Ford Mustang Forum banner
1 - 7 of 7 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter · #1 ·
Hi

I have a 85 GT and yesterday I was checking it's timing. When I pulled off the advance hose the idle didn't change. The connection on the carb (holley) is the right place for the advance as per the instruction manual. So I did a test and hooked it to full manifold vacuum and now I feels much better in the midrange even sounds better between 2000 and 3000 RPM. Not so peaky when the 4 barrels come on.

I put a vacuum gauge on and manifold vacuum read a bit low. Could I have a vacuum leak and it is causing not enough advance under load?

One other thing, the idle surges when on the full manifold vaccum
Thanks Ron
 

·
Super Moderator
Joined
·
40,151 Posts
welcome to the site,enjoy!!!!what did you set your timing at?
 

·
Registered
Joined
·
2,467 Posts
Welcome ..I have an 85 GT too...my vac advance is to a ported vac port on the carb..when i bought my car its was on the constant port...i switched it to a ported thats were its suppossed to be...I also i have my timing very high maybe like 16-18 degress...it pings a little but it runs awesome that high if i lower the timing it runs crappy every car is different tho...hope this helps you...Oh yeah i have an edelbrock carb too...the holley was gone when i bought the car thank God....lol
 

·
Registered
Joined
·
46,010 Posts
If you have low vacuum, then yes that would affect how much advance you'll have. But then you might could get the distributor checked out to make sure it's operating properly.
 

·
Registered
Joined
·
2 Posts
Discussion Starter · #5 ·
Heavy Metal - I set it to 11-12 Deg.

My 85 GT. Not sure what's a ported vacuum port however it should be in the right spot. I have a Edelbrock RPM and 600 holey.

When you disconnect the advance hose does your idle drop? It makes no difference with mine plugged or unplugged.

Maybe I also need alot of advance. I'm just getting it throught the vacuum advance being hooked to full manifold vacuum.

EagleAutosorts - Yes I think I will get the distributor checked.

Thanks
 

·
Registered
Joined
·
2,467 Posts
Heavy Metal - I set it to 11-12 Deg.

My 85 GT. Not sure what's a ported vacuum port however it should be in the right spot. I have a Edelbrock RPM and 600 holey.

When you disconnect the advance hose does your idle drop? It makes no difference with mine plugged or unplugged.

Maybe I also need alot of advance. I'm just getting it throught the vacuum advance being hooked to full manifold vacuum.

EagleAutosorts - Yes I think I will get the distributor checked.

Thanks


Well were are you disconnecting the vac off the dist? or carb if your are you should pick up idle because your causing a vac leak.... and mine when removed the timing doesnt move...I hook it back up it still doesnt move until i give it gas then i see the timing move so it could be a bad vac advance or you dont have it hooked up right?
 

·
Registered
Joined
·
1 Posts
Heavy Metal - I set it to 11-12 Deg.

My 85 GT. Not sure what's a ported vacuum port however it should be in the right spot. I have a Edelbrock RPM and 600 holey.

When you disconnect the advance hose does your idle drop? It makes no difference with mine plugged or unplugged.

Maybe I also need alot of advance. I'm just getting it throught the vacuum advance being hooked to full manifold vacuum.

EagleAutosorts - Yes I think I will get the distributor checked.

Thanks
you should have your vacuum advance hooked to a timed or spark port on the carb. if you hook it to a full time vacuum sorce it will be fully advancing the distributor at all times even on idel this could cause serging on idel and it will speed the idel up when you disconect the hose from the vacuum advance it shouldnt make any differance to engine speed at idel because the timed port is not in the area of high vacuum in the carb at idel this is the way it should be
 
1 - 7 of 7 Posts
Top