340 Build.

-
Tedmon1971

Tedmon1971

Well-Known Member
Joined
Dec 7, 2015
Messages
46
Reaction score
2
Location
Libertyville IL
Hey there everyone! So I'm going to try and make my duster do mid 12s hopefully with the 340 I bought. It's fairly stock from what I rememeber and it's a 71 block. I have a weiand action plus intake, Holley 750, and hooker comp headers. I'm also getting the heads cleaned and ported and get the valves seated. Any advice for a cam shaft? I was looking at a 3200 stall and I will be running with either 3.91 or 4.10 gears. Looking for a good solid roller. Any other advice for some extra power would be great!
 
With the 4.10's, MoPars 284/.528 mechanical cam will have enough for you.
That would be 241*'s at .050 & just a tad over .500 lift with lash factored in.
You can look at other manufacturers cams with similar durations at .050.

After your heads are Done, ask for the flow numbers to determine where it stalls. You may want To look into a cam that has more lift as the heads/engine maybe able To use it.
 
Compare that intake to your head ports. The one I have has 318 ports
 
rumblefish360 said:
With the 4.10's, MoPars 284/.528 mechanical cam will have enough for you.
That would be 241*'s at .050 & just a tad over .500 lift with lash factored in.
You can look at other manufacturers cams with similar durations at .050.

After your heads are Done, ask for the flow numbers to determine where it stalls. You may want To look into a cam that has more lift as the heads/engine maybe able To use it.
Click to expand...
Rumblefish. I believe that getting that cam is going to be a touch difficult. I just bought one 3 days ago that is supposed to have been the only one left on the shelf. part #p4120653 or p4120653ae or p4120659 or p4120659ae. I tried everything to find it, with lifter, without, Chrysler has 11 on bo. Bob at Motor State grabbed it for me out of the Detroit wear house. I do agree it should be a good choice, if available.
 
measure and cut as needed for a true 10.5:1 or better. 4.10 gear or more. solid roller cam-20-701-8 Comp or a little more. Comp pro magnum rockers
 
had a similar combo in my 73 duster 340 .30over pop ups close to 11-1 j heads ported by me some what ok job 2.08inx1.60ex roller tip rockers 1.5s prws had to clearence them hitting retainers 528 solid purple shaft 700 double pump on air gap style manifold 1 5/8 headers and 3'' ex/ mufflers 4.10 gears 727 with 32-3500 stall on foot break ran 7.7 all day long in the 8th with bad 60ft 190-95s idled at about 1000rpms and always got a double take sounded wicked it will make you smile so go for it
 
I have the comp 20-741 solid roller in a stock stroke 340 and i think it would get you where you want to go if your heads can handle the lift. its certainly not a mild cam but its not obnoxious either and it has a nice long range.
 
MoPar is slowly discontinuing the small block parts. If that cam is no longer available (to whom ever is reading this thread) consider it as a reference point on another cam from another manufacturer.
 
Marcohotrod said:
measure and cut as needed for a true 10.5:1 or better. 4.10 gear or more. solid roller cam-20-701-8 Comp or a little more. Comp pro magnum rockers
Click to expand...
A .040" to .050" cut off the stock open chamber heads should get you around 10.5 SCR with the stock pistons and .028" head gaskets; chamber size should end up around 65 cc's. Don't forget to make the matching cuts from the intake. Be sure to check the valve-to-piston clearances.
 
Ran a 70 340 swinger x heads 10.5 comp. stock pistons, weiand dual plane ,cheapo 232-242 112 hyd cam and also 242-242 508 paw cam 750 vs carb 3000 conv. 4.33 rear. Ran 12.0 with 232 cam, 12.20 with paw in very good air ,12.0-12.40 in summer .Nothing special should have no problem with a street solid roller to get where you want to be.
 
joec said:
Ran a 70 340 swinger x heads 10.5 comp. stock pistons, weiand dual plane ,cheapo 232-242 112 hyd cam and also 242-242 508 paw cam 750 vs carb 3000 conv. 4.33 rear. Ran 12.0 with 232 cam, 12.20 with paw in very good air ,12.0-12.40 in summer .Nothing special should have no problem with a street solid roller to get where you want to be.
Click to expand...
Did you do new pushrods/springs?
 
stock pushrods, mp 510 lift springs.Nothing special just a rering/new bearings,cheap ger converter.I remember it was alot slower with a torker int picked up 3 tenths with the dual plane.This was about 12 years ago. The 232/242 cam was a Wolwerine had around 480/503 lift
 
rumblefish360 said:
MoPar is slowly discontinuing the small block parts. If that cam is no longer available (to whom ever is reading this thread) consider it as a reference point on another cam from another manufacturer.
Click to expand...
Sign of the times.
I have one NIB left and 1 used, a very broad usage and overall good cam for making about 390-400hp with stockish heads as long as you add the usual suspects...headers,intake and carb 'with someone who knows how to tune'
 
In the mid>late 80's......1971 Cuda, (3500lbs+), stock 340 block/2.02 heads, no porting...10:1, Holley Strip Dom, 850DP, DC.590"sft, although less cam is perhaps more, 1.75" Hedman hdrs, 727, T/A 4200 verter, 4.30's 10x28's, on stock leaf springs with clamps, shock extensions, snubber = [email protected]
 
Strip Dominator or M1. 4.10 gear. 1.75 headers. As much lift as you can get.

In an A body you will get into the 11's
 
Maybe it's just me, but it seems the "bigger is better" mentality is alive and well. You could run deep into the 12's with 9.5:1 CR, pocket ported 2.02 heads, a 220-224 @.050 cam and 1.6 roller rockers, an air gap manifold with a 750 carb, 1-5/8 headers, and a 4.10 gear. A little tuning ability will also be a plus, engine and chassis. Oh yeah, it won't sound as mean. There's always a compromise somewhere.
 
Last edited:
Hot Metal said:
In the mid>late 80's......1971 Cuda, (3500lbs+), stock 340 block/2.02 heads, no porting...10:1, Holley Strip Dom, 850DP, DC.590"sft, although less cam is perhaps more, 1.75" Hedman hdrs, 727, T/A 4200 verter, 4.30's 10x28's, on stock leaf springs with clamps, shock extensions, snubber = [email protected]
Click to expand...
I'm still relatively new to the mopar/muscle car engine building world (I can only rebuild a jeep 4.0) lol even though 95% made total sense to me, what does the DC stand for?
 
Tedmon1971 said:
I'm still relatively new to the mopar/muscle car engine building world (I can only rebuild a jeep 4.0) lol even though 95% made total sense to me, what does the DC stand for?
Click to expand...
DC stands for Direct Connection. That was Mopars performance parts department before it changed to Mopar Performance many moons ago.
 
Ohhhhhh okay that makes total sense now. I knew of direct connection, I just didn't use my head lol. That whole set up sounds hot! Thanks a lot! The rest of that all sounds almost identical to what I'm looking to do, the only difference is my CR is 10.5 and I'm going to be running super stock springs. Thanks again!
 
Tedmon1971 said:
Ohhhhhh okay that makes total sense now. I knew of direct connection, I just didn't use my head lol. That whole set up sounds hot! Thanks a lot! The rest of that all sounds almost identical to what I'm looking to do, the only difference is my CR is 10.5 and I'm going to be running super stock springs. Thanks again!
Click to expand...
If the pistons are stock, it probably isn't 10.5, but if it is, you'll have to run a little more cam with pump gas. Get the 3400 pound SS springs and use a snubber. Rides a tad stiff, but it will slap you back in the seat when you nail it. I have a customer using this combo running 12:30s, with a 9.0:1 360. Surprises a lot of big block guys.
 
B3RE said:
If the pistons are stock, it probably isn't 10.5, but if it is, you'll have to run a little more cam with pump gas. Get the 3400 pound SS springs and use a snubber. Rides a tad stiff, but it will slap you back in the seat when you nail it. I have a customer using this combo running 12:30s, with a 9.0:1 360. Surprises a lot of big block guys.
Click to expand...

I'm only taking the guys word for it that I bought the motor from. Super avid mopar guy and he said he last checked it at 10.5. But then again, that was back in the 80s the last time he was running it. The motor is still unmolested since he last tinkered with it and all I did was try cleaning the carb to make it fire, which it did. Either way, I still have the ability to make it a higher CR before I decide it's ready to go. Regardless though, I really appreciate the info!
 
Tedmon1971 said:
I'm only taking the guys word for it that I bought the motor from. Super avid mopar guy and he said he last checked it at 10.5. But then again, that was back in the 80s the last time he was running it. The motor is still unmolested since he last tinkered with it and all I did was try cleaning the carb to make it fire, which it did. Either way, I still have the ability to make it a higher CR before I decide it's ready to go. Regardless though, I really appreciate the info!
Click to expand...
Glad I could help.
 
If you can take and post a photo or 2 of the pistons with the heads off, especially with one at TDC, someone may be able to ID the pistons and we could get a better idea of the CR you have.
 
You must log in or register to reply here.
-

Back
Top