anyone who has ever did a 4.3 to v8 swap or vice versa

[benoit454]

anybody who has ever done a 4.3 to v8 swap on these fullsize trucks, I need some help. Do the frame mounts get moved? This is a 4wd too. did exhaust get reused or not? Are the frame mounts different?

I ask because I have an 88 k1500 that had a 350 and now I have a 91 s10 with a 4.3 and was going to dump the 4.3 in the k1500 to drive and build the s10 later. I know I need a fan shroud and maybe some other stuff but the biggest thing was the motor mount location and frame pads.

Also does the computer get changed or could? or just the chip?

[lester622]

frame mounts are different. Also the v6 frame mounts cost about twice what the v8 mounts cost.

Computers are different from v8 to v6 as well

[benoit454]

I seen a video online that showed the v6 had plates that bolt on the frame because the v6 mounts further back then a v8 and I bet those would be hard to find.

when you say the mounts are more which ones do you mean? the v8 frame mounts are like 3 each on rockauto and the v6 mounts but they are the block mount and a bit more but only like 6 or 7.

[lester622]

The v6 frame mounts come with that plate that sets the mount back, When I priced them for my truck they where around $80 a piece. The v8 ones where around $15-$20 a piece.

The motor side mount should be the same v8 or v6

[benoit454]

yours a 2wd or 4wd? I couldn't find anything but the block side mounts for a 4.3 4wd and they were cheap. now lmc had some for 95 and up with a plate and they were a hundred a side, but it didn't say 2wd or 4wd I don't think.


if it's gonna be that much I'll either fab my own from flat plate to use s10 mounts and pads or just rebuild my 305 for it.

[lester622]

2wd and 4wd use the same frame mounts and motor side mounts. Only difference is on a 4wd there is a plate that goes behind the motor side mounts with a long rod coming off of each one that mounts to the transmission and one mounts to the transfer case.

Mine was a 2wd, after seeing the price of the v6 motor mounts and me building the truck to tow a car trailer every now and then I just bought a parts truck with a v8 and changed everything over.

[Palf70Step]

Someone on the board did one recently from V6 to a BBC. Just got to find his name & thread.

Here ya go.

It was DirtyLarry

http://67-72chevytrucks.com/vboard/s...d.php?t=498233

[benoit454]

hmm wonder why I can't send him a pm?

as for 2wd and 4wd no they are different I just removed my frame mounts and they have a step up in them on the bottom 2wds are flat.

[Palf70Step]

PMs can be disabled from your profile.

[benoit454]

lol I had no clue.

in his thread you can see the difference, the older like 95 and older 2wds had those metal plates that bolted on and used the ruber mount on the block like a 2.8 s10 frame mount, looks the same.

on the 96 and newer the mount is made like the newer s10 4.3's all stacked together and bolts on the frame and comes back, but mine being 4wd not sure the lower rear would have anything to bolt to.

Not to mention I can't find them listed on the local junkyard website, and I'm not paying $35 a side from rock auto for them not knowing if they'd have anything to bolt to.


I'm honestly thinking flat plate and bolt to my old holes, then use the stock s10 frame brackets and engine side brackets to mount it up. I've got the 91 s10 here with all that on it.

[lester622]

Originally Posted by benoit454

hmm wonder why I can't send him a pm?

as for 2wd and 4wd no they are different I just removed my frame mounts and they have a step up in them on the bottom 2wds are flat.

Ive used them both ways and never really noticed a difference.

[benoit454]

ok, it's a pretty big step up lol. I guess I'm gonna have to find those plates, make some to use stock s10 stuff or just forget it lol.

[Marty68]

i put pins and bushings in an s blazer - same method- i used the aftermarket crap, i will always use gm stuff now too much work to KNOW you will have to do it twice.
former co-worker quote - "we never seem to have enough time to do right but we always have time to do it twice"

[Palf70Step]

Originally Posted by benoit454

lol I had no clue.

in his thread you can see the difference, the older like 95 and older 2wds had those metal plates that bolted on and used the ruber mount on the block like a 2.8 s10 frame mount, looks the same.

on the 96 and newer the mount is made like the newer s10 4.3's all stacked together and bolts on the frame and comes back, but mine being 4wd not sure the lower rear would have anything to bolt to.

Not to mention I can't find them listed on the local junkyard website, and I'm not paying $35 a side from rock auto for them not knowing if they'd have anything to bolt to.


I'm honestly thinking flat plate and bolt to my old holes, then use the stock s10 frame brackets and engine side brackets to mount it up. I've got the 91 s10 here with all that on it.

When I put the 4.3 in my 70, I used the stock small block mounts. I had to shift the mount trees back on the frame & drill new holes, but it worked out in my case.

[benoit454]

did you do any mods to the trans crossmemeber? I'm all for moving them back and redrilling or something. I just didn't want to run into too short or too long driveshaft.

I've got 2 sets of stock v8 block mounts, didn't know they'd fit.

oh I see you moved it back about 2 inches or 3. I can't move mine that far on my 88 4wd the mounts are weled on the frame and I coul dmove th epads back and drill holes but not alot, maybe 2 inches? I have to measure and see. Can you measure to see how far back your new holes are from the old ones?

[Palf70Step]

Since the 70 used totally different style mounts than the newer ones (like shown), everything was modified. I believe I moved them back about 2 1/4 or 2 1/2 inches back from where I had the V8. I used a stock automatic cross member and in a stock location (holes were already there).

I made extensions from thick angle iron to slide the lower portion of the bracket backwards.

I am not real positive on the 88-94 year mountings. I know they have the big attachment the use to move the V^ brackets back (saw it in a junkyard years ago).