AMC Eagle Den Forum

The Mighty 258 => Engine Electrical Systems. => Topic started by: jim on September 01, 2011, 09:50:30 PM

Title: timing after mcu bypass test
Post by: jim on September 01, 2011, 09:50:30 PM
1983 wagon but with a 1980 non-feed back carb.  Mcu test finally done, hopefully correctly.  It did start right up and idle fairly well after bypassing the mcu.
What should the timing be?  600 - 700 ft above sea level.
Do I still need to plug the dist vac and time it at 1600 RPM?

Is the mcu bypass likely to help with the almost-impossible-to-start-when-hot issue?
It starts great when cold, or it did before the bypass.  I hope that doesn't change.
Title: Re: timing after mcu bypass test
Post by: GRONK on September 01, 2011, 10:22:59 PM
remove dist vac and cap the port on the carb/intake
set timing to 9 deg at 650RPM
Hook vacuum up to PORTED vacuum after set (not intake vacuum)
Title: Re: timing after mcu bypass test
Post by: jim on September 01, 2011, 10:51:58 PM
Thanks. 
That's what I needed to know.
I think mine is already on the carb port.  That was done when the motor/carb were installed about 6 or 7000 miles ago.
Title: Re: timing after mcu bypass test
Post by: jim on September 06, 2011, 04:41:38 PM
Well, I got the timing set to 9.  It didn't help the hard starting when warm.  It starts great cold and runs great.
When it doesn't start I can't tell whether it's flooded or starved.  Mostly I think it floods extremely easily, but holding the throttle open doesn't help.
Title: Re: timing after mcu bypass test
Post by: GRONK on September 06, 2011, 06:08:26 PM
Check your power valve (make sure there is no fuel inside the cover.  Maybe try lowering your float just a little bit.  Maybe think of insulating the base of the carb from heat? (Thick thermal gasket)

Your choke isn't closing when warm is it?  Could be a fast idle adjustment too.

Can you send me pics of your install?

[email protected]
Title: Re: timing after mcu bypass test
Post by: jim on September 06, 2011, 07:59:00 PM
We'll be leaving before daylight tomorrow morning, so I won't be able to get a picture any time soon.  My choke does sometimes close when it's warm, but not always.  When it does close, it seems to be stuck and takes a small tap to make it open.  After several tries it will sometimes backfire, and then after just a couple more tries it will start.
I don't know about the power valve.
Title: Re: timing after mcu bypass test
Post by: GRONK on September 07, 2011, 08:35:30 AM
The choke should never be closed when warm.  Might need to add another gasket behind the choke cap to space it away from the choke housing (If the choke tang is rubbing on the cap)
Title: Re: timing after mcu bypass test
Post by: jim on September 07, 2011, 09:56:39 PM
After much trouble at the first pit stop I may have stumbled on a work around.  If it doesn't start right away I close the choke and turn it over, open the choke and turn it over a time or 3 and it starts.  It has worked 3 or 4 times.  It sometimes backfires a time or 2 first and then starts.

Once again it starts great when cold and runs great once it starts.  We made 700 miles today with no problems except for starting.