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I've got a problem with a 4.3L in the 86 GMC 4X4 Short Box. It started missing and blowing cold exhaust out of one side. Also loud lifter tappit noise on that side of engine. Checked plugs and found one fouled. Replaced all plugs. Still missing with cold exhaust and tappit noise. The truck has 123000 miles and have noticed in the past smoke on compression coming down from the mountains.

Worked on our engine on Saturday. Checked fire on that side of the 4.3L. Spark was weak on two cylinders. Removed and cleaned the distributor cap and rotor. Running better but still missing at low RPM with no noise from lifter, high RPM does'nt miss but noise from lifter. Removed valve cover and found nothing obvious. Now blowing warmer exhaust but blowing blue smoke from that side. Rebuilt top end couple of years ago. Now it must be time to replace engine. Should it be a 4.3L long block? Or a SB350? What problems would arise from a conversion? Motor mounts? It has a 4 speed transmission. Will bolt to bell housing? Can the emmissions be removed (no DEQ here)?

Any advise on direction of transplant for this '86 GMC 4x4?

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75 Luv 350/TH350 (Project in progress)

the 4.3 and the 350 have the same bell housing.

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4.3l V6. 5 speed MT 2.55 in the back.

Is your truck a TBI? We did a swap on a 1990 GMC short bed that had a 4.3. If I recall the 350 TBI has one additional wire of the ECU that needed to be hooked up for the truck to run properly. Or It could be the other way around maybe it needed one more wire added. (Depending on what year motor you get) If you need more info I'll call me buddy and find out. We took the complete motor ECU wiring and everything under the dash and hood.

If it's Carbed your good to go!

It's got a carb... Decided to go with a long block 4.3L, removing all emmissions, with Edelbrock intake manifold 2111 and Edelbrock 4BBL 1404 carb, etc. Waiting on the long block now.... the old engine is out.

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75 Luv 350/TH350 (Project in progress)

Nice.

Plug wires? Rotor and cap replacement might be in order-even if you did clean them. Electricity can be weird..

Picked up long block. Installed front & rear seals, new oil pump, oil pan, new intake, new valve covers, etc... New engine is in... Going to work on installing new carb, temp sensor, water pump and rest of accessories this weekend. Waiting for oil pump primer to arrive. Better get a new distributor cap & rotor also. Will post picture when finished.

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75 Luv 350/TH350 (Project in progress)

Getting closer to completion...

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75 Luv 350/TH350 (Project in progress)

Purty...

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