hole in my head

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6tfo

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Is this bad?
 

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how much did you mill the heads?

cuz the ring around the chamber is where the firing ring is and the cyl bore... chabmer usually goes to it on the upper side

if you did mill those that is how think your deck is on the heads and they are paper weights now...
 
The heads were worked by the previous owner. 3 angle, new springs, valves, retainers etc. He didn't say anything about them being milled (maybe for a good reason). He's not around anymore to ask.
 
I wouldn't chance it. The hole will probably get bigger with combustion conditions then you're through to the cooling jacket, filling the cylinder with coolant, broke piston, bent rod, bent crank, window the block. If you're lucky you'll just overpressure the cooling system and blow every hose off her as you're flying down the freeway.

Stick a fork in her she's done.:sad11:
 
I wonder how much it takes to mill them to closed chambers like that? Damn. You know....that could be repaired. you could center punch the hole, drill and tap it to 1/8" pipe and screw a pipe plug in it. Then mill the plug to the head surface. It's cheap as hell to try.
 
Okay thanks all. This is the excuse I needed to buy new heads. Now considering the Edelbrock 60779 or 60719. Trying to figure out the whole open verses closed chamber thing. Yes, I'm a novice to all this.
 
looks like alot of milling, but I dont think alot was taken off where the hole is, since that would be the upper part of the chamber. looking at my heads, it looks to be close to 3/8" thick right there. It was probably a casting flaw (air bubble). I would take it to the machine shop and have it pressure tested if it passes i would run it. What about having a machine shop put a cylinder head crack repair pin in the hole?
 
Clean it, enlarge it, weld it, pressure check it.

The Edelbrock open vs closed chambered heads issue is one of the open chamber for the early 340 pistons that come up above the blocks deck height. The chambers are machined bigger for there clearance. Theres a few more cc's in the chamber for clearance. If you run this head on a flat top (And a max height of zero deck) the comprsion calc's out slightly lower.
 
Thanks for all your comments. Here's my plan and I'd really appreciate your feedback. I'm not trying to save money or waist it either.

1. Buy a dial indicator and make sure the top of the piston is below the blocks deck.
2. If so, buy Eddy 60779 heads, closed chamber, if piston is above deck 60179 open chamber.
3. Remove purple cam 484 lift, dur .050 241/241
4. Install Comp cam CL-20-670-4, 474 lift .050 233/240 lobe sep 110
5. Put it all back together. The rest of the engine goes like this:
6. Eddy RPM airgap intake, 650 cfm eddy, TTI headers, MSD ignition

I just want a strong running 340. Don't want to race nobody. Will this set up (if put together right) do the trick?

Here's a couple pics of the car. It's my bro's that we've restored. He bought it in the 70's. Seems like we've been working on it since 2002. Gotta get er done and get to work on that 64 chevy truck in the background!!!
 

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My self, i would stick with the 484 cam............. but if you have bought the comp cam, it will work too.
 
the .484 purple cam is a good cam for mild performance and a good sound other than that they are junk i would go with comp any day over a purple shaft based on updated profiles of newer style cams
 
Nice buildup. Either cam will do.
I'm not dead sure on the open Edel. head's abilty to be used in a positive deck height piston. It's the chambe I have not seen in hand that throws me. Though if the piston is at zero deck or less (AKA Lower in the hole) then it is good to go.

Going with a Edel. AVS Thunder carb huh? I like the old AVS carbs alot.
 
Thanks all. I chose what I think is the milder of the two cams because the 340 is a 73 with lower compression. Purple or Comp brands don't matter to me, I just want a strong running engine that'll idle decently in traffic. If either cam would do that I'd probably just leave the purple in. Still would appreciate your feedback on this.

Yes Rumblefish we chose the AVS, don't remember exactly why but most likely from things we've learned on this site. Nice to hear your feedback on that choice.
 
The 302 heads in stock form dont have enough port for a 340.imo

On the thought of repair, a pin job can be done as well as the plug screws, I have run them hard with no issue.

I would make sure to have at least high nines in the compression depot if running aluminum heads.

And 915 heads are a casting that was used on 340/360's, they work good, even better when ported.
 
i would just pressure test the water jacket. use the biggest drill bit not to get into the valve seat and drill down to the bottom of the void and weld it. clean it up with a long file and not look back. out a little time and alot fewer dollars. they really milled the poop out of those heads, never seen one cut that much.
 
Head is JUNK! You better spend some money to sonic that entire deck. I'll bet there are thin spots all over the deck.

If you go ede's, get the closed chamber 60779 regardless of whether the piston is out of the hole. Buy the right head gasket to get your clearance and run them. Another head choice is the Iron RHS X head as well that is a stronger runner in either the 1.92 or 2.02 form than the ede.
 
My J heads are done. Now what to replace them with. Does a 73 340 .030 over have the compression for the Eddy 779? Someone suggested otherwise. Here's a picture of the pistons, I don't know anything about them.
 

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6tfo said:
Does a 73 340 .030 over have the compression for the Eddy 779? Someone suggested otherwise.
Click to expand...

I'd love to hear the rationale for that?

I know what I'd put on it and it's not ede's. :)
 
oh wow, I thought they were 302's for a second there, if those are J's..they are either a casting flaw 'if just milled to flat' or they milled way too much like .120+!!
Mine are at 60 and theres a ways to go till they become closed chamber.

Must have been going for 40's
 
go with the 60779 edelbrocks and that comp cam i promise you you will be happy it will be a great driver and have plenty to throw you in the seat if you want and run fine on regular gas
 
I have always wondered if that kind of head milling could be done. I want to see if this head runs alright, if it does, I might try this with my slant six....

If that hole isn't through to the water jacket, have someone drill it and weld it up. Then just pressure check it. If there's enough metal there to keep the head from warping and blowing your head gasket, I see no reason why you couldn't run it.
 
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