6066 (1960-1966) GMC Truck Club
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6066 (1960-1966) GMC Truck Club (https://6066gmcclub.com/index.php)
-   Transmissions and Rear Ends (https://6066gmcclub.com/forumdisplay.php?f=10)
-   -   478 to SM420 (https://6066gmcclub.com/showthread.php?t=49916)

TJ's GMC March 10th, 2017 05:54 AM
Re: 478 to SM420
 
Quote:
Originally Posted by bigblockv6 (Post 66557)
First of all lets not call the LS engine a Chevy:pullinghairout: Chevrolet does not deserve any credit for those engines:teehee:. It is a Corporate GM engine manufactured by "The GM Powertrain Division" and was used by all GM divisions. I'd rather see someone stick one of these in their GMC rather than that ubiquitous small block 350:ahhhh: Just whatever you do don't give up on the 478 project because you'll have something that's different yet pure GMC and will have more than adequate power:thumbsup:
Looking at the GMC V6 heads and the LS heads....port designs were very similar to! :teehee:

AZKen March 10th, 2017 10:45 PM
Re: 478 to SM420
 
Sounds like BBV6's info on 401 is a good compromise. Be sure to take some Video of your 305 running so that when you sell it, folks can see it ran good. Did it smoke after sitting for years or it just smokes? If it's after sitting, could "tighten up "after awhile, after some thermal cycles. Does it smoke out the exhaust or breather or both? A bunch or a little? I had a 56 Chevy as a kid and ran it on 90 wt gear oil...and it still smoked. The gas station guy would ask me three times if I meant 90 wt. Don't do that.

arepoff March 10th, 2017 11:12 PM
Re: 478 to SM420
 
Smokes light blue while running. This truck is off a wheat farm, it travelled in the fields all the time so I figure it has ate plenty of dirt in its life. I know the chassis has around 400k but I think this is the 2nd engine (at least).

bigblockv6 March 11th, 2017 03:56 AM
Re: 478 to SM420
 
Quote:
Originally Posted by TJ's GMC (Post 66572)
Looking at the GMC V6 heads and the LS heads....port designs were very similar to! :teehee:
I've got an LS1 in my 02 Trans Am, I see no resemblance in the port design whatsoever:pullinghairout: The LS1 ports are what they call "Cathedral ports", which have a triangular shape at the top of the port.:teehee:

TJ's GMC March 11th, 2017 05:37 AM
Re: 478 to SM420
 
Quote:
Originally Posted by bigblockv6 (Post 66590)
I've got an LS1 in my 02 Trans Am, I see no resemblance in the port design whatsoever:pullinghairout: The LS1 ports are what they call "Cathedral ports", which have a triangular shape at the top of the port.:teehee:
I'll have to scout that picture again, the heads were different but the ports were pretty similar. Not giving chevy any credit by any means. :lolsmack2:

arepoff April 20th, 2017 10:22 PM
Re: 478 to SM420
 
Good news! My GMC will be staying all GMC. I found a rebuilt 305E with 0 miles, picking it up this weekend. Still plan on FiTech and HEI distributor.

fishhunter679 May 30th, 2017 07:07 AM
Re: 478 to SM420
 
Hows your progress?

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