340 CYLINDER HEADS

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coyote42

coyote42

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Hello my engine gurus. A couple years ago I rebuilt my 68 340 short block. When I did I put .030 flat top pistons that sit at true zero deck with 2 valve reliefs, -5cc if I remember correctly. It has been on the shelf for a bit all oiled and wrapped up. I did this thinking I was just going to get the factory X heads redone with the large chamber. I hope to get my 67 Cuda back from paint this summer so the engine project is back on. I have been looking into aluminum heads instead of the X heads. There seem to be some decent priced Aluminum heads between Speed master and Edelbrock, could even do Trick flow. Your brand experience?
My question is, with my piston at zero deck, what CC chamber would get me around 10:1 + or - a little? I see chamber of 63cc and 65cc on the aluminum heads. It would be a .040 gasket and I have read some about how quench works. I don't want to have compression too high to run pump gas. Its a street car that I will take on trips and the strip just for fun sometimes. Want a little extra street torque more than top end HP. 727,3:55, Edel RPM intake, roller hyd cam, I have 68 340 manifolds or could go headers.
Thanks in advance.
 
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may be cheaper to just buy and run aluminum heads now days! Machine costs have gone up quite a bit. By the the way can you share what wheels are on back of car in your avatar!! Looks awesome. Any backspace specs? 15x8 or 15x10's?
 
QuickDart360 said:
may be cheaper to just buy and run aluminum heads now days! Machine costs have gone up quite a bit. By the the way can you share what wheels are on back of car in your avatar!! Looks awesome. Any backspace specs? 15x8 or 15x10's?
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Yep, that's why I'm asking what chamber size. The rear wheels on our 70 Duster are 14X10 265/50/14 on a 8 1/4 w/3:55 SG. no spacers, came with the car.
 
I don't think you can go wrong with any one of the 3. I have SpeedMasters. I bought them bare had them ported and set up for my application. At that time TrickFlow wasn't an option. Between my dad and I we have installed 4 sets of Trickflow heads, all of them nice and no issues. Never used an Edelbrock head, but I assume their quality is good. We have used ProComp/Speedmaster heads for other peoples builds and they worked fine, no issues and in every application they were bought bare and built to application. If you buy an assembled head get it inspected by a known good shop.

Per compression, the dynamic compression could be dealt with via camshaft selection. I would not use head gasket thickness to tune your static compression unless it was to achieve quench.
 
dano said:
I don't think you can go wrong with any one of the 3. I have SpeedMasters. I bought them bare had them ported and set up for my application. At that time TrickFlow wasn't an option. Between my dad and I we have installed 4 sets of Trickflow heads, all of them nice and no issues. Never used an Edelbrock head, but I assume their quality is good. We have used ProComp/Speedmaster heads for other peoples builds and they worked fine, no issues and in every application they were bought bare and built to application. If you buy an assembled head get it inspected by a known good shop.

Per compression, the dynamic compression could be dealt with via camshaft selection. I would not use head gasket thickness to tune your static compression unless it was to achieve quench.
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I have not picked a cam yet, middle of the road is where i'm headed, not crazy. I said .040 gasket because its about average thickness.
 
coyote42 said:
I have not picked a cam yet, middle of the road is where i'm headed, not crazy. I said .040 gasket because its about average thickness.
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If your zero deck on the piston the Felpro 1008 works good with closed chambers at 0.039" compressed. I measured a set after they were compressed and they were at .039". I kept them to use for rocker and push rod mock up.
 
coyote42 said:
Hello my engine gurus. A couple years ago I rebuilt my 68 340 short block. When I did I put .030 flat top pistons that sit at true zero deck with 2 valve reliefs, -5cc if I remember correctly. It has been on the shelf for a bit all oiled and wrapped up. I did this thinking I was just going to get the factory X heads redone with the large chamber. I hope to get my 67 Cuda back from paint this summer so the engine project is back on. I have been looking into aluminum heads instead of the X heads. There seem to be some decent priced Aluminum heads between Speed master and Edelbrock, could even do Trick flow. Your brand experience?
My question is, with my piston at zero deck, what CC chamber would get me around 10:1 + or - a little? I see chamber of 63cc and 65cc on the aluminum heads. It would be a .040 gasket and I have read some about how quench works. I don't want to have compression too high to run pump gas. Its a street car that I will take on trips and the strip just for fun sometimes. Want a little extra street torque more than top end HP. 727,3:55, Edel RPM intake, roller hyd cam, I have 68 340 manifolds or could go headers.
Thanks in advance.
Click to expand...

Unless things have changed since I bought my Edelbrocks, the only reason to run their 65 cc heads is if your pistons are above deck at TDC, like my TRW's are, which is why I have the 65 cc heads. 65 cc heads are just 63 cc heads machined to clear pistons. If your pistons are zero deck, then I'd run the 63 cc heads, with whatever thickness gasket will give you the desired quench. If the CR isn't high enough with uncut 63 cc heads, they can be milled without affecting your quench clearance.
 
On a 360;

I speced mine out to be 9.98-1 with KB-107’s @ zero deck and 72cc “J” heads and a 4.100 X 038 (IIRC) head gasket.

I made a move to the Edelbrock rpm head @ 63cc (many many years ago) and it ran just fine on the pump swill. The ratio went to 10.82-1

Your 340 with the same head gasket as above with an iron head is, 9.28-1 and with a 63cc aluminum head it is 10.26-1. This IS pump gas ratio land.

IF you can wait for a Black Friday sale, go for the heads. There is also a CNC version offered. Here is a link to ProMaxx’s CNC head where you should scroll down some to see the cylinder heads air flow rates;
Shocker 185 Mopar CNC (Sold in Pairs) - PROMAXX Performance Products
 
Having went the Speedmaster route and then sending them to a Head guru from the board here I can tell you that if I had to do it over again Trickflows would have been my route. The Speedmasters were not ready OOTB and I opted to have some work done for additional money I could have done Trickflows. I'm happy with it but that's just 20/20. The flip side is our local track closed up so I won't even put headers on my motor now.....

Trickflow has nice products. And that's not to say they will be a guaranteed OOTB deal but it's as close as you will find a set....

JW
 
rumblefish360 said:
On a 360;

I speced mine out to be 9.98-1 with KB-107’s @ zero deck and 72cc “J” heads and a 4.100 X 038 (IIRC) head gasket.

I made a move to the Edelbrock rpm head @ 63cc (many many years ago) and it ran just fine on the pump swill. The ratio went to 10.82-1

Your 340 with the same head gasket as above with an iron head is, 9.28-1 and with a 63cc aluminum head it is 10.26-1. This IS pump gas ratio land.

IF you can wait for a Black Friday sale, go for the heads. There is also a CNC version offered. Here is a link to ProMaxx’s CNC head where you should scroll down some to see the cylinder heads air flow rates;
Shocker 185 Mopar CNC (Sold in Pairs) - PROMAXX Performance Products
Click to expand...
Thanks Rumble for that info. No rush yet so I may wait for Black Friday.
 
I have run 11.3Scr at 900 ft elevation, with alloys, flat-tops and tight-Q; don't short yourself, target at least 175 psi at your elevation, and you will have a ton of fun. For a streeter, I had great results with a 270/276/110 cam; 223/[email protected]
Mine ran on 87E10, and made fantastic fuel mileage.
If I build again, I think I will try to run 87E10 at ~190 psi.
To answer your question;
at 4.07 x 3.315 your swept is 706.74, and to get to 10/1 will require a total chamber volume of; 706.74/10-1=78.527cc. The Felpro .039 is 8.8cc and so, 78.53 less 8.8+5=64.7 for the rest.
With alloys, I would run 60cc heads, for an Scr of 10.7, and a cam with an Ica of about 64*, to get a Dcr of 8.42 @500ft elevation . The pressure is predicted to be 175psi. I ran that exact combo on 87E10 at full power full-timing of 32 to 34 degrees (correct for alloys). Car went 106 @12.9 with a 2.2 60ft right out of the gate at 3650 pounds and 720ft elevation
Oh sorry, mine was a 360. But otherwise the same.
 
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My 340, 10.2/1, +.030, flat top, zero deck, .039 gasket, 182 psi, 63cc closed Edel heads, Edel air gap, 222* 226* @108* roller, 1.6 rockers, EFI, will run on 91 no problem and maybe 89 but I havent tried. I push the timing and it likes 94. It can get 24 mpg and the power accel always brings on a smile. It's made to make torque and cruise. 1/4 mile,,?? 347 ft elevation
 
AJ/FormS said:
I have run 11.3Scr at 900 ft elevation, with alloys, flat-tops and tight-Q; don't short yourself, target at least 175 psi at your elevation, and you will have a ton of fun. For a streeter, I had great results with a 270/276/110 cam; 223/[email protected]
Mine ran on 87E10, and made fantastic fuel mileage.
If I build again, I think I will try to run 87E10 at ~190 psi.
To answer your question;
at 4.07 x 3.315 your swept is 706.74, and to get to 10/1 will require a total chamber volume of; 706.74/10-1=78.527cc. The Felpro .039 is 8.8cc and so, 78.53 less 8.8+5=64.7 for the rest. With alloys, I would run 60cc heads, for an Scr of 10.7, and a cam with an Ica of about 64*, to get a Dcr of 8.42 @500ft elevation . The pressure is predicted to be 175psi. I ran that exact combo on 87E10 at full power full-timing of 32 to 34 degrees (correct for alloys). Car went 106 @12.9 with a 2.2 60ft right out of the gate at 3650 pounds and 720ft elevation
Oh sorry, mine was a 360. But otherwise the same.
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Thanks AJ! Was that cam custom ground? With that cam and (60cc)10.7 compression you ran 87 octane with no pinging? Great. That must have to do with the Quench I was reading about. My 67 is rated at 2970lbs on the reg, plus 200(me). I,m looking for a strong 340 but not over the top and un drivable. I'm the type with reasonable expectations, lol.
 
LJ67barracuda340 said:
My 340, 10.2/1, +.030, flat top, zero deck, .039 gasket, 182 psi, 63cc closed Edel heads, Edel air gap, 222* 226* @108* roller, 1.6 rockers, EFI, will run on 91 no problem and maybe 89 but I havent tried. I push the timing and it likes 94. It can get 24 mpg and the power accel always brings on a smile. It's made to make torque and cruise. 1/4 mile,,?? 347 ft elevation
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How about a look at your cam card, please.
 
Speed masters need a good valve job to make around 530hp
and are the cheapest.

Wouldn't even consider the edelbrocks.

Promax or/then Trickflow in flow and dollar
 
512Stroker said:
How about a look at your cam card, please.
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it's a Hughes roller. I remembered 108* but seems its a 110*,,,my bad

cam card.JPG
 
The wife’s engine is like AJ’s w/the TF heads, 1.6 rockers and a similar Comp cam Hyd roller. Cam card below.
9B76F182-8F77-4AC2-8DAD-3E02C316ABF1.jpeg
9B76F182-8F77-4AC2-8DAD-3E02C316ABF1.jpeg
 
LJ67barracuda340 said:
My 340, 10.2/1, +.030, flat top, zero deck, .039 gasket, 182 psi, 63cc closed Edel heads, Edel air gap, 222* 226* @108* roller, 1.6 rockers, EFI, will run on 91 no problem and maybe 89 but I havent tried. I push the timing and it likes 94. It can get 24 mpg and the power accel always brings on a smile. It's made to make torque and cruise. 1/4 mile,,?? 347 ft elevation
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LJ67 thanks for the input that is just what I am looking for, torque and cruising. I don't need to be a street hero, lol
 
why run zero deck? is it a modern gas issue? I have KB 243s in my 340 and I think they are stock above deck type. So far no issues on pump gas.
 
coyote42 said:
LJ67 thanks for the input that is just what I am looking for, torque and cruising. I don't need to be a street hero, lol
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I'm using a 5 speed with 2.66 first .68 5th and 3.55 rear. I'd love to try it with an auto and about 2200 converter but thats too much work, lol. The engine will pull down to 1500 in OD with out complaining if I'm careful. I dont do that much though. Desk top dyno on this combo shows a near dead flat torque curve from 2500 to 5000. I hesitate to quote numbers but the graph shape is what I was looking for. The cam stops lifting when the heads stop flowing.
 
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