The Stovebolt Site Forums The Shop Area Engine Shop TBI

I've gotten so I need to rebuild my old Rochester about once a year. She's long in the tooth, just like me.
I've been thinking about going to a Holley 5200, but then ....
I've been told there are bolt-on TBI kits for old Chevy sixes. Anyone have any experience with these?

No experience with a bolt on kit, but I can help you build a kit from standard GM parts available at the junkyard if you want. I do lots of TBI conversions for hot rod and 4x4 guys around here, if I didn't have twins on the 39 I'd be slapping a 4v manifold and TBI on it. I put them in bunch of jeep 258s which is very similar to a 235 setup.

Here's my recipe for a stovebolt TBI system:
4 bbl manifold
holley tbi adapter
Wiring harness and all sensoers out of an 87-91 G series van.
747 ecm from 87-91 truck, van, astrovan with a 4.3 chip I like the 87 chevy astro van with a 5 speed chip best
The chip needs to have the VSS/EGR logic removed (you can run without it removing these if you want, or a speedo adapter and leave the EGR solenoid with no hookup)
Computer controlled HEI from a 250 (grind and modify to fit)
Knock sensor from a computer controlled 250
O2 sensor, you can make a bung for this out of a spark plug anti fouler and put it just below the collector.
Temp sensor in the thermostat housing, I have been able to use a thermostat housing with a npt port in it off a 250 on some 235s.

It can be done without all this work with a megasquirt kit, 4.3 throttle body and your vac advance distriutor. There's a guy on ebay that will sell you an already put together megasquirt for a good price (around $300).

Chris

www.diy-efi.com has a lot of good info in the GM-ECM section.

You can modify a standard HEI distributor for computer control, too.