Bottom end info?

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Captainkirk

Captainkirk

Old School Mopar Warrior
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Hi all, Captainkirk here.
Just found out from the machine shop my cast crank is pitted on the rod journals; they'll have to be ground at least .010 under. I have the original motor from the car ('69 340). I believe this motor has the forged crank? If so, any problems with using it in a '72 340 block? I intend to use the damper & flywheel that came with the forged crank, if I do end up using it. I was gonna stay with the '72 rods, unless someone tells me why I shouldn't. Appreciate your input! :thumblef:
 
No problem with the block. Whenever I get any machine work done I like to mock up my engine and check all the clearances before sending the rotating assembly back to the machine shop to be internally balanced. All 340 engines were internally balanced so as long as your damper and flywheel are neutrally balanced you should be set to go. If the rods are in good shape I'd use them. They should be floaters, so check the pin to bushing clearance on the small end.
 
stroker416 said:
All 340 engines were internally balanced so as long as your damper and flywheel are neutrally balanced you should be set to go. If the rods are in good shape I'd use them. QUOTE]


Not true,
The later 340's had cast cranks and were externally balanced and used pressed pins.


BJR Racing
Click to expand...
 
Pulled the crank on the 340 tonight.....it does NOT appear to be a "forged" crank due to all the casting flash on the forward counterweights, but rather a cast crank.....in which case there would be no advantage to using it. Does anyone know exactly when they made the transition from forged crank to cast? This engine (the "doner" engine) is out of a '72 Duster, but was equipped w/ Carter AVS, Hi Flo exhaust manifolds, and has the "X" heads w/ 2.02 intake valves and has a casting date (?) of 10-69 on the right side of the block. The pistons have the valve "smilies" on them.The damper is thinner in diameter than the one on my "good" 340 and does NOT say "Use with cast crank only" as the one on my "good" 340 does. Anybody know the answer here?
As always, thanks for your help. I knew all this once, but have "forgotten" over the course of time! You guys are awesome!
 
'Kirk,
The last factory steel crank that I remember was in 71, as for the dampner. Sounds to me like the block and heads are correct with the dampner but the crank isn't. What you may have is a 318 crank which carries the same dementions as the 340 counterpart and they were internally balanced, but you'll have to check the casting # of the crank to be for sure.


BJR Racing
 
Kirk; Unless your going to make a serious engine in terms of power, the balance is not an issue and the cast crank is up to snuff on great street power.
 
Well, I'm trying to set up a low 12's engine. I'm reusing the pistons and probably the heads. At this point cam & induction are up for grabs. This will be normally aspirated and I'm gonna try to stay off the bottle (nitrous) for now, but I'm open to whatever will give me the best torque/HP ratio. I doubt with the "J" heads, ported or not, that I'll be able to push it to much over 400HP but you guys are the experts and know more what I can achieve better than I do. Thanks for the replies!
 
I'm sure there are plenty of 360's running low 12's and they all had cast cranks from the factory.
 
400 HP well it's easily done with J heads. THANKS OldVart! for the confidence! Not to shun anyone but it's just parts. We are going to go this weekend if the weather permits to run a experimential engine,..........it will be a DODGE! OK sorry I'm going to Talladega.........for Jack Roush....... and the 06 car, Todd Kluever is a very good friend of mine and my nephew is his gas man so I have to support there cause. I hope you all understand.

BJR Racing
 
The old MoPar "tips" section recomended there pocket ported 2.02 heads and a 284/.528 solid cam to run the time. The heads are old style units they had in mind. Also 4.30's and a 28 inch click.
The heads should be able to run high 12's unported.
You don't need to port the heads for 400 hp, but it would help.
 
The "J" heads I'm running have already been ported & polished years ago, I have a set of untouched "X" heads as well, but my machine shop guy says the smaller valves will give me better torque down low and that the 2.02's only really work upstairs of 7K rpm. True?
 
Hot Dog!
Dropped the crank off at my engine builder this A.M......took him about 3 seconds to ID it as a forged crank! Now all thats left is for him to mic the journals and see how bad the wear is.....

crank 340.jpg
 
and that the 2.02's only really work upstairs of 7K rpm. True?
Click to expand...
NO! IMO no way.They'll pay off mid RPM range in a performance build, but he's right about torque. Also, since your looking for low 12's, I think the low end torque is something you need not worry about so much between the gear set and torque converter need to run the times in a more strip like car.
 
Ahhhhh, 4spd. Guy after me own heart.

(Row row row your boat...)
 
Yeh.........nothin' beats jammin & slammin' and the smell of burning rubber.....
s'cuse me, the thought makes me weep! (snif!) :sad2:
 
LOL ! I hear ya. I want to get back to the 4spd in my Cuda bad sometimes. It's going to have to wait thogh. First things first.
 
As the bottom end is slowly being developed, I'm looking ahead for more answers. This much I know already for sure;
Bore will be standard 4.04
Pistons will be TRW 13:1's, if I run with my ported J heads w/1.88 intakes, heads cc'd true CR should be between 11:1 and 12:1
Crank will be standard stroke, either cast or forged, if it mics out OK.
The cam I was running (should I decide to reuse it; it's practically new) was an Automotive Alliance (????........I never heard of 'em either). Grind is as follows:
Lift: .450(I) .475(E) duration 298 (I) 308 (E) hydraulic tappets.
It was very lumpy (I like lumpy) and I had no complaints, but my machinist says today's cams are much better and we could possibly match the grind to the ported heads. Make any sense?
I am considering a six-pack setup, or the dual quad setup I mentioned in other threads, but present setup is Holley 650 DP on a Torker 340. Ignition to be determined. I'd appreciated your input.
 
Low 12s with a stick and a good driver will need to make about 425 hp at the crank and the right gears. The J or X heads could do this easy. If it were me, I'd have the Js flowed to see if they are ported well, or just look good. A little bowl cleanup, and gasket matching, and you'll get 425 from them with the right cam. You could also just sell the Js, and use teh $$ for the Xs. They'll need a little I'm sure. They always do. Dont skimp on the valve work. You'll make more power with a great valve job and ok port work, than good porting and low end valve jobs. If you want a pump gas engine, you'll need to keep the dynamic compression below 9.5:1. That depends on both your static ratio, and the closing event of the intake valve of any cam you plan to use. You can build a higher static ratio (like 10.8-11:1) and run a modern cam with iron heads and be fine on pump premium. I'd go like 11:1, with a cam like this Crane (hydraulic, runs strong between 3K and 6K, peak hp should be around 6300 depending on heads, and will be "softer" on the tires when you side step it..lol).
http://cranecams.com/?show=browsePa...-360 C.I.&partNumber=690221&partType=camshaft

For the rest, either an M1 single plane matched, or an Air Gap RPM matched will do fine. I'd lean towards the air gap.
 
Agreed on the ratio. Your list of 11 to 12 - 1 ratio is way high for any pump gas.
A moder cam is the way to go.
Porting the heads would only take a pocket porting. Gasket matching a plus.
Decide on the induction system you want. It's a personal thing. Sexy/expensive six-pak or ave. everyday 4bbl is up to you.
Ignition. From what I have found experimenting over the last few months, I can only recomend as a bottom base line and nothing less to start with, none other than a Chrysler Chrome box and upgraded coil. Over at 4secondsflat.com, you can speak to Don and get his set up. It is a little better than the Chrysler box, bolts/plugs in no problem. His box has a advantage over the Chrysler box in mileage. Others swear by a power gain as well. I have not track tested it.
click here; http://4secondsflat.com/
 
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