TBI head swap to 180 AFR - The 1947 - Present Chevrolet & GMC Truck Message Board Network

chris989 · 07-21-2024, 04:06 PM

Hello all,

1989 v2500 5.7 4l80 original build
https://67-72chevytrucks.com/vboard/...d.php?t=696544

I am on the fence with regards to swapping a pair of AFR 180cc heads and ditching the TBI swirl. My original build has been great but thinking of making an upgrade. The truck currently get 15+ on the highway,, ~13 around town and ~10+ towing. I don't want to mess that up swapping to a BBC but always looking for a little more torque.

Has anyone swapped about the swirl ports and seen again? was it the same?
I am not really interested in "vortec" heads,,, I would consider in aluminum any AFR, Trick flow, or edelbrock.

Yes i understand the value of a roller cam but for the price tag i would stroke the 5.7 first..

https://www.airflowresearch.com/180c...nder-head/p540

Thanks,
Chris

**kwmech** · Yesterday, 10:59 AM

I've been on the fence with the same thing. I think the route I'm going to take is a roller cam swap first. I'm looking at the SUMMIT 8800 cam and go from there.

**THI** · Today, 09:43 AM

Years ago I swapped out the TBI heads for some older "smog" heads - 993 castings. Even though the compression was down due to the 76cc chamber vs the 64cc chamber of the TBI heads, they flowed enough more that you could tell the difference. I also replaced the weak TBI cam with the standard 307-350-400 cam. I had the intake modified to bolt up to the older heads. Had the parts laying around or I would have used an aftermarket cam.

This was on a 1990 K1500 and it improved the drivability, would rev higher and faster, pulled strong and got over 20 mpg on the highway and 15 mpg around town. This was an inexpensive build project for my son who just got his license at the time using what was laying around my shop. We bought the truck with a blown engine, freshly built TH700-R4 and new tires. My son drove it until it was totaled when he was rear-ended (truck bent into an upside down "V") and my son walked away!

**kwmech** · Today, 11:58 AM

Wow, that's funny I just dropped off some 993 heads at the machine shop with the new roller cam valve springs. How much compression do you think you lost? AND how did you convert the intake manifold? I was considering taking a smog legal 4 bbl manifold I have from edelbrock and having the top of it shaved off and welding in a 1'' thick helix throttle body spacer

**THI** · Today, 01:05 PM

Compression dropped to 8:1 with the 993 heads - same compression on the HD version of the 5.7 TBI used in the 3/4 & 1 Tons. The 993 heads are much better flowing than the TBI heads so that helped make up some of the loss due to compression.

I used the stock TBI intake and had the center bolt holes elongated so bolts would go straight in and had the top surface machined to be parallel with the mounting surface.

07-21-2024, 04:06 PM	#1
chris989 Registered User Join Date: Dec 2011 Location: Boise, Idaho Posts: 566	TBI head swap to 180 AFR Hello all, 1989 v2500 5.7 4l80 original build https://67-72chevytrucks.com/vboard/...d.php?t=696544 I am on the fence with regards to swapping a pair of AFR 180cc heads and ditching the TBI swirl. My original build has been great but thinking of making an upgrade. The truck currently get 15+ on the highway,, ~13 around town and ~10+ towing. I don't want to mess that up swapping to a BBC but always looking for a little more torque. Has anyone swapped about the swirl ports and seen again? was it the same? I am not really interested in "vortec" heads,,, I would consider in aluminum any AFR, Trick flow, or edelbrock. Yes i understand the value of a roller cam but for the price tag i would stroke the 5.7 first.. https://www.airflowresearch.com/180c...nder-head/p540 Thanks, Chris

Yesterday, 10:59 AM	#2
kwmech Senior Member Join Date: Mar 2003 Location: Colfax-California Posts: 8,495	Re: TBI head swap to 180 AFR I've been on the fence with the same thing. I think the route I'm going to take is a roller cam swap first. I'm looking at the SUMMIT 8800 cam and go from there.

Today, 09:43 AM	#3
THI Active Member Join Date: Jan 2017 Location: Traverse City, MI Posts: 177	Re: TBI head swap to 180 AFR Years ago I swapped out the TBI heads for some older "smog" heads - 993 castings. Even though the compression was down due to the 76cc chamber vs the 64cc chamber of the TBI heads, they flowed enough more that you could tell the difference. I also replaced the weak TBI cam with the standard 307-350-400 cam. I had the intake modified to bolt up to the older heads. Had the parts laying around or I would have used an aftermarket cam. This was on a 1990 K1500 and it improved the drivability, would rev higher and faster, pulled strong and got over 20 mpg on the highway and 15 mpg around town. This was an inexpensive build project for my son who just got his license at the time using what was laying around my shop. We bought the truck with a blown engine, freshly built TH700-R4 and new tires. My son drove it until it was totaled when he was rear-ended (truck bent into an upside down "V") and my son walked away!

Today, 11:58 AM	#4
kwmech Senior Member Join Date: Mar 2003 Location: Colfax-California Posts: 8,495	Re: TBI head swap to 180 AFR Wow, that's funny I just dropped off some 993 heads at the machine shop with the new roller cam valve springs. How much compression do you think you lost? AND how did you convert the intake manifold? I was considering taking a smog legal 4 bbl manifold I have from edelbrock and having the top of it shaved off and welding in a 1'' thick helix throttle body spacer

Today, 01:05 PM	#5
THI Active Member Join Date: Jan 2017 Location: Traverse City, MI Posts: 177	Re: TBI head swap to 180 AFR Compression dropped to 8:1 with the 993 heads - same compression on the HD version of the 5.7 TBI used in the 3/4 & 1 Tons. The 993 heads are much better flowing than the TBI heads so that helped make up some of the loss due to compression. I used the stock TBI intake and had the center bolt holes elongated so bolts would go straight in and had the top surface machined to be parallel with the mounting surface.



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