340 with edelbrock heads overheating

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What are the lift numbers on the new cam?

What was wrong with the 340 cam that you took out of it?

Lift 430/444
Duration: 268/276

Just wanting more? >
More Trouble?

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Try the Felpro 8553 PT, Perma-Torque this time around.

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You need to do a LOT of measuring and diagnosis before slinging that back together. I do agree though that the short block is probably ok.
 
i agree on the short block being okay. i'd be interested in seeing the valves/combustion chambers on the heads-- both sets.
 
The thing is, if the valves on the Edelbrocks are making contact, what's to stop the iron head valves from hitting? I know the Eddys have 2.02 and 1.6 but that's splittin hairs when discussing piston to valve clearance.
 
Edelbrock 340 aluminum heads are recommended to use their Edelbrock #7326 head gaskets with a compressed thickness of .050 ths.

The Felpro 1008 head gaskets have a compressed thickness of .039 ths.

That is .010 ths difference between the 2 head gasket brands bringing the valve to piston clearance .010 ths closer using the felpro 1008 head gaskets.

That along with a slightly higher lift cam > valves kiss the pistons?

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George Jets said:
Edelbrock 340 aluminum heads are recommended to use their Edelbrock #7326 head gaskets with a compressed thickness of .050 ths.

The Felpro 1008 head gaskets have a compressed thickness of .039 ths.

That is .010 ths difference between the 2 head gasket brands bringing the valve to piston clearance .010 ths closer using the felpro 1008 head gaskets.

That along with a slightly higher lift cam > valves kiss the pistons?

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That's just it. They shouldn't. There should be a mile of room. Something's missing somehow. Like the deck clearance of that combo. I'm really curious about that. Although it appears those pistons are the 72/73 style, "WHERE" do they sit at TDC? Without that info, we're all just guessing.
 
Valve position in the head comparison.

Granted the J heads are the 1.88/160

vs the Edelbrock 2.02/160

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What are the cam specs again? Where was it installed at during the rebuild, was that checked and were valve to piston clearances checked when installing those aluminum heads as well?

Are you 100% sure you never over rev’d it at some point?
 
Edelbrock recommends longer than stock pushrods with their 340 aluminum heads, wonder how much longer the OP went?

Then if the deck has been milled besides (or cleaned up by the machine shop) that throws the whole mix off too?

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That piston damage could have been caused by the cam shaft timing being incorrect. Years ago I set the timing chain incorrectly and had those very same results on the top pistons. 1 had a hole in it, hangs on my bench for a reminder to take your time to measure everything.
 
Looks like stock length 340 hydraulic pushrods are 7.5" in length.

Wonder what length new pushrods the OP installed on his recent 340 aluminum head build?

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This thread - I read as much as I could stand - is full of the usual bad ideas.

In those pics, I don't see any sign the valves were hitting the pistons. Maybe they were, but it doesn't look like it. And of course, even if they were it would have nothing to do with overheating.

Do people really think 2 degrees of intial timing, or any timing, is gonna turn an engine from a cool runner into an overheat-er? I guess they do.....

Since the issue began with the head swap, that's where to start looking. Not the freakin radiator, not the freakin shroud. Not a freakin clutch fan and for f'in sure not a GD water pump pulley or thermostat.

I always wonder why guys think their ultra-bad *** V8 has any more right to overheat than a stock Slant 6. I'm also amazed that the same guys think their 700HP engine makes 700HP all the time so of course it needs a 700HP radiator. It don't.

This issue is more than likely head gasket related...but then, looking at the crummy condition of the block head surface who knows...? I was expecting to see a fresh, clean engine given that it had just seen a head swap.
 
Looking at the photos of the pistons, look the brow on top has more of a bevel on one side. Could the previous builder have installed pistons backwards? My old eyesight not the best!
 
RustyRatRod said:
The thing is, if the valves on the Edelbrocks are making contact, what's to stop the iron head valves from hitting? I know the Eddys have 2.02 and 1.6 but that's splittin hairs when discussing piston to valve clearance.
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The Piston is chasing the intake valve to close. .140 / .070 is a big difference in that case
 
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.
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First, a fresh engine will tend to run warm until "broken in". This is not as much a problem with the newer rings and cylinder hone finish they require. 50 to 60 years ago the chrome face rings reqired fairly course hone stones to allow the rings to wear into the cylinder walls. This created a lot of friction. One guy I worked with rebuilt a 390 and it was so tight the starter could not turn it over. They towed it around the block to get it started. Ran hot for a couple of weeks and then warm most of the summer. Once he got about 10k miles on it the temps settled down.
Considering you will have modern cylinder finish, I would not expect this to be a concern.
With the recent assembly with new heads, is it possible the head gaskets were installed front to back or upside down,blocking coolant passages or closing the rear and leaving the front open allowing the rear cylinders to not receive coolant flow?
Was a new thermostat installed that may not be functioning correctly?
 
ok, thanks everyone for your responses.
The weird thing is not every cylinder has the issue where the valve hit the piston. Some are the exhaust valve some are the intake. Some pistons have a lighter impression than others.

Wouldn't if the cam was installed wrong this would happen to all the pistons, exhaust and intake valves?

Maybe the push robs were to long, or i got over zealous at adjusting them?

i see the edelbrock head gasket is thicker than the one i used. That could explain it too.
 
Early a body said:
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?
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Before removing the heads I would verify the thermostat opens properly. Suspend the therostat in a pot of water and use a thermometer to measure water temperature when the thermostat starts to open. You have to have it hanging so you can see it just coming off its seat.
Start with inexpensive and easy tests first. Remember Occam's Razor and Murphy's Law. And then KISS.
 
Dale Davies said:
is it possible the head gaskets were installed front to back or upside down,blocking coolant passages
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The only way that front to back is possible is if one punches new dowel location holes in the gaskets.
The gasket upside down? Surely you can’t be serious?
 
Clay it to be sure. Reuse your old head gaskets and mock it up and see.

Rod lengths can do what you're seeing. My 340 was like that, I found out once I got them to a competent machine shop.
 
i measured the push rod length and its 7.5. so i am good there. my thinking now is its cam timing and may have been like this prior and the edelrock valves hit again bending valves. not sure how i did not have the over heating problem before. i am going to be incredibly pissed if both heads have bent valves.

I am going to take both heads down to the engine builder and have him check both out and take him the motor and tell him to figure it out since he built the dam thing. He better pay for the repair too.
 
from examining the pistons, the valves didnt hit the pistons. if such was the case, it would have been on the other side of the piston, towards the inside of the engine. so, if i am right, the piston hit the head somewhere else in the chamber. have your heads inspected by a pro. also, bring each piston down one at a time and have a good look at the cylinders. make sure you dont open the engine twice. by the way, you cannot put the head gasket up-side down on a small-block mopar.
 
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