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GMC V6 and V12 Engines Engine repair and rebuilding

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  #1  
Old January 22nd, 2021, 04:00 AM
arepoff arepoff is offline
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Default 478M swap

I'm sure this has been discussed but I searched the threads and didn't see any step by step swap detailed. I have K1000 with 305E, I have purchased a 478 that needs to be assembled. I'm have the following questions:

Do I swap timing/front cover from 305 to 478? Or run the 478 setup?
Who makes the reduced flywheel for the 8 lug crank?

I do need lifters, rod/main bearings, piston rings etc for 478. Any good suppliers beyond Egge and Hastings?

Thank you

Alexi
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  #2  
Old January 22nd, 2021, 07:06 AM
WE7X WE7X is offline
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Default Re: 478M swap

I am pretty sure I recall a thread many years ago to the effect that you needed to use the 305 timing cover.
It seems to me there was some issue with the vertical position of the water pump also, relative to the radiator in the smaller chassis. Maybe there was a different water pump setup??
I am really digging back in old memory for that, so do not put a lot of credence in my memory.
Somebody else will likely chime in.
Fun projects....mostly only take time and money!
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1970 RM7500 (school bus chassis -motor home)
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  #3  
Old January 22nd, 2021, 03:32 PM
lizziemeister'sV6 lizziemeister'sV6 is offline
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Default Re: 478M swap

The timing chain cover is the water-pump housing on a 305 - this will fit your 478M - you will need to plug the balance shaft oil holes under the cover/ change the timing gear/chain set-up - the crankshaft/flywheel switch over is where the problem/expensive part comes into play. The person to contact on here would be BBV6 (Pete C.) as he has done this engine switch. From my experience on these motor swap/improvement would be a 351 of some version - far easier and less expensive with a good improvement.
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Old January 22nd, 2021, 07:54 PM
arepoff arepoff is offline
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Default Re: 478M swap

Thanks for the info, helps me move forward.
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Old January 23rd, 2021, 01:34 AM
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LEWISMATKIN LEWISMATKIN is offline
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Default Re: 478M swap

Quote:
Originally Posted by lizziemeister'sV6 View Post
The timing chain cover is the water-pump housing on a 305 - this will fit your 478M - you will need to plug the balance shaft oil holes under the cover/ change the timing gear/chain set-up - the crankshaft/flywheel switch over is where the problem/expensive part comes into play. The person to contact on here would be BBV6 (Pete C.) as he has done this engine switch. From my experience on these motor swap/improvement would be a 351 of some version - far easier and less expensive with a good improvement.
that would be the idler gear mount and return to a roller chain. While a 401 has to have this done as well, the flywheel is a direct bolt up on the 401. The 478 will have to have a special flywheel made for it.
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Old January 23rd, 2021, 11:12 AM
George Bongert George Bongert is offline
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Default Re: 478M swap

Quote:
Originally Posted by lizziemeister'sV6 View Post
The timing chain cover is the water-pump housing on a 305 - this will fit your 478M - you will need to plug the balance shaft oil holes under the cover/ change the timing gear/chain set-up - the crankshaft/flywheel switch over is where the problem/expensive part comes into play. The person to contact on here would be BBV6 (Pete C.) as he has done this engine switch. From my experience on these motor swap/improvement would be a 351 of some version - far easier and less expensive with a good improvement.

Greetings, lizziemeister!

Not only will he need to change from timing gears to timing chain and sprockets, he will also need to change the camshaft itself, since the original 478 camshaft will now be rotating CW instead of CCW. There is a difference between cam grinds on CW and CCW rotating camshafts.
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  #7  
Old January 23rd, 2021, 10:41 PM
arepoff arepoff is offline
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Default Re: 478M swap

the 478 timing setup has an idler gear inbetween the crank and cam gear so they will turn the same direction. George Bongert am I missing something with the timing? I don't think I have ever seen an engine valve train turn opposite direction of crank.
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  #8  
Old January 24th, 2021, 05:40 AM
George Bongert George Bongert is offline
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Default Re: 478M swap

Quote:
Originally Posted by arepoff View Post
the 478 timing setup has an idler gear inbetween the crank and cam gear so they will turn the same direction. George Bongert am I missing something with the timing? I don't think I have ever seen an engine valve train turn opposite direction of crank.

Greetings arepoff!!

OK. The idler gear between the crank and the cam explains a lot. You will be OK with the timing chain and sprockets set up. As to engines where the camshaft rotates opposite of the crankshaft, there are many, but to name a couple of examples, International Harvester tractor and industrial engines, and the same with John Deere tractors and industrial engines, and Chevrolet inline 6 cylinder engines. There are more, but too numerous to mention here.
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