340 x heads on a 70 318

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gary peed

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I have a set of 69 340x heads off a GTS AND HAVE HEARD IT WOULD HELP A 318 ANY INFO. WOULD BE NICE.
THANKS FABO MEMBERS
 
Oh it will help greatly reduce the 318 crappy compression even worse. Useless you change the pistons for higher compression the X heads will only hurt the motor.
If you want different heads look for the 302 casting swirl port heads be a better bet.
 
someone had told me that before too I think I will hold on to the heads and find a nice 340 block I have everything else just need a good block to put everything in,
Thanks for your input.
Gary
 
Don't be afraid to pick up a 360. It will have more torque than that 340 and they are easier to find and cheaper to build.
 
duster360 said:
Don't be afraid to pick up a 360. It will have more torque than that 340 and they are easier to find and cheaper to build.
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Only 360/318 worth anything are the late 80s/early 90s LA roller block.
 
covering-ears.jpg


No 360 Fans allowed :D

Don't be afraid to keep the 318. Lol! I had the opportunity to purchase a 360 for a killer price, but refused because I had so many people tell me that a 318 won't do this or that. I've hurt a lot of feelings.

I would go with the "302 casting" heads (that's what I have). I got my engine out of an '87 Diplomat. I know with a little porting and bigger valves, my little 318 will need slicks or a radial... Well, it do now, but I manage to make the hard tire work. May help if I add CalTracs one of these days.
 
You guys are pretty harsh. I've run a 318 stock internals with a ported #302 swirl port in a 3400lb Dakota. Best of 14 @ 96MPH. With 727 and 3.23.

Nothing wrong with a 318, infact I'm halfway done my 318/390 build with 894 ported X Heads. Power to the underdog.
 
mini said:
You guys are pretty harsh. I've run a 318 stock internals with a ported #302 swirl port in a 3400lb Dakota. Best of 14 @ 96MPH. With 727 and 3.23.

Nothing wrong with a 318, infact I'm halfway done my 318/390 build with 894 ported X Heads. Power to the underdog.
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Again, unless you boost the compression on the 318/360 (piston swap) or swap pistons (same compression ratio) and turbo/supercharge the motor, it just is lacking. Boost the comp on either and now you got a winner.
 
1970Duster said:
Again, unless you boost the compression on the 318/360 (piston swap) or swap pistons (same compression ratio) and turbo/supercharge the motor, it just is lacking. Boost the comp on either and now you got a winner.
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:thumleft: compression is your friend. So is flow, but in a .040 - .090 "in the hole 318 block, a zero deck or nice KB piston is almost mandatory.
 
1970Duster said:
Again, unless you boost the compression on the 318/360 (piston swap) or swap pistons (same compression ratio) and turbo/supercharge the motor, it just is lacking. Boost the comp on either and now you got a winner.
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Would milling the 302's and running a thin gasket help a little or a lot? I've heard different numbers on how much to mill the heads before you have to mill the intake side.
 
It will make a dog outta that 318 with a stock set of pistons in it. I tried that years ago in a mud truck. Put a set of J heads on a 318. Had a hell of a lot of torque but had zero RPM's!!! LOL! Motor is still alive and now has a set of stock 318 heads on it. Runs good for what it is. Mild cam, Eddy intake and carb
 
Bad Sport said:
Wow, I'm sure there is a bunch of guys with 500 HP engines out there that are gonna be disappointed to hear that.
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You can run whatever block you want to make power but if you have to buy a block get a roller block. Remember a roller cam brings you into the power curve sooner and keeps you there longer. Just sayin.
 
JoJo said:
Would milling the 302's and running a thin gasket help a little or a lot? I've heard different numbers on how much to mill the heads before you have to mill the intake side.
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Yes it would increase compression, the more you mill the bigger the increase. That said you'd be better off swapping pistons and you get WAY more bang for the buck than milling parts.
 
The easiest way to get your compression to "reasonable" is put 10.5 pistons in it with the X-heads, you will end up around 9.2. (Been there > done it already)
 
As with any engine, the 318 with the X heads can be made to run very well if all of the other components match. Even with low compression.
 
RustyRatRod said:
As with any engine, the 318 with the X heads can be made to run very well if all of the other components match. Even with low compression.
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Yes, the increased flow will offset the compression drop if you just bolt them on.


Putting higher compression pistons will make it even better if you are willing to go that far.
 
"You can run whatever block you want to make power but if you have to buy a block get a roller block. Remember a roller cam brings you into the power curve sooner and keeps you there longer. Just sayin"

They make drop in roller lifters for any small block
 
Not trying to be an a** here.....but I have to ask why folks make such a big deal out of "x" heads now-a-days? They are 40+ year old iron heads. I understand if someone is restoring a car but....By the time you buy them, get them inspected and gone thru you will probably be right in the ball park of the RHS (Indy?) iron heads....which are new....

While I am rambling, don't get the allure of the infamous "WAS a 340 car....that often times now has a wedge in it.....There is a thread on here about a guy buying a disaster of a "340" car.....seriously, by the time the guy buys the motorless car, does all the necessary cosmetic work etc, hunts down a "340" etc he will be into the thing for 4 times what it is worth....I just don't get some of this stuff....
 
Gary Peed, If you already have a 4bbl (600cfm range) and a dual plane intake with dual exhaust (headers a plus), you can bolt the 340 head on and get a noticeable gain in power. Yes, if you change pistons, the gain will be greater, but whoever said that you will loose power with stock pistons is insane. We have bolted on 340 heads, 360 heads (cut .040) on stock block 318's and have always picked up noticeable hp. If you have the heads, and want to bolt them on your engine, you will increase your horsepower for sure. For one, almost every 4bbl intake has bigger ports than your stock 318 heads, giving you better port matching. 2nd, flow will always trump compression. Proof??? Put 11 to 1 compression pistons in a stock 318 2bbl, and I will run a 8 to 1 compression 318 with 4bbl, 340 heads, 340 cam, with headers and I will smoke your 11 to 1 318 so bad you will never know where I went. Compression helps for sure, but flow is most important, and remember, your motor is a air pump. The more air flow, the more horsepower..... So bolt them on and go faster...
 
X heads flow about 40 + cfms over 273/318
The best option would be magnum stock or aftermarket
Or ported 302 heads. That way you get the flow gain along with a bit or a CR bump all win. 2nd would to be to port out the 318 heads you got no loss in CR. 3rd you would be 340/360 heads you will lose some of the power gained by flow with loss of CR and would have to be very careful with cam choice since the engine will be very low in compression. Having said that I put 360 heads and intake with a 305 carb and a 340 cam in a 76 dodge pickup with stock exhaust and it was definitely quicker.
 
My brothers barracuda ran a stock piston 360 with 2.02 j heads and ran a 13.50 @99 so if you have the right cam it will work and run on 87 pump all day.
 
This thread is heating up :D

I had a guy tell me to put 360 heads on my 318 without milling or anything, but I've heard so many people say to have the heads milled. I know everything on the internet is true (Lol!), but I'd rather "measure twice and cut once" with my setup. So far, I'm loving my 302's in stock form.

The decisions!!!

:sad2:
 
Since he already has the heads, throw them on there but get a Whiplash cam which has zero overlap and keeps your effective CR right where it's at, which would be around 8:1 with a thinner gasket. Should be a good combo good to the tune of about 330-350hp, but more importantly, instant torque.
 
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