289 help

[mdb205]

Ok, so if anyone has read my last few threads you will know about all of my rebuild problems; beak-in, bent valves, overheating, etc. Right now the engine is in the car and has a brand new coolant system. It's still trying to overheat on me. That's the first problem. The second problem is that the carb is running really rich and the engine still wants more fuel... So we're thinking the the cam is too big. It's a high energy 268h comp cam. Instead of getting a different cam we were thinking of putting smaller ratio rocker arms on it. Has anyone ever had any similar problems? or have suggestions on what I could do? Keep in mind all of the engine internals and components are brand new and now have about 200 miles on them. My wallet is thinning out and I need the car running this week. Any help would be awesome!

[jdub]

Eight times out of nine, if you overheat after a rebuild, it's because the coolant system has air in it.

"The carb is running rich but the engine wants more fuel"

That statement makes no sense to me.

268h is a decent sized cam but I don't think changing to different rocker arms is your answer.

Have you messed with ignition timing much?

[mdb205]

The coolant system has been burped multiple times.

The carb runs fine at idle but when we put it in gear it runs too lean and has trouble driving. (That's what my carb guy says, I haven't looked at the settings personally)

The timing is right where it should be, but we are messing with it to see if it helps.

Thanks for the quick reply

[68convert]

A common overheating problem is that the head gaskets are installed wrong. IIRC there is a TOP FRONT stamped on them. The other issue that I have seen is the small hose between the water pump & radiator (5/8" by 4"or 5" long) having a kink. The car would do okay at lower speeds but would over heat at highway speeds. We had checked the head gaskets installed a water pump and even replaced the radiator before we found that one.

Good luck

[mdb205]

Well I know for sure the head gaskets are on right. The radiator got rodded out over the weekend because it was clogged and we thought that it was the overheating problem. The radiator went back in yesterday. I cleaned all the hoses out and put a new spring in the lower hose to the pump, so no kinks. The water pump is clean and is only about a year old.

[68convert]

Did you check the small by-pass hose?

[Klutch]

I'm sorry if I'm asking for information provided in previous posts, but I didn't see your other posts. So...

- Do you have a new radiator? If not, has it been serviced lately? Old radiators are notorious getting clogged.

- Is it overheating at highway speed, or when idling?

- Do you have a shroud installed?

- Are you running a factory style fan, or a "racing fan"?

As to your other issues...

- What makes you think it's running rich?

- What makes you think it "needs more fuel"?

Please give us some details about the symptoms you're experiencing and we can likely help. But I'm almost certain that focusing on the cam is barking up the wrong tree.

[tycooley]

Call Mustangs and more 2065 Sperry Ave Ventura, CA 93003 (805) 642-0887 they might have a true mustang guy that can help.

[TheDude]

Originally Posted by tycooley

Call Mustangs and more 2065 Sperry Ave Ventura, CA 93003 (805) 642-0887 they might have a true mustang guy that can help.

Ouch. This forum is full of "true Mustang guys" with plenty of experience and wisdom. If you're referring to them because they are close to Santa Barbara, then you're fine and haven't pissed off a bunch of Mustang enthusiasts.

[mdb205]

The bypass hose should be good, but I will check it again. The radiator is less than a year old and was completely cleaned out 2 days ago. It's also a 3 row radiator. I also have a shroud and a six bladed fan with a clutch. My carb guy knows what he's doing and I trust what he says. By "needs more fuel", I mean that it is still running lean, even though the carb settings are as rich as they will get.

[Bucket Lister]

The vacuum advance on the dizzy may not be advancing. You can check this with a timing light. Full advance should be around 32 to 34 degrees.

[RobReam]

Are you sure it’s not a reverse rotation water pump?

[mdb205]

We're looking into the distributor. It was working before the rebuild. The water pump was also working fine before the rebuild.

[Caper50]

Did you check the thermostat to make sure it installed correctly; the spring side towards the engine. Also it's not uncommon to see a new thermostat fail.

[mdb205]

Sure did, we just put in a third thermostat today just to make sure.