dart gt
Well-Known Member
has anyone ever put 302 heads on a 70 340?
302 cylinder heads
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dodgetkboy78
EDELBROCK HEADS SUCK!
A guy at Moparchat has 302 heads on a 340, but it is turbo. I have put them on a 360........
Why would you want to tho?
Why would you want to tho?
dart gt
Well-Known Member
it is going to cost around 1000.00 dollars to put hard seats in my j heads.the 302 already have them and i wont loose any compression while trying to burn regular gas.
moper
Well-Known Member
It's a small port for a 340. You may or may not feel the difference. I know I could. If it were me, I'd put the seats in. BTW, a grand for installing unleaded seats (as part of a valve job) is expensive. Is it correct to assume you mean the heads will be competely redone including new hardened seats? Or that's just for the seats?
1wild&crazyguy
Banned
I bet the small port air speed is keeping some bottom end tq below the turbo.
I would use the 360 heads on a 340 over the 302's myself.
dodgetkboy78
EDELBROCK HEADS SUCK!
Thats exactly the purpose, plus the closed chamber helps when it boosts. It's pretty interesting, all the testing and stuff he has done, why, if I hadn't of been banned for leaving, I would leave him a PM and see if I could get him over here. Lots of manifold testing and stuff he has done. Interesting guy, his name is Turbododge there.
Big bore, short stroke, the small port heads just seem to kill everything the 340 stands for. I would use 360 heads too, how about a new set? 308 heads are still pretty common too.
Big bore, short stroke, the small port heads just seem to kill everything the 340 stands for. I would use 360 heads too, how about a new set? 308 heads are still pretty common too.
1wild&crazyguy
Banned
sure.
I'd like to get some and play with them, see if they are worth a crap or just more paper thin late model castings you pull yer hair out over when you hit water.
Yeah I figured the closed chamber [anti detonation] factor helped when the boot hit too.
If rumble wants to maybe he could pm the guy over there and invite'em here.
I'd like to get some and play with them, see if they are worth a crap or just more paper thin late model castings you pull yer hair out over when you hit water.
Yeah I figured the closed chamber [anti detonation] factor helped when the boot hit too.
If rumble wants to maybe he could pm the guy over there and invite'em here.
dodgetkboy78
EDELBROCK HEADS SUCK!
He should, he would be tons of help with all the turbo questions that have popped up too.
I have ported 308 heads, I think it's a catch 22, I think the intake side cant be as opened up as the X and J heads, and the exhaust can be opened more...... So with adjustments of cam and intake, you would think the 308 head would be better in the last RPM's, and the X-J head would be better in the beginning? (Smaller ex port, more torque)
They have the same issue the 302 heads have, big pushrod hole. And they aren't closed chamber either.
I have ported 308 heads, I think it's a catch 22, I think the intake side cant be as opened up as the X and J heads, and the exhaust can be opened more...... So with adjustments of cam and intake, you would think the 308 head would be better in the last RPM's, and the X-J head would be better in the beginning? (Smaller ex port, more torque)
They have the same issue the 302 heads have, big pushrod hole. And they aren't closed chamber either.
bremereric
Well-Known Member
In Larry Sheppard's "How to Hot Rod a Small Block Mopar" he says the swirl port combustion chamber on the 360 Cast 308 heads are the best stock heads for a small block Mopar. He says to install some stainless steel 2.02 intake valves and 1.66 exhaust valves. :read2:
1wild&crazyguy
Banned
The thing is, j exh ports can be opened up huge, so big they can get lazy with flow per lift , like when you see them flow 200's but it took 6-.700 lift meanwhile they are at 175@.500 and 140@.400... It gets or 'can get' worse at lower lifts, but it really depends on whos porting them and for what.
I think it comes down to more or less work and how flexible they are to begin with as a casting.
The 308's that I've seen have a flatter floor and sick pinch, that was the only thing I remembered from seeing them.
I don't know about smaller exhaust ports making more torque, I do know the smaller ports [intake or exhaust] has the air speed on the higher side in comparison to something bigger like an X head 'on the same bore', or 906 vs max wedge, but in the end which one do you think is gonna make more torque, regardless of rpm?
I would think that if you put a '72' 318 head on a 340 cam'd 360, it would make peak tq sooner [though less] hold it to 3000 but then just drop off from there till choked at 5000rpm or around, but I've never tried it....
maybe I'll actually do math on this instead of just thinking out loud.
1wild&crazyguy
Banned
yeah ? for what? stock replacement? strip? then what after that?
I hate Larry sheepherder.
dodgetkboy78
EDELBROCK HEADS SUCK!
WHile he has some good points, I think the book was written for dummies.
A 318 head 360 works great, in a work truck, or MPG vehicle. In fact, I have seen a 360 with 318 heads get over 20MPG in a 3.55 gear, 32" tired 4x4 short bed truck.
No ****.
Power after sayyyyy, 45-5K?
Nahh, and a big power drop from 3500 on, I mean, I guess the more you port, the more power it will make at a higher RPM, but where do you draw the line, and use 360 heads?
A 318 head 360 works great, in a work truck, or MPG vehicle. In fact, I have seen a 360 with 318 heads get over 20MPG in a 3.55 gear, 32" tired 4x4 short bed truck.
No ****.
Power after sayyyyy, 45-5K?
Nahh, and a big power drop from 3500 on, I mean, I guess the more you port, the more power it will make at a higher RPM, but where do you draw the line, and use 360 heads?
dodgetkboy78
EDELBROCK HEADS SUCK!
The 308 head is said to have a W-2 ex port.........
moper
Well-Known Member
308s have a great exh port. Getting the int/exh ratio is usually problematic in LA heads... Which is why the 308s are a "best choice". It's not a W2... Not even close. But it is the model the Magnum exh port is designed from.
1wild&crazyguy
Banned
exactly where I was going on the flow ratio, but it's not as big a deal as it is getting in, especially with the intake and carb to consider as detriments.
intake usually cuts the intake flow down meanwhile the header tube increases the exhaust flow, think about that.
dodgetkboy78
EDELBROCK HEADS SUCK!
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