Q's on Buick 350 in my J-truck - Pirate4x4.Com : 4x4 and Off-Road Forum

dangerous toy · 10-13-2005, 07:42 PM

I just bought a 1970 J4000, it has a buick 350 thats not running well so i did a compression test and 2 opposing cylinders have around 15 psi, the rest have around 125 psi. Bad cam? is this motor worth digging into? i dont know much about it, i can get a pontiac 400 for cheap and im told that it should bolt up to my trans (t-18) is the buick 350 a buick v6 with 2 more cylinders ?(like the 4.3 and 5.7 chevy, same bore and stroke) Im trying to decide what to do with this motor, any input would be great. thanks

bigjeepguy · 10-13-2005, 07:55 PM

Quote:

Originally Posted by dangerous toy

I just bought a 1970 J4000, it has a buick 350 thats not running well so i did a compression test and 2 opposing cylinders have around 15 psi, the rest have around 125 psi. Bad cam? is this motor worth digging into? i dont know much about it, i can get a pontiac 400 for cheap and im told that it should bolt up to my trans (t-18) is the buick 350 a buick v6 with 2 more cylinders ?(like the 4.3 and 5.7 chevy, same bore and stroke) Im trying to decide what to do with this motor, any input would be great. thanks

The 350 is a good engine. I believe you could make the v6 work with that (I know the bellhousing is the same), but I don't think you would want to. The Buick 350 is a fairly light v8 (contrary to what it looks like ), and it prevents good power in stock form. I had one in a j4000 that I had, and it was a really nice combo (especially when combined with the t18)

I think the v6 would really be working hard for the weight that you have, it would be doable, but I personally would not like it. If it were me, I would probably just swap in a buick 455. You only gain about 100lbs over the 350, and the torque is insane! It will also bolt in. Conveniently, I also have a 455 for sale in the for sale forum for $300, pm me if interested. I was going to put it in the j4000 that I had, but school got the best of me.

Peter_C · 10-13-2005, 08:02 PM

You need to run a CLT aka cylinder leak down test to see where you are loosing compression at. If you have an air supply you can set each cylinder on top dead center then pressurize the cylinder with an adapter of some kind (Compression tester with the valve removed works) and listen to where the leak is. Whooshing from the exhaust would indicate a bad exhaust valve, and remove the oil cap and listen there for noise which would indicate bad rings.

desert_freak · 10-13-2005, 08:12 PM

I swapped in a Dauntless 350/TH400/D20 from a '69 Wagoneer into my '74 J10 in place of the 258/T-15/D20. I have never been overly impressed with the Buick and I've had lifters clacking since I put it in. Aftermarket parts are not abundant (TA Performance is the only company to make a aftermarket 4 barrel intake at llike $350+) and even good used parts are not that easy to find. I had both of my exhaust manifold go within about 6 weeks of each other after the swap and finding used ones was not easy. In short if it needs that much work I'd go with something else. A Big Block Buick or a Caddy 500 would be my choice if gas was not an issue. I am dropping a 6.2l diesel in mine with a 700R4/208 combo. I should double my mileage without a problem.

Chevy engines are abundant and cheap! Novak and advance adapters make motor mounts to drop a chevy in out trucks but you would have to probably look for a SM420 or SM465. I picked up a 4 bolt main, 4 barrel sbc/sm465 combo cheap for $300.

Don't give up on the J-truck, if you've never owned one or drove one for a while I think you will find that they are great trucks with TONS of character. I wouldn't sell mine for anything.

Good Luck!

P.J.

10-13-2005, 07:42 PM	#1 (permalink)
dangerous toy Registered User Join Date: Feb 2001 Member # 3500 Location: Walla Walla Posts: 318	Q's on Buick 350 in my J-truck I just bought a 1970 J4000, it has a buick 350 thats not running well so i did a compression test and 2 opposing cylinders have around 15 psi, the rest have around 125 psi. Bad cam? is this motor worth digging into? i dont know much about it, i can get a pontiac 400 for cheap and im told that it should bolt up to my trans (t-18) is the buick 350 a buick v6 with 2 more cylinders ?(like the 4.3 and 5.7 chevy, same bore and stroke) Im trying to decide what to do with this motor, any input would be great. thanks

10-13-2005, 08:12 PM	#4 (permalink)
desert_freak Registered User Join Date: Apr 2003 Member # 18449 Location: Riverside, CA Posts: 34	I'd say dump the Dauntless 350 I swapped in a Dauntless 350/TH400/D20 from a '69 Wagoneer into my '74 J10 in place of the 258/T-15/D20. I have never been overly impressed with the Buick and I've had lifters clacking since I put it in. Aftermarket parts are not abundant (TA Performance is the only company to make a aftermarket 4 barrel intake at llike $350+) and even good used parts are not that easy to find. I had both of my exhaust manifold go within about 6 weeks of each other after the swap and finding used ones was not easy. In short if it needs that much work I'd go with something else. A Big Block Buick or a Caddy 500 would be my choice if gas was not an issue. I am dropping a 6.2l diesel in mine with a 700R4/208 combo. I should double my mileage without a problem. Chevy engines are abundant and cheap! Novak and advance adapters make motor mounts to drop a chevy in out trucks but you would have to probably look for a SM420 or SM465. I picked up a 4 bolt main, 4 barrel sbc/sm465 combo cheap for $300. Don't give up on the J-truck, if you've never owned one or drove one for a while I think you will find that they are great trucks with TONS of character. I wouldn't sell mine for anything. Good Luck! P.J.

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10-13-2005, 08:02 PM	#3 (permalink)
Peter_C Registered User Join Date: Aug 2004 Member # 34538 Location: Santa Rosa Posts: 443	You need to run a CLT aka cylinder leak down test to see where you are loosing compression at. If you have an air supply you can set each cylinder on top dead center then pressurize the cylinder with an adapter of some kind (Compression tester with the valve removed works) and listen to where the leak is. Whooshing from the exhaust would indicate a bad exhaust valve, and remove the oil cap and listen there for noise which would indicate bad rings.