V6 to v8 swap

[Langabeer84]

I have a 89 c1500, it’s 2wd single cab with a 5 speed manual. I was just wonder what all I need to put a 383 in it it will be carbureted, and if the trans in it currently will bolt right up. Thank you in advance!

 

[SUBURBAN5]

Depends of your fly wheel. I've got a 98 vortec and gm sends the correct flexplate to hook up with a 1/2ton. My trans was the 4l60e. I remember gm listed a part# for manual transmissions (flywheel) I've got the ht383e. Yours would be a ht383 I think unless your building your own or going aftermarket. But yes they sell the correct flywheels you just have to confirm yours and order the correct part. Heres a pic what I'm referring to keep in mind it's a slightly different motor since mine is a vortec but will hopefully help out

 

[DamHoodlum]

Also depends if you have a 1 piece or 2 piece rear main block

In other words , Your current flywheel wouldn't work with an earlier 2 piece rear main block

 

[Schurkey]

You'll have to regulate the fuel pressure downward from 9--13 to perhaps 5--6--7 psi. You "could" do this with a dead-head regulator, but since the plumbing is already there for a return, you'd be crazy to not use a return-style regulator. The pump will last longer, too. Of course, you'll have to extend/modify the engine-compartment end of both the supply and return plumbing.

You'll need a non-computer-controlled distributor. A "good used" Delco 4-pin/vacuum advance "coil in cap" HEI should be fine. You may need a different distributor gear, if you're using a steel camshaft.

I assume the V6 has the same accessory drive as the V8 engines of the same year. The intake manifold you select will need bosses for the alternator brace, (easy) and the A/C compressor brace. (Good luck. I still need to fabricate a new brace for my '88 to suit the new manifold.) You should be able to use the thermostat stud for the belt tensioner brace unless the manifold moves the thermostat housing.

You'll need to deal with the "shift" light on the dash, if your vehicle has one. I despise "shift" lights, I'd pull the damn bulb if needed. MAYBE, with no computer, the light never comes on.

Make sure your new engine is balanced to compliment the flywheel and damper. I'm not sure how the V-6s are balanced. If the new engine is neutral-balanced, the flywheel will have to be neutral balanced. Your damper is already neutral, I think. If the engine has the same out-of-balance that the original engine has, the original offset-balance for the flywheel and neutral-balance damper should be OK. But if this new engine has the old "400 small-block" balance, you're gonna need a new damper and a custom flywheel. In other words, the damper/flywheel balance AND the flywheel bolt circle both have to match the new engine.

Make sure the timing indicator on the timing chain cover, matches the timing mark on the damper. There's at least two different alignments, maybe more.

V-6 to 383? Bigger radiator, different radiator shroud. Different upper and lower radiator hoses. Shorty headers with a proper Y-pipe such as a JBA 2831SY. Maybe stiffer springs. You'll be lucky if you don't need a stronger transmission. Guys blow-up the light-duty 5-speeds with stock V-8s.

Start saving up for a Treasure Yard 9.5" rear axle with 11.x Duo-Servo rear brakes, and custom axle shafts to convert it to 5-lug so you can keep your current wheels. And then expect to put some sort of posi/locker in it.

Look on your glovebox decal, find out if you have JN3 brakes. JN3 is terrible. Small booster, small master cylinder, small pistons in the calipers, thin front rotors, shiity "10-inch" 254mm rear drums. JB5/JN5 is substantially better except for the same crappy rear drums.

Why would you use a carb? Seems like a giant step...backwards.

Consider selling the truck, and buying one with a V-8 and stronger drivetrain to begin with.

 

[DamHoodlum]

Its not really all that complicated, I did the same thing to my truck 20 years ago and haven't looked back. All of the parts you need are readily available.

Most of the V6-V8 brackets will interchange, I used the V6 starter, flywheel, water pump, power steering, AC serpentine setup. But I also replaced it with an (1 piece main) late model block.

Yes your tranny is weak but can suffice until you could upgrade later

Go for it, Just do you, If you need any help let me know

 

[kennythewelder]

Its not really all that complicated, I did the same thing to my truck 20 years ago and haven't looked back. All of the parts you need are readily available.

Most of the V6-V8 brackets will interchange, I used the V6 starter, flywheel, water pump, power steering, AC serpentine setup. But I also replaced it with an (1 piece main) late model block.

Yes your tranny is weak but can suffice until you could upgrade later

Go for it, Just do you, If you need any help let me know

Very clean, nice job.