Head Swap Options For 5.7L 350 TBI Engine

[Majoraslayer]

There is a dummy drive in the back that connects the cam to oil pump. Pull that out and a distributor can take its place.

B body cars had a towing package available that had a mechanical fan

That makes more sense, I noticed the dummy drive installed in the hole but didn't understand that's what it actually did.

 

[Moofus02]

That makes more sense, I noticed the dummy drive installed in the hole but didn't understand that's what it actually did.

Takes the place of the distributor to drive oil pump

 

[Moofus02]

I'm not sure how to run the ignition but you could run the lt1 injection in batch fire with tbi computer. I haven't figured out the ignition part.

 

[99xcss4]

a tpi l98 intake will fix the ignition problem

 

[tayto]

As I understand it, the LT1 block is cast differently from other 350 blocks when it comes to the coolant passages. Because of the reverse flow cooling, it isn't able to flow coolant to most other 350 heads correctly. Part of that includes a special water pump that runs on a shaft connected to the timing set instead of a serpentine pulley, so you're kinda limited to using that weird pump without a bunch of machining to the block. Then you need to plan everything else around that pump, including an electric fan conversion since you can't attach a clutch fan to the water pump.

It was also designed with a front-mounted "Opti-Spark" distributor. That's not too difficult to convert to a traditional distributor, but you do have to change the intake to a carb style, and if I remember correctly, swap the gear inside the block that drives the rear distributor. Otherwise, the block itself is cast to support a rear distributor.

I am not trying to convince you to use the LT1, but we've already shared an intake that would allow you to keep TBI and its distributor. You will need an adapter plate, spreadbore to TBI, this can be made out of 1/2" thick sheet of aluminum and basic hand tools if on a budget. this is how I did it when I did my first TBI conversion in the early 2000s. This means no optispark, or rewiring. If you don't have A/C or plan to keep A/C I don't see the accessories not working. Yes you will have to run e-fans, the mechanical fan that came on b-bodies is off centre from the water pump centre line and the belt tensioner is unobtainium. the block has the holes drilled for stock SBC motor mounts. Regardless of what you do you are going to need PROM tuning. Like I admitted earlier the only expensive thing here is the GMPP intake.

 

[Moofus02]

I am not trying to convince you to use the LT1, but we've already shared an intake that would allow you to keep TBI and its distributor. You will need an adapter plate, spreadbore to TBI, this can be made out of 1/2" thick sheet of aluminum and basic hand tools if on a budget. this is how I did it when I did my first TBI conversion in the early 2000s. This means no optispark, or rewiring. If you don't have A/C or plan to keep A/C I don't see the accessories not working. Yes you will have to run e-fans, the mechanical fan that came on b-bodies is off set from the water pump centre line and the belt tensioner is unobtainium. the block has the holes drilled for stock SBC motor mounts. Regardless of what you do you are going to need PROM tuning. Like I admitted earlier the only expensive thing here is the GMPP intake.

Corvette accessories drive has the ac mounted up high

 

[tayto]

Corvette accessories drive has the ac mounted up high

it does, but the last set i saw go for over $800 USD on ebay. The F-body or B-body are (somewhat) easier to find and much cheaper (about 1/3rd of the price). The only fitment issues you run into with the F/B body accessoroes is if you are keep the A/C compressor. I have done a few swaps and a torch and a large hammer is all i've needed to clearance the frame. Some cut out and weld in new metal.

 

[Majoraslayer]

I got my Vortec heads, so I'm on track with that build plan. Today I took off my intake and discovered I do in fact have roller provisions, so I'll be using the Vortec heads with the LT1 cam. That means I'll have the following setup:

- Ultimate TBI Mods
- TBI Stock Block/Lower End
- Vortec Stock Heads (Drilled For Coolant Bypass)
- LT1 Stock Roller Cam/Springs/Lifters
- GMPP Vortec-to-TBI Intake w/EGR
- Short Headers, Dual Exhaust To X-Pipe Crossover, Flowmaster 40's & "Infinite Flow" Cats
- EBL Modified ECM For Tuning

For you guys that are infinitely more knowledgeable on this, what would be a realistic horsepower and torque estimate for a setup like this? Would I need to account for over 300 HP possibly damaging my 700R4, or should I be pretty safe in the sub-300 zone that the 700R4 can safely handle?

 

[Sean Buick 76]

I wouldn’t worry about the trans there is no magic Hp number just be respectful of it while driving. just focus on getting the TBI to fuel the beast

 

[Majoraslayer]

I wouldn’t worry about the trans there is no magic Hp number just be respectful of it while driving. just focus on getting the TBI to fuel the beast

I mostly learned about it's supposed limitations while considering a 454 swap. According to reading around online, apparently they're rated to withstand around 350 horsepower but are generally known to actually start blowing up around the 300 horsepower mark. I ask less out of being overly optimistic about power gains, and mostly an abundance of caution to avoid unexpectedly adding on the cost of a transmission swap (one way or another). I figure with the TBI, Vortec, and LT1 engines all being rated at factory specs within tolerance of a 700R4/4L60E, hopefully mating the good parts of them together will still be within it's spec to handle without too much trouble. I know even the 700R4 can be upgraded to withstand a lot more power, but that's another cost I'm trying to avoid if I can.