I need more power scottie!

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mikess68

mikess68

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have a numbers match 72 318 swinger. want to keep the motor with it so i need to know how to get a few more horses from that mouse in the cage that i have. i have a 4bbl, and intake on it. helped a little. will 340 heads fit on it and will they help??

other than a major rebuild to a motor that runs perfect, what can i do to get a little more out of it? nos is not the answer. im looking mechanical.

tks Mike
 
If your not changing your pistons the bigger chambers on the 340 heads will lower your compression and will probably lower your power. If you are changing your pistons the bigger valves in the 340 heads will help your power.
 
Get some P&P work done on your heads,a good valve job and a bigger cam will get you more HP.:D

Scottie :cheers::burnout:
 
IMO, the bigger and port work will be somewhat cancelled out without the addition of larger valves in the heads. Opinions vary, but that's mine.
 
What do you have for exhaust manifolding and pipe(s)? Ignition? Are all the internals factory stock?
 
Moper makes some good inquires. I'll assume this is a all dead stock engine.

First, what gear ratio do you have & ...
Are you willing to change the gear ratio?
Would a torque converter change out be OK?

How much power (A guess her is OK) would you be looking to make?

Truth be told, a 318 can not make good use of a 340/360 head very well unless the engine is realtivly pumped up well. The stock heads you have are more than capable of allowing the engine to make enuff power to propeling the car into the 14's easy and still be a better chocie than a 340/360 head.

Porting the 318 head can get you into the 13's and 12's.
However, it can be a catch 22 at this point since porting the head can cost more than a 340/360 head which may perform at the same level.

(FWIW, MoPar used to sell a ported 318 which made 55 HP more than a 340 head.)
 
He's dead Jim, you grab his phaser, I'll get his wallet.

Why captain I don't believe my ears

I don't believe your ears either Spock, now grab his boots.

Dammit Jim, I'm just a doctor, not a mechanic!
 
mikess68 said:
have a numbers match 72 318 swinger. want to keep the motor with it so i need to know how to get a few more horses from that mouse in the cage that i have. i have a 4bbl, and intake on it. helped a little. will 340 heads fit on it and will they help??

other than a major rebuild to a motor that runs perfect, what can i do to get a little more out of it? nos is not the answer. im looking mechanical.

tks Mike
Click to expand...

I think I will answer about the 340 heads. Yes, yes.
 
Didn't Chrysler have later 318 head that flowed better? 302 comes to mind. Could be dead wrong. Never ran a 318.
 
The 302 is generally known to be the best 318 to run since it was about the pinnacle of 318 heads for best flow & performance. The head can be worked on to flow about 240 cfm if properly done. More may be possible if a "Max Effort" drag porting is done. I do not really see much more out of it. The head's windows can be opened up to a 340's window.
 
I would like everyone to know this

All LA 318 intake and exhaust ports are the same no matter casting, with the exception of the #234 heads that do not have an exhaust heat cross over to heat the intake

The only perk to the 302 heads are closed chambers.
However...the 234 casting heads also have closed chambers, plus the benefit of no cross over that hurts ex flow on one port per head.

234 casting heads from 1967 imo r thee best LA 318 heads the factory ever cast.



gear it, mill the 340 heads and run them....or port the 318 heads and run them.

each will cost, one will just cost more.
 
get a small block stroker with aluminum heads, intake, holley 4bbl, nice cam, headers. keep the 318 in storage. you could have the 318 refreshed/oiled/bagged before you store it.

i would not put money into souping up the 318 unless you plan on going all out with a custom crank/custom pistons/etc.

adding to it as it sits, i dont think it's a good investment buying accessories.
even if you just switch to a 360 with 10:1 compression and nice heads you will get way more bang for your buck than tweaking the current motor.
 
p.s. the 318 is more of a workhorse motor than performance... it will last a long time if you take care of it, has reasonably good performance, and is quite dependable. for performance you need to get more cubes, or do something crazy. more cubes is cheaper than the going crazy route (ie custom build, or supercharger, etc)
 
85 318 truck heads had heart shaped heads and 9-1 comp,with 340 purple cam,carb,intake and headders low 14s is easily obtainable,providing your running 323s,sorry i cant remember casting#
 
in my opinion,the 915 heads casting #3418915 are probably his best bang for the buck,and easy to come by.
 
moper said:
What do you have for exhaust manifolding and pipe(s)? Ignition? Are all the internals factory stock?
Click to expand...

rumblefish360 said:
Moper makes some good inquires. I'll assume this is a all dead stock engine.

First, what gear ratio do you have & ...
Are you willing to change the gear ratio?
Would a torque converter change out be OK?

How much power (A guess her is OK) would you be looking to make?

Truth be told, a 318 can not make good use of a 340/360 head very well unless the engine is realtivly pumped up well. The stock heads you have are more than capable of allowing the engine to make enuff power to propeling the car into the 14's easy and still be a better chocie than a 340/360 head.

Porting the 318 head can get you into the 13's and 12's.
However, it can be a catch 22 at this point since porting the head can cost more than a 340/360 head which may perform at the same level.

(FWIW, MoPar used to sell a ported 318 which made 55 HP more than a 340 head.)
Click to expand...

We still havent heard your goal.....you said a few more Hp......10-20 more?
Or are you thinking 100-200?
 
thanks to all that replied. Im not building a race car, more show and cruizer. I do like to hear the tires bark and cry from time to time. to answer some question:

i have a elde carb, looks prob the 550-600 variety and a elde stock height intake. the headers are run into about 2 inch pipe with a couple of cherry bombs. its stock 318 but the guy that i got it from had the motor out, put in a cam at least i think, painted it and put it back in. i want to think after that much trouble he did something nice to it. it has the same heads and block. if i could compare, it seems to be compared to about a 283 stock chevy in regards to HP (not a HiPo one). it has a slight idle that sounds like a mild cam change. i would not call it a lope, but idles like a stock 340,(just a little something there). the guy won't tell me anyting about the motor due to low price of the car (he set the price then got mad for selling it cheap!) so i'm on my own.

I thank you all for the tips. if i pull it i'll just change the pistons and heads and be done with it. but sounds like i'll wait till the resto is complete, bang it a few times and see what happens. ill look at the build sheet and see what rear end it has.
 
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