Back again with overheating problems

[mustangsilly]

I have been on the forum before with the never-ending saga of overheating issues with my 66 200 Mustang. I am convinced that the problem is NOT in the cooling system. I have replaced EVERYTHING in the system: water pump, radiator, cap, both hoses, thermostat (twice) and the heater core. With an infrared the temp at the top tank is 220 and, if I didn't have a recovery system, the radiator would boil over after about 7 minutes of idling. The temp gauge pegs even when driving short distances in cool (under 70 deg weather). I've also played with the timing between 0 and 12 deg BTDC and that didn't solve the problem.
So I think it's time to start looking elsewhere. I'm thinking maybe valve timing? I installed a Classic Inlines 264 cam when I did the rebuild. Weird thing is, the engine only pulls about 10" hg. of vacuum. The instructions on the vac gauge say 17-22 is normal. I've checked for leaks between the carb and manifold but spraying carb cleaner doesn't reveal any leaks. And the car runs fine- just super hot.
Another weird thing is the vac port on the HW5200 doesn't show any vacuum reading at all. I had to tap into the transmission manifold port to get vacuum to the distributor. I still have the old cam, so do you think putting it back in would cool the engine down? Should I get a different carb? Should I just shoot the thing? Whatever suggestions you have would be greatly appreciated.

 

[bubba22349]

I have been on the forum before with the never-ending saga of overheating issues with my 66 200 Mustang. I am convinced that the problem is NOT in the cooling system. I have replaced EVERYTHING in the system: water pump, radiator, cap, both hoses, thermostat (twice) and the heater core. With an infrared the temp at the top tank is 220 and, if I didn't have a recovery system, the radiator would boil over after about 7 minutes of idling. The temp gauge pegs even when driving short distances in cool (under 70 deg weather).

Was it a new radiator and do you have fan shroud? If its not a new or a quality record radiator it can cause this heating problem How far was the block bored out is it over.040? Have had few blocks that were bored out to .060 over because of core shift cylinder walls can be thin for street use. Also are you running a 50/50 mix of antifreeze or water? If water there is a product called water wetter that can drop the temp 10 to 15 degrees.

I've also played with the timing between 0 and 12 deg BTDC and that didn't solve the problem.
So I think it's time to start looking elsewhere. I'm thinking maybe valve timing? I installed a Classic Inlines 264 cam when I did the rebuild. Weird thing is, the engine only pulls about 10" hg. of vacuum. The instructions on the vac gauge say 17-22 is normal. I've checked for leaks between the carb and manifold but spraying carb cleaner doesn't reveal any leaks. And the car runs fine- just super hot.

I still have the old cam, so do you think putting it back in would cool the engine down?

The cam by itself is not going to make it run hot! Would have to be set up very retarded on timing from straight up to cause what you are describing and would not run very well. Did you check the cam timing when you installed it (degreeing)? So changing back to the stock cam won’t be fixing it. Is this a vacuum reading at an idle or going down the road at cruise? A performance cam dose not always read at as high of vacuum as that of a stock cam so you can't always go by the instructions with a vacuum gauge.

Another weird thing is the vac port on the HW5200 doesn't show any vacuum reading at all. I had to tap into the transmission manifold port to get vacuum to the distributor. Should I get a different carb? Should I just shoot the thing? Whatever suggestions you have would be greatly appreciated.

The carb is not going to show any or much vacuum at an idle. Are you setting the timing with the vacuum disconnected and plugged? I assume that you do have timing light to check the timing. The Initial timing should be from around 8 to 12 degrees depending on your local conditions i.e. like the altitude, temp, fuel rating, and the type of trans. Generally for a street car you don’t want the distributor hooked up to straight manifold vacuum as you have it now. Those are a nice carb for a mild engine combo if they are in good condition it should not be the problem. Do you know how to set the carb and timing using your vacuum gauge? Sorry about all the questions don’t know what your skill level is or some of the info that would help to figure this all out. so just don’t shoot it! :nono: Trying to read between the lines think you need to first go back to work on setting the timing right and put the vac. adv. on the ported instead of straight manifold vac. Sure with some time it can be fixed keep trying one thing at a time.

 

[69.5Mav]

mustangsilly

the temp at the top tank is 220

What is the Temp at the bottom Tank? The engine heat is obviously getting into the coolant. The Bottom tank temp will show weather it is getting out of the radiator and into the air.

Your profile shows Denver as your home base. In Denver the air is a lot thinner, ask me how I know. This causes several things to happen.
1. Your mixture won't be correct.
2. Your vacuum gage will read low, 14" instead of 20" if memory serves me right.
3. The thinner air will pull less heat out of the radiator.

So I would make sure your mixture is correct. Too lean will cause overheating among other problems. Being at 5,000 feet would normally make your mixture, correct at sea level, to rich but check it any way to be sure.

Reading the temp drop from the top to the bottom will tell how much heat your radiator is dissipating should be at least 40 degrees Farinhiet. You might need an Aluminum radiator and a big electric fan if you don't already have them.

Good Luck

 

[rbohm]

8) one of the other things to check is how much junk is in the coolant passages. casting sand, rust, etc. all conspire to prevent proper heat transfer. also a lean fuel mixture, and overly retarded timing will also cause overheating. unless your balancer is new, you cant really trust the timing marks on it.

 

[mustang6]

I agree with the concerns about mixture- the right way to measure would be with a wideband O2 sensor. I suspect this also because it is very hard to get a HW 5200 to run rich or even stoch on these engines.

 

[80broncoman]

I just noticed you posted DENVER in you location. what height are you at?? 5000? or 7000?
When I was offroading at a very high elavation (12,930 ft) last year when I parked for lunch I heard my Jeep boiling. I checked the gauge and it said 210 like it always does. mine didn't boil over as it has a puke tank. It was the lower pressure causing the "boil over"
At a higher altitude there is less air to cool the engine. If you want sea leval cooling performance you need a bigger raditor and a more powerful fan.
If some one say this raditor is fine they may want to know what altitude you are at.

 

[rbohm]

8) the other issue with high altitude is the lower pressure also lowers the boiling point of coolant.

 

[mustangsilly]

Some good suggestions here.
I've tried bigger main and idle jets, but fouled the plugs. However, I may have gone too large. I will also try a higher pressure cap (currently using 13lb.) Fan shroud and 6 blade fan are from original setup (which had AC, but doesn't now). Radiatior is a 3 row copper core new radiator purchased from NAPA. Original was 2 row. I am running 50% ethylene glycol. I checked vacuum by teeing into the tranny vac line. Seems like vacuum at the carb base should be the same as manifold, but I get 0" at the vac port on the carb.

Thanks for your suggestions and I will let you know if any of the above works.

 

[69.5Mav]

mustangsilly

What is the Temp at the bottom Tank?

Have you checked the bottom of the radiator tank temperature yet?

 

[66 Fastback]

What distributor are you running? Is it the old load-a-matic?
Whether it is a load-a-matic or a distributor with centrifugal advance, does the vacumm cannister hold vacuum?
When you suck on the hose to the canister, can you see a change in the ignition advance and the engine rpms?

If you have the load-a-matic, the distributor is not compatible with your weber carb.
If you have a later distributor, tee the distributor vacuum line into a manifold vacuum source.
At idle, the vacuum advance should be contributing to the total timing. Total advance should be running somewhere in the neighborhood of 25 deg at idle. Without the vaccuum advance timing contribution, the ignition timing will be retarded and will run hot. With vacuum advance, the engine idle will be more stable, increasing engine vac, and run cooler.

As rbohm stated, the balancer could be slipped. If it is, the timing may be off significantly.
Doug

 

[69.5Mav]

Any Progress?

 

[LaGrasta]

I'm following along closely as I too suffer with your symptoms. I'm next going to rebuild my carb…

 

[mustangsilly]

Here's where I am now....
I checked the timing (again). Initial setting with a timing light connected is at 10 BTDC. When I did the rebuild, I put in a double roller chain with a keyed timing gear. I intalled it a 2 BTDC so I am compensating for that. It's an automatic trans, so the recommended setting is 12 deg. Also, the Falcon Six book suggests advancing timing to the point of pinging and then backing it off until it quits pinging. None of those adjustments made it run cooler.

Now I have the Weber torn down and am reading the jets. It is jetted as shown below.

Primary Main 132 Secondary Main 135
Primary Air corrector 195 Secondary Air corrector 175
Primary Idle 65 Secondary idle 75

I sent these numbers in to pearcemanifolds.com (a great Weber info an tech website) and they are supposed to send recommended jet sizes back based on engine, driving conditions,etc. So once I hear from them, I will let you know what they suggest.

 

[JackFish]

Can you please verify that TDC really is. If the balancer has slipped then all the tuning you do won't help.
The other question is was the cam degreed?

 

[bubba22349]

You set the cam at 2 BTDC. Can I ask you why? Is the cam ground advanced way off of straight up? If not this is retarding the cam timing it would kill some of the low end torque! Would be opposite direction needed for a low power small engine usually this is reserved for an engine that has to much low end torque like in a BB V8.

 

[mustangsilly]

Last chapter (I hope) of the overheating problem. I talked to a tech at one of the performance engine shops in town about my problems. He suggested going to a 15 lb cap from the stock 13 lb. Since the car operates at Denver altitude the higher pressure cap helps compensate for the lower boiling point at 5000+ feet. Second, I re-jetted the HW carb to richer idle and mains. I went from 75 on the idle to 90 and from 135 on the mains to 160. The carb must have been too lean, although you wouldn't think that would be likely at this altitude. I also advanced the timing to 14 BTDC where I got the highest vac reading. Those changes have dropped the upper tank temp to 190 on an 85 deg ambient temperature day. I can live with that. I also think I'll try running synthetic oil to see if that brings the temps down even more.

Thanks for everybody's help and suggestions.

 

[MPGmustang]

mustangsilly,

thanks for your update, i've been following this and hope to do the same. although i'm keeping ym 1bbl 1100v, i also hope changing the jet will lower my temp... I don't know my current temp but in AZ heat (110 all day) it gets hot...

glad to see there is also other way's of cooling the car.

(ps i know for a fact my A/F ratio is 14+ WOT and I do love the pedal)

 

[Lazy JW]

......

(ps i know for a fact my A/F ratio is 14+ WOT).....

That's actually a bit lean at WOT.

 

[Lazy JW]

..... I installed a Classic Inlines 264 cam when I did the rebuild. Weird thing is, the engine only pulls about 10" hg. of vacuum......

That seems a bit low even at your elevation; that really isn't a radical cam but it probably could stand another 4º advancing from the sounds of it. You didn't mention compression ratio, also what is your measured cranking compression?
Joe

 

[mustangsilly]

My CR is 9.0:1 after milling and decking. The cylinder compression avg is 110 psi. The timing at idle is 14 BTDC and vacuum gauge reads 10 hg at idle. Keep in mind, all these readings are at high altitude (Denver).
I still think the vacuum is too low, but the tranny shifts OK. I would like to get a reading on the AF ratio just to see if the jetting is close. But the plugs read OK, just a slight rusty brown after 200 miles of driving. I really think it was the lean fuel condition causing all the heating problems. I wish I'd tried rejetting the carb before spending $400 on all the cooling system changes and upgrades. Oh, well, live and learn....