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4.3L V6 in a 4x4 K5

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TheAmazingBman

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I'm putting a 4.3L V6 in my 1990 K5 that me and my dad built a few years ago. The major problem I'm running into is I need the engine mounts pushed back 4.5" to have the transmission mount line up. Does anyone know how I get my hands on some stock engine mount frame trusses from an 80's style K10 with a 4.3?
 
I don't think that combo ever existed. They got the 250 i6, which would be a better swap candidate either way in my opinion. Any particular reason you're going with a 6 cyl?
 
Me and my dad built this engine together, it was the first one. He passed away last year and I wanted to put it in something. It's time to put it into use instead of just sitting in the shop. Thanks for the information. I have a mechanical engineer friend and he is going to make some custom trusses for it if I couldn't find anything stock.
 
That's probably the best reason I've heard so far. But a 4x4 blazer is a heavy turd to get moving. Get some decent geared axles and you should be set. Were there different frame mounts in the 90s trucks? Might want to start there for ideas since that's what the motor came in
 
I'd imagine your best bet would be junk yard pickin to get the frame mounts and you're gunna have to weld or drill and bolt them where they need to fit on the K5 frame. AFAIK 4.3s never came in square bodies, hell I doubt they even came in post 91 K5s.

That or fab your own frame mounts to fit the 4.3 motor mounts. Probably be easier, cause if you go to a junk yard you gotta get those suckers off, not something I'd wanna do there if it uses those big heavy duty rivets.

And like Xenomarine said, start thinking about gearing. You're gunna want a minimum of 3.73, and that's with stock sized tires.


EDIT: Maybe I'm wrong, did some searching, guess they started putting 4.3s in 85+? Never seen one before, only V8s and I6. But then again this was wiki, so I don't necessarily believe it.
 
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Pretty sure maybe 86 but for sure 87 came with 4.3s. I worked at a plant that had one in a c10.
 
Now that I think about it, it was actually 2 trucks. One was a 86 the other a 87. HUGE fan shroud.
 
mrschaeferpants said:
I'd imagine your best bet would be junk yard pickin to get the frame mounts and you're gunna have to weld or drill and bolt them where they need to fit on the K5 frame. AFAIK 4.3s never came in square bodies, hell I doubt they even came in post 91 K5s.

That or fab your own frame mounts to fit the 4.3 motor mounts. Probably be easier, cause if you go to a junk yard you gotta get those suckers off, not something I'd wanna do there if it uses those big heavy duty rivets.

And like Xenomarine said, start thinking about gearing. You're gunna want a minimum of 3.73, and that's with stock sized tires.


EDIT: Maybe I'm wrong, did some searching, guess they started putting 4.3s in 85+? Never seen one before, only V8s and I6. But then again this was wiki, so I don't necessarily believe it.
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Yeah, I might start looking at the junk yard. They started putting the 4.3L in C10's in 1985. I have a 1986 block. I'll be running 33's with 3.73 gears so I think it will do alright. I've owned a few fullsize trucks with 4.3L's but nothing as heavy as a K5 (it might be similar to the 4.3L long bed 4x4 Silverado I owned with 35" Swampers and 3.55 gears). The block is bored .30 over, with port and polished heads, a high performance 4 barrel intake and the biggest cam you can put in it.
 
Try your local chevy dealer parts departement, you 'd be surprised whats still available.

Edit: as for the comment above about the 250-6 being a better engine, NO way those intergrated head turds don't even make good boat anchors the 292 on the other hand is a good engine.

My best freind in Highschool had a 4.3/SM465/NP208 stepside on 31" BFG MT's It was faster then my 85 Dodge with 225 slant six?NP435/208 on 32" BFG MT's but mine was better crawling around with a load on .


I think we all have gotten spoiled to big V8 and diesel power . I actually like driving those old "under powered" trucks
 
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