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Hi all,
I have a 1968 block that has been stroked to a 347 that runs too hot for comfort. The car runs about 15 degrees above the 180 thermostat temp and when I stop at a traffic light, get caught in slow traffic, or use some of that horsepower it goes to 200 to 210. At longer lights or consecutavie lights she gets hotter (210 to 220) and slowly returns to the 195 range. I put a brand new 180 stat in it yesterday and went to a show with the above results, on the way home it was a cool 75 degrees out no traffic, no lights and she ran at 190 degrees.
I am currently running a stock water pump, Champion 3 core Aluminum radiator with attached Champion aluminum shroud and a 13 inch flex fan tucked into the 16 inch opening. I also have a 16 inch pusher fan on the outside of the radiator on a toggle switch. I have tried several other combinations with simalar results. I am begining to thing it is an internal problem and not just timing/airflow/thermostat issue.
I should also add that the car does not have the power I expected from 400+ hp, the idle sucks in park (rough) and in gear (have to feather it)
Other set-up items to help you help me are:
60 cc Pro Comp Aluminum heads
10:1 compression
650 dbl pumper
new upper hose
new lower hose (with spring)
The timing is set at 12*
2600 stall
*CAMSHAFT* intake .496 ehaust .520
cam timing @.050 intake 224/ehaust 234
I know the cam is the rough idle problem and I am planning on pulling it.
any suggestions on a replacement? could it be my horespower an temperature problem as well? I have been fighting this motor for over a year and am ready to put a stock 302 back in the car. Thanks in advance for any help.
Jeff
 

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from what I see, wrong combination of cam, heads and carb...
To make 400 you'll need better heads, more cam and better induction...not to mention a great set of headers, I'd talk to Trick Flow and see if they can help you out.
The heat problem? Maybe a high volume water pump? Maybe wrong cap, it may not be venting or you need a unvented kind...I'm sure others will chime in.
 

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Hi all,
I have a 1968 block that has been stroked to a 347 that runs too hot for comfort. The car runs about 15 degrees above the 180 thermostat temp and when I stop at a traffic light, get caught in slow traffic, or use some of that horsepower it goes to 200 to 210. At longer lights or consecutavie lights she gets hotter (210 to 220) and slowly returns to the 195 range. I put a brand new 180 stat in it yesterday and went to a show with the above results, on the way home it was a cool 75 degrees out no traffic, no lights and she ran at 190 degrees.
I am currently running a stock water pump, Champion 3 core Aluminum radiator with attached Champion aluminum shroud and a 13 inch flex fan tucked into the 16 inch opening. I also have a 16 inch pusher fan on the outside of the radiator on a toggle switch. I have tried several other combinations with simalar results. I am begining to thing it is an internal problem and not just timing/airflow/thermostat issue.
I should also add that the car does not have the power I expected from 400+ hp, the idle sucks in park (rough) and in gear (have to feather it)
Other set-up items to help you help me are:
60 cc Pro Comp Aluminum heads
10:1 compression
650 dbl pumper
new upper hose
new lower hose (with spring)
The timing is set at 12*
2600 stall
*CAMSHAFT* intake .496 ehaust .520
cam timing @.050 intake 224/ehaust 234
I know the cam is the rough idle problem and I am planning on pulling it.
any suggestions on a replacement? could it be my horespower an temperature problem as well? I have been fighting this motor for over a year and am ready to put a stock 302 back in the car. Thanks in advance for any help.
Jeff

HI! did you build the engine for racing or street?
what size is your rad? why a 13 inch fan, get a 18 inch shroud and put in a 17 inch fan. your fan should be about 1 inch from the rad.
what is your total timing advance?
was your carb adjusted using a vacuum gauge?
what are you running for ignition?
which spark plugs and gap?
is your thermostat sensing bulb toward the engine.
is you rad overflowing. what pressure is your cap.
do you have access to a infra red thermometer, your gauge or sending unit might be off.
 

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Cooling issue
My shop manual says a 66 289 T-Stat is fully open at 212 degrees. Doesn't sound like it's too far off from your modded engine.

Feathering issue:
Are your "double pumpers" working? Air cleaner off and engine OFF, look down the carb and work the throttle to wide open. Should see two solid piss streams of fuel shooting down the carb bores. In your case should see 4, one in each of the 4 bores.
 

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A 13 inch fan in a 17" shroud is a problem. I bet that your problem disappears when you put a stock size 17" fan on it.
Note: You are not overheating unless the coolant is boiling over and that won't happen until about 250F.
Still it is running warmer than I like.
 

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Air fuel ratios and timing play a huge factor in cooling. If you are too lean it will get HOT in a hurry. A rich mixture will actually cool the engine.

Your initial timing and timing curve will also play a factor in temps. You can go too far in either direction, retard or advance.

A good way to check these is at a dyno tune. Exhaust temps are a great way to check for proper combustion and tell you if you have some type of weirdness going on in a particular cylinder.

By chance, what size are your pulleys? Make sure the pulley ratios are correct. DO NOT use underdrive pulleys, they are horrific.
 

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worra is headed in the right direction... sounds like a vacuum leak. will cause rough idle, lean condition, and in turn overheating.
 

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I don't consider your temp an issue. Running a solid 210 degrees would be great. Most modern engines run that and actually more efficent. I'd work on running part as mentioned and see what effect that makes. I'm assuming you're running premium gas. 10:1 compression and above should run it and will tolerate less timing. Too far advanced will make it run hot, think that was already mentioned.
 

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I don't consider your temp an issue. Running a solid 210 degrees would be great. Most modern engines run that and actually more efficent. I'd work on running part as mentioned and see what effect that makes. I'm assuming you're running premium gas. 10:1 compression and above should run it and will tolerate less timing. Too far advanced will make it run hot, think that was already mentioned.
It is a problem, if he has a 180 degree temp thermostat, it should stay at 180, otherwise something is off.

I will agree 210 is OK, but the engine has to be tuned for it. 180 is best for old school carb'd engines.
 
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