Is this any different than dropping in a 350? Anything I should be concerned about? Would Fast-Burn heads bolt on to it? I might be getting the opportunity to get one at a fairly good price. Thanks!

 

The 400 needs it's own harmonic balancer and flex plate/flywheel since it's externally balanced. It's also a 2 piece rear main seal and may not work with whatever transmission you're using due to bolt pattern of the torque converter/clutch.

The heads will work once the steam holes have been drilled into them.

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Stephen's racing page

87 IROC-Z Pro ET Bracket Race Car and knocking on the SuperPro ET class
383 stroker (carbed) with double hump cast iron heads and pump gas
LS6 Big Block buildup now in progress

Best results before the engine blew up
Best ET on a time slip: 11.857
Best corrected ET: 11.163
Best MPH on a time slip: 117.87
Best corrected MPH: 126.10
Best 60 foot: 1.662

Racing at 3500 feet elevation but most race days it's over 5000 feet density altitude!

Member of the Calgary Drag Racing Association

 

*edit* Above post got to the answer first

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ASE Mechanic/Machinist/Smog Tech

1999 NBM Trans Am
1986 Chevy 3/4 ton pick up
1981 corvette
1995 Kawi ZX6R

GO #3

[This message has been edited by Engineboy (edited October 08, 2000).]

 

Scott,

Out-of-the-box Fast-burn heads may not be the best selection for a 4-1/8" bore unless you have installed the larger valves. The heads can be machined for 2.02/1.60 valves without cutting through the hardened seat areas. The port volumes are already substantially larger than the heads that likely came with the 400, so feeding the beast should not be a real problem once tha valves are adequate. In addition, the small chambers of the fast-burns will make for a pretty significant static compression ratio on the larger bore. Just tbe careful you don't go too high with compression.

Properly prepared Fast-burns on a 400 could produce over 500 HP at the crank with a decent camshaft, over .525" lifts. (Of course I'd recommend a roller.) That should move a Thirdgen rather nicely.

As far as the crankshaft seal, this can get a little tricky, but since you'll have to use the unbalanced 400 flexplate, you may not have an issue.

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Later,
Vader
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"Make Me Bad"
Adobe Acrobat Reader 4.0

 

I am a little confused? I am running a 700R-4 Tranny. I really want to keep it cause of the overdrive (need SOMETHING that is going to save a little on gas, as I plan on running 3.73's also). There has got to be someone who has done this with a 700R4. Anyone......? Thanks for your help, guys.

 

My car had a 383 and used to have a 700R4. The 383 is externally balanced the same as a 400. You just need to make sure the 700R4's torque converter will bolt up to the flex plate. If the flex plate has dual bolt pattern then it should bolt up with no problems.

Problems with 2 piece rear main seal blocks start when you have newer manual transmissions because of how the flywheel is designed and the use of a pilot bearing.

 

If the flex plate doesnt have a dual-bolt pattern, can it be modified or is there a converion flex plate available?

 

Hey Scott...I did this a few years ago with my 91 RS. You shouldnt have any problems bolting it in. I used a stock 400 flex plate with the 700r-4 tranny with no problems. If you have any questions you can email me and i will try to answer them.

Mike

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Black 90 IROC, L98, A4, 323 gear. SuperRamed 406 in the works!

 

Thats exactly what I want to hear. What kind of power are you making? What fuel system are you using? Carb, TBI, TPI? Heads, cam? I was planning on making 400 hp with a 350, and now 400 would just not be enough for this engine, what kind of power do you make?

 

i would add that you should have the block drilled for the inline bolt pattern starter as opposed to the diagonal bolt pattern that at least mine came with.the full size starter wouldn't fit and i didn't want to drill it from under the car. or you can buy the 502 mini starter from GM. maybe that will save you from some of my heartaches.

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86 camaro 405 sm. blk. th 350 tranny 3.42 gears