Worth Fooling With The 318?

[Road_Runner]

My 73 Barracuda came with a recently rebuilt stock 318 2 bbl with a decent dual exhaust (stock manifolds).  I've started gathering parts for a 340 I'll eventually drop in but that could be a year or two depending on funds, time to work on it, etc.  So I just picked up a set up 302 heads and I was thinking about having them gone over and putting them along with an LD340 or Mopar dual-plane intake & Carter AVS on it.  From what I've read here and elsewhere it sounds like the 302s will bump my compression slightly, but I don't plan on going as far as a cam swap. Question: Will this return a worthwhile bump in performance or am I wasting my time on the 318 without bumping the compression further with pistons & swapping the cam?  Right now the engine runs like a sewing machine but unfortunately is about as fast as one! 

Thanks, Jim

[Aussie Challenger]

If you fit the 302 heads and a 4 bbl manifold & carby it will let the motor breath better especially as you have a freer flowing dual exhaust. It will wake up the 318 and make it more responsive and could improve the economy as well. Check your distributor to make sure that it is advancing properly, possibly may need maintenance.   

[Road_Runner]

If you fit the 302 heads and a 4 bbl manifold & carby it will let the motor breath better especially as you have a freer flowing dual exhaust. It will wake up the 318 and make it more responsive and could improve the economy as well. Check your distributor to make sure that it is advancing properly, possibly may need maintenance.   

Yeah, that was kind of my thinking.  Just a little unsure how limited it will be with stock cam & pistons.  At least I think both are stock since the original owner rebuilt the engine.  I wouldn't mind sticking with the 318 for a while if I can get decent performance from it, especially if the gas mileage is decent, too.

Later, Jim

[Chryco Psycho]

the Later 302 /308 castings are definatly worht using , we gained 41 RWHP switching out ported 308 heads from X castings on a 340 . If  it is worth doing financially is another ?

[Road_Runner]

the Later 302 /308 castings are definatly worht using , we gained 41 RWHP switching out ported 308 heads from X castings on a 340 . If  it is worth doing financially is another ?

What should I expect to pay for someone to do the work on these heads?  Do you have an opinion on how they'd work just cleaned up on the 318?  How do you think these compare with the RHS heads for the 340?  Am I crazy to consider getting a set of 'correct' J heads for the 340?  Lastly, I'm still struggling with this part of my plan, but I'd like to use the TA/AAR style exhaust manifolds I picked up for the 340, does this make sense worrying about how the heads flow if I use these manifolds instead of headers?  Thanks for the advice.

Jim

[GoodysGotaCuda]

milled 360 J-heads, cam and a performer rpm..mine runs alright. Ran a hell of a lot better with the high stall converter I previously had in it that helped with the lack of torque. Clicked a 13.6x in the 1/4, okay, not fast, not too slow.

[Chryco Psycho]

Weill I would port your heads for approx $500 but is it worth it on a 318 head probably not
I would not spend the $$ for original X or J castings , just not worth it IMO you can make more power with cheaper heads & sell the X or Js to fund it .
 the 302 heads justr cleaned up & bolted on should gain you some decent power & efficiency .
 I have not tried a set of the RHS  heads so I cannot compare but the reports seem favorable .
With the right cam choice , wider CL around 112* the manifolds will work ok , you will give up some power obviously

[Road_Runner]

milled 360 J-heads, cam and a performer rpm..mine runs alright. Ran a hell of a lot better with the high stall converter I previously had in it that helped with the lack of torque. Clicked a 13.6x in the 1/4, okay, not fast, not too slow.

Sounds like a similar build to what I might eventually do to the 318 if I keep it vs. the 340.  I just had my trans rebuilt and they put in a new stock converter so I know I'm giving up something there but I at least went with a shift kit for crisper shifts.  From some of your earlier posts I seem to recall you were running a 3.91 gear to get into the 13's, I'm not sure I want to go that steep on the Barracuda unless I also go for some kind of overdrive unit to keep the rpms down on the highway.  13's out of a 318 car is darn good though, and since I'm building this to be a driver not a dragster absolute speed isn't my #1 priority.  It just has to be fast enough not to look like a poser.  Thanks for the info.

Jim

[Road_Runner]

Weill I would port your heads for approx $500 but is it worth it on a 318 head probably not
I would not spend the $$ for original X or J castings , just not worth it IMO you can make more power with cheaper heads & sell the X or Js to fund it .
 the 302 heads justr cleaned up & bolted on should gain you some decent power & efficiency .
 I have not tried a set of the RHS  heads so I cannot compare but the reports seem favorable .
With the right cam choice , wider CL around 112* the manifolds will work ok , you will give up some power obviously

Thanks again, this helps.  Not sure what my decision will be yet, but I know a little more than I did.

Later, Jim

[GoodysGotaCuda]

Sounds like a similar build to what I might eventually do to the 318 if I keep it vs. the 340.  I just had my trans rebuilt and they put in a new stock converter so I know I'm giving up something there but I at least went with a shift kit for crisper shifts.  From some of your earlier posts I seem to recall you were running a 3.91 gear to get into the 13's, I'm not sure I want to go that steep on the Barracuda unless I also go for some kind of overdrive unit to keep the rpms down on the highway.  13's out of a 318 car is darn good though, and since I'm building this to be a driver not a dragster absolute speed isn't my #1 priority.  It just has to be fast enough not to look like a poser.  Thanks for the info.

Jim

Yes I have 3.91s, high stall converter, both of those make a HUGE difference. I currently have a stock converter in mine because somehow the snout broke on my high stall. It's a flat dog out of the hole now. 

[Road_Runner]

Yes I have 3.91s, high stall converter, both of those make a HUGE difference. I currently have a stock converter in mine because somehow the snout broke on my high stall. It's a flat dog out of the hole now. 

 

I'm not sure what rear gear mine has, wouldn't be surprised if its a 2.xx in the 8 3/4 since I think the std gear was an extreme highway gear.  My problem is mine has no getup at all that I can tell, with the stock 2 bbl a steeper gear would only make it run out of steam at an even lower speed.  I don't mind keeping the original 318 in there if I can get it moving along, but I wonder if its worth it since I have a 73 340 block sitting in the garage...

Thanks, Jim

[71chally416]

If it's a complete dog I doubt changing heads and intake will make much difference, especially if you retain the stock cam and exhaust manifolds. Those are the two areas you'll get the biggest gain tossing the stock pieces. Build the 340.