california swap.

I live in California and I have a 1989 Astro RS with a 350 TBI engine in it. At this point the engine is completely stock and must go through both the referee station to be checked for safety and then through a tail pipe smog test. The engine is a 1992 chevy 350 out of a silverado with 90k approximate miles. After I get it legal my plan is to rebuild and port and polish some stock TBI heads install an LT1 cam same as the Buick roadmaster had add some short tube headers (I got them for free) They are hedman 68600 shorty headers to be exact. 3 inch single exhaust all the way back through a sonic turbo muffler and high flow converter (brand new) I have added a 3 wire 02 sensor too. I plan on a better intake manifold too in the future along with bored out stock TBI and police car injectors. Do I need a new chip when this is done and does anyone here do them? my ecm/pcm is a 7747 and I have a couple spares as well as spare TBI units. I am welcome to any ideas. My plan for the van is long distant driving and towing a small camper at time. Thank you , Mark

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Originally Posted by markincali

I live in California and I have a 1989 Astro RS with a 350 TBI engine in it. At this point the engine is completely stock and must go through both the referee station to be checked for safety and then through a tail pipe smog test. The engine is a 1992 chevy 350 out of a silverado with 90k approximate miles. After I get it legal my plan is to rebuild and port and polish some stock TBI heads install an LT1 cam same as the Buick roadmaster had add some short tube headers (I got them for free) They are hedman 68600 shorty headers to be exact. 3 inch single exhaust all the way back through a sonic turbo muffler and high flow converter (brand new) I have added a 3 wire 02 sensor too. I plan on a better intake manifold too in the future along with bored out stock TBI and police car injectors. Do I need a new chip when this is done and does anyone here do them? my ecm/pcm is a 7747 and I have a couple spares as well as spare TBI units. I am welcome to any ideas. My plan for the van is long distant driving and towing a small camper at time. Thank you , Mark

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Better off to run the hotter F/Y-car LT1 cam as the cam specs are much closer to the L98 cam in the TBI 9C1 Caprice.

I live in Washington State, which has emission laws that are less stringent than California Emissions laws. My 93 K1500 passes Washington State emissions with the following engine modifications:
Stock TBI Heads expect for the "Z28" valve springs and 1.6 ratio roller tip rocker arms.
Modified Stock TBI Intake, the throttle bores were bored out to 54mm to allow using a 670 CFM 454 Throttle Body. The bored out throttle bores were radius-ed to allow better flow transition into the plenum area.
1993 454 Throttle Body with Cop Car Injectors.
Stock Vortec 5.7 liter L31 roller camshaft conversion.
Stock TBI engine compression ratio.
Shorty headers flowing into the stock Y-Pipe then into a 3" Catalytic Converter with a 3" single exhaust system.
Open Element K&N Air Filter Assembly

The 1993 K1500 computer is part # 16168625 not 1227747.

I Custom Tuned / Custom programmed the chip myself.

I average about 16 MPG on road trips to / from Seattle, mostly 70 MPH speed limits. Slightly less MPG towing; as to be expected.

The performance from 0 - 60 MPH is about 7 seconds, for a 5200 Lb Vehicle.

Would my 93 K1500 pass California Emissions, I doubt it, because the HC's and CO's are passing at the upper limits for Washington State.

I think you can get past both the referee and safety inspections without problem.

The California tailpipe test will not be as easy!

dave w

OK Thank you. I can do whatever I want after I pass because the county I live in require one smog test and that's it, Mark

I also live in a cal. county that only requires that first smog test. Where do you live?