GM 5.7L TBI & Thunderbolt IV compatibility

[Panoguy]

Long story short - my purchased (5-yrs.-ago) reman. short block was improperly assembled, resulting in wristpin SEVERELY etching #2 cylinder wall.

Yay.

I have a handle on pulling a complete 5.7L Vortec TBI out of a 1998 Chevy 2500HD truck. I'm wondering if I can use the TBI (I'd need to add an electric fuel pump) with my current Thunderbolt IV ignition/Alpha 1 outdrive setup?

If this won't work, how-about pulling-off the TBI, & using my Quadrajet, instead... going old-school - would this be more practical? Any thoughts or suggestions would be much appreciated.

Thanks!

 

[Scott06]

Long story short - my purchased (5-yrs.-ago) reman. short block was improperly assembled, resulting in wristpin SEVERELY etching #2 cylinder wall.

Yay.

I have a handle on pulling a complete 5.7L Vortec TBI out of a 1998 Chevy 2500HD truck. I'm wondering if I can use the TBI (I'd need to add an electric fuel pump) with my current Thunderbolt IV ignition/Alpha 1 outdrive setup?

If this won't work, how-about pulling-off the TBI, & using my Quadrajet, instead... going old-school - would this be more practical? Any thoughts or suggestions would be much appreciated.

Thanks!

Automotive tbi will not be marine rated for fuel and electrical safety stay with the carb assuming it is a marine w jet

You need an 8 bolt vortec intake Michigan motorz sells a decent cast iron one. You may have an issue with pulley alignment but all else should carry over

Flywheel may be different is the truck a manual if so u can use the automotive flywheel

 

[Panoguy]

@Scott06, I guess if I go w/ carb, the only "surprise" would be switching from a manual to electric fuel pump - no biggie.

I'm not sure if truck is manual or auto trans... I'm going to look @ it tomorrow. I have all GM 5.7l marine goodies that I can transfer to the "new" engine.

 

[Scott06]

You will need a low pressure marine fuel pump and wire it through a oil pressure switch so it wont run if ignition is on but engine isnt running . Search the threads you will see wiring examples for this safety feature.

is your q jet an electric choke or divorced heat stove? If heat stove you will need a electric choke conversion fro. Somewhere like cliffs qjets

 

[matt167]

A 1998 would have vortec spider injection. You could find a marine MPFI manifold but you need a distributor that has locked advance

 

[Scott Danforth]

The only thing you will use from the truck motor is the short block and heads

You will need to install brass core plugs and marine head gaskets.

You will need to swap over your marine stuff from your current motor. Water pump, electrical system, accessory drive, oil pan and dipstick, fuel system, etc.

Since your current motor has a stove tube choke, my guess is that it's a Q-jet. So you will need a new intake manifold for the vortec heads

If you keep your current stove tube choke, there are electric choke conversions for about $40

98 truck motor EFI would be an explosive risk in your boat. The batch fire spider assembly fails in the trucks.

 

[76SeaRay]

The truck cam may be close but you might want to consider changing out to a marine cam while the engine is out and while you would be changing the intake manifold you have access to the lifters. I went with a Comp Cams Xtreme Marine Cam on my engine which started out as a 96 5.7L vortec truck block. I set it up with roller cam, roller lifters, and roller tip rockers with push rod guide plates.