400 engine Help Needed

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733404spdCuda

733404spdCuda

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Need Advice.

I have a very low mileage 400 with 8.5 compression that makes very little power.

I don’t want to spend a bunch of money building the motor or stroking it since it in a nice street car. Ideally if I can find 400hp I would be happy.

I’m looking for ideas to bump up the compression and make more power. (Deck the heads? Buy after market heads? What do you recommend?)

I’m also looking for advice on a cam and intake for this combination.

It also in a heavy b-body
 
wen you say you dont what to spend much $$$$$ how much do you what to spend.and how far do you want to go with it.....Artie
 
At 8.5 compression, you'll either need to Swap in some different pistons for higher compression or add either a Super charger or a Turbo charger (twin would be better) but with the stock bottom end, you'll have to limit that amount of boost.
 
The truth is, the 8.5 to 1 is the factory rating. If checked, you are really probably in the 7's. Not busting on you, just letting you know I haven't ever seen a non blueprinted engine of any brand make it's advertised compression.
You can only do so much with the existing pistons. If you are willing to pull the engine, an aggressive block deck, and some milled closed chamber heads would be your best bet, along with the .020" shim head gaskets.

For the cam, I'd keep duration on the short side, in the 220ish range at .050", given it is in a heavy car. I really like the Performer RPM for an intake. Good luck.
 
I think with a small cam and a regular performer 383 intake with a small four barrel you will make it much faster. Only so much you can do with low compression. The rpm intake is a nice peice but unless you are going to put pistons in it the smaller ports of the performer will give you better bottom end. I have a low compression '83 318 with that set up and it bumped up the power nicely.
 
Check out 440 source.com for some cheap heads that will perform well for a street car.
You can raise your compression in a number of ways, one by simply installing a thinner head gasket. Or machine the deck. If you only want 400hp, that's pretty easy to reach with a 400 engine.

Check out Amazon.com for 'Big Block Mopar Engines'. There are a couple books that are very good and contain much of the information you're looking for.

I would suggest reading (or online search) the last 12 months worth of Mopar Muscle or Mopar Action magazine for the intake information. One of those had an article that tested different intake manifolds and which one performed the best. Can't remember specifically where I read that article.
 
733404spdCuda said:
Need Advice.

I have a very low mileage 400 with 8.5 compression that makes very little power.

I don’t want to spend a bunch of money building the motor or stroking it since it in a nice street car. Ideally if I can find 400hp I would be happy.

I’m looking for ideas to bump up the compression and make more power. (Deck the heads? Buy after market heads? What do you recommend?)

I’m also looking for advice on a cam and intake for this combination.

It also in a heavy b-body
Click to expand...

We just built a nice 400 using KB pistons, mildly ported oem 906 heads that will be in Car Craft this month. It made 427HP with stock rockers. 1.6 rockers would have added around 15Hp.
Here's the low down...http://www.forabodiesonly.com/mopar/showthread.php?t=179546
 
I read the car craft article and it is almost Identical to a build we did at SharaDon Performance. The only real difference was we used 440 source heads with a 484 284 mopar performance cam and we hade the same 427 hp with 9.5 to 1 compression. These motors can be built on the inexpensive side of things and make good power for a cruiser! Good luck with your build and keep us updated on your build!
 
CarCraft mag ran a good article on a 400 build in the latest edition. Used pretty much all factory type parts. But still not cheap. Made 426 HP. May give you some ideas though.

Pat
 
You might consider using the new 75cc Edelbrock E-Street cylinder head. It is supposed to be out in about 6 weeks. Summit Racing is selling them for $979.95/pair. Order them now and get them at that price. Edelbrock's part number is 5090. Jeg's had them also the last time I looked.
 
IQ52 said:
You might consider using the new 75cc Edelbrock E-Street cylinder head. It is supposed to be out in about 6 weeks. Summit Racing is selling them for $979.95/pair. Order them now and get them at that price. Edelbrock's part number is 5090. Jeg's had them also the last time I looked.
Click to expand...


I agree. I think the key is compression and closed chamber heads are the simplest way to that, plus a better port, lighter, and very close to within the budget when you combine them with a cam, intake, and gaskets.
 
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