1998 350 vortec bolt in a 1971 gmc 1500 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 02-24-2015, 09:34 PM   #1
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Exclamation 1998 350 vortec bolt in a 1971 gmc 1500

hey i have a 1998 gmc 1500 350 vortec and i was wondering if 1..
it can be striped down to a basic carb system and 2 if it will bolt up in place of the 305 ?? help please
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Old 02-25-2015, 01:24 AM   #2
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Yes GM performance and edelbrock both sell a 4bbl intake that will bolt up to the vortech heads. As far as bolting the engine in everything else should be the same as far as bell housing and motor mounts. The only other problem I see is if you plan on using the stock 71 exhaust manifolds you will have a issue with the dip stick because the early blocks they were on the drivers side and late blocks the on the right side. If you're using headers there shouldn't be a issue.
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Old 02-25-2015, 07:01 AM   #3
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Correct me if I'm wrong, but the 350 block and 305 blocks are the same. Only difference is the 350 uses a longer stroke crank to achieve 350ci.
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Old 02-25-2015, 11:41 PM   #4
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Not sure, but I think the 305 was a different bore. Most hot rodders would junk the 305'* and go 350. If I remember correctly I think the 307 was a 283 block with a 327 crank or vice a versa.
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Old 02-26-2015, 01:24 AM   #5
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Wasn't a fan of the 305 and it sure wasn't popular. My brother had a 305 and installed a set 0f early 350 heads. The only time I ever saw a 305 scream.
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Old 02-26-2015, 06:32 AM   #6
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Found this


1998 350 vortec bolt in a 1971 gmc 1500-image-3745840823.jpg

Looks like I was right about the 307 block and crank.

Last edited by 75 racer; 02-26-2015 at 06:34 AM.
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Old 02-26-2015, 06:54 AM   #7
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Ahh, I see my partial mistake. I was thinking of the 383 stroker.

Ok, that kind of corrects my engine difference, but it doesn't say if the blocks are different. Still, you can bore a 305 block to 4.00" and turn it into a 350.
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Old 02-26-2015, 07:20 AM   #8
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Quote:
Originally Posted by Mike1995 View Post
Ahh, I see my partial mistake. I was thinking of the 383 stroker.

Ok, that kind of corrects my engine difference, but it doesn't say if the blocks are different. Still, you can bore a 305 block to 4.00" and turn it into a 350.
I think the blocks are cast differently and there isn't enough meat to boar it that much. If you could us racers would be cultivating every 305 we could get a hold of. And yes a 400 crank in a 350 makes a 383. We built a few of them in my racing days. I even built a 377 witch is a 400 block with a 350 crank. You had to be carful with the 400 blocks because the cylinders are siamesed and tend to have heating issues in a race application.
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