 9.5:1 to run unleaded fuel. To get more hp, the 5.565" connecting rods become the weak point as the main cap area is the weakest part of the 400 but going to 350 5.7" rod gains strength but also gets the connecting rod dangerously close to the camshaft.
03-14-2006 04:59 PM
Scat or Eagle rods with capscrews instead of nuts and bolts are cheap insurance if you make more than 425-450hp. Less than that and I would just get some ARP bolts for the stock 400 rods.
03-14-2006 07:10 PM
i hear what you all are saying but i want to keep it stock with some upgrades to gain around 400+ hp looking for the proper configuration can anyone help
03-14-2006 07:19 PM
Nitrous. Get some good pistons and put a 150 shot on the motor.
03-14-2006 07:31 PM
What are you wanting to keep stock? The stock crank should be able to handle the power you're looking for. You might need to have the engine bored so you'd need new pistons. You're going to have to put a decent sized cam in it and it'd really help with a set of good aftermarket heads as Tornado Tech mentioned. If cost is a main issue for wanting to keep stock parts then you should sit down and figure what it is going to cost to recondition the rods and the cylinder heads to be suitable for a 400+hp application then compare that to what it would cost to buy a set good set of aftermarket heads and rods. I'd bet you'll be surprised.
03-14-2006 07:52 PM
thanks guys for all the input now i can start calculating all of the parts and componets ill need to get it just right thanks again