Lots of questions on rebuilding 400

[Brandon]

Will a 440 piston work in a 400? If so what has to be done?

How much can be taken off the deck safely? .060? The heads?

What do stock 452's flow? after cleaning up the ports?

Now for the big one, What mech cam should i use if i get the comp. ratio up to say 10.5, iron heads ported with Mopar templates, in a E-body drag car? Also what size headers? 1 3/4" or 1 7/8"? I'm hopeing for low 11's I'm I crazy?

This is only going be to used 1 year hopefully, then I'll build a 452 stroker with another shortblock.

I realize I'm asking a lot of questions but I don't know alot about Mopar's yet. Any anwsers or opinions would be great.

Brandon

[polarapete]

A better plan would be build a basically stock 400 motor, put it in the car and sort out the chassis at the track. You can run in the street bracket class, have fun, polish your driving skills and maybe even win a few. All the while you can drive the car to the track and save for the roll-cage that you will find is required when you start running 11's in the quarter.

While you do that you can connect with some local Mopar racers and learn how you can build your stroker 400 shortblock.

[Doug Wilson]

Really outstanding advice from polarapete. This is how we should all do it... but most of us don't take our own good advice!!

[Brandon]

Only problem with that idea is the car is already stripped, fiberglass front end, lexan windows all around, aluminum floor pans, 12point roll cage, etc. You get the idea I bought the car already done minus an engine.

I've already got a car I've been running in street for the last 2 years and it's getting alittle old. So I'm looking to go faster.

I'm looking to find out what kind of comp ratio I can get from of a stock 400 by milling and or by using 440 pistons.

The idea is build this engine this year then another next year and use this one for a spare incase something happens to the new one.

Thanks for the replys though,
Brandon

[451Mopar]

Keith Black has a KB-240 Flat top piston for the 400 block. I think the piston would normally it would sit 0.024" below the deck if my calculations are correct. If you mill the block to get a true Zero deck, and use a steel shim type 0.020" thick gasket you should be able to get 10.0:1 compression with a fairly stock cylinder head of 82-83 cc volume. If you mill the heads for 80 cc the compression goes up to 10.23:1.
77 cc Head volume would give you 10.55:1 compression with the 0.020" head gasket or 10:1 compression with the 0.040" head gasket.

I think an oversized 440 piston for the low compression engine may also work. Silvolite replacement 440 piston #SL-1276 has a Piston compression height of 1.912". The Keith Block #KB-240 pistons Compression height is 1.908".
Another posability is the #SL-1263 440 piston with a Compression height of 1.970" This piston would sit 0.038" above the top of the stock 400 deck. You would have to check how far down the first ring sits on the piston to make sure it is still down in the bore? If it is, you could run a thick felpro gasket and get 11:1 comprssion with an 82cc cylinder head volume, but these 440 pistons would need valve reliefs cut into them. If the valve relieds dished the piston 5cc like the KB piston then the compression drops to 10.5:1 compression for the SL-1263.

Stock 452 Cylinder heads flow about 235 cfm @ 0.500" lift on the intake. This could support 450+ HP. Larger 2.14"/1.81" valves and porting really help flow, but add to the cost. Porting the heads with Larger valves may get the flow up to 260+ cfm @ 0.500". Check the cost of rebuilding the stock heads. Muscle Motors is selling 906 heads with the larger valves, bronze guides, hardened seats, new springs/retainers for $699.

Use the 1-7/8" headers.
The Hughes HEV3945BS solid cam (239/245@0.050", 0.546"/0.560" lift) should work pretty good and make very good mid range torque.
If the chassis is setup with alot of gear and converter you could use the next step up cam, the HEV4550BS (245/250@0.050", 0.560"/0.575" lift.)
You will need the matching valve springs with these cams and you will have to do the cam/engine break-in with only the outer valve springs , then re-install the inner valve springs after the cam break-in.

[Brandon]

Thanks that's just the kind of info I was looking for. I knew someone here would come though.

I remember hearing something about the 440 piston skirt being too long? Is this true? or just BS?

KB doesn't make a forged piston do they? I'm toying with the idea of a small shot of NOS something like 125 shot, would the cast KB's hold up?

See I wasn't lying when I said a lot of questions, lol. I just don't want to build another slow piece of junk, done that with the pontiac I got now.

I'm surprised no wise cracks about building a 400, yet

Brandon

[dynorad]

400's are good engines, especially after you stick a 440 crank in it.

[rumblefish360]

I agree with dynorad. Nothing wrong with them. The could use a 383 fordged crank and a stout cam and etc...
It'll run well. It's bad wrap from the smog error still has it down.
It's a great replacement for an ailing 383. Like "free cubes!"
How can ya go wrong with that?

[dave571]

Lots of numbers have been thrown uo here, but here's some more.

The stock 400 is about 7.5:1 comp. Piston comes within .100 of the deck on the close ones, and up to .125 on others(actual measurements taken from my engine prior to reassembly)

I milled .085 off of my block deck. and used closed chamber 516 heads. Punch up the numbers at www.kb-silvolite.com (using a felpro gskt, which is .039 when compressed,measured not rated) and we get 9.9:1 (zero piston head volume, there are no valve reliefs)

Piston/ head clearance is .054(mopar engine book does not recommend less than .060, but we have questioned that on other discussion boards) and with a .490"/272 duration cam, there is still better than .100" valve to piston clearance.

400's do have a bad rap, as not having much torque. I find that mine has way more torque than I thought it would. I am very pleased with the performance that it has given to my 5000 pound van. And alot of ricers and mustangs are less than pleased.

I've heard of using the 440 piston, and then you have to mill the top down so you can get the compression you want. Apparently, it is a common thing to do.