the finer points of the 3.8 and 4.3...can parts be interchanged?

[navyblue2000]

i've been doing some research, so maybe stuff won't make me look like a total fool...
back in the day, the 305 and 350 were externally identical. you could put 350 heads on a 305 and whatever not. nowadays, the 3.8 and 4.3 are somewhat brothers to their cousins the 305 and 350. the 3.8 has the same bore/stroke as the 305, and the 4.3 the same at the 350. it would be obvious that the 4.3 heads would flow better than the 3.8 heads. GM parts direct's performance parts states a lot of parts available for 90* v6s, which is what the 3.8 and 4.3 are. however, they don't really specify an engine displacement most the time. i'm curious as to know, are 3.8 and 4.3 parts interchangable? flame on, and if i'm right, thx for any advice

[wolf]

ummm.....
what you said is true for chevy 90* v6's(4.3,3.8[229 ci.]) but your car has a buick 3.8 90* v6(231 ci 3.8 bore,3.4 stroke)

[nova]

A lot of the stuff meant for a 350 will fit on the 4.3L since it is a 350 block with two cylinders cut off. I don't think anything will interchange between the 3.8 and the 4.3 though.

[scottblack]

Very interesting topic, I would like to know also. Where do you get that we have a Buick motor? Are you referring to the GN engines? If so, you are way off. They are the same size, but that is about it. I don't know much, but if thats what you are referring to then i must correct you good sir! LOL, no flames intended.

If those 4.3 heads could go on, wow, welcome to a new breed of performance parts. Wonder if the cam would go on also?

Scott

[wolf]

Scott Black <blockquote>quote:</font><hr> I would like to know also. Where do you get that we have a Buick motor? Are you referring to the GN engines? If so, you are way off. They are the same size, but that is about it. I don't know much, but if thats what you are referring to then i must correct you good sir! LOL, no flames intended.
<hr></blockquote>
3800 series 2 thats the current engine its derrived from the old GN type 3.8,very similer but not exactly the same
GMPP has heads for the 3.8 ,but I think there the heads that are already on the f-bodys
i don;t know what the sock vave size is but the gmpp heads are machened for 2.02 intake 1.6 exhaust here's the link
https://www.spoperformanceparts.com/

[tim haynes]

we do have a buick engine in the early 90s there was a chevy 3.8 and a buick but eventually chevy discontinued there version and adopted the buick 1

[Patrick Javert]

GMPP also has aluminum heads for our cars, I think. we have iron heads. If parts from a 4.3 liter can be swaped w/ a 3.8, we could also swap intakes, throttle bodies, and maf sensors for better ones that flow more.

[wolf]

did some digging- stock 3.8 heads are cast iron,1.8/1.5 valves
I think the gmpp heads will fit....heres the info on them:
25500030 Stage II Cylinder Head (Aluminum)
The aluminum Stage II cylinder head is a light alloy head with rectangular intake ports and square exhaust ports. 100 valve angles, unfinished seats for 2.02" diameter intake valves and 1.60" exhaust valves are installed. This uses 3/4" tapered seat spark plugs. Comes without valve guides installed.
Technical Notes: Stage II aluminum heads use the six bolt pattern found on Stage II blocks which require longer studs and are available from aftermarket sources. Requires rocker cover P/N 25500122, rocker cover gasket P/N 25500175, intake gasket P/N 25500173, exhaust gasket P/N 25500174, and intake P/N 25500029 or P/N 25500170.
the 4.3 heads won't fit-even if they did you woldent get much of a performance gain out of them,cast iron 1.9/1.5 valves

[FirebirdGT]

<blockquote>quote:</font><hr>Originally posted by wolf:
did some digging- stock 3.8 heads are cast iron,1.8/1.5 valves
I think the gmpp heads will fit....heres the info on them:
25500030 Stage II Cylinder Head (Aluminum)
The aluminum Stage II cylinder head is a light alloy head with rectangular intake ports and square exhaust ports. 100 valve angles, unfinished seats for 2.02" diameter intake valves and 1.60" exhaust valves are installed. This uses 3/4" tapered seat spark plugs. Comes without valve guides installed.
Technical Notes: Stage II aluminum heads use the six bolt pattern found on Stage II blocks which require longer studs and are available from aftermarket sources. Requires rocker cover P/N 25500122, rocker cover gasket P/N 25500175, intake gasket P/N 25500173, exhaust gasket P/N 25500174, and intake P/N 25500029 or P/N 25500170.
the 4.3 heads won't fit-even if they did you woldent get much of a performance gain out of them,cast iron 1.9/1.5 valves<hr></blockquote>


No, Stage II heads will NOT fit.

Look in the Technical Database, Specifications, Engine section - the whole history of the 3800 is there.

[wolf]

well oops [img]redface.gif[/img] [img]graemlins/dunce.gif[/img]
what engine do those heads fit then?