95gmc305

so i bought this truck from my cousin after my uncle passed away and it was his last project before becoming ill...i had no idea where he left off so i tightened the exhaust up...the relashed the valves(first using the shop manual one turn down, asked alot of ppl and they said 1/4,1/2,or 5/8s of a turn)...at the time the distributor was one tooth advanced...replaced with new one and put back to shop manual specs...it idled fine and reved pretty normal but when i would drive it it would be a little sluggish in first and the once at 2500-3000 rpm it would want to fall on its face....there were no engine codes being thrown at the time but backfired pretty bad....it has no catalytic converter, no o2 sensors, its a 305 5spd, at the moment it runs and idles when in base timing with no poppin pinging clicking(lack of power is evident of course(is it bad to drive in bypass mode????)) ive replaced the map and iac with junkyard ones but cant seem to figure it out....any help would be greatly appreciatied, it feels like ive tried just about everything....thanks guys

95gmc305

timing is dead on in bypass mode as well

mhotrodscooter

iTrader: (13)

how did you adjust the lifters? sounds like a couple crossed wires

95gmc305

shop manual says bring it to zero lash, then one full turn(half at tdc half 360over), manny ppl i talk to say 1/4, 1/2, or 5/8ths of a turn down after zero lash...i double triple quadruple checked the plug wires......the previous distributor was one tooth advanved for some reason and i put it back to the shop manuals specs

retorq

No O2 sensor and no codes?? Sounds fishy ...

ezdaar

iTrader: (1)

Pop timing cover off and make sure cam is properly timed.
Put #1 at TDC, make sure harmonic balancer hasn't slipped.

You said you replaced DIST with new unit. Is it elect or mech advance?
Backfiring is a timing related issue.

Obviously install O2's.

Is it safe to assume this is a TBI motor?
If so pop the injector cover, pull injectors and clean the filters.
Aswell the FP regulator is located under that cover, check it for holes and any binding..

95gmc305

i havent popped the cover yet but i rotated the motor twice over by hand to 0 tdc the turned back until the rotor moved...it was only 6 degrees difference so im pretty sure it is ok but could take a double check....it is electronic advance...the truck had no o2 sensors hooked up except one with a single black wire(shorty edelbrocks into y pipe into 3.5 inch exhaust w/flowmaster...no cat)it is a tbi...will have to try cleaning the filters and fp reg....is it ok to drive in base mode???is there a way to see if they played with the computer at all or if there is a cam in it w/o taking the plate off???and thanks much ezdaar

ezdaar

iTrader: (1)

Ecu should have a small rectangle plate cover, pop it off.
If its OEM chip it will be solid black with small print..
Aftermarket useually has a sticker on it, telling you who made it etc..

dirt track racer 81

iTrader: (45)

Are you driving it around with the wire that you unplug to set the base timing?

TIM Z

iTrader: (12)

Brown and tan wire IIRC.