340 with edelbrock heads overheating

-
E

Early a body

Well-Known Member
Joined
Jun 25, 2018
Messages
253
Reaction score
114
Location
Nevada
340 .40 over with less than 1,000 miles on rebuild
stock pistons
flat tappet cam
initial timing at 12 degrees
edelbrock avs 800 cfm carb
1964 dodge dart

I decided that i would swap out the x heads to eddelbrock 340 heads.
Installation went fine but now i have developed an overheating problem.
At idle it will heat above 210. I have not tried to see where it would stop i just shut it down.

the radiator i had on it cooled just fine would not get past 180. This was a champion 2 row 19"- this is on a 64 dart

Changed to a wider 22inch 3 row champion radiator that i had stored away. no difference
changed to a 160 thermostat . no difference

Using 273 adjustable rockers and double checked to make sure the valves are adjusted properly

coolant looks good . I am using prestone 50/50 premixed

oil looks good Valvoline 10-30 vr same oil i use in all my flat tappet cars

Not sure what else it could be. Did the head gasket blow but did not cause cross contamination of the oil and the coolant?

Thanks in advance.
 
Double check ignition timing and carb jetting.
Did you degree the cam.
 
rumblefish360 said:
Double check ignition timing and carb jetting.
Did you degree the cam.
Click to expand...
no , i did not degree the cam. Cam was installed by the builder. I have doubled and tripled check the ignition maybe more than that today. I have a feeling it may be running lean. I have the the primary jets at 107 and the secondary at 101 plus the rod is a .65-.037. I smell no unspeant fuel out the back of the exhaust.
 
10 degrees initial is a bit low, IMO, but you say it only started running hot with the head swap. You might still try some more initial timing.
 
ok, so its getting late but i went out and sprayed some carb cleaner around the base of the carb. When i spray the rear of the carb where it meets the intake the car stumbles and stalls out. Looks like I have a vacuum leak. Could this be the cause of the overheating. Please say yes because i am tired of messing with this thing.
 
Early a body said:
At idle it will heat above 210. I have not tried to see where it would stop i just shut it down.
Click to expand...
My opinions; for at idle/vehicle stopped.
At Idle, the jets are NOT active
At idle, 12* is adequate
At idle, any hot-lash more than zero is adequate
At idle, alloy heads should be sucking the heat out of the cooling system,
The thermostat sets the minimum coolant temperature. It has nothing to do with the maximum.
The thing that sets the maximum, is the efficiency of the system.
As to efficiency; Your rad should have a temperature difference, measured by IR-gun, from top to bottom, of about 30*F.
>If it is less, your first option is to make sure the rad is clean and the fins are passing air, and, if you have a condenser in front of it, then same for it.
>Your second go-to is the fan shroud and matching 7-blade fan.
>The Third is to speed up the water pump, or add more vanes or install an anti-cavitation plate.There is no such thing, at idle, of ramming the water thru the system, too fast.
>Fourth is to install a thermostatic clutch onto the fan; it will strive to limit the max coolant temperature to it's set point.
>When checking your engine temp; find the hottest place around the t-stat housing, and mark it, then forever after, use the same location.
>If you are running electric fans, well I'm not yur guy.

<<My 11/1, 367 once had an unsolvable overheat issue; It turned out to be some combination of tight piston skirts and/or too small ring gaps. After hitting a wall in diagnostics, I had no choice but to tear it down. I added .0005 skirt clearance and .004 top-ring gap. After reassembly, it is impossible to overheat it, so long as the fan-belt stays on. No other changes. And, it makes more power. and it gets better fuel economy.
 
Early a body said:
ok, so its getting late but i went out and sprayed some carb cleaner around the base of the carb. When i spray the rear of the carb where it meets the intake the car stumbles and stalls out. Looks like I have a vacuum leak. Could this be the cause of the overheating. Please say yes because i am tired of messing with this thing.
Click to expand...
Probably not helping. To lean can cause overheating. Retarded timing can too and it doesn't take much to go from lean and/or incorrect initial timing overheating to no over heating.
 
Early a body said:
ok, so its getting late but i went out and sprayed some carb cleaner around the base of the carb. When i spray the rear of the carb where it meets the intake the car stumbles and stalls out. Looks like I have a vacuum leak. Could this be the cause of the overheating. Please say yes because i am tired of messing with this thing.
Click to expand...
I doubt it.
In all likelihood, you have compensated for that air leak with the mixture-screws. All that happens with a big cam is that the idle-speed goes up. To get the speed down, usually you just retard the timing. and so, at idle, everything ends up copasetic.
Now that you have discovered it tho, you gotta fix it, lol.
 
dano said:
Probably not helping. To lean can cause overheating. Retarded timing can too and it doesn't take much to go from lean and/or incorrect initial timing overheating to no over heating.
Click to expand...
Probably closer to correct than AJ is since the OP stated there was no smell that leads to think it’s rich in any way.
Let’s start with the basics and work forward.
Seal the carb, bump timing another 8*’s.

Once the carb leak is taken care of and the timing is re set, try 18*, re jet as needed. Look for a brown ring around the plug. The closer it is to the base of the porcelain the better it is.

Please post cam specs
Do you have a fan shroud and what fan do you have?
Was the car a six cylinder?

Report back,
 
ok, i fixed the leak at the base of the carb. but still wants to oveheat. 210+ at idle.
ill have to find the cam specs, but its a custom grind from oregon cams.
has always been a v8. Befre the head swap no colling problems. I am thinking i got a bad head gasket at this point. Crap. These cars are no fun to work on with no space.
 
If all you changed was the heads , Then I would do a leak down test to see if the valves are sealing. Did you check intake fitment? Could it be sucking air from the lifter valley?

Seal off the breather holes in the valve covers and the PCV hole. Also plug the PCV hose. Start it and see if there is a difference with the valve covers sealed. This will tell you if its sucking air internally
 
Early a body said:
ok, so its getting late but i went out and sprayed some carb cleaner around the base of the carb. When i spray the rear of the carb where it meets the intake the car stumbles and stalls out. Looks like I have a vacuum leak. Could this be the cause of the overheating. Please say yes because i am tired of messing with this thing.
Click to expand...
Yes it damn well could be.
 
Early a body said:
ok, i fixed the leak at the base of the carb. but still wants to oveheat. 210+ at idle.
ill have to find the cam specs, but its a custom grind from oregon cams.
has always been a v8. Befre the head swap no colling problems. I am thinking i got a bad head gasket at this point. Crap. These cars are no fun to work on with no space.
Click to expand...
Pull some more timing in it and see if that helps. I would start at 16 initial and bump in 2 degree increments from there.
 
Nobody has mentioned the obvious......
Well, obvious to me.
Alum has faaaar less strength than iron/steel. The deck thickness of E heads is going to be about 5/8" thick. The deck thickness on iron heads is probably about 3/8". Similarly, the columns around the head bolt holes, port wall thickness, etc. Guess where this extra thickness comes from.....
intrusion into the coolant space so that the alum heads have less coolant volume in them.
I believe a better water pump &/or smaller pump pulley would likely fix the problem.
It should be tried.
 
Bewy said:
Nobody has mentioned the obvious......
Well, obvious to me.
Alum has faaaar less strength than iron/steel. The deck thickness of E heads is going to be about 5/8" thick. The deck thickness on iron heads is probably about 3/8". Similarly, the columns around the head bolt holes, port wall thickness, etc. Guess where this extra thickness comes from.....
intrusion into the coolant space so that the alum heads have less coolant volume in them.
I believe a better water pump &/or smaller pump pulley would likely fix the problem.
It should be tried.
Click to expand...
I hoped not to get there so fast. I always try not to spend the money if I don’t have to but sometimes you just have to break out the wallet. Recently, I did just what you said. After exhausting the basics, I went and grabbed a Milodon pump. I have yet to install it. Im pretty sure that will fix my similar issue as the OP.
 
If you have a bad head gasket you'd see it in the oil and/or coolant unless its between cylinders, which would cause other issues.

Does the car overheat when you drive it?

What are you running for fans?
 
Yea, still waiting on answers. Fan shroud? Kind of tan, how many blades? Clutch fan or not?
 
Early a body said:
340 .40 over with less than 1,000 miles on rebuild
stock pistons
flat tappet cam
initial timing at 12 degrees
edelbrock avs 800 cfm carb
1964 dodge dart

I decided that i would swap out the x heads to eddelbrock 340 heads.
Installation went fine but now i have developed an overheating problem.
At idle it will heat above 210. I have not tried to see where it would stop i just shut it down.

the radiator i had on it cooled just fine would not get past 180. This was a champion 2 row 19"- this is on a 64 dart

Changed to a wider 22inch 3 row champion radiator that i had stored away. no difference
changed to a 160 thermostat . no difference

Using 273 adjustable rockers and double checked to make sure the valves are adjusted properly

coolant looks good . I am using prestone 50/50 premixed

oil looks good Valvoline 10-30 vr same oil i use in all my flat tappet cars

Not sure what else it could be. Did the head gasket blow but did not cause cross contamination of the oil and the coolant?

Thanks in advance.
Click to expand...
You didn't mention it, I'm assuming you verified with an IR gun or some other method that you do actually have an overheat situation. How are you measuring temp.? Factory or aftermarket panel gauge?

Yes, a blown head gasket can pump hot air into the coolant system and not mix with the oil.
 
Early a body said:
340 .40 over with less than 1,000 miles on rebuild
stock pistons
flat tappet cam
initial timing at 12 degrees
edelbrock avs 800 cfm carb
1964 dodge dart

I decided that i would swap out the x heads to eddelbrock 340 heads.
Installation went fine but now i have developed an overheating problem.
At idle it will heat above 210. I have not tried to see where it would stop i just shut it down.

the radiator i had on it cooled just fine would not get past 180. This was a champion 2 row 19"- this is on a 64 dart

Changed to a wider 22inch 3 row champion radiator that i had stored away. no difference
changed to a 160 thermostat . no difference

Using 273 adjustable rockers and double checked to make sure the valves are adjusted properly

coolant looks good . I am using prestone 50/50 premixed

oil looks good Valvoline 10-30 vr same oil i use in all my flat tappet cars

Not sure what else it could be. Did the head gasket blow but did not cause cross contamination of the oil and the coolant?

Thanks in advance.
Click to expand...
I would take the heads back off, and make sure all of the coolant passages were machine out. I have bought new Edelbrock products missing required tapped holes. Just a thought.
 
dano said:
If you have a bad head gasket you'd see it in the oil and/or coolant unless its between cylinders, which would cause other issues.

Does the car overheat when you drive it?

What are you running for fans?
Click to expand...
when i am driving it will maintain the temperature it was at while at idle. It will not cool down. I am going to try a water pump next. I ordered a high volume one from summit. if this does not cure it off come the heads.

i guess its possible there is some sort of obstruction in the cooling system somewhere. Not sure if doing a coolant flush will help at all.

i used felpro head gaskets. What head gaskets is everyone using when swamping to aluminum heads?
 
iScamp said:
You didn't mention it, I'm assuming you verified with an IR gun or some other method that you do actually have an overheat situation. How are you measuring temp.? Factory or aftermarket panel gauge?

Yes, a blown head gasket can pump hot air into the coolant system and not mix with the oil.
Click to expand...
yes i used an ir gun and it did confirm its overheating. Its reads 220 or so at the thermostat housing and at either side of the intake manifold where the heads meet. . The radiator is working as the temperature in is much lower than it going out. I cant remember the number but it was significantly cooler.

heads are over 200 as well .
 
I think that the radiator is significantly cooler is key. You are not getting enough coolant flow. AJ, earlier said, aluminum heads will 'suck the heat out' at idle. If the top end is overheating and you can grab the lower hose and it's a comfortable temp. , I think you have a flow problem.

would consider whether the lower radiator hose is collapsing. The water pump may be sucking it flat.
 
What are you running for fans? The Champion electrics with their shroud are known to cause issues at both idle and driving.

Is all the air burped out of the system?
 
Last edited:
I'm running hot as well. I "think" my issue is coolant flow. My crank pulley diameter is small because that was the only one I could come up with that was the right height (if thats the correct description) to line up with the other pulleys. The damper I bought (on the advice to run the best one I could afford) is thicker than original, which I didn't think of, I went with what they said "fits small block mopar" . I did at least learn through this whole process that "fits" probably means- fits but requires many other modifications.
I could move the Alternator out, but then the W/P doesn't line up, if I space the W/P pulley out, then the fan gets too close to the Rad. etc,etc.
PS, Does anybody know a good source of mopar crank pulleys with different heights and diameters? Or smaller diameter W/P pulleys?
 
You must log in or register to reply here.
-

Back
Top