83 LG4 heads vs 86 LG4 heads

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Jun 4, 2009 | 09:00 PM

Josh R

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83 LG4 heads vs 86 LG4 heads

Are there any differences between 83 and 86 LG4 heads? I know that the motors compression ratios are different because of the pistons but are the heads the same?

Jun 5, 2009 | 11:02 AM

Atilla the Fun

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Re: 83 LG4 heads vs 86 LG4 heads

pop the valve covers and check the casting numbers. They should all be 416s.

Jun 5, 2009 | 06:49 PM

Randy82WS7

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Re: 83 LG4 heads vs 86 LG4 heads

difference in compression would be pistons.

some later LG4 are higher compression according to GM specs

all the early ones are less

Jun 5, 2009 | 08:01 PM

Damon

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Re: 83 LG4 heads vs 86 LG4 heads

Should be. Wasn't until 87 that they started using the centerbolt valve cover heads.

You're correct- the compression ratio differences over the years were due to different pistons being used.

Jun 6, 2009 | 02:43 PM

Josh R

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Re: 83 LG4 heads vs 86 LG4 heads

ok ill check the casting number. And yeah i think in 85 they uped the cp to 9.5 where as before it was 8.5 or something. Just making sure i wasnt lowering my compression by changing heads. Thanks.