Switching from E85 to 87

Medic262

Member
Switched from e85 jet to 87 jet and I can’t seem to get my motor to idle now. Runs fine wide open but will not stay running at idle. I have a stock appearing engine. What do I need to check thanks
 
I'm going to assume that the E 85 jet was bigger than the 87 jet jet. It's important to know!! If my assumptions correct, the engine is probably lean on the low-speed. And I'm going to assume, it's probably lean on the top end too. That's a big assumption. You may have been too rich with EE 85 needle and now, with the 85 needle, you're very close to being jetted right on the top end. A pin set measuring .011" – .060" can be purchased on eBay for less than $50. They come in what is called plus or minus sets, get the minus set.

"Tuning is tough!" (Al Nunley)
!!
 
My engine builder switched the jet out to one for 87 octane and left the needle said it would be fine. It’s a dyno cams 212 engine
 
My engine builder switched the jet out to one for 87 octane and left the needle said it would be fine. It’s a dyno cams 212 engine
The last thing I want to do is get between you and your engine builder. Still, changing jets is something you should learn about. Air density (Longacre sells a gauge) changes hour to hour, day to day, you should be able to tune for those changes. Anybody that tell's you differently is wrong.
 
He didn’t tell me anything different he out a jet in the carb that’s for 87 that should run fine but it won’t idle currently without throttle being put to it. There’s a small brass screw with a spring on the side is that a mixture screw
 
Just an update got it running idled like crap idle screw is all the way in still doesn’t want to idle much at all. Now it black smokes a bit when giving it throttle
 
I'm not exactly sure what that needle does. Maybe someone else will come on and tell you.

Not knowing if the carburetor is rich or clean on the low end, it's hhard to give advice.
 
Yes thats a mixture screw . Will it help ? Maybe turn it out a turn and see how it acts . Then in or out to suit your need .
 
If youre turning the idle mixture screw all the way in and the motor doesnt die you may have a vacuum leak (carb gaskets maybe)
 
Back
Top