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g20 engine upgrade options?
#729055 October 19th 2017 12:59 am
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hey guys, I'm thinking about upgrading the engine in my van for more power. What do you guys suggest? It's late 70s G20 with a 350. I live in the Rockies and am using it as a daily driver, it's running really reliably, but as much I love the van, it's just really lacking in power and speed, even on flat roads, but especially on steep grades. What's the best bang for the buck option without sacrificing reliability? I'd love to throw a 454 in there, of course. or a Cummins diesel if it wasn't sacrilege and changing out every damn part in the engine bay.

Re: g20 engine upgrade options?
nomadgames #729061 October 19th 2017 9:04 am
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I had the same consideration after I bought my G20 last month. It has a 350 (had one anyways) and I did not want to reconfigure anything for more power. After looking at the title and seeing an empty weight of 6500 lbs (!) I decided to with torque instead of horsepower. I watched several videos of burnout competitions at van nationals. Most of the vans struggled to get the tires spinning even with a water puddle and dudes jumping on the bumper.

My Advice: Find your self a 406 (400) cubic inch small block.They made these from 1970 to 1980 when GM needed to get the heavy chevys (caprice) and Pontiac (Catalina, bonneville) off the line.
These 400's have the same bolt pattern for the motor mounts and everything including the exhaust manifolds are a direct bolt on.

These motors also ended up in the delivery box vans. This motor can be converted tomake a 383 stroker motor easily. In stock 2 barrel form, they made 265 HP. I ordered mine from Gearhead Engines with a mild cam, Performer intake, and a 650 4 barrel carb. Headers will come later once I find side pipes.

Do some research on line. When I get this beast on the road next week, I'll give you an update. After it's broken in, I'll post some tire smokin' dyno numbers.


Re: g20 engine upgrade options?
nomadgames #729062 October 19th 2017 9:14 am
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Re: g20 engine upgrade options?
nomadgames #729064 October 19th 2017 10:20 am
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good info, thanks!

Re: g20 engine upgrade options?
nomadgames #729065 October 19th 2017 11:27 am
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A 383 stroker is based on a 350 block with a 400 crank. Personally, I'd find a late model SBC with FI and do a swap.


Tucson-it's a dry heat...like an oven
Re: g20 engine upgrade options?
Hasan Ben Sobar #729066 October 19th 2017 11:43 am
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Originally Posted by Hasan Ben Sobar
A 383 stroker is based on a 350 block with a 400 crank. Personally, I'd find a late model SBC with FI and do a swap.



I did think about doing a swap with a TBI engine. I had a 91 c1500 with the TBI 5.7 and that thing was great. I'm not super stoked on putting FI in a 78, though, kind of want to keep it carbed. although FI would help with all the altitude change I drive through on a regular basis.

Re: g20 engine upgrade options?
Lettercraft #729068 October 19th 2017 11:47 am
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Originally Posted by Lettercraft

$6000 for the engine? oof

Re: g20 engine upgrade options?
nomadgames #729069 October 19th 2017 11:56 am
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Originally Posted by nomadgames
Originally Posted by Hasan Ben Sobar
A 383 stroker is based on a 350 block with a 400 crank. Personally, I'd find a late model SBC with FI and do a swap.



I did think about doing a swap with a TBI engine. I had a 91 c1500 with the TBI 5.7 and that thing was great. I'm not super stoked on putting FI in a 78, though, kind of want to keep it carbed. although FI would help with all the altitude change I drive through on a regular basis.


TPI, not TBI. Throttle body injection is crap. Nice thing about the swap is the 4 speed auto that comes with it. Your altitude is why I suggested TPI.



Tucson-it's a dry heat...like an oven
Re: g20 engine upgrade options?
nomadgames #729070 October 19th 2017 11:58 am
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I liked my TBI. easy to work on and reliable as hell. but i'm not an engine expert. I would like 4 speed, I currently have 3 speed.

Last edited by nomadgames; October 19th 2017 11:58 am.
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