heads question

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Dartsun

Dartsun

Mopar Dude
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I have a 69 340 engine with stock j heads. My question is should I build these heads up for my 340 or just go buy some aluminum heads? Im not building a race engine just a strong runner.
 
Depends on your HP expectations

Depends on how much is wrong with the heads and who you can get to do it.

I'm going to guess that by the time you buy some new aluminum heads, ship them, get them checked out, you'll be in 'em at least 2K for the pair

I am not interested in drag racing, or big numbers. I found a retired guy here who does head work, the heads did not need surfaced, and were in good shape. Not counting the price of six exhaust valves, he only charged me 150 for cleanup and a simple valve / guide job
 
Will you want to go farther with the engine in time? If the motor is just going to be a mild street motor then I would stick with iron heads. Head work can get expensive but in the long run it should still be cheaper then aluminum heads.
 
I've kicked around the idea of aluminum heads myself. The thing stopping me is that I spend a lot of time thinking about power gained Vs. dollar spent. That puts aluminum heads down towards the bottom of the list. Especially in a street car.
 
A 1969 340 should have X heads. But the J heads can be improved with a good porting job and 2.02 intake valves. They can be safely be made to flow 245 to 250 cfm on the intake at. .550 valve lift and about 165 on the exhaust at .550 valve lift. That is only about a 10% to 15% improvement over stock but some of the aluminum heads don't flow much better out pf the box. So the improved J heads should work great in a street 340. Not sure about hardened valve seats though...
 
Thanks for the input. Yes that engine should have x heads but they were snagged at somepoint and replaced with j heads. The 340 is bored .30 and has a nice cam. I think with some better flowing heads the 69 dart should go quite nice
 
Unless it's a numbers car a set of aftermarket heads is the why to go dollar for dollar. I put aluminum eddy heads on my 340 and sold my rebuilt x heads to help towards the cost.
Something to think about.
 
1970Duster said:
Unless it's a numbers car a set of aftermarket heads is the why to go dollar for dollar. I put aluminum eddy heads on my 340 and sold my rebuilt x heads to help towards the cost.
Something to think about.
Click to expand...

Just curious. .. was there a substancial improvement in the performance with the new eddy heads? And did the engine run cooler?
 
You'll find the improvement down towards the last couple hundred feet at the drag strip assuming your cam lift, duration or carburetor isn't the bottleneck. From stoplight to stoplight??? Probably not so much.
 
With all of the new stuff available now, if I had the money to rework iron heads, I would buy NEW aluminum ones.
 
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