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GMC V6 and V12 Engines Engine repair and rebuilding

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  #1  
Old October 22nd, 2022, 05:42 PM
tbucketnut tbucketnut is offline
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Default All 305 V6s are not created equal

Interesting problem I have with assembling my 305 for my GMC.
First off I was unable to use the original 305 in my 64 1000 wideside. I made a short trip down to Oregon and bought a used 305. I had this block cleaned mag'd and bored and honed to fit my pistons. At this point I had accumulated over the past two years, new pistons, main and rod bearings, cam and bearings , new timing gears and chain, and had the heads gone through with hardened exhaust seats.

I do all my own engine assembly and noticed right a way the .020 under main bears were loose in the webs and main caps -what the ****. Through a little bit of digging, I learned that blocks produced in 1973 and 74 had different housing bores for the main albeit the same journal sizes. It takes a 5061M main bearing set instead of a 4067M like 60-72 engines have.
Rod bearings are the same.
Did notice the rods in this 74 305C engine are a lot beefier than the 305E engine.
Cheers fellow friends,
Steve
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Steve Stock
Gig Harbor, Wa

1953 Chevrolet 3100
261 cu inch, SM420
Finished Cab off restoration

1964 GMC 1000
305 V6, SM 420
Restoration is now started, still looking for an oldsmobile style power steering pump
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  #2  
Old October 22nd, 2022, 10:31 PM
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AZKen AZKen is offline
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Default Re: All 305 V6s are not created equal

Good info Steve. Don't forget to post a video of the first start up! You can go into business rebuilding GMC V6.
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Old October 23rd, 2022, 03:05 AM
tbucketnut tbucketnut is offline
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Default Re: All 305 V6s are not created equal

I'll try and get a video up when the times comes.
If Somebody here needs a freshly ground and polished crank .020 undersize on the main journals and .020 undersize on the rod journals, with a set of almost impossible to find matching main bearings and a set of matching rod bearings. I will sell for my machining cost and bearing costs picked up in Washington State. This is ready to go for a 60- 72 block all cubic inches with 3.58" stroke.

Steve
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Steve Stock
Gig Harbor, Wa

1953 Chevrolet 3100
261 cu inch, SM420
Finished Cab off restoration

1964 GMC 1000
305 V6, SM 420
Restoration is now started, still looking for an oldsmobile style power steering pump

Last edited by tbucketnut; October 23rd, 2022 at 01:42 PM.
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