Re: 340 Build Questions
[Re: Scat]
#2269251
03/14/17 12:20 PM
03/14/17 12:20 PM
|
Joined: Jan 2005
Posts: 4,441 Michigan
MarkZ
Worthy
|
Worthy
Joined: Jan 2005
Posts: 4,441
Michigan
|
Another vote for a 4" crank. Having driven my 360 and my Dad's 408, both with Eddie heads, the increase in torque is unbelievable.
1987 Fifth Avenue - 512/518/D60
|
|
|
Re: 340 Build Questions
[Re: Scat]
#2269263
03/14/17 12:30 PM
03/14/17 12:30 PM
|
Joined: Mar 2007
Posts: 3,285 West Coast, USA
jbc426
master
|
master
Joined: Mar 2007
Posts: 3,285
West Coast, USA
|
I like the 4" reciprocating assembly idea too. You can buy a nice kit with pistons etc for under 2$k. Throw on some massaged Eddies and a nice cam from Dwayne Porter, and tune it with a wide band.
Make sure you spend some time tuning the chassis, so it will hook up. It will need it.
1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's 1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
|
|
|
Re: 340 Build Questions
[Re: Scat]
#2269283
03/14/17 12:53 PM
03/14/17 12:53 PM
|
Joined: Jan 2003
Posts: 14,506 So. Burlington, Vt.
fast68plymouth
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 14,506
So. Burlington, Vt.
|
Step 1-
-determine the TOTAL budget for the motor upgrades. More than likely, this will determine the best path to take.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
|
|
|
Re: 340 Build Questions
[Re: fast68plymouth]
#2271838
03/18/17 04:27 PM
03/18/17 04:27 PM
|
Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
Master
|
Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
|
Step 1-
-determine the TOTAL budget for the motor upgrades. More than likely, this will determine the best path to take. This is the best place to start.. dont just throw money at it.. get a plan of attack.. figure out the HP or ET you are looking for
|
|
|
Re: 340 Build Questions
[Re: Scat]
#2272536
03/19/17 08:15 PM
03/19/17 08:15 PM
|
Joined: Apr 2015
Posts: 58 Wi
Scat
OP
member
|
OP
member
Joined: Apr 2015
Posts: 58
Wi
|
I pretty much put the buggy in front of the horse on this one. The Budget i thought i had is gone doing repairs on the car to get it back on the road. I do plan on this winter starting a 416 for it with some hefty heads and built for some rpm. But as for now im just gonna be looking at a cam upgrade for the time being. I pulled the heads to see what i had so far and they are 2.02 Mopar J heads, Lifter valley oil sheild, windage tray, and Stock compression pistons. So Just a cam upgrade and new springs at this time is all that i got left in the budget. lol I have a set of hooker headers that would be going on for the mean time till i get the new motor built.
Thanks
73 Duster 340 a518 6pack
|
|
|
Re: 340 Build Questions
[Re: Scat]
#2272556
03/19/17 09:11 PM
03/19/17 09:11 PM
|
Joined: Feb 2005
Posts: 28,312 Cincinnati, Ohio
Challenger 1
Too Many Posts
|
Too Many Posts
Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
|
I recently Purchased back my dads 73 340 Duster. While im going through it quick replacing stuff from setting i was gonna do a quick once over of the engine to pick up some more power. Currently is a 4spd car with stock rotted exhaust. What he had done to it already in the past from what he can remember is, Put a 340 Steel crank in it, Mopar 474 lift "hemi grind" hyd cam and has a 6pack intake set up on it. I was planning on putting in 10.5 to 1 pistons and a larger cam to wake it up a bit more. I know alot of people try to say stray away with the 6 pack but its how he had it so it will stay with the motor. Not really looking for street manners but just power on pump gas. Ideas?? Before you can use more cam you need more compression. I'd do that before a cam. That 73 will be is a dog compared to earlier higher compression 340 as you know. Like said above KB243 pistons worked good for me with a stock bore and a hand hone job. Lighter pistons were noticeable and my true compression was 10.4-1. I CC everything when I rebuilt the motor. The pistons cost 250 bucks I think, cheaper than a cam swap and safer to install and more bang for the buck.
|
|
|
Re: 340 Build Questions
[Re: 67autocross]
#2295677
04/28/17 04:25 PM
04/28/17 04:25 PM
|
Joined: Jan 2003
Posts: 16,376
dogdays
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 16,376
|
Here's what I'd do: KB 243 pistons or more expensive/lighter slugs SCAT SCA26123 forged 4340 rods Keep the forged 3.31 crank
Here's why: Stock piston/pin is something like 720/165 gram Stock rod is 758 gram KB 243 is 597/132 gram Scat rod is 585 gram
That's 329 grams PER CYLINDER 2632 for all 8, that's 5.8 lb.
That engine will feel like you just added 40 cubic inches because there's so much rotating mass to accelerate now. With no other changes it'll feel like a different engine.
I don't think you need a stroker. I'd use that money for heads with some decent squish.
I'd leave the cam for now, I don't think its holding you back. Wait until you have the engine in its new configuration and then look at changing the cam. Especially as right now it is broken in.
And keep the 6-pack! I think you have most of a very desirable engine there.
R.
Last edited by dogdays; 04/28/17 04:30 PM.
|
|
|
Re: 340 Build Questions
[Re: dogdays]
#2295809
04/28/17 10:23 PM
04/28/17 10:23 PM
|
Joined: Nov 2006
Posts: 1,074 Manitoba Canada
67autocross
super stock
|
super stock
Joined: Nov 2006
Posts: 1,074
Manitoba Canada
|
Here's what I'd do: KB 243 pistons or more expensive/lighter slugs SCAT SCA26123 forged 4340 rods Keep the forged 3.31 crank
Here's why: Stock piston/pin is something like 720/165 gram Stock rod is 758 gram KB 243 is 597/132 gram Scat rod is 585 gram
That's 329 grams PER CYLINDER 2632 for all 8, that's 5.8 lb.
That engine will feel like you just added 40 cubic inches because there's so much rotating mass to accelerate now. With no other changes it'll feel like a different engine.
I don't think you need a stroker. I'd use that money for heads with some decent squish.
I'd leave the cam for now, I don't think its holding you back. Wait until you have the engine in its new configuration and then look at changing the cam. Especially as right now it is broken in.
And keep the 6-pack! I think you have most of a very desirable engine there.
R. Just did a 340 a few months ago with that exact bottom end along with the old solid lifter cam, with ported J heads it pulls hard....
A new iron curtain drawn across the 49th parallel
|
|
|
Re: 340 Build Questions
[Re: fast68plymouth]
#2304725
05/15/17 08:33 AM
05/15/17 08:33 AM
|
Joined: Jan 2003
Posts: 27,421 Balt. Md
383man
Too Many Posts
|
Too Many Posts
Joined: Jan 2003
Posts: 27,421
Balt. Md
|
Step 1-
-determine the TOTAL budget for the motor upgrades. More than likely, this will determine the best path to take. I agree as you need to know your budget first. Also how fast are you looking to go and will it be just a street car ? I built a mild 340 years ago for my girlfriends Dart Sport. The eng was basically stock as I checked it out and freshened the 340 up using the stock pistons and heads as it was a 1970 eng. I did a little mild bowl blending on the heads and used the same cam you have the MP .474 hydraulic flat tappet with stock rockers and shafts. It actually had the 318 Eddy dual plane intake and I used a 650 DP. I recurved the stock dist and added headers and 2.5 dual exh. I used a 904 I had traded for a few years earlier and it had a stock 318 converter. 8-1/4 rear with 4.10's and G/60-15 street tires. The 904 trans was all stock also. I liked that cam as it ran great in that car. We took it to the track and my first pass it blew the tires off and ran a 14.07 at 106 mph. After nursing it out of the gate I got it down to 13.40's @ 105 mph through the exh on street tires. I would power brake it to about 2000 rpm and then just let off the brake to launch and then slowly put it on the floor. I could launch that way and not spin the tires. I feel that car would have run 12's with a good trans , converter and tires as with the 105 mph it had the power to run 12.80's capped up. And the eng was basically stock internally other then the .474 cam. If your only looking for a 13 second street car that cam will work fine. Ron
Last edited by 383man; 05/15/17 08:36 AM.
|
|
|
|
|