BillyDavNav

Hey all,

I have a 95 c1500 W/T with the 4.3 v6 in it (5 speed manual) and I'd like some more get up and go. Supposedly the 350 uses the same engine mounts and everything as the 4.3, and from my understanding the 4.3 is just a 350 with 2 cylinders cut off.

My dad has a 4 bolt main 350 block in the barn he said I could have. I'd like to do it right and build it to last. I have about 3 grand I'd be willing to put into it. Any advice? It's my daily now and needs to be reliable, but if I could get 350-400 horse out of it that'd just be dandy.

Just to be clear, I don't have heads or anything. Just the block right now.

Thank you all in advance!

oilcanhenry

Nothing wrong with the 4.3-liter Chevrolet motor. You are correct. It's more or less a 350/5.7 liter with two cylinders missing. If you want more HP then a swap would be best to the 5.7/350, not modifying the .4.3 liter mill. Should be pretty easy, but I believe you'll need the ECM for that swap. Since you likely have OBD I, you'll need the ECM for that, not OBD II. As for trannys' in pickups, I'd rather have a slush box than an automatic. No need to worry about transmission temperatures for one thing. Keep us informed how it goes if you wish to do so.

BillyDavNav

Hello,

Definitely planning on swapping in the 350, but not sure what parts to build it with. Sorry for not being more clear!

oilcanhenry

Well, you'll need a shorter fan shroud, as the 4.3 liter has a long one. I suppose, if you don't care about aesthetics, you could just cut it back with a sharp tool to make it fit properly. What year is the 350 mill you plan on installing into your Chevy C-1500? TBI system? What kind of heads will you be installing, for instance.

The more information you can give us, the better that we can help you with your 4.3 to 5.7 project, BillyDavNav..

BillyDavNav

Hello again,

I'd like it to look nice, so I'll go with a shorter fan shroud. I believe the block is a 69, but I'll confirm tomorrow. Definitely older. As I said before, the only thing I have is the block. I'd appreciate advice on everything else. I'm thinking a holley carb, but I'm open to suggestions. I heard the vortec heads are good, but again open to suggestions. Thank you again!

oilcanhenry

Pretty sure Vortec heads were meant for fuel-injection motors. Not even sure they'd bolt up to a 1969 Chevy motor, but I could be mistaken. Yeah, Holley Carbs were my favorite brand, and trust me, I know all about carburetors. A Holley 650 CFM would work great in a 1969 GM motor. They were built before smog motors came around in1 1973, so you'll have a high compression motor, not 8 to 1 as they dropped to.during the early 1970' to 1986-87 when fuel injctied motor were allowed for high compression motors once again.

BillyDavNav

I'll go with the 650 holley then. What do you think for heads and rods? Cam recommendations? I'd like to keep the build around 3 grand. (Also, 350+ horse would be nice)

oilcanhenry

I'd go for the stock heads for a 1969 motor. Crane is a good cam, but I wouldn't push it too far, unless you don't mind a rough idle and loping. I put a light Crane in my Jeep, along with a Cloyes timing chain, and it did increase HP some, but an inline 6 cylinder is only going to do so much.

The 304 AMC V8 was a good motor, but the FoMoCo distributor was up front on the engine, made deep water crossings very iffy, as they were not like the Prestolite distributor on the 258 I-6. The AMC 258 I-6 was as good as the Chevy 250 I-6. I'd definitely go with a Cloyes timing chain on your build. They will last forever. The stock GM timing chain is good, but Cloyes is simply better.

The best way to reach 350 HP is to keep the compression ratio's high, but it all depends on if you want to run regular grade gasoline or premium high-octane grade gasoline. Too, I'd absolutely go with Fel-Pro head and intake gaskets, the best ones ever made, and well worth the extra money.