340 Heads Recommendations- Aluminum vs Cast J

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madhatta360

madhatta360

1973 Duster 340 H-code TX9
FABO Gold Member
Joined
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Messages
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Location
Allentown, PA
Need advice on where to go with my head situation in the Duster, been looking at posts on here Speedmaster with work or just rework the J heads and call it good, I’m just gonna be street driving and maybe a rip down the track once ina blue moon for fun, no racing.

Trying to decide money vs gain on either building up bare speedmasters or reworking my J heads, would use valve springs for my cam.

340 supposedly .30 over
915 J heads- unmolested
Crane cam 284 H12 pt# 150062
Eddy Air Gap intake
4spd w/ 3.55 suregrip
LT headers 1 5/8
Holley 4150 dbl pump
Supposedly steel crank, haven’t been able to confirm if that’s true per previous owner

Anyways, suggestions, advice, feedback welcomed, thanks dudes!

B562583C-EEA7-4B6D-B9E8-8F49296F1C32.jpeg
 
madhatta360 said:
Need advice on where to go with my head situation in the Duster, been looking at posts on here Speedmaster with work or just rework the J heads and call it good, I’m just gonna be street driving and maybe a rip down the track once ina blue moon for fun, no racing.

Trying to decide money vs gain on either building up bare speedmasters or reworking my J heads, would use valve springs for my cam.

340 supposedly .30 over
915 J heads- unmolested
Crane cam 284 H12 pt# 150062
Eddy Air Gap intake
4spd w/ 3.55 suregrip
LT headers 1 5/8
Holley 4150 dbl pump
Supposedly steel crank, haven’t been able to confirm if that’s true per previous owner

Anyways, suggestions, advice, feedback welcomed, thanks dudes!

View attachment 1716038498
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@pittsburghracer I’ve seen your name plastered all over the heads discussions haha what do you suggest? Also I’m in Allentown, Pa and have seen ur photos and work, I’d be down to talk shop once I get this figured out.
 
Probably aluminum, but what I would do is have the iron heads checked out to see what all they need. That small investment will be beneficial even if you decide to sell them, since you can advertise them knowing what they might need.
 
madhatta360 said:
Need advice on where to go with my head situation in the Duster, been looking at posts on here Speedmaster with work or just rework the J heads and call it good, I’m just gonna be street driving and maybe a rip down the track once ina blue moon for fun, no racing.

Trying to decide money vs gain on either building up bare speedmasters or reworking my J heads, would use valve springs for my cam.

340 supposedly .30 over
915 J heads- unmolested
Crane cam 284 H12 pt# 150062
Eddy Air Gap intake
4spd w/ 3.55 suregrip
LT headers 1 5/8
Holley 4150 dbl pump
Supposedly steel crank, haven’t been able to confirm if that’s true per previous owner

Anyways, suggestions, advice, feedback welcomed, thanks dudes!

View attachment 1716038498
Click to expand...
Seems like a good setup already. Is there an issue with the heads? If you want to play then just go straight to the Trickflow. Money ahead in the long run.
 
Bodyperson said:
Seems like a good setup already. Is there an issue with the heads? If you want to play then just go straight to the Trickflow. Money ahead in the long run.
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Yeah I mean it runs pretty good right now, I plucked the trans to have it gone over and do a new clutch kit. Trying to get it freshened up. Yeah I’m leaning towards Aluminum and just building for future
 
madhatta360 said:
Yeah I mean it runs pretty good right now, I plucked the trans to have it gone over and do a new clutch kit. Trying to get it freshened up. Yeah I’m leaning towards Aluminum and just building for future
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I opted for the Promaxx heads. I have not run them yet but they get good reviews.
 
If they are the 2.02 j heads and are crack free. Just run them.

My current set up is 340 .30 over with 10.2-1, comp XE285HL, roller rockers, stock airgap, 750 DP with 2.02 J heads, right at 390HP per a superflow 901 dyno.
 
If the j heads are still in reasonable condition I would probably be inclined to just do a valve job/bowl blend, swap your springs over and use them.
If they are badly warped, need guides and valves replaced or your going to chase more power down the track then alloy heads might be a good move depending on machining costs in your area
 
Scody21 said:
If they are the 2.02 j heads and are crack free. Just run them.

My current set up is 340 .30 over with 10.2-1, comp XE285HL, roller rockers, stock airgap, 750 DP with 2.02 J heads, right at 390HP per a superflow 901 dyno.
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That’s respectable, I have the smaller 1.88 J’s
 
From what I understand, Speedmasters should still be sent out to be "checked". J heads are what 200 diollars plus the cost of rebuild so say $700 for Js vs 1200-1800 for speedmasters its all what you want to spend. I have a set of Js in the machine shop now waiting for the estimate I dont see it being more than 500. Also are you racing or street restoration? If racing yes go with aluminum as they will end up being ported at some point right?
 
Cost and bang for buck this day and age I'd just go aluminum.
Sure anything can run.
As stated if they are 2.02 and in decent shape then run them.
If not you will spend more money to have less power.
Plus aluminum saves a few pounds.
 
Gotta agree with that above. Machine work is pricey with little return on the iron heads. Even more so when you make the move to aluminum heads. I would go straight to the trick flow heads. They cost a little more than the Edelbrock heads but offer more all over.

The cost to port iron heads to the OOTB Edelbrock level is t justified IMO unless you WANT to run ported iron. The price of Edelbrock heads ported to a trick flow head level doesn’t readily add up in my head. Bellow are screen ***** of the better Edelbrock head currently available at Summit vs the closest TF heads. The TT heads are currently out of stock. They’re worth waiting for. IMO, the expense is justified. Even if you’re not taking full advantage of the head, it flows better. It will also give you a higher ceiling to grow into should you decide.


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If you’re going to go Speedmaster you’re better off buying them bare like you mention. If as an asssembly the springs they come with will be way more pressure than you need with that Crane cam. So now you’d have to buy springs to suit, possibly retainers (if you can’t reuse the ones the heads came with) and pay for them to be checked over, setup. Not to mention if your going to use oem stamped rockers the valve heights on those assembled heads will be all over the place (they were on the two sets I dealt with not too long ago) so you’ll need to get all that corrected or accommodated for somehow) as well as having the shaft saddles checked and possibly corrected.
Or you can just use adjustable rockers and leave the valve heights as they are.

Bare you need the valve job and to ensure the valve heights are the same, set up etc and the saddles dealt with. With that small a cam why bother with aluminum heads to begin with. Just have the J’s reworked, with some bowl work, quality valve job and setup with some matching springs for that cam and roll.
 
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You have "J" heads, tighten the guides, good valve job, clean up the bowls, maybe stainless exhaust valves and run them. If done right, it will be plenty for what you want to do.
 
nah...if it's running good stick with what you have. J heads will support 400 hp and your probably OK.
the aluminum heads will reduce the weight in your wallet...and it will be noticed.
 
Appreciate the incite and info from all above, connected with Pittsburghracer and he’s gonna get me all setup with worked SM heads, can’t wait to get them installed
 
Scody21 said:
If they are the 2.02 j heads and are crack free. Just run them.

My current set up is 340 .30 over with 10.2-1, comp XE285HL, roller rockers, stock airgap, 750 DP with 2.02 J heads, right at 390HP per a superflow 901 dyno.
Click to expand...
Scody, I PM'd you.
 
Scody21 said:
If they are the 2.02 j heads and are crack free. Just run them.

My current set up is 340 .30 over with 10.2-1, comp XE285HL, roller rockers, stock airgap, 750 DP with 2.02 J heads, right at 390HP per a superflow 901 dyno.
Click to expand...
I was just going back over on this thread and realized we have a similar build on a 340. Mine has a slight compression advantage at 10.5-1, nothing really! But I’m running the ProMaxx CNC 2.08 Shocker head and 1-5/8 headers. The cam was modified for a 108 instead of the 110 LSA.

Glad you dyno’d it.
 
rumblefish360 said:
I was just going back over on this thread and realized we have a similar build on a 340. Mine has a slight compression advantage at 10.5-1, nothing really! But I’m running the ProMaxx CNC 2.08 Shocker head and 1-5/8 headers. The cam was modified for a 108 instead of the 110 LSA.

Glad you dyno’d it.
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Did you get the Shocker heads flowed?
 
Around here a basic rebuild is $800-$1000 plus parts. Its not hard to spend $1500 on a proper rebuild (I've got a set in for rebuild as we speak). Inexpensive aluminum heads are hard to come by but more available down south. I'd be leaning towards aluminum.
 
madhatta360 said:
Need advice on where to go with my head situation in the Duster, been looking at posts on here Speedmaster with work or just rework the J heads and call it good, I’m just gonna be street driving and maybe a rip down the track once ina blue moon for fun, no racing.

Trying to decide money vs gain on either building up bare speedmasters or reworking my J heads, would use valve springs for my cam.

340 supposedly .30 over
915 J heads- unmolested
Crane cam 284 H12 pt# 150062
Eddy Air Gap intake
4spd w/ 3.55 suregrip
LT headers 1 5/8
Holley 4150 dbl pump
Supposedly steel crank, haven’t been able to confirm if that’s true per previous owner

Anyways, suggestions, advice, feedback welcomed, thanks dudes!

View attachment 1716038498
Click to expand...

Might be a good idea to check out how proud the 340 pistons set above deck height. Custom head gaskets can be expensive.

If the budget allows the speedmasters would be nice provided you can set them up for quench with your short block.

Nothing wrong with running the J heads either though on a budget build.

Either way it will be a fun combo.
 
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