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GMC V6 and V12 Engines Engine repair and rebuilding

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  #41  
Old October 16th, 2018, 09:10 AM
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Cayoterun Cayoterun is offline
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Default Re: Gmc V12 in trucks

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Originally Posted by Cayoterun View Post
Thanks, BillT for a good belly-laugh to start the day. Did the floor boards shake, and you looked in the rear mirror to see how much pig iron was scattered on the pavement??

Since on irrigation wells, the motors ran at a constant speed, we'd tune them at night and use the exhaust as a guide. With the stub pipes on each head, blue flame would be at the pipe tips, so we could tune each distributor on each side of the motor, by tuning in each distributor to max blue flame.
More V12 trivia: Since the irrigation motors run at a constant rpm, under load,

spark advance wasn't necessary, so if you find on the distributors the advance may be locked, rusted, or disabled, in one position, that is the reason. It was tuned at the operating rpm it normally ran.
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I think I'll fix it myself, and pay the extra $500.
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  #42  
Old October 16th, 2018, 01:23 PM
Motiv8 Motiv8 is offline
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Default Re: Gmc V12 in trucks

Gentlemen, I believe the conrods of 351 will swap w/ 702 (never bothered), you may find 351's are Arma cast iron and 702's are forged steel. Some think 702s are configured as 2-351 V6s. I believe they are 2 inline 6 cyls . Each bank timed and tuned separately, then combined. Have built many V 12s including Lincoln, Packard and many today obscure makes. Many stagger each inline bank from the other a few block angle degrees to reduce harmonics. That necessitates separate bank tuning.
Synchronizing carbs can be done accurately w/ exh analyzers.
Fuel mileage is one -two mpg they tell me. JMHO David
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  #43  
Old November 3rd, 2018, 12:15 AM
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Cayoterun Cayoterun is offline
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Default Re: Gmc V12 in trucks

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Originally Posted by Cayoterun View Post
Thanks, BillT for a good belly-laugh to start the day. Did the floor boards shake, and you looked in the rear mirror to see how much pig iron was scattered on the pavement??

Since on wells, the motors ran a constant speed, we'd tune them at night and use the exhaust as a guide. With the stub pipes on each head, blue flame would be at the pipe tips, so we could tune each distributor on each side of the motor, by tuning in each distributor to max blue flame.
BillT: If a muffler had blown off at the header, and clattered around under-neath, you may have had a heart attack. LOL------Love the ol' 12s and stories.
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I think I'll fix it myself, and pay the extra $500.
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  #44  
Old November 3rd, 2018, 03:25 AM
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Cayoterun Cayoterun is offline
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Default Re: Gmc V12 in trucks

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BillT: If a muffler had blown off at the header, and clattered around under-neath, you may have had a heart attack. LOL------Love the ol' 12s and stories.
OOps: I forgot you said it didn't have mufflers.
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