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sam thorburn
Tribal Scout

United Kingdom
3 Posts

Posted - 29 Sep 2016 :  10:00:14 AM  Show Profile  Reply with Quote
Hey all. I'm planning a rebuild on my 77 W72 (y6) 400.I've got a bit of a dream sheet together and was wondering if some experienced eyes could have a look over it to see if I've made any rookie mistakes.

Scat 488 stroker kit. 4340 forged crank and pistons.

KRE ally D-port heads. 310cfm machined.

Lunati voodoo hyd flat tappet cam.
268/276 duration (227/233@.050
110 lsa/106 icl

KRE north wind intake. 310cfm matched.

Comp cams stamped roller rockers. (Undecided on ratio but probably 1.5)

I've got a stock th350, 3.23 8.5" 10 bolt rear end and 28" tyres. The thing I'm getting stuck on is torque convertor selection. I want good street manners and avoid slip as much as possible. Without a dyno figure for the motor it's tricky as i don't know where peak power/torque will be.

Thanks in advance

Sam

Blued and Painted
Chief PONTIAC

USA
3405 Posts

Posted - 29 Sep 2016 :  12:50:41 PM  Show Profile  Reply with Quote
Its not recommended to stroke up a 557 400 block because of thin main journal bulkheads.
There are many posts where the stamped roller tip rockers over heat and fail at the pivot ball socket. For a couple more bucks get a full roller rocker arm from comp, crower, or harland sharp.
Th350 is a tuff transmission and should do fine.
3.23 is a good street gear.. Upgrade if it brakes.
A general rule of thumb on torque converters is to stall 500rpm's Over the low number of the camshaft power band.
Cam looks a bit small for a 488.

There.. did i blow everything up?


Bull Nose Formula/ 461/ Q-Jet/
TH400/ 3.08 8.5 / R44TS.

Edited by - Blued and Painted on 29 Sep 2016 12:52:29 PM
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tjs44
Cochise

USA
412 Posts

Posted - 29 Sep 2016 :  1:15:10 PM  Show Profile  Reply with Quote
cam is very small for that size engine!Ditto on the rockers.The block should be OK for street driving but is a grenade waiting if racing or hard beating.Tom
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sam thorburn
Tribal Scout

United Kingdom
3 Posts

Posted - 29 Sep 2016 :  3:04:29 PM  Show Profile  Reply with Quote
Guys, thanks for the info. I'm kinda leaving towards keeping it a 400 now. I save 2k that way!
So general consensus: the aforementioned setup, minus the stroker kit, but switch the stamped rockers for full rollers? Keep it 1.5?
The advertised cam is from 1700, would a 2400 b&m tork master be ok?
Forgive my ignorance, I'm English ;)
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