i have a '90 firebird 5 speed, i replaced the 305 with a 350 from a '89 chev cube van (ran on propane).

350 stuff im using: engine, knock sencor,

305 stuff im using: ecm '746, prom APTY, throttlebody,injectors, iac,tps ect...(pretty much everything!)

it runs and has power but about 1 min after i start the idal starts to increase and decrease in a rythum 1000 rpm - 400 rpm roughly. after about 10 mins it seems to idal fine at 800ish rpm. it has done this since i put it all toghther (a few months). im stoked that i got it going but want it to run right! i got a timing light on it and cheaked it with the wire unhooked and it reads 50* advanced? some say i need prom, esc and injectors and some dont! ive spent hours online and hasseled many parts guys and dealers and hope you can help. please give imput if you have experience that can help me!

 

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Which damper do you have on the 350?

 

stock fuel pump ??? What psi are you running !
Nina your posts always make my eyes go ,>.<, nice colors
and she ? or he srry if im wrong, is got good suggestions!

 

thanks,

do i need tps for 350 cause parts guy says 350'S were multiport and im tbi.

yes, stock fuel pump. i dont know how to cheak pressure. i seemed to drive pretty good. does that mean my pressure is ok?

i had the 8'' on (was on the engine when i pulled it from the cube van) after some research i put on the 6''. The timing mark IS right i cheaked this morning. i changed it cause of a vibration. turns out it was a missing ps pump bolt which one should i use. (fylwheel is fron 305 as is the 6'' balancer)

 

No, if its functioning properly a 305 and 350 TPS are identical. If you need to source 350 TBI parts for your ride, look at the same year Caprice 9C1 cop car. Injectors are 61# rather than 55#, Knock sensor is different, and finally the chip is way different.

If you have a 6" 305 harmonic balancer and a 350 timing chain cover for an 8" harmonic balancer, the mark is in the WRONG location. Put the correct 8" balancer on it and you should be able to correctly set your timing. FWIW, I run the 6" 305 balancer and timing cover on my 350.

 

That's what I was getting to. It's not 6" vs. 8", or 305 vs. 350, but where the timing mark is on the damper ring.

 

good call! i cheacked the timing mark by finding TDC on intake stroke and sticking a piece of wire in their to feel if the piston was at the top. the 6" seemed to be the same, so much for short cuts! i took it off and "guess what?" the marks are way different! so i reunited the 8" with its origional tc cover and had no problems finding base timing 0* with the wire unplugged!

their was never an"ses" light on (comes on briefly when starting so i know it works) so i figure oth o2 is ok. is that right? however i did decide to mess with the tps and it read .78v so after breaking one of the bolts and loosening the other i removed some of the plastic around the mounting holes and bolted it back on with only one bolt (which made it easier to adjust) and set it to .54v . car now runs without worring me! thank you!

any ideas on how to get the broken bolt out? theirs about an 1\8" sticking out of the tb

and does anyone know a p# for an adjustable tps? mine works for now but messed it up pretty good with the drill!

 

"50 degrees" was the clue. The difference between 12 o'clock and 1:30-ish is about 45 degrees.