To 340 or not.........

[btceng]

I have been trying to find a 3440 for my 72 Challenger for a while. I found one today. It's a 72 model out of a 72 Little Red Express. It has the appearance of being all original and the owner says that it has been in his possession for 14 years. He had a 72 Duster that he had been racing. He reports it to have only 20,000 miles on it. It is a complete engine with the factory accessories still on it including a/c. It has j heads on it. He thinks it is the higher compression model offered in 72. Does this sound right so far?

There is also a 727 built for racing with the reverse valve body, another set of heads, a set of headers, various bolts, an additional oil pan, and a starter. He wants to sell it all for $1k.

Apparently, he traded a built 360 for it 14 years ago and it has been in his shop ever since. The deal seems good but I'm no expert.

How much of a performance gain would I see over my mildly built 318 with cam, 4 barrel, and duals. I also have a 904 in good condition behind the 318. I have been interested in installing 3.55s and a posi. Have 2.76 now.

 

[Chryco Psycho]

Sounds like a decent deal even if you have to go through the 340 , check for the thin 1" damper on the crank to confirm it is a steel crank .
It will beat up a 318 !!

 

[Big Jim]

X2! Just watch how your stall speed in the convertor matches up to rear end ratio. Too much stall and you'll cook the trans. Reverse pattern valve bodies not that bad on the street- just have to get used to it (and explain to the wife you have to shift it yourself) other than will need a different shifter. Good Luck- keep us posted!

 

[DetMatt1]

It all sounds good except they didn't make the Little Reds until `78 and I'm not sure that a 340 was ever used in a truck.

 

[btceng]

Yeah, I did a little research and found that it couldn't have come from a Lil Red, at least not originally. It is coded to the year 72. Apparently, compression went from 10.25:1 to 8.5:1 in 72. Also, the crank from forged to cast sometime in mid year production.

Question. By installing the hp 340 cam and 2.02 valves, assuming the good crank, would it still make good power without changing the pistons?

My little teen is okay. I could live with it unless the 340 is going to make a big difference. Also, the emblems are cool.:laughing5:

 

[burdar]

There isn't a low compression and a high compression version of the 340 in 72. They were all lower compression.

340's and 318's are basically the same engine. The difference is that Chrysler never intended the 318 to be a performance motor. They never gave it good flowing heads or a 4-barrel carb.(in the 80's the cop cars did get a 4-barrel on the 318's) You can build a 318 with the same parts as a 340 and get it to run great. The advantage the 340 has is the added cubes.

$1000 is a decent price for a 340 I think. The 340 has this mistique about it that usually demands a higher price. If you don't care about originality, you can build a 360 to look just like the 340 and the only person that will know is you. You can usually pick up a 360 for next to nothing.

 

[btceng]

I have another lead on a 68 340 out of a Dart. It is coupled to a 4 speed and is in stock appearance. I assume that in any case, it is a better candidate than the 72 block, given that both are in stock condition. Am I right here? I believe, though I have not visually verified, that the 68 wears the X heads and the owner claims it to be a screamer. It will crank and run so that is encouraging.

 

[Chryco Psycho]

Maybe if you wanted to stroke the 340 out to 408/412 you would replace the cank & pistons anyway , the X heads are OK but the later 308 castings are worth a ton of HP over the X heads , if you are leaving it stock the early high compression is the better buy but I bet you will pay a lot more for it . The 360 stroked is the other option , you can get a 360 for $200 easily drop in a stroker & make some great power

 

[btceng]

Decisions, decisions, decisions...........Hate 'em. Thanks guys.

 

[burntorange70]

Lets back up a little.

Got any goals for this motor/car?

HP# you would like to see?

1/4 mile time?

Or is this a fun driver you would like a little more from?

 

[cudas rule]

I have a 340 listed on here to check out the pics on my home page cudas rule.

 

[btceng]

Lets back up a little.

Got any goals for this motor/car?

HP# you would like to see?

1/4 mile time?

Or is this a fun driver you would like a little more from?

I'm in it for the fun factor, although, I live a couple of miles from an eighth mile track. What I would like is about 350hp, nice firm shifts, great sound, and the ability to hold a respectable street credibility. Currently, my teen sounds great but with no gear and too much cam, it's hard to back it up.

 

[btceng]

The answer to my thread title is.........340. I purchased the 72 date coded motor and 727 today. I hope it was a decent deal but the guy selling it says that he is selling out because his 7 year old daughter has been diagnosed with a brain tumor. I was buying it for the advertised price at that point. I really feel for them.

Anyway, the extra set of heads that he had with the deal have me wondering what they are. Attached is the number. Thanks for any help. He had a clutch fan, new alternator, and car oil pan and windage tray that I was needing also.

 

[btceng]

Found the casting number. Off of a 68-74 318. Nothing magical.

 

[Chryco Psycho]

cool sounds like you got a decent engine for a decent price

 

[btceng]

Do any of you have a suggestion for a rebuild recipe? I want a mildly built but reliable driver. I haven't verified it yet but the j heads are supposed to have the big valves and indications by the dampener appear to indicate a forged crank. The last owner says that this motor was purchased as a crate motor from an engine shop in Atlanta some 20 years ago. I'm not sure what's in there at this point.

Suggested cam, pistons, machine work, etc. is appreciated. How about a 350hp target. Easy, huh?

 

[Chryco Psycho]

well you need to get 9.7 range for compression , you could build a stroker out of it & get a new crank rods & pistons if you need to change pistons to get the compression you need . The J heads are ok & do have the big valves but the other option is to sell them for good $ & build a set of the later 308 heads from 87-92 Dodge trucks , with some port work you can gain 40 rwhp over the J heads , I would look at a Lunati Voodoo cam , they are specifically designed to take advantage of the wider Mopar lifter & make more power , depending what you want you can go to a flat tappet hyd cam or a hyd roller or a flat tappet solid . 350 hp should be easy considering they made about 320 stock !! I am not sure what intake you have but the factory one is decent , next step would be the Eddy RPM Air Gap

 

[Chryco Psycho]

Indy has the LA X head available & RHS has a good head for the LA as well

 

[burntorange70]

Very easy to make 350HP.

750 carb, air gap intake, headers, cam some thing like a comp or Lunati 268 or 273 would stillbe very street frendly. Don't know what your compression is but if you get it around 10.1 or so that combo should be in the 380 hp range some head work or RHS heads could putyou close to 400HP.

 

[btceng]

Thanks guys. I'll tear it down this weekend and see if I can determine what I'm working with. The guy that I got it from says that it in good running condition. That's hard to believe based on all of the grease and grime on it. It looks as if there must be at the least some gasket problems. My 40 year old 318 looks new compared to this thing.

It might be cool to go the 4 inch stroke .030 bore and see what happens. How reliable is a stroker?