[speedfreek]

The timing is set correct but under w.o.t. it rattles bad, sounds like valve rattle, spark knock or whatever you call it. It's a stock 305. Could it be cheap gas? I'm running 87 octane.

 

[jcdubs]

Double check your timing and try premium gas.

 

[DjD]

Patrick - what year and what's it in? Is it computer controled? Carb or fi?

 

[speedfreek]

Patrick - what year and what's it in? Is it computer controled? Carb or fi?

It's in an 86 truck. It's carburated, the dist has a large 4 or 5 prong plug on it. The carb has all those electric plugs in it. I don't know if it has a computer.

 

[DjD]

Sounds like what was in my '86 El Camino. Computer controled carb... Run 91 gas in it and see if it clears up and then maybe try 89 if it does. Mine ran ok on 89... I never touched mine it passed smog here and threw a check engine light sometimes but it always cleared before I got worried enough to do anything about it. Was told I shouldn't play with if it it started and ran cause the computer control was not one of GMs better ideas...

 

[BAMiller]

Is your EGR valve working? I don't think a 86 truck engine has computer comand control {ccc } unless it has Calf. i/m. But it may have an electronic dist with a knock sensor' they called it e.s.c. I think. If the egr valve is not hooked up or not working it will make it ping.

 

[speedfreek]

Is your EGR valve working? I don't think a 86 truck engine has computer comand control {ccc } unless it has Calf. i/m. But it may have an electronic dist with a knock sensor' they called it e.s.c. I think. If the egr valve is not hooked up or not working it will make it ping.

Dang, you might be right! I took off the egr when I swapped intakes. I'll have to put it back on and see if it works! thanks:thumbsup:

 

[travis]

If you reused the original carb, but changed intakes and did away with the EGR, then my bet also is that is the problem.
FWIW, 3/4 tons with 305's in '86 still had the old style HEI (non computer), no ESC, etc, although it did have the feedback q-jet and a catalytic convertor. When I got mine, the carb was shot, the distributor was shot, the exhaust system was shot, etc...you get the idea. It still ran good up to 55 mph but died after that. I yanked the exhaust system and added a set of 1 5/8" flowtech headers, dual 2 1/2" exhaust with generic "muffler shop" turbo mufflers, a weiand 8004 non egr dual plane intake, a 600 edelbrock carb, and a accel blueprint series (stock replacement) HEI. I had to add an aftermarket TV setup for the 700r4 tranny because of the edelbrock carb. Even with 200K miles, that little sucker ran really good, and highway mileage went from 11mpg to 19mpg after the bolt ons.