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

**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.

Today, 01:05 PM	#1
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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