Hello,
I have a 1985 K5 with a 305 v8. I have a Rochester 4bl carb (reman) just installed. I bought this Blazer about 9 months ago, after redoing the wire rat nest and replacing many of the vacuum lines. I got it running well at idle.
I have replaced the following:
1. distributor cap
2. Plugs and wires
3. coil
4. egr valve
5. Carb
6. fully rebuilt transmission

I am having an issue with bog at full throttle. I get a backfire from the carb right after the bog when I try to kick the carb for acceleration. I have timed the engine to 9 before. The engine starts great usually on the second try and pump off the accelerator. The cold start runs well and the auto choke seems to be functioning properly. I can drive it at low speeds and under slow acceleration, but if I kick it or try to get the kick down to work it bogs, sputters, and dies. I have run compression checks and all are within specs for a 35-year-old engine. I have adjusted all valves to spec. I have checked and rechecked my vacuum lines to diagram and they are correct. I am assuming there is a vacuum leak because my secondaries are not kicking in at all when full throttle is applied while parked.

I AM AT MY WITTS END and out of ideas and diagnostics. Any input will help.

 

I would start with making sure that you do not have an exhaust restriction.

George

 

Keep in mind, the 305 is a pretty gutless engine to begin with.

 

gutless yes, but no legs and ***** not so much

 

Have you disconnected the timing connector when setting engine timing?

 

Regarding timing, what Les said and this covers most of it:

https://www.jalopyjournal.com/forum/...g-305.1054916/


George

 

I have an EFI ignition on the motor, there is no timing advance to disconnect (no vac advance). The only thing I have not done yet, though I have looked for vac leaks, is try to adjust the carb even though it is a reman. I have thought about the exhaust. It has the stock manifolds and connections, it looks to have a newer cat. The Blazer sat for the better part of 6 yrs. The only other thing I can ask is, that the engine does have cruise control (which is disconnected) and there is a vacuum reservoir does this res have anything to do with secondary activation? I can find no diagrams showing the vacuum routing to and from the res.

 

this is a single wire electrical connector located in various underwood locations. It's how you set base timing on an EST engine. Common issue forgotten by many who aren't familiar with EST (not ECM). ELECTRONIC SPARK TIMING. Location and instructions should be specified on your underhood emissions sticker.

 

this is a single wire electrical connector located in various underwood locations. It's how you set base timing on an EST engine. Common issue forgotten by many who aren't familiar with EST (not ECM). ELECTRONIC SPARK TIMING. Location and instructions should be specified on your underhood emissions sticker.

 

If you really have an EFI (electronic fuel injection) distributor and a carb, then you have a mess. If this is the case get an old fashioned HEI for $40 off of Amazon.