Head Swap Options For 5.7L 350 TBI Engine

[Majoraslayer]

At the moment I have a couple prospects lined up for some heads. One guy has them installed on a motor and is asking $400 for the set. The other guy is selling some for $100. The $100 set are 062 and have surface rust from sitting, and the $400 set are the 906 and are currently installed on an engine. I already have a budget plan for the build, and it's contingent on finding a good deal on used heads. $300-$400 for a decent, un-cracked set of used heads is pretty much it. If $1200 for aftermarket is the only option then I'd just stick with TBI. I already have the budget set aside for the EBL upgrade so I'll good control over tuning options as well. I'm well aware of the costs involved in this "hobby", I've been fighting this truck for almost 20 years lol. I've narrowed it down to two upgrade paths depending on what parts I find:

1) Vortec heads, LT1 cam (if my block supports it), GMPP intake (if the deal comes through I found).

2) TBI heads, Edelbrock Performer flat tappet cam, Edelbrock Performer TBI intake.

 

[L31MaxExpress]

If your block supports it I would use a roller cam regardless of what heads you put on it.

The Performer TBI cam is not the greatest grind. It has less intake duration than the factory TBI 350 cam. A MTC1 performs and runs better than that Performer cam ever thought about. To this day I do not understand Edelbrocks logic on that cams grind. Added exhaust duration is not what the TBI needed. A single pattern cam has more average torque using the swirl ports. The 3702 has a massive 20* intake/exhaust duration split at 0.050" yet these heads favor a single pattern grind with equal intake and exhaust duration given their somewhat restricted intake ports.

I have run both the F-car or Vette LT1 cam and the production 96 LT4 cam with TBI and TBI heads. It is a definite improvement over what was there stock at every point in the powerband.

 

[tayto]

If you want cheap power, I'd stick the LT1 in. I do agree that the intake for it throws budget out the window somewhat. Is your LT1 iron or aluminum heads?

 

[Majoraslayer]

If you want cheap power, I'd stick the LT1 in. I do agree that the intake for it throws budget out the window somewhat. Is your LT1 iron or aluminum heads?

Aluminum heads.

I made several build plans with parts lists and costs, and the LT1 swap ended up way more expensive than the alternatives at the target power I'm looking to build. Thanks to the reverse flow cam-driven water pump, I would need all new brackets and accessories as well as an electric fan setup. Also, as I understand it there are two ways to mount it in the truck: either swap older mounting ears onto the block and give up one of the accessory bracket mounting holes for A/C (at least from some comment I saw), or modify the frame. Neither one of those options sounded appealing. Adding that on top of the cost of an intake and TBI adapter made it a much more expensive alternative than the others.

 

[Sean Buick 76]

Yes ditch the lt1 dont spend good money after bad

 

[98 Nitro]

I remember you from the TGO and FSC boards and to take any power claims you make with a grain of salt, and that you love to argue. Having said that hey believe what ya want.

 

[98 Nitro]

If your block supports it I would use a roller cam regardless of what heads you put on it.

The Performer TBI cam is not the greatest grind. It has less intake duration than the factory TBI 350 cam. A MTC1 performs and runs better than that Performer cam ever thought about. To this day I do not understand Edelbrocks logic on that cams grind. Added exhaust duration is not what the TBI needed. A single pattern cam has more average torque using the swirl ports. The 3702 has a massive 20* intake/exhaust duration split at 0.050" yet these heads favor a single pattern grind with equal intake and exhaust duration given their somewhat restricted intake ports.

I have run both the F-car or Vette LT1 cam and the production 96 LT4 cam with TBI and TBI heads. It is a definite improvement over what was there stock at every point in the powerband.

Yes the Melling cam is a cheap upgrade over stock if you ate going with TPI or 350 Vortec heads. The Eddy cam according to it's designer who use to be an editor at CHP magazine said it was for those early 80s 305 engines, I also agree a single pattern cam would be better for TBI heads or 305 Vortecs heads.

 

[Erik the Awful]

Out of curiosity, what is the difference in the blocks between the TBI and LT1? I was not aware there were differences.

 

[Majoraslayer]

Out of curiosity, what is the difference in the blocks between the TBI and LT1? I was not aware there were differences.

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.

 

[Moofus02]

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.

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