Stroker/Cost effective?

[Rob1]

I realize up front this question doesn't supply enough specific information, but I'm just looking for general information.

My question is in building a street 340 to around 400hp what gains can be expected by stroking the motor with a similiar build up? I know, more cubic inches = more ponies but just how much gain can be expected. Thanks in advance.

[6 packin]

Building a 340/360 to get 400 horses...isnt that hard, and doesnt need to be exotic too with stock cranks........hmm.....maybe you should shoot for 500+ horses with a stroker crank?

[ChallengerChuck]

If it were me,I would simply nab a crank that is in good condition from a 360 and then cut its main journals down to 340 size.Race prep the 360 crank as neccessary and use a 4-bolt 340 block.Slap on a hydraulic roller cam,Edelbrock Performer RPM aluminum heads,and a complete Six-Pack intake,and you would indeed be ready to rock and roll.
NOTE:An Edelbrock Performer RPM Air-Gap intake manifold could be substituted for the Six-Pack intake,but it wouldn't be quite as sexy!

Just my two (2) cents worth(?)..................

[skankweirdall]

Building 340's can be an expensive proposition to start with. First there is the parts scarcity, even if you have one to start with there isn't much in shelf stock pistons. So you are already handicapped. However, getting 400 horses from it does not require a stroker. The other thing you need to think about with a stroker is do you have enough cylinder head to feed it and exhaust it properly? You can get by cheaper with a closer to stock head with the stock stroke albeit a little more radical. The extra cubes won't give you alot of extra horsepower if you can't feed them. It will give you more torque down low though. A very desirable condition for a street car.


Chuck, there aren't any 4 bolt 340 blocks unless you go to an MP block. The T/A blocks had the meat in the main webbing to add 4 bolts to them, but none left the factory that way. Besides it isn't necessary anyway, they ain't Chevys. I've used 2 bolt blocks with ARP studs forever without a problem, and I twisted my 340's to 8,000.

[Rob1]

I just recently re-aquired my first car, a 72 340 Duster. I'm just kicking around ideas. I know four hundred hp isn't a real feat but the next one hundred gets expensive. If a stroker and head work or just getting a better pair could realistically get to 500 hp with a good street temperment it would certainly catch my attention. Thanks for the input. Rob

[skankweirdall]

Actually Rob, if you plan your combo and buy the parts to achieve your goal the first time it's not that bad. Now if you buy in steps, trying to maximize each combination along the way then you'll spend a small fortune. Don't ask me how I know.

[Rob1]

skankweirdall

After kicking around some ideas I'll come up with a plan and present it and get some imput on what to change or stick with. Right now I'm getting ready to address getting the rubber to the road. I've been looking at moving the leaf springs and wheel wells in to get more tire. On one hand it seems wrong to do any cutting on the other I want a rod and not a resto. Should leave me plenty of time to plan the engine which is part of the fun. So far a stroker really sounds like a good way to get more hp and torque and still be a cruiser. I really need to do some research and get back up to speed as I've been out of the hobbie for too long. I can hardly wait to get started, there's a certain Buick GS my cousin owns...........

[ChallengerChuck]

skankweirdall:

Please forgive my relative ignorance on this issue.My thinking (however flawed) was that all 340 blocks made from 1968-1972 were 4-bolt;the T/A blocks just had that much more meat in them.And yes,I am fully aware of the fact that these are NOT Chevys;Mopars don't have the problems with rear main seals that Chevys have!
I would still go with a modified 360 crank.However,given budget limitations,I would go with early 340 heads that are slightly ported.I would still go with the Edelbrock Performer RPM Air-Gap intake.
Again,just my two (2) cents worth(?)......................

[dwc43]

I'd just go 360 and be done with it. We race 360's and puch over 400 with X or J heads 2.02 1.60 valves and a cast iron Thermoquad intake and 800 cfm carb. We have to run the intake per the rules for my class/ KB pistons on '68 - '69 full floating pin rods. They are lighter. Dont need an exspensive stroker to get 400 plus with lots of low end torque, just needa 360 and very little cash.

[ChallengerChuck]

dwc43:

Indeed,yours would be the most cost-effective route so far suggested.There are plenty of 360s out there;many of the early blocks could be modified for 4-bolt main caps if my information is correct.
My ONLY quibble with this particular solution would be the larger main bearings of the 360,as compared to the 318/340.The larger main bearings would create more internal friction than what would be the case of the 318/340.Being predominantly a Ford man,I know that Ford racers get around this problem of the 351W by simply installing main bearing spacers so that they could utilize the smaller 351C main journal diameter,thus reducing internal friction.Do you Mopar guys solve this problem in a different manner?
Just curious...........................

[dwc43]

Narrow bearings some. Mostly the 5th one. It's in the mopar book even.

[kamstra]

I would agree with Rob1 in that you would get better street manners from a 408 or 416 versus a 340 at the same horsepower rating.
It is true that the 360 have a larger bearing surface and would have great internal friction... yet it would have nominal inpact on horsepower. In the 400-600 hp range... bearing friction is almost irrelevant compared to the opportunity cost of using those funds towards better head flow.

[dwc43]

Thats true Kamstra but it can be reduced some with very little effort. As a racer we always go for everything that we can get with in the rule book anyways.

[kamstra]

BTW, Rob. I am building a 408 sroker at this time to achieve your listed results of decent power with good street manners

My Mild build is as follows:

360 block 30 over with KB pistons (I would suggest different pistons) Magnum Rods
4 inch Mopar Stroker Crank, Internally Balanced (expect to atleast double your crank cost just to balance)
Edelbrock Heads
Comp Extreme Hi Lift 275 (this is a new Comp Grind)

I am still in the building stage so no results for a while

[6 packin]

Yea, we dont need to run spacer bearings


Yea, I have been there done that.
Back before I seen the light i ran a 400 small block chevy with 350 (destroked) crank which requires spacer bearings. Let me tell ya, that stuff is just a waste of money! No way would i spend my money building a new engine and run some kinda band-aid like that. There is no need to with Mopar, just get the right parts. If any thing build the 360, bore it .030 and have it internal balanced. You cant go wrong with that!

No one here has even mentioned that stuff before, the only reason they done it before..........Im talking 10+ YEARS AGO, Is because they had to....now the company maks the cranks, with popular journal sizes to choose from!

[speedfreak440]

I'm not a huge edelbrock fan but on there website they list a package (alum. heads-intake-cam) that makes 417 hp. on the stock 340 crank, I currently run a 340 myself and dont let the short stroke fool you, these things make pretty serious torque on the bottom end without alot of work.

[ehostler]

The EB heads and intake are great, but their cam is only good for hitting things (or people). Get a qualtiy cam from Racer Brown, Hughes, or Ultradyne.

[skankweirdall]

Dang Ed, I hope you don't carry around an Edelbrock cam. Just in case I should meet you somewhere.

[ChallengerChuck]

Again,being mainly a Ford man,I don't claim to be really knowledgable in this regard.However,I know some Mopar tuners that have told me word for word what ehostler has said concerning the Edelbrock camshaft.The most common complaint was that it was essentially a Chevy hi-po cam machined to fit a Mopar engine.
To what if any degree are these complaints true?
Just curious...............................

[kamstra]

CChuck- Many cams are developed based on the Chevy Engine as there is a greater market for Chevy parts than anything else. The Mopar engine has the benefit of a larger lifter bore at 906. Ford being a bit smaller and Chevy having the smallest. A larger lifter bore allows you to create a camshaft that provides a higher lift at any given duration. The benefit is great amounts of air/fuel without the negatives of a longer duration cam ie, less engine vacuum and poorer street manners.

I hope this makes sense.

[Tomasso B Cuda]

I have a 416 stroker with e heads now with over 7000 miles of hard running including track time on the road course and I have had no problems!!. It cost about $7000.00 to build it the correct way but the real cost to get it to the point where the car could be driven was more like $9000.00. A 360 built like a stock 340 rebuild with stock everything cost me $4000.00 complete and it makes 300-325 hp, 18 mpg highway and does not use any oil. Crate motors may be cheap but that is what you get-cheap with outdated cam profiles. You get what you pay for, for the money stokers are the best way to make inexpensive, dependable hp. You can even build a stoker with less $$$$ than I did but I built mine with long term durablity in mind. Just don't be cheap on the choice of rocker arms and pushrods.


To build a 340 to get the 440 hp this mild cammed small block puts out I would have had to spend as much and I would be in the "other" category [#2] or close to it as my engine builder puts it.

My 3700 lb car with driver gives you a 107mph 1/4 mile trap speed, 144 mph top end @6000 rpm, 15 mpg highway. pump gas 92 octane min

Stoker motor pistons have less "oil control" so your oil consumption may be more than a conventional pistoned engine, but other than that you can't beat the torque monster that a stoker is.

Driving an engine that does not require to be reved above 6200 rpm to make 440 hp and tons of torque across the powerband gives you long term dependablity and the ability to beat up new corvettes, mustangs and the beloved camaro. You also have very little need to downshift...



My engine guy's opinion, he has over 40 yrs of experience.

Category 1
6200 rpm max
cam no bigger than 520 lift, 108-110 ctr line
10:1 compression alum head
9:1 comp iron head
user friendly, can be driven anywhere
pump gas
reasonable cost

Category 2
8000 rpm max
big cam, valve springs
big compression
big headache big cost
mods $$$$$ to survive above 6500 rpm
not user friendly
high maintenance
racing gas

[ChallengerChuck]

kamstra:

I know about the Chrysler lifter bore diameter.In fact I know of some racers some years ago that would machine their blocks for the Mopar lifter bore diameter.They did this so that they could run in essence a hot hydraulic roller cam without the hydraulic roller lifters.Since then,race techs caught on to what was going on and banned this modification completely.
Just an interesting little tidbit of information.................

[cuda66273]

Try this one on for size.....

Use your 340 crank and have it offset ground to 3.435 stroke by reducing the journal size to 2.00

While it's in the grinder have it widened to fit Chevy small journal rods and radiased to take the Chevy race bearings. (we sell the cranks for $525 ready to go and $50 for the core if you don't have a good one)

Now at .030 you have 362 CID

and....off the shelf, Chevy small journal rods at 6.125 length bolt right in....cheap and plentiful.(Eagles at $600 a set if you want or there's lots of other GOOD manufacturers)

Diamond has a great custom piston and ring pack for about $650.00

Top it off with a set of X,O or J heads with a 2.02 valve do a basic bowl hog, blend and port match. Swap in some 11/32 SS valves from REV and a ST21 Racer Brown Cam kit and you'll be in hog heaven and the bank won't repo your Credit Card.

You can step up to the Eddy head castings, be sure and check the rocker shaft saddles, they're not the same altitude and need some hand massaging to get the correct shape on the oiling hole and elevation....about $100-125 is what we charge to get them corrected.

I'm building one right now for a customer...going in a 66 Barracuda, 2900#'s 4.56 gear, 12.5:1 compression, Dynamic convertor, 30" tires should run low 11's easily.


....and it's still a 340

[Rob1]

Thanks again for all the responses, I was looking for some ideas to chew on and I've got a good start.

[kamstra]

C-Chuck- I did not know that... interesting
Cuda66. I really like those ideas.
I had heard and had considered grinding my crank down as I already have a set of decent chevy I beam rods (I don't know what to do with them otherwise)

[djswwg]

Just my 2 cents, but I would avoid the Edel. cam too. I've never seen an engine with one that had any balls. (Mopar, Ford, or GM) They tend to be a bit overpriced too..............djs