Leifs86

Here's the story. 86 Z that a previous owner replaced the 305 with a 350 HO crate motor and used all the stock 305 equipment on, carb, intake, ecm, emissions etc. The car ran pretty decent but over a two year period I had to replace the carb, computer and dist. module so I decided to bypass all the computer stuff and go old school. I put a Summit rebuilt q-jet and black cap vacuum advance distributer on it. I set the timing at 10 btdc and scoured the intake and carb for vacuum leaks. The car is very fast now. Responsive and smooth under load but it idles like crap. What happened? It never idled rough with the computer except for an occasional miss. The cam is more aggresive than an Edelbrock performer but nothing crazy and it doesn't lope smoothly as it should. Any ideas?

Thanks,
Leif

Z's r Best

How about your egr valve? Never had the issue on my Z's but I've gotta S10 Blazer that will (every so often) get a piece of carbon stuck in the EGR valve. It will accelerate fine, cruise down the road at higher speeds okay but it will idle (jumpy bumpy jerky) like garbage. I get a check engine light (OBD2 and it knows the EGR valve is incorrectly positioned -too far open) and when I get home I pull the egr valve off and sure enough it's hung open with a little piece of hard carbon. Pop that out put it back on and everything is sweet again.

For what it's worth, I tried carb cleaner and a long brush to clean the egr passage in the intake manifold but it didn't help much. Then I went to the Chevy dealer and got a can of the "top end cleaner" which is a foaming carbon solvent spray and pulled the egr valve off and soaked it good down in the egr passage. Let it set and fired it back up. No problems for about 6 months now.

With no computer (and maybe even with one and an OBD1 set up) you wouldn't get a check engine light. The egr vavle is pretty easy to get to on that manifold isn't it? check it out.