88 mustang

[Oldboy]

Hello,
Posting for my neighbor;
88 mustang gt, 5.0 , big cam of unknown spec.
He reports little vacuum at idle ,15 inches at WOT ,
hard to stay running at idle , but runs very well lots of power .
This is obd1 i think. No codes so far , checking for vacuum leaks .
Any thoughts on where to look?
Thanks

 

[BlueNorther]

yes, look at your third line above "big cam no specs"

also "no pictures it never happened"

 

[MercuryMac]

I shouldn't even be talking, because of little experience with big cams, but this is what popped into my mind. Could your friend have the gauge hooked up to the distributer vacuum port and the distributer hooked up to the gauge port? There also could be some sand or flakes of dirt in the idle circuit. Food for thought. Good luck diagnosing.

 

[lowbudget50]

I am never really worked on any of the 5.0 stuff, but I've had a couple buddies who have had them and they have never put big cams in them because the computer needed reworked or something of that nature to make them run properly I have never personally done much with them but that's what I have been told from guys who have

 

[redidbull]

Is he still running the factory FI! If so it is OBD1 and does have a computer and as mentioned before it will need to be reworked. Depending on just how big the cam is it may never run much vacuum at idle. Jim

 

[Old Iron]

Line 6 says it's OBD1

 

[Bamamav]

Yep, cam and computer have to be matched if going big. Could have some vacuum leaks, but that will usually cause a high idle.
I threw away the FI on mine and went with a 4 bbl. That way I can put whatever cam I want in it at a later date.

 

[redidbull]

I threw away the FI on mine and went with a 4 bbl. That way I can put whatever cam I want in it at a later date.

I will want to talk to you about that in the near future. I really want to do that.

 

[Bamamav]

It's easy to do. Since you have a 88, it should be a roller cam, so you need a distributor with a steel gear or change the one on your current distributor. If you want to stay with the Ford Duraspark system, get a distributor for a 85 Mustang GT with a manual transmission, it will have the steel gear. If you want to run an old style points distributor like I did, you can get the gear off of eBay for $35 or so, just make sure you get the steel gear with the smaller diameter shaft. Sometime in the 80's they went to a larger shaft on the distributor.

Any small block 289-302 intake will swap. Since the injected timing cover doesn't have the hole for a fuel pump, you'll have to run electric, but not a high pressure like the FI one, 7-10 psi is good. Changing to a front sump pan is another can of worms I won't go into unless you need to know.

Anything else you need to know, just ask. I've changed a couple from FI to carb, so I pretty much know what to do.

 

[redidbull]

It's easy to do. Since you have a 88, it should be a roller cam, so you need a distributor with a steel gear or change the one on your current distributor. If you want to stay with the Ford Duraspark system, get a distributor for a 85 Mustang GT with a manual transmission, it will have the steel gear. If you want to run an old style points distributor like I did, you can get the gear off of eBay for $35 or so, just make sure you get the steel gear with the smaller diameter shaft. Sometime in the 80's they went to a larger shaft on the distributor.

Any small block 289-302 intake will swap. Since the injected timing cover doesn't have the hole for a fuel pump, you'll have to run electric, but not a high pressure like the FI one, 7-10 psi is good. Changing to a front sump pan is another can of worms I won't go into unless you need to know.

Anything else you need to know, just ask. I've changed a couple from FI to carb, so I pretty much know what to do.

Thanks for the info. I have an 89 F150, is that too a roller cam? Jim

 

[Bamamav]

Thanks for the info. I have an 89 F150, is that too a roller cam? Jim

Ford changed to roller cams in mid 1985 for cars, around 86-87 for trucks. Any block made 85 and later has provisions for the "spyder" for the roller lifters, but could still use the standard flat cam. 89 should be a roller cam, but who knows what was changed on it since it was new. Only way to tell for sure is pull the intake and look.

 

[redidbull]

Ford changed to roller cams in mid 1985 for cars, around 86-87 for trucks. Any block made 85 and later has provisions for the "spyder" for the roller lifters, but could still use the standard flat cam. 89 should be a roller cam, but who knows what was changed on it since it was new. Only way to tell for sure is pull the intake and look.

Thanks. I will check it out. I have no room for it inside for the winter but it is next to my barn so I plan on doing a few things to it. If I pull the intake I will want to go carb at that point. I am going to start a thread on the small block ford so we don't hijack this one. Jim