187 heads on 350

[Outlaw 190 Proof]

Hi everybody I have a 89 K2500 4x4 350 TBI with a TH400 ECLB truck that I am rebuilding and right now trying to make a decision on the engine build.

I know vortec or aftermarket heads would be the best but I don't have the money to do the vortec swap.
I just looked at the casting number of the heads on my 350 and it has 4102187 heads on it which I am pretty sure are 305 TBI heads with 58cc heads.

For my build my plan was originaly to gain compression ratio (9.5:1 at the most so I can run 87 octane)
port and polish stock heads and intake
ultimate TBI mods
keep my TBI spacer
new cam
any bottom end work needed
and reassemble with new felpros.


Question is now are the 187 heads better then the regular 350 tbi heads?

I have a edelbrock performer carb 2101 intake manifold and I am wondering it with these heads it would be a good idea to swap to carb. If I go carbed I know I need a regulator, distributor, coil, and carb.


The truck is just going to be a driver for long distance and my towing truck. It will be pushing 37s so torque is important and I am reading the TBI heads are good for that. I have another truck that is my DD so this one won't be driven much really.
thanks for any help

 

[slowburb]

I am pretty sure these are swirl port heads like their "5.7L" counterparts. The smaller chambers may afford you a bit more static CR, but I'm unsure of the intake port volume. If they can't breathe as well as the 193's, you're not gaining much of anything. Flow trumps compression every time.

 

[Outlaw 190 Proof]

ya see that is the part I am worried about is the flow being to little.

I am also worried that those heads are the reason for it running like it is currently (backfiring when reving it up, bogs down and won't move unless I put the truck in 4 low.


I know the valves in the 187s are smaller then the 193s.

 

[Outlaw 190 Proof]

Found a flow rating:
187 heads: 165 intake with 1.84" valve and 140 exh with 1.50" valve

193 heads: 178 intake with 1.94" valve and 146 exh with 1.5" valve.


Looks like the 187s flow way less.

I can see why my buddies dad put them on this truck thinking higher compression better HP but didn't figure in the flow part.

Guess my budget it out the window now to decide keep TBI and find some vortecs or carb heads and go carbed.