340 Stroker Ideas

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67autocross

67autocross

A new iron curtain drawn across the 49th parallel
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I killed the some rod bearings in my 69 Valiant’s 340 and want to build a new engine for it over the winter, something modern with EFI and air conditioning possibly a magnum roller cam engine with EFI and air conditioning or a Gen III Hemi. I have a 72 Scamp that is sitting with no power train and figured that since I have a good 340 block and heads that it would be a good time to build a mild stroker to put in it and get it back on the road again.

What I want to build is a low RPM engine ( under 5000 ) that makes lots of low end power that I can run on low octane pump gas and be dead nuts reliable. I have a well built 727 and 2500-3000 stall convertor that I will use along with 2.94 sure grip center section and 28” tall tire.

The 340 currently has a 480/500 solid lifter cam and ported J heads with roller rockers that are all in good condition, I could re-use the cam or go with something different depending on suggestions.

So my question is what stroker kit should I be looking at for this kind of combo and should I keep the cam? Thanks
 
I would almost go gen 3 hemi ...not sure what a crate hell cat would be price wise.
After that the 5.7 and the 6.1 are starting to show up in wrecking yards more often.

I went with a molnar crank and rods with forged dished pistons. I got it all from cambell enterprise. I went overboard with the w2 heads and she breaths like crazy but starts to nose over around 6 grand.
I just added the fitech setup on the top end.
For the camshaft I called up lunati and used their reccomendation for street/strip and 3.55 gears with a 4 speed all stuffed into my 3300 lb dart
 
What is your cam duration? I suspect it is kinda long, which is gonna hurt the bottom end torque.... which is what you say you want.

Also, the TC seems wrong for a low revver....... If you want to get on it but not ever go over 5000 RPM, then if the TC locks at say 2800 RPM, then your operating RPM range is waaaay to narrow. The trans gear steps are not going to work with that narrow an RPM range. You'll havea to go well past 5000 RPM.
 
A few fellas here have built low rpm stroker's. Small cammed engines that are shipping out high 400 to 500 ft. KB's. Of Tq.

The 4 inch arm kits are cheapest and easiest to get. There are also 4.25 & *I think* it was a 4.125 arm kit that can be purchased from Hughesengines or Rod Bloomer. (4.25 kit also.)
 
Do you have any links to the builds? The old 340 would rev high but it got a bad tank of gas and died... So I want to build a low spinning engine with low compression
 
Punch in stroker in the search bar and limit the search to small block or performance forums.
I'll dig up some old Mag articles.
 
Tracy,"68 fishy" has a real common sense 408 4 "inch arm build... He likes mid range torque,over high end pull. Might do a search on his posts.Real common sense guy...
 
You can do it easilly. It comes down to cost. The cam is critical. You may just resign yourself to replacing that. You don;t need anything fancy either, but I would go with forged pistons and studded mains.
 
Checked the black today and it needs to be bored over, now thinking about a 40 over 4.25 crank setup
 
Has anyone tried a kit from Clegg Machine? They have Scat kits for reasonable prices.
 
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If you what something in a 4.250
I would talk to Rod Bloomer BPE
Nice Guy
I got mine from him
 
Be nice if the 3.79" were still available, good all around crank and easier on the block. 4" is the go to and available from every manufacturer out there. Lots of people can't be wrong.
 
m880 said:
Be nice if the 3.79" were still available, good all around crank and easier on the block. 4" is the go to and available from every manufacturer out there. Lots of people can't be wrong.
Click to expand...

I think you can get 3.79" cranks still, or at least I'm hoping to find one. I would want one that uses chevy rods so it can use a 6.250" rod with an off the shelf 408 stroker piston. A 1.45" compression distance 408 piston would be a zero deck piston with a 9.6" deck height. There are other 408 piston compression depths that will also work for this combo. It would make a nice durable long rod stroker motor IMO. With a custom piston a 6.300" rod would also be a possibility that I would consider.
 
I think Mancini racing has the 3.79 cranks.
 
Have a look at my recently completed 408 hydraulic roller cam engine. I posted all the specs for it on this site a few weeks ago. 10.1 compression, reliable, big torque, these were what I went for also. I do have 3 centre section for it, one of which is a 2.94 for those long trips. Look up W2 408 build. I posted dyno sheets.
 
m880 said:
Be nice if the 3.79" were still available, good all around crank and easier on the block. 4" is the go to and available from every manufacturer out there. Lots of people can't be wrong.
Click to expand...

I have 340 main 3.79" stroke cranks in stock, they all have 2.1" SBC rod journals as well.

Rod
 
What kind of stroker do you recommend for a low RPM (5500) pump gas engine? I would like to keep the compression down to 9:1 with my 68cc ported J heads...thanks!
 
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