340 or 360 for hp

[btceng]

The car is coming along but I have the urge to ditch the 318 and build a mild 340 or 360. get differing opinions on which to be in the market for. I really want the 340 because of it actually being available for the 72 Challenger but a trusted friend suggests the 360 because of the availability. What should I expect to pay for a buildable 340? I have found someone with a stock (down to the TQ) 340 and 4 speed out of a 70 Dart. It is in a 76 Roadrunner that he wants to get rid of. I don't think that I have a need for the Roadrunner (rusty) but he doesn't want to separate it. I have also found a friend with a 360 mated to a 727 out of an rv with only 60,000 or so on it. 360 was running good at time it was removed. He thinks that the 360 is a 76 model.

I have a stock 4bbl manifold for a 360 on my 318 now and some nearly new parts like cam, lifters, Edelbrock carb, double chain, and electronic ignition. I could use them to help build either the 340 or the 360. Oh, one more thing. I have a good 904 with the slapstick and would like to upgrade to a 727.

Help me out again, guys. Thanks.

 

[PlumCrazy440]

440 IMO. But every 340 I have had run like scalded dogs.:3gears:

 

[btceng]

Yeah, I thought about that too. I have been able to find a good number of 440's and even know where one of those mated to a 727 out of an rv is located and for sale. I have no experience with the big blocks and the chassis changes that may need to be done worry me a little. I am looking for a relatively inexpensive power upgrade but nothing radical.

 

[Cranky]

Sticking a big block into an E body requires very little chassis changes. Depending on what you're wanting to do with the car, the 318 torsion bars will work and so will the leaf springs but if you want the car to handle on the street, an upgrade will be in order. A small block is lighter when each is built similar. You will need a set of big block motor mount brackets to set the BB in. Wiring is a bit different but that's not a big issue. Radiator might need to be changed and of course, the exhaust is different...

 

[burntorange70]

Will need a BB trans too. Going BB will take the most $$$. 340 is next due to the initial cost. 340 and 360 shold cost about the same in parts to build.

Just depends on what you can find. I would look for a motor that all ready has the CR uped. Like to see some thing around 10-1. Be nice to find some thing with good heads on it too. Not worth paying a little less for some thing that needs the pistons and heads changed IMO.

Also the 904 should be just fine behind a SB. Will use up less power to turn it compared to a 727 and weigh less. People run them in drag cars all the time. Should be good fr what you are doing. There may be some mods you can do to it to make it even stronger too.

 

[burdar]

It's going to cost more to build a 340 and you'll be down 20 cubes from the 360. It's getting harder to find rebuildable 340's so they are going to cost more. 360's are still readily available and have the advantage of extra cubic inches.

You can dress up the 360 to look just like the 340. No one will know but you.

 

[btceng]

Thanks. All things that I have considered. I am going to try for the 340. It's too nostalgic to pass up. The guy says that it is out of 70 Dart Swinger. What's the 4 speed worth? Also, are there any other parts that are useful from a 76 Roadrunner that may fit in my 72 Challenger? I'm thinking possibly suspension or brake parts.

 

[burdar]

Suspension is going to be completely different. If you can get it cheap, you can part it out. Save all the little plastic door lock clips as they didn't change much over the years. You won't get a lot of money for F-body parts but you might make a few bucks. Those cars are rust prone. Any clean sheetmetal should be saved.

 

[shadango]

Seems like you can get a 360 built up and make great power for less than the 340s sell for.....

re: small versus big block....It depends on what parts you have and what you still have to buy.

I have a 318 (cam, J heads, dougs headers, ede intake/carb, beefed up 727 and breakaway convertor) that runs great....but one day the decision will come.....rebuild? 360 stroker? Big block?

I already have 1" t bars in the front and add a leafs in the back....but still plenty to consider....

For me to go to a big block I would need new:
-headers and the exhaust rework to mate up to the existing 3" exhaust
-k member
-radiator
-tranny/convertor
-intake

Seems like a lot to "throw away" this soon in the game (my car has only been together since may of 09.).

AH...one day....when money is of no importance...LOL

 

[Cranky]

Seems like you can get a 360 built up and make great power for less than the 340s sell for.....

re: small versus big block....It depends on what parts you have and what you still have to buy.

I have a 318 (cam, J heads, dougs headers, ede intake/carb, beefed up 727 and breakaway convertor) that runs great....but one day the decision will come.....rebuild? 360 stroker? Big block?

I already have 1" t bars in the front and add a leafs in the back....but still plenty to consider....

For me to go to a big block I would need new:
-headers and the exhaust rework to mate up to the existing 3" exhaust
-k member
-radiator
-tranny/convertor
-intake

Seems like a lot to "throw away" this soon in the game (my car has only been together since may of 09.).

AH...one day....when money is of no importance...LOL

If you already have a V8 K frame in the car, you don't need to swap it out for the big block....

 

[shadango]

If you already have a V8 K frame in the car, you don't need to swap it out for the big block....

Sorry....

Maybe I am thinking of a Hemi swap in?

........I can dare to dream....LOL

 

[71solo2challenger]

IMO you pay for the privilege of saying 340. Machine work costs the same, parts cost the same. But you pay a lot more for the 340 block vs. the 360 block. For basically the same power levels. I've gotten 340s and sold them to people that want that magic number. I'm building up a 360.

 

[shadango]

IMO you pay for the privilege of saying 340. Machine work costs the same, parts cost the same. But you pay a lot more for the 340 block vs. the 360 block. For basically the same power levels. I've gotten 340s and sold them to people that want that magic number. I'm building up a 360.

Thats kind of what I always thought.....although the steel crank in the 340 contributes to some HP gains, doesnt it?

My thought is that when it comes time to replace the 318 I have it will be a 360 stroker crate engine.....keep my headers, tranny , rad, etc......

If I were starting fresh I would go big block...but tossing tons of parts to go big block makes the big block swap as expensive as a 360 stroked I would think......

 

[Cranky]

Sorry....

Maybe I am thinking of a Hemi swap in?

........I can dare to dream....LOL

No need to be sorry.....

 

[btceng]

Is there any issues concerning the rv engines and transmission? I'm figuring the heads to be good but the cam and possibly intake needing replacement. The tranny should be heavy duty right?

 

[71solo2challenger]

trans probably won't have the boss for the floor shifter.

Intake is most likely a 2bbl.

its the RV Big Blocks that have a weird head arrangement

 

[S-S-P]

I have been down this road myself and I'll share another option not yet discussed.

The 318 Stroker Kit. Under 2k complete and yields 390 CID. Now you don't need the extra motor; just use the one you already have. The machinework is gonna be about the same, and 390 CID makes more power than the stock 340 or 360, and cost much less than buying and then stroking a 340 or 360. Plus, keep in mind, the most popular 360 stroker is only 408.

Bang for buck, I'd consider the 390.

 

[burntorange70]

I have been down this road myself and I'll share another option not yet discussed.

The 318 Stroker Kit. Under 2k complete and yields 390 CID. Now you don't need the extra motor; just use the one you already have. The machinework is gonna be about the same, and 390 CID makes more power than the stock 340 or 360, and cost much less than buying and then stroking a 340 or 360. Plus, keep in mind, the most popular 360 stroker is only 408.

Bang for buck, I'd consider the 390.

You got a good point there. Another way to go for sure.

 

[cudaman70]

360

It's going to cost more to build a 340 and you'll be down 20 cubes from the 360. It's getting harder to find rebuildable 340's so they are going to cost more. 360's are still readily available and have the advantage of extra cubic inches.

You can dress up the 360 to look just like the 340. No one will know but you.

I plan on doing that as well

 

[btceng]

I have a book on stroking the Mopar small blocks. I have definitely thought a lot about doing that. I didn't know if I had the skills to pull it off. Sounds reasonably easy, though. I suppose I'm one of those that's hung up on the magical 340. Not sure why. I've known several and they just smoke those Fords and GM's.