strokedls1

iTrader: (1)

Looking into changing my heads and was curious if a ls7 will work on a 4.060 bore. Is it possible to go a size smaller on the intake valve?

x phantom x

iTrader: (14)

If I remember correctly, 4.060 is the smallest bore the LS7 heads will work on.

JZ'sTA

iTrader: (23)

Man you normally know these answers.
From what I have "read" 4.060 is the smallest.
However I have seen a few 346 cubic inch 3.898 bore LS1's with the 4.125 bore AFR 225 heads on top.

There are very few combo's I can even picture that would make puting the LS7 heads on worth it.
Their runners are very very big for a 383 or smaller motor.

Richard@WCCH

iTrader: (3)

Negative Jason. Nominal bore size is 4.100". The exhaust valves are very close to scrapping the bores on a 4.060" setup. The valve placement in the LS7 is the reason. They're moved to different locations than LS1 heads. I have some unported LS7 heads that the guides could be moved to clear a smaller bore. A bit of work yes, but it would make an exceptional small bore LS7 setup.
Call me at the shop and I can explain better.

Richard

strokedls1

iTrader: (1)

Yah I was gonna give you a buzz. The ls7 heads I saw at your shop looked nice, but I didn't want to steal too much time bsing. I am up in the air about these L92 heads with the composite gm intake. I know they will work fine. I do have some offset bores so clearance does play a big roll to me.

Thanks for the replies guys. I figured the vavles would be too tight. Hopefully the L92 heads and intake pan out.

x phantom x

iTrader: (14)

Richard .... I had a discussion with I believe ETP about this awhile ago, and they said that the valve is very close to scraping, but it would work on a 4.060" (absolute minimum tho). Now, I personally wouldn't run an LS7 head on anything below a 4.100", but that doesn't mean it can't be done. If the valves did hit on a 4.060", then that would be a different story. Obviously you would know more about this then I would, I'm just going by what I've heard from other head manufacturers.

Richard@WCCH

iTrader: (3)

The block I checked the heads on was a std. bore LS2 block. We checked each chambers valve/bore fit. On two bores the exhaust valves scraped the bore. On two other bores, the exhaust valves hit the top edge and would not fully open. A 4.060" bore would yield an additional .030" of valve/bore clearance. In the case of the two cylinders that had valves that hit, you would have less than .030". This is still not a safe amount on a hot, running engine in my opinion. Others may disagree. Static clearance doesn't guarantee the parts won't hit once the engine is run.

Richard

x phantom x

iTrader: (14)

Yeah I agree ... even if it would fit, it's not worth the risk to run the valves that close to the limit.

stang90gt50

iTrader: (6)

Will L92 heads fit on a 4.000 bore?

vmax1500

How about ETP's small bore LS7 head that is made for a 4.00 bore?

http://www.etheads.com/mainpage.htm
Cylinder Head: G III LS7 Application: Street / Race
Port Volume: 250cc Chamber Volume: 35cc to 72cc
Test Bore: 4.000" Test Pressure: 28.00" Water
Intake Valve: 2.125" Exhaust Valve: 1.600"

Valve Lift Intake Exhaust Valve Lift
.100" 73 56 .100"
.200" 154 110 .200"
.300" 236 166 .300"
.400" 287 199 .400"
.500" 321 214 .500"
.550" 336 219 .550"
.600" 345 222 .600"
.650" 350 226 .650"

Exhaust to Intake Flow Ratio 68%

Jobber Price: $2,850.00 Retail Price: $3,199.99

strokedls1

iTrader: (1)

The cost and wait time on the ETP stuff is a definite cancellation for it. I have dealt with the lies and bs of head delivery before and won't go that route again. I don't know about the valve placement on the l92, but I would venture to say no on a 4" bore. The intake valve size was 2.150 and the ls7 is 2.200. If the ls7 doesn't really fit at 4.060, then the l92 is gonna be in the same close proximity for a 4.00" bore.

Richard@WCCH

iTrader: (3)

I'm hoping to have some of these answers soon. I don't believe the valve guide centerlines are the same between the L92 and LS7. I'll wait to comment on the L92's fit on a 4.00" bore.

Stay tuned,

Richard