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**'68OrangeSunshine** · 02-26-2025, 05:53 PM

Mr Kalums -- is your truck manual or automatic?
My '71 GMC Jimmy had rams horns when I bought it in 1995, but the PO's engine sucked valves on Cylinders 6 and 7 when I tried to tune it up to pass Pima County emissions. When I was re-engining with a 350 crate motor, I noticed the PO had installed mismatched stock exhausts. One had been capped where reblended exhaust fumes were infused back into the combustion chamber for the early smog A.I.R. system, the other was pre-emissions. The A.I.R. system was gone. I am quite sure they were dissimilar in CFMs. One may have been canted and the other straight down.
It was simpler for me to get Heddman headers.

02-26-2025, 05:53 PM	#10
'68OrangeSunshine Senior Member Join Date: Feb 2002 Location: Tucson, AZ USA Posts: 8,118	Re: 71 GMC engine swap-arino Mr Kalums -- is your truck manual or automatic? My '71 GMC Jimmy had rams horns when I bought it in 1995, but the PO's engine sucked valves on Cylinders 6 and 7 when I tried to tune it up to pass Pima County emissions. When I was re-engining with a 350 crate motor, I noticed the PO had installed mismatched stock exhausts. One had been capped where reblended exhaust fumes were infused back into the combustion chamber for the early smog A.I.R. system, the other was pre-emissions. The A.I.R. system was gone. I am quite sure they were dissimilar in CFMs. One may have been canted and the other straight down. It was simpler for me to get Heddman headers. __________________ Every 25 years I like to rebuild that 292, whether it needs it or not.



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