I am the proud new owner of a k5 blazer and joined this forum for it's incredible wealth of knowledge concerning tbi's. I want to run propane cuz it's cheap here in Montreal but i am running into a problem concerning timing. I bought a used impco kit for a carbed 350 and had to buy a tbi adapter. My problem is with timing. I need to advance it to take full advantage of the propane conversion. I plan on using the truck as a switchable dual fuel vehicule so in essence be able to flick a switch to change fuels. There was a module that piggy backed the ecm in the past but it is now discontinued and I don't want to spend a fortune for a MSD timing adjuster or expensive aftermarket ecm just for a few points of timing. Is there a way to fool the distributor or ecm into doing this? I am well versed in electronics so even hard to accomplish solutions will be appreciated.

 

No need to fool. Just advance timing at the distributor. Disconnect the brown plug so ECU is not in control. Then reconnect. Years back i ran a hyperchip with cold therm and they suggested advancing in that manner I think 2-4d....

 

I also run 87 octane gasoline so 15 degrees of timing is going to give me detonation. That is why I want to have switchable timing on the fly

 

The easiest way to do this is via either two PROMs or a larger PROM with a switch. This way you can have a gasoline tune in one PROM/area, and a propane PROM/area to use. A flick of a switch can be used to select which one.

I though that Craig had something like this (www.moates.net), but looked briefly and didn't see it. Best to email with your current set up and ask about a BIN/calibration switcher for it.

Craig just supplies the hardware, IIRC, tuning/PROM-burning is up to you.

RBob.