High compression in a 400 BB on a budget?
#1304827
09/16/12 04:01 PM
09/16/12 04:01 PM
|
Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
HotRodDave
OP
I Live Here
|
OP
I Live Here
Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
|
I know the 400 has a bigger bore but if my calculations are correct I can use a low compression 440 piston in a .060 over size in a 400 with a smaller oversize and with the added compression height I could really bump the compression on an budget 400. Am I missing something?
I was also trying to come up with a way to use a LY rod in a 400 to get the compression up but I keep comeing up with the piston too far out the deck, is there an off the shelf piston for this scenario?
I already have 516 heads with big ex valves and some minor bowl work and milled .010 but compression ratio is still pretty low.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
|
|
|
Re: High compression in a 400 BB on a budget?
[Re: HotRodDave]
#1304829
09/16/12 04:13 PM
09/16/12 04:13 PM
|
Joined: Oct 2005
Posts: 164
Savannah, GA
mopar400
member
|
member
Joined: Oct 2005
Posts: 164
Savannah, GA
|
KB has a set of pistons. What comp are you shooting for? Low comp 440 pistons would prob smack the valves in a 400
Last edited by mopar400; 09/16/12 04:15 PM.
1965 Fury II
1970 Challenger 440, 509 cam, 11:1 w/ 452 iron heads, 6.99 1/8, 11.29@ 120mph 1/4
(1999 Magnolia Drag strip track champion)
1992 Jeep XJ Crawler
|
|
|
Re: High compression in a 400 BB on a budget?
[Re: HotRodDave]
#1304830
09/16/12 04:27 PM
09/16/12 04:27 PM
|
Joined: Oct 2005
Posts: 164
Savannah, GA
mopar400
member
|
member
Joined: Oct 2005
Posts: 164
Savannah, GA
|
These are the KB's Amazon Summit
1965 Fury II
1970 Challenger 440, 509 cam, 11:1 w/ 452 iron heads, 6.99 1/8, 11.29@ 120mph 1/4
(1999 Magnolia Drag strip track champion)
1992 Jeep XJ Crawler
|
|
|
Re: High compression in a 400 BB on a budget?
[Re: mopar400]
#1304831
09/16/12 04:32 PM
09/16/12 04:32 PM
|
Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
HotRodDave
OP
I Live Here
|
OP
I Live Here
Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
|
I am hopeing for around 10 to 10.5 to 1
The 440 pistons are so thick it would not hurt to cut a couple valve notches in them. They would still be around .020 below deck. I could easily do valve notches here at the shop.
I already have a nice used set of the 440 .060 over pistons. I do not want to buy pistons unless I could get them real cheap and be able to use the long rods since long rods help a restricted head turn a little more RPM.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
|
|
|
Re: High compression in a 400 BB on a budget?
[Re: Brian Hafliger]
#1304839
09/17/12 03:28 AM
09/17/12 03:28 AM
|
Joined: Jan 2003
Posts: 2,933
Finalnd, Perkele
jyrki
master
|
master
Joined: Jan 2003
Posts: 2,933
Finalnd, Perkele
|
I have done that. Using the low CR piston you end up with a piston about .020" below the deck at TDC. With a 80cc head nad a .040" head gasket you'll have around 9.8:1 The 66-71 piston will give you about .040" positive deck, that's what we used (TRW L2266 F) With open chamber heads close to 90cc and huge valve pockets we had a little over 10:1, had to form the piston tops slightly to fit the chambers. It worked actually pretty well, but nowadays that there are lighter HC pistons readily available, I doubpt that it is very cost effective.
Plynouth VIP '67 TT IC EFI
|
|
|
Re: High compression in a 400 BB on a budget?
[Re: jyrki]
#1304840
09/17/12 10:11 AM
09/17/12 10:11 AM
|
Joined: Jan 2003
Posts: 9,876
Weddington, N.C.
Streetwize
master
|
master
Joined: Jan 2003
Posts: 9,876
Weddington, N.C.
|
Yeah IIRC the 2266 (TRW 70-72 piston) should be close (6.36" 383/400 rod) but you better check your skirt to CW clearance (it's been over 20 yrs since I done one like that). Whack about 1/2-5/8" off the length of the pressed 1.09" pins and you'll save ~45 grams on each slug and still have plenty to do the job, that's an old Dick Landy BB trick. There's no way (I am aware of) to use a 6.76" rod with a factory 400 or 440 size mopar slug for this scenario. And I've built most of the Frankenstein variations over the yrs. A bit of 'inverse' trivia....Mopar settled for the 4.15" RB Stroker crank length because it allowed for the use of a standard 4.342" 400 piston compression height. After all the math was cyphered and done...just building a decked 383 using the taller 68-69 HP pistons with 67 Magnum closed chamber heads were a lot cheaper (and quicker) than the 400's. That was way before the reasonably priced KB's which is definately the way I'd go these days  Brian's magazine combo is excellent, I'd just use the '67 heads and I think the Crower 32242 is the perfect 383/400 cam.
Last edited by Streetwize; 09/17/12 10:47 AM.
|
|
|
Re: High compression in a 400 BB on a budget?
[Re: mopar400]
#1304843
09/17/12 11:57 AM
09/17/12 11:57 AM
|
Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
HotRodDave
OP
I Live Here
|
OP
I Live Here
Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
|
Are you kidding about the stroker kits? I don't see any stroker kits under $2000  Stroker VS what I have both need a bore job and gaskets so all that is a wash. Useing what I got only costs me a balance job and the $2K kits need that checked anyhow. I have some 383s sitting here but no good high compression pistons. Plus I figure the extra cubes and less shrouded valves has got to help the 400 run a little stronger.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
|
|
|
Re: High compression in a 400 BB on a budget?
[Re: HotRodDave]
#1304844
09/17/12 01:52 PM
09/17/12 01:52 PM
|
Joined: Oct 2005
Posts: 164
Savannah, GA
mopar400
member
|
member
Joined: Oct 2005
Posts: 164
Savannah, GA
|
Quote:
Are you kidding about the stroker kits? I don't see any stroker kits under $2000
Stroker VS what I have both need a bore job and gaskets so all that is a wash.
Useing what I got only costs me a balance job and the $2K kits need that checked anyhow.
I have some 383s sitting here but no good high compression pistons. Plus I figure the extra cubes and less shrouded valves has got to help the 400 run a little stronger.
I didn't have enough good used parts laying around to use without work. I prefered to spend the $2000 for the kit. By the time I had a crank machined, balanced, bought new KB pistons, bearings, rings for the 400 it was a good bit of money. So far everything has checked out good on the stroker parts, I pick up an extra 50 cubes and I have no extra machining to make it work. Just a bore and hone. Some day I would still like to do a 400 cube motor with higher compression but it just wasn't a good move for me this time. I also have a very light rotating assly. with the stoker compared to the factory stuff.
1965 Fury II
1970 Challenger 440, 509 cam, 11:1 w/ 452 iron heads, 6.99 1/8, 11.29@ 120mph 1/4
(1999 Magnolia Drag strip track champion)
1992 Jeep XJ Crawler
|
|
|
Re: High compression in a 400 BB on a budget?
[Re: AndyF]
#1304845
09/17/12 03:22 PM
09/17/12 03:22 PM
|
Joined: Jan 2003
Posts: 75,042
U.S.S.A.
JohnRR
I Win
|
I Win
Joined: Jan 2003
Posts: 75,042
U.S.S.A.
|
Quote:
I did a low cost high compression 400 engine years ago for one of the magazines. The trick was to use Hemi rods and a shelf stroker piston. Worked great.
That is a great way to do it but the problem now is that hemi rod , I'm going to ASSuME 6.965 , is no longer available. 6.860 is the longest hemi spec rod available now .
|
|
|
|
|
ill be watching this 1 
I ended up buying the stroker kit. I was really wanting to build a 400 with higher compression and almost purchased the KB pistons. I ended up needing a crank and some other parts and couldn't justify the cost. If I had a machine shop I would definetly build something like original poster is talking.