Decision Point: Hop Up 318 In Car Now or Build 340

[Road_Runner]

I'm at the point that I'd like to either go forward with hopping up the 318 that is in my Barracuda now or leave it totally alone and just work torward getting the 340 block I have built and ready to drop in.  I  have a pair of 302 heads, LD340 intake, Hipo exhaust manifolds and will pick up a 650 AVS if I decide to upgrade the 318.  Its a great running but slow, slow, slow engine right now.  I'd rather not go inside the engine if I don't have to but guess I could try to swap cams if that's going to be a huge difference.  I know I'm asking a VERY subjective question, but here goes:

Should I go forward with the 318 upgrades and see if that satisfies my needs, or am I just wasting time & money if I do and should just move forward with the 340?    I don't want to  but I need to decide how I'm going to be spending my $$ and my winter.

Thanks in advance, Jim

[Road_Runner]

I guess I should add that I don't want a race car, I've got the Roadrunner for that, just something that won't embarass itself when cruising around town.  Think a nice peppy daily driver.

Thanks, Jim

[Topcat]

Good article on 400 HP 318 worth reading

http://www.moparmusclemagazine.com/techarticles/mopp_0409_318_engine_build/photo_01.html

[Road_Runner]

Good article on 400 HP 318 worth reading

http://www.moparmusclemagazine.com/techarticles/mopp_0409_318_engine_build/photo_01.html

Thanks for the great link, I bookmarked it.  But my situation is a little different, at least in what I'm trying to decide between right now.  If I was going to do a full build of either engine I would be very inclined just to build the 340 which is my option #2.  Option #1 is to hop up the 318 with bolt-ons so although the 318 can be built into something stout, will I be happy enough with the modded 318 to move onto the body work, paint & interior work to make it the nice driver I want it to be?  If so, when it does come time to rebuild I might just leave the 318 in there with a few more internal mods like cam & pistons to add compression.

Thanks, Jim

[JoltinJoe]

The guys always say to put a 340 in.  Will sell better in the end.

[Road_Runner]

The guys always say to put a 340 in.  Will sell better in the end.

I'm not sure I'm that concerned about resale.  Two Mopars : Two Kids.  Sounds like an equitable inheritance to me.  But I know what you mean, even if the 318 is original and although I think it is based on how original the rest of the car is I haven't verified numbers, it still would probably be worth more with the 73 340 in it.

Thanks, Jim

[Chryco Psycho]

What year si the 318 ?
early 318 were decent for power but most seem to be underpowered even with mods ,probably due to lack of compression , I have driven 273 s that were more impressive .
at least with the 340 you can build it right with all the matching parts & get some decent power out of it

[ChallengerGary]

I agree with Chryco.  What year is your 318?  The compression will severely limit the results of any bolt-ons if it is too low.  Although, look at it this way, those bolt-ons you have are a less than one day job.  Why not throw them on the 318 since you already have them and then decide.  Afterall, you don't need them to build the 340....

[Road_Runner]

Thanks all.  The 318 is a 1973.  It was rebuilt by the original owner several years ago, but hasn't been driven very much since then so its more or less a 'recent' rebuild.  It sounds decent through the duals, but if the cam is something other than stock I can't tell.  Based on the lack any perceptable kick in the pants when I nail the throttle I would doubt the compression is anything other than stock. Sounds like the compression is going to mute the impact of any mods, but as ChallengerGary said I could just bolt on what I have & who knows.  Chryco, doing the 340 'right' is exactly what has me weighing whether to even bother with the 318.  If I build the 340 I'm going for it HP wise.  I don't think I want to stroke it, but much better heads, maybe roller cam, better pistons, and maybe even TTI headers would all be in the plan.  If I stick with the 318, I'd like to keep it looking more stock with the hipo exhaust manifolds.  Any additional feedback would be greatly appreciated.

Thanks, Jim

[Chryco Psycho]

by 73 the compression was low , changing the pistons when it was rebuilt could yeild anything for compression .
 Only you can decide what you want to do & what budget you have available

[ragtopdodge]

Don't waste your time and $$$ on the lo-po 318.

Build it once, build it right.  340...if you have such a block.

[Moparal]

Did you see the forsale adds where glennster was selling his 4 inch crank and 273 rods? It all need rebuilding, but you could stroke that 318 to a 390 .  He also has some fresh J heads ready to install on there to. You could make that 318 scoot

[the_engineers]

I think the 340 is inevitable at some point.  In the meantime, I'd go with some "universal" hop-ups to the car that will benefit either motor, first.  Good headers and exhaust, converter, steeper gears...if it's truly an "around town" vehicle, get 3.55's or 3.91's.

These changes alone will definetely wake up the car.

If it's close to being "enough", swap in the 302's (which will raise compression a little), get a mild cam and add the intake.  If you've already got the stuff, the money's already spent.  Now evaluate the car.

[JoltinJoe]

I think the 340 is inevitable at some point.  In the meantime, I'd go with some "universal" hop-ups to the car that will benefit either motor, first.  Good headers and exhaust, converter, steeper gears...if it's truly an "around town" vehicle, get 3.55's or 3.91's.

These changes alone will definetely wake up the car.

Do you usually put a torque converter in ever build?  I was under the impression that tq's don't 'apply' to every build.

[Cooter]

I know a buddy that seccessfully bored an early '67-'68 318 Truck block .130 over(4.040) and installed aftermarket 340 pistons...Lemme tell 'ya, that little motor fooled alotta people...