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#723189 - May 02nd 2017 3:13 am '85 G20 305 to 350 swap?  
Joined: May 2017
Posts: 1
85Chebby Offline
85Chebby  Offline

Joined: May 2017
Posts: 1
I have a 1985 G20 conversion van that has been stored inside the majority of it's life, however the seals/gaskets are old and leak on both the transmission and engine. The van was always grossly underpowered and I like to take it on trips out west and do some mountain driving so I'd really like to upgrade if possible. I'm not trying to make a dragstrip van or anything, but I would like a very reliable upgraded engine/transmission. Also will be upgrading/replacing the brakes and full suspension at the same time.

Is this something that has been documented that I can read up on? I've never been a V8 guy, I've mainly worked on GM 60/90* V6 engines and have a lot of experience in that area.. but never worked on Trucks or Vans or any type of V8 so this is all new territory for me.

So basically if anyone has some suggestions and or links/info/posts on this type of scenario please let me know~

#723192 - May 02nd 2017 9:08 am Re: '85 G20 305 to 350 swap? [Re: 85Chebby]  
Joined: Nov 2013
Posts: 1,810
Dyno_Dave Offline
Dyno_Dave  Offline

Joined: Nov 2013
Posts: 1,810
Welcome aboard 85Chebby. [Linked Image]

Not sure what builds are documented here, but I'll add this. If you've worked on Chevy 90* V6s, you've essentially worked on a small block Chevy. The 4.3 is a 350 with 2 cylinder cut off. And the old 229 is based on the 305. So you'll find a lot that seems familiar when you work on one.

I'm assuming you are not wanting to go the crate engine route. I don't think you'll find the 305 to 350 swap to be too troublesome. To make sure the performance parts match, a simple answer is to use a kit, like one from Edelbrock. If you are keeping a carb. and don't want the factory CCC computer and feedback carb, the Eddy package will get you a new carb, cam, lifters and intake, and designed to work together. Buy yourself some headers, and you'll have a nice power increase with a minimum of fuss.

Power Package

#723196 - May 02nd 2017 11:22 am Re: '85 G20 305 to 350 swap? [Re: 85Chebby]  
Joined: Jun 2010
Posts: 12,571
frscke1 Offline
frscke1  Offline

Joined: Jun 2010
Posts: 12,571
Van Diego California
Welcome to the site 85 ..... Id put a 454 in it Again welcome !

'93 CHEVY G30 454 4X4 SPORTVAN EXT 146" WB
#723219 - May 02nd 2017 10:03 pm Re: '85 G20 305 to 350 swap? [Re: 85Chebby]  
Joined: Sep 2009
Posts: 1,039
Bullet Offline
old hand
Bullet  Offline
old hand

Joined: Sep 2009
Posts: 1,039
Bristol, TN
If you are looking for an easy peasy swap that will give you quiet reliable service, pick up the GM truck crate engine. They can be had for around 2 grand with a warranty. As for the swap, it's unbolt, pull, replace, bolt back. I recommend a Performer style intake with good carb and a standard HEI with a vacuum advance. The engine comes out the front. It's easier if you raise the front about 4-6 inches. Pull your intake and bolt your pull chain as close to the top of the engin as you can. If your cherry picker has links in the chain hook, shorten up. If you make effort to hook tight to the engine and you raise the van so the cherry picker arm is more parallel to the ground instead of angled downward so much, ir will clear the firewall with a couple inches of wiggle room. Piece of cake. The reason I recommend the truck engine is that it is cammed for low end torque which is what you need to move a conversion van. If it has a 700R4, replace the torque converter, those years have a cronic shutter problem which causes heat slipping, and eventually failure. PM me and I can get you some good info on minor mods to the transmission that will make you much happier with it's performance and will make it last much longer especially in hard mountain climbs.

'85 GMC Shorty
'99 AWD Astro
'98 Suburban K2500
'77 Pontiac Astre (future Big Chief)
'95 Jeep Wrangler
"I thought you weren't allowed to talk to guys with vans??"
#723234 - May 03rd 2017 10:54 am Re: '85 G20 305 to 350 swap? [Re: 85Chebby]  
Joined: Feb 2002
Posts: 386
Lionvan Offline
Lionvan  Offline

Joined: Feb 2002
Posts: 386
vanland Des Moines
I got a 350 pu suv van engine from Jeg,s for $1800 delivers to Des Moines. 215hp . The car motors are 195 hp. It is a Goodwrench made in Mexico. Paid a shop. About $1500 parts and labor to install. Took 5 days. Runs like a champ. Oh yeah it is in my 90 G20.

[IMG]A foolish faith in authority is the worst enemy of truth. Question Authority.
#723744 - May 17th 2017 3:15 pm Re: '85 G20 305 to 350 swap? [Re: Lionvan]  
Joined: May 2015
Posts: 7
Billygoat Offline
Billygoat  Offline

Joined: May 2015
Posts: 7
Physically a 305 and 350 are the same. I just pulled my motor to replace head gaskets. Dropped it through the hole. Didn't want to take the front end apart.

You may want to go with the next generation of engine, 1987-95. They have better gasketing, one piece rear main seal and everything else will bolt right on. I upgrade my 1978 350 to a 1995 roller motor. Only had to change the flex plate (center hole was smaller) and the intake (2 center bolts are angled). All brackets, A/C, carb, fuel pump, trans, water pump, power steering pump, etc, were from the 78 engine.

Attached Files Van92.jpgVan95.jpg
Last edited by Billygoat; May 17th 2017 3:16 pm.

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