Thread: V6 3.4 or 4.3 How can you tell

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I have a chevy v6 that I'm not sure if it's a 3.4 or 4.3. It came out of a S10 but not sure of the year. Looking on the web I can't find a site that will help with the ID numbers. How can you tell if it's a 3.4 or 4.3?

i have a picture of my 4.3 but for some reason i cant post it .. a 4.3 is basically 3/4 of a 350 V8

The 3.4L is a member of the 60º V6 engine family. The 4.3L is a 90º V6, and looks like a short version of a 350 Chevy V8.

Bob

may have something to do with you being a new member .. i can post pictures everywhere else .. perhaps in the morning i can show you mine

Thanks Bob. This may be a dumb question, but I think I know how to figure the 90 degree and 60 degree of a motor, but could you refresh me? Is this a straight line from the cylindor to the crank then back up the other cylindor?

here's a 4.3 V6...joe

this is a 3.4...

a 4.3 will fit a V8 bell housing .. a 3.4 will not

Originally Posted by redavenport

Thanks Bob. This may be a dumb question, but I think I know how to figure the 90 degree and 60 degree of a motor, but could you refresh me? Is this a straight line from the cylindor to the crank then back up the other cylindor?

Yes, the bank angle is the angle formed between the main bearing bore centerline and the centerline of the cylinder bores in the left and right bank. The GM family of V6 engines which include the 2.8, 3.1 and 3.4 have a 60º bank angle. The V6 engines that were derived from the V8 retain the 90º angle.

Bob

Thanks Bob. That helps alot. And thank you for the photos TooMany2Count

I was alomost not going to post to this.Haft heartedly I am addressing the statement that 4.3's are only a cut down 350.The fact is the spacing of the bores,the split journals,and the offset of the rods makes it very different than 350's.

they are pretty much a 350 minus 2. 4 inch bore 3.48 stroke same water pump works there close enough

as for the OP,

the 3.4 is indeed in the same family as the 2.8 3.1 3.4 60* v6 also known as the 3100, 3400

Originally Posted by 1gary

I was alomost not going to post to this.Haft heartedly I am addressing the statement that 4.3's are only a cut down 350.The fact is the spacing of the bores,the split journals,and the offset of the rods makes it very different than 350's.

Yes, they're different internally, but the o.p. was looking for visual cues to identify a 4.3 and those are very much like a 350 V8. By the way, the bore centers of a 90º Chevy V6 are the same as the small block V8 engines. They addressed the split crank throw issue with narrowed/larger rod journals. The 3.8 Buick V6 did eventually get a "spread" bore spacing in the 3800 Series to eliminate the off center rods, but that's a horse of a different color.

Bob

Originally Posted by redavenport

Thanks Bob. That helps alot. And thank you for the photos TooMany2Count

do you know what you have yet ?

Originally Posted by 1gary

I was alomost not going to post to this.Haft heartedly I am addressing the statement that 4.3's are only a cut down 350.The fact is the spacing of the bores,the split journals,and the offset of the rods makes it very different than 350's.

same bore spacing, same hd bolt pattern (use 3/4 of a 350 torque plate when boring) same piston, same rod length (use v-8 rod by narrowing big end), timing chain/sprokets, rocker arms, push rods, lifters, water pump, oil pump.......

[shrug]
Russ