Thread: TBI swap 1990 pickup

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Originally Posted by sawking

Yes that does help.I'll probly get that cam for it. Does my older 350 have 1.5 rockers on it and Does the 1990 350 have 1.6 rockers on it. Which ones should I use. Also will the tbi intake fit on the older 350. Or should I get a adapter for the four-barrel intake to tbi

I just did this conversion on a 91 PU. We replaced the 350 with a 383 and a mild cam. The heads were ported and we installed headers and dual exhaust. Between the computer and the TBI, we had nothing but problems. It was too lean and it would fall flat on it’s nose. So we got a TBI off of a 454 which helped a little and we added a one inch spacer but the fuel economy was not good.

Finally we installed a Holley carb and an HEI distributor, what a difference. We can fry the tires without any problem and the fuel economy went up. So now we have all this TBI junk laying around collecting dust.

As for mounting the TBI and intake on the 355, you can make it work if you message the center 4 bolt holes of the intake. The newer heads have a different angel to the four center bolt holes. Obviously you don’t mess with the threaded bolt holes in the heads.

Originally Posted by TyphoonZR

I just did this conversion on a 91 PU. We replaced the 350 with a 383 and a mild cam. The heads were ported and we installed headers and dual exhaust. Between the computer and the TBI, we had nothing but problems. It was too lean and it would fall flat on it’s nose. So we got a TBI off of a 454 which helped a little and we added a one inch spacer but the fuel economy was not good.

Finally we installed a Holley carb and an HEI distributor, what a difference. We can fry the tires without any problem and the fuel economy went up. So now we have all this TBI junk laying around collecting dust.

As for mounting the TBI and intake on the 355, you can make it work if you message the center 4 bolt holes of the intake. The newer heads have a different angel to the four center bolt holes. Obviously you don’t mess with the threaded bolt holes in the heads.

I never thought of opening the holes up further in the stock intake to line up. Smart. If you were running lean, you COULD get bigger injectors, or buy a new TBI which jegs sells.
Also, as you stated you had a 383. Thats understandable of the fuel consumption increase, and performance loss as far as fuel economy. Mine sucked too at first, but I took my truck down to the dyno and had it tuned perfectly and now, i get great gas mileage.

Ok if go the TBI way I have to get-
Different tbi mine is worn out-100+
Different cam-150+
Adapter for intake-50
300 dollars

With Carb
Carb- 350
Maybe a new msd hei distributor-150
500 dollars plus the carb will be new compared to used tbi unit.

Now I'm leaning towards the carb conversion.
Is there anything I should add or minus from either of these options.