340 Stroker: experiences with parts

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testerli33

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I was able to buy a 340 engine, which I would like to build up for my Duster over the winter
The idea is a nice stroker, roadworthy
I've thought about it a lot, but there are so many brands and parts that the more I research and search, the more I lose track
Starting point:
1970 Plymouth Duster
904 automatic, Stock
8.75 rear end, 2.94 with position
Wheels: 15x8, 255 60 R15
Front: TB 1.08, Hellwig Sway Bar, Billstein Shocks
Rear: Hotchkis Leaf Spring, Billstein Shocks
340 of 1971, J Heads
HP exhaust manifold from the 340 (I know that headers would be better, but here in Switzerland it is not easy to check them, which is why the HP cast manifolds are tight)
Disc brakes with brake booster

Which stroker kit manufacturer do you recommend? You read a lot of good things about Scat, less about Eagle, but I can't judge.

The Heads: Does it make sense to keep the J Heads, just port them and reuse them? Or go on aluminum heads?
Edelbrock, Trickflow etc. there are so many Or diw Indy Steel Heads?

Camshaft?
Converter from the 904 stock or another? If yes, how much stable?

I currently have a Ofenhauser spider on the engine, will I continue to use it?

What carburetor? So size? Type? Etc.

roller rockers? yes or no?

Lots of questions, I know, but I can hardly see through them at the moment, so it would be cool if you could show me the right one

The goal is a roadworthy engine, great torque out at the bottom, no high-revving screamer

Or does anyone even have a "shopping list"?

20230529_150101.jpg
 
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what are your goals hp wise ? I'm making 450 with 340 a simple 573 lift cam TF Heads , Reliable driver Street demon 750 3:55 / 8.75 with an overdrive have 2way adjustable QA-1 shocks with 1.25 sway bars front and back car is a blast on the highway and backroads
 
I don't have a target in that sense as far as horsepower is concerned.
I like the larger displacement that comes from stroking, and the logically higher torque that comes with it.
As written, it should be an engine for cruising, i.e. torque out below, and not power at 5000 revolutions and more

But I definitely find the performance impressive, with "only" Trickflow heads and a matching camshaft
 
Just my opinion, if you don't want headers, it's not worth the extra 60 cubes to choke through exhaust manifolds. I would build the 340 to do what you want.
 
I would chose scat over eagle. Buy the best heads you can afford. Iron or aluminum. By the time you put hardened seats in and port the j heads, your already there with the aftermarket. Headers definitely, but save the iron manifolds, they are pricey and only going to go up. Sell the j heads to a restorer. I would spec out the rest of the build with your engine builder. You may want to jump up to 3:23 gears.
 
I currently have 340 stroker 416 scat rotating assemblies are the way to go... The forged assemblies are probably overkill for what you're going to do... Unless you want to do nitrous or forced induction... Heads... Definitely want the best head you can afford... Trick flows are the way to go ( if you have the coin for it ) but I've seen speedmaster and edelbrocks ported out to flow very nicely... ( I have a set that do) However finding a good CNC Porter in Europe could be difficult... If that's the case trick flows your best bet.. headers would be really nice TTI headers 1 7/8 for the win ... Even with stock exhaust manifolds you would still see torque and horsepower gains... But not like you will with the TTI headers....TTI headers fitment on A bodies are the best) Edelbrock air gap intakes are nice especially for street strip applications ( be careful the Chinese copies) sometimes they don't fit correctly... Even if you had to run a factory four barrel until you found one you would still be better off than buying some of that Chinese repop stuff .... ( Had a bad experience with no name air gaps) 3.23 gears would be nice ( if your going to Street the car ) try stay at 3:55 or under) unless for some reason you're running an overdrive or aftermarket transmission application) even with 2.93 gear a stroker has plenty of power and torque push it out of the hole ️⛳ I run 2.76 sure grip gears when I highway my car it's fine for road trips... Only thing I can thing you may want to think about is compression ratios... ( Not Shure what's available as far as octane availability in Europe) but scat offer stroker kits with different types of dish Pistons ..
 
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I went with a Molnar Technologies 4 inch stroke rotating assembly and .04 overbore in my 340 (418 cubic inches)
High Performance Molnar Rods & Crankshafts | Molnar Technologies
There was a lot of fears with scat and eagle at the time with crankshaft failures.

This would be the next step up. 4.180 stroke for 435 small block.
STROKER KIT, 340/435 SMALL BLOCK :: HUG-435-RACE-KFH

I went with cast iron W2 heads. Later switched to Indy W2 (rectangle port). The engine loves to rev and power is up high so I ran 4.30 gears in the 8 3/4. I only use the car for street cruising.
For street I would go Edelbrock, but I know nothing about the trickflow heads. The stock heads would work but the cost to rebuild vs new aluminum heads is very close.
 
moparlvr166 said:
Just my opinion, if you don't want headers, it's not worth the extra 60 cubes to choke through exhaust manifolds. I would build the 340 to do what you want.
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I’m running the stock 340 exhaust manifolds. 410 CI at 6400-6500 shift, stripe at 6800. Will it make more power with headers? Sure, but it would be WAY down the priority list to getting the highest flowing head you can. It a sorted car, you can pretty easily run mid 10’s with those exhaust manifolds. Molnar,K1,Scat forged rotating assembly. The highest flowing aluminum head you can get. Go through the 904 so it will live(not that hard to do) Solid flat tappet should get you where you want to be. I recommend an EDM lifter. Talk to a good cam company and get that settled. Then talk to converter company, I just got a 9.5” PTC for my 904 with a pretty conservative flash rpm. Very happy with it, the lower flash helps with my little tire, but would also help a street car that lives on slick roads.
 
I would add a set of Doug’s headers. You will have zero issues with fitment( and having had both Doug’s and TTI’s the Doug’s fit better)
I have no idea what your budget is, but the scat stroker kit will work just fine, using one with the Icon pistons myself.
Head wise, if you want a true readily available head, the trick flows are a true bolt on, and paired up with an air gap intake will make for a nice combo.
PTC makes a nice 9.5 street strip converter, cam wise, so many choices it’s hard to select one without specific needs
 
go with hughes for assesment on your project they specialize in mopars and carry an excellent catalogue of pasts and full stroker sets. you wont be dissapointed. I did my 426 SB stroker with their parts and runs awesome
 
updated:
I took a look at the 340, mounted on it is an Offenhauser Mainfold, Model 360, and I was able to get hold of a couple of Indy Steel Heads with the 2.02 valves.
Maybe I can incorporate these parts into the project, otherwise I'll sell the parts on
 
testerli33 said:
updated:
I took a look at the 340, mounted on it is an Offenhauser Mainfold, Model 360, and I was able to get hold of a couple of Indy Steel Heads with the 2.02 valves.
Maybe I can incorporate these parts into the project, otherwise I'll sell the parts on
Click to expand...
Which cylinder head are you referring to? Is it the LA/X head with LA rocker arm shaft? MA/X with Magnum rockers? Rebuilt stock heads from Indy? Got any pictures?
 
Hi! remembered your nickname from the german mopar forum....so you got the heads from Dejan? Good Stuff, ran the Indy X for a while on my 408.

I went with a scat kit, zero problems with it. here on the board is a Molnar Dealer, check the for sale area. I also use a 904 with little modifications, it holds up well (car runs mid tens in the quarter).

Have fun building it!

Michael
 
Simon I am just starting to plan a build using the Hughes 426 kit mentioned above along with iron heads (probably heavily worked J heads) and exhaust manifolds. I'll be following along. Nice Duster by the way!
 
BrianT said:
Simon I am just starting to plan a build using the Hughes 426 kit mentioned above along with iron heads (probably heavily worked J heads) and exhaust manifolds. I'll be following along. Nice Duster by the way!
Click to expand...
Manifolds like more lobe separation.
 
Scat Balanced 4" kit. Cast crank will be fine under 500 hp on the street. Molnar is a good brand too.

I think Edelbrock head would be fine. But with Trickflows you get better quality and flow. In your situation where labor might be expensive to double check a set of Edelbrock heads, the Trickflows might be a safer bet even though they are overkill.

What octane rating gas do you have there? That will determine static compression. Then you have to pick a cylinder head. After those two items, you can pick the rotating stroker kit with the piston that closest matches the compression you want. You'll be using a compression calculator that you plug in the head cc, compressed gasket thickness, piston dish, pin height, stroke, bore, etc, etc.

Then go to Bullet for a custom cam before you finally buy the kit. You might make adjustments on the kit per their recommendations. Discuss the need for roller rocker with them.

Comp cam has a good steel roller rockers with longevity.

Intake would be a Edelbrock Air Gap dual plane intake. I would not mess with that Offy Spider deal.

That's it. Keep it simple.
 
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Those cylinder heads can be ported out to a pretty good level for performance. The intake is a very old one. Port matching it to the heads will help with a little power and improve the fuel quality from intake manifold into the head and cylinder. You could use an upgraded intake manifold.

What is it that you mean when you said headers are hard to check?
Are headers hard to get into the country or is it a legal issue?

For a rotating assembly. I myself would look at ether a Scat or Molnar.
For headers, ether the TTI or Doug’s. I like the TTI’s.
If you’re not going to port the LA-X heads and purchase new ones, look to the Trick Flow heads. Same for your intake manifold, if your not going to re use the Offenhauser, get a RPM-AG.

Nice looking Duster. Enjoy the build.
 
mr rumble is spot on
No way id build a nice motor like that and run that intake i ran it in the old days it wasnt on long
air gap will blow it away the entire rpm range
myself i would run a single plane your low end torque will be immense
 
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