Choosing the right stroke for a 340

[340inabbody]

have you got a 340 yet? if not the same 4'' stroke will get you 390-396 from your original 318. with no very expensive 340 core to buy as well you'll have more left for better heads etc. just a thought?
neil.

I have the 340 already.

 

[340inabbody]

Yeah, the 318 stroker would be my go to, especially if I didn't have a 340 block. It will do everything you want and then some. I would talk to Ken at Oregon about the hydraulic roller cam.

Who is Ken and what is Oregon? Is that a shop? I need to keep educating myself and talking to folks is a great way!

 

[autoxcuda]

I have the 340 already.

bigger bores un-shroud the valve more. Should help flow.

 

[340inabbody]

bigger bores un-shroud the valve more. Should help flow.

Your talking about bigger intake valves on my steel heads? I live in AZ and between the high heat and shitty gas is pointing me to aluminum heads. Tired of retarding engines because of that…..

 

[Garrett Ellison]

Ken Heard at Oregon Cam grinding. He may not have cores but if you have a stock hydraulic roller cam core he can grind about anything you may want on it. You'll want to run Morel lifters on a hydraulic roller. I myself would probably go with an MP .533/284 flat tappet solid, though.
http://www.oregoncamshaft.com/

 

[Unconventional]

<~~~~ Likes the way a 3.25ish x 4.00 runs

 

[autoxcuda]

Your talking about bigger intake valves on my steel heads? I live in AZ and between the high heat and shitty gas is pointing me to aluminum heads. Tired of retarding engines because of that…..

no. same size valves with smaller bore gives less space between valve to cylinder wall

 

[340inabbody]

no. same size valves with smaller bore gives less space between valve to cylinder wall

I don’t follow…. Can you explain less cryptically? I don’t rebuild engines and modify heads but once or twice in a lifetime.

 

[rumblefish360]

RPM potential has more to do with airflow capabilities of the combination and less to do with the stroke.

Head flow/intake style/cam specs will dictate rpm range of a combination, more so than stroke.

The longer arm will wear things out at high rpm faster, but that's a different topic.

And valve train stability!!!!

 

[ir3333]

...best stroke for what?
Mileage, torque, street fun, 1/4 mile , circle track, cruising, tire smoke....
There is no perfect canoe.

 

[rumblefish360]

My alloy headed 11/1 367 has more torque than 325/50-15s can handle on the street. I have run it with a 292/292/108, a 270/276/110, and she currently has a 276/286/110; the 270 was my favorite. She went 93 in the Eighth with the 276 cam@ 3457 pounds. Her normal weight is 3650 me in it.
Forget a long flat torque curve; one of two things will happen; 1) if a stroker, it will have freight-train torque impossible to harness.
2) if a 360 it will still have a preponderance of low-rpm power meaning lots of tire spin, but the top end is no weak.
We are not in the 80s anymore, there is no good reason to compromise your combo with low-compression. Alloy heads will support cranking pressures up to 200psi still on pump gas. I have run 185/190 on 87E10

Lemmee show you something;
Say your engine has a dead flat torque curve of 400ftlbs from 2000 to 6000. the formula to convert torque to horsepower is
torque times rpm, divided by 5250
watch this;
400 x 2000/5250= 152hp
400 x 2800/5250 = 213hp
400 x 3600/5250 = 274hp
400 x 4400/5250 = 335hp
400 x 5200/5250 = 396hp
400 x 6000/5250 = 457hp
Is that what you want?
I don't think so.......
Because ;
1) yur not gonna run a 2000 stall, so kiss 152hp goodby
2) yur not gonna run a cam on the street, that would get you 457hp at 6000, so kiss that goodby.
3) the 396hp at 5200 is already pushing the power peak pretty high for a streeter.
4) the faster you drive, the more power you need.
5) the slower you drive, the less power you need
6) if your combo can smoke the tires with 3.55s all thru first gear, then you obviously have more power at slow speed than you need.
Therefore do I say, for your combo, forget a long flat power curve.
Instead, tailor the power to what the chassis can handle, and still provide the kick you want, and let the torque be what it will be.
Here is what you might like; simple easy cheap and effective. the dip at 3200 is obviously an anomaly, probably a fueling issue, Ignore it and extrapolate from say 3800 to 3000 in a straightline.
Look at the powerpeak up near 5700. This is more peak than you need. 5700rpm with 3.55s and 27s is 46mph in first/77 in second .............. so not the best fit. It really wants more gear or less cam for your combo.
More gear will destroy your cruise-rpm.
Less cam will increase your cylinder pressure and increase your low-rpm power, at the expense of high-rpm power. But honestly, 437hp at 46mph is still spinning the tires, and as a streeter, ask yourself how often will you be at WOT at 77 mph. So, IMO, you can easily ditch that 5700rpm cam.
> now, draw a line, right across the graph at 400ftlbs. With a 360engine it will not be possible to pull the torque up to your 400ftlb line, in the rpm range that you will normally be driving, unless maybe you stroke it; even then 400@3000 is a heck of a thing for the chassis to try and deal with, and there is NO good reason to go there, as you can make the numbers down there, with gearing. That's why you have a transmission, and a Convertor..
So again; forget a long flat torque curve.
> now go back to the power peak at 5700. Do you see how slowly the power is dropping off? there is at least 300 maybe 400 more rpm left in her. Lets say a first gear outshift at 6200. With 3.55s and 27s, that is now 50 mph. In the zero to 60 contest, that only leaves you 10mph to pull in second, beginning at 3660 rpm, down around 250/260 hp, on this graph.
This is messed up.
For a streeter; You have waaaaay to much power in First gear, and are seriously choked in Second gear.
IMO, again, you would be better off with a much smaller cam, and hit Second gear much sooner.
Now I know you said "no strip racing" but
who builds a 437 hp engine and never stretches it out. What would be the point of that?

What you really need/want is another lower gear in the trans, or an overdrive, and any old SBM, at that point; Ask me how I know.



View attachment 1715845108

Over simplified and misleading as well as your “Tires will be spinning” BS…., but I get the point your trying to make about your great and awesome car & how everyone else’s sucks. Good grief.

Re-reading to try and fully comprehend what you are saying and recommending.

He’s telling you his way is the best way. For a good street machine, he does a good job.

Let me curve it….

Stay with a mild cam, stock stroke, pump gas engine and couple other with an OD transmission. Run as much compression as you can stuff in there with the cam selected.

AJ has a excellent street combo.

IMO, you’ll be looking at a cam with a 108 centerline and a mild amount of overlap ground on an semi aggressive cam lobe. No need to go nuts here. Also try and find that cam with some decent lift to take advantage of the cylinder heads flow abilities.

 

[K.O. SWINGER]

...best stroke for what?
Mileage, torque, street fun, 1/4 mile , circle track, cruising, tire smoke....
There is no perfect canoe.

Or maybe there's a few? If you're running a b-body satellite sport which is basically a roadrunner body, a 4-in stroker is kind of a no-brainer with that kind of weight it really works against the shorter stroke combos that would really shine in a 3000 lb car.

 

[autoxcuda]

I don’t follow…. Can you explain less cryptically? I don’t rebuild engines and modify heads but once or twice in a lifetime.

Eliminating Cylinder Head Valve Shrouding for Improved Performance - Part 9

Look at valve on right in the picture below. And treat that moved out right side line as cylinder wall. That moved out line is a bigger cylinder bore.

A 318 has a 3.91” bore originally, and 360 has a 4.00” bore and your 340 block has a 4.04” bore.

the bigger the bore, the less red area shown below:

Below: Fig. 9.10. Air does not enter the cylinder evenly all around the intake valve. Here, better than 60 percent enters via the valve’s “A” half. This means the “B” half is in less need of de-shrouding. Note: the flow exiting the valve is turning, thus generating swirl.

Below: Fig. 9.8. A hemi-style cylinder head has zero valve shrouding. This comes about because as the valve opens, the distance from the edge of the valve to the cylinder wall increases from A to B.

 

[340inabbody]

...best stroke for what?
Mileage, torque, street fun, 1/4 mile , circle track, cruising, tire smoke....
There is no perfect canoe.

Street funzies

 

[340inabbody]

My alloy headed 11/1 367 has more torque than 325/50-15s can handle on the street. I have run it with a 292/292/108, a 270/276/110, and she currently has a 276/286/110; the 270 was my favorite. She went 93 in the Eighth with the 276 cam@ 3457 pounds. Her normal weight is 3650 me in it.
Forget a long flat torque curve; one of two things will happen; 1) if a stroker, it will have freight-train torque impossible to harness.
2) if a 360 it will still have a preponderance of low-rpm power meaning lots of tire spin, but the top end is no weak.
We are not in the 80s anymore, there is no good reason to compromise your combo with low-compression. Alloy heads will support cranking pressures up to 200psi still on pump gas. I have run 185/190 on 87E10

Lemmee show you something;
Say your engine has a dead flat torque curve of 400ftlbs from 2000 to 6000. the formula to convert torque to horsepower is
torque times rpm, divided by 5250
watch this;
400 x 2000/5250= 152hp
400 x 2800/5250 = 213hp
400 x 3600/5250 = 274hp
400 x 4400/5250 = 335hp
400 x 5200/5250 = 396hp
400 x 6000/5250 = 457hp
Is that what you want?
I don't think so.......
Because ;
1) yur not gonna run a 2000 stall, so kiss 152hp goodby
2) yur not gonna run a cam on the street, that would get you 457hp at 6000, so kiss that goodby.
3) the 396hp at 5200 is already pushing the power peak pretty high for a streeter.
4) the faster you drive, the more power you need.
5) the slower you drive, the less power you need
6) if your combo can smoke the tires with 3.55s all thru first gear, then you obviously have more power at slow speed than you need.
Therefore do I say, for your combo, forget a long flat power curve.
Instead, tailor the power to what the chassis can handle, and still provide the kick you want, and let the torque be what it will be.
Here is what you might like; simple easy cheap and effective. the dip at 3200 is obviously an anomaly, probably a fueling issue, Ignore it and extrapolate from say 3800 to 3000 in a straightline.
Look at the powerpeak up near 5700. This is more peak than you need. 5700rpm with 3.55s and 27s is 46mph in first/77 in second .............. so not the best fit. It really wants more gear or less cam for your combo.
More gear will destroy your cruise-rpm.
Less cam will increase your cylinder pressure and increase your low-rpm power, at the expense of high-rpm power. But honestly, 437hp at 46mph is still spinning the tires, and as a streeter, ask yourself how often will you be at WOT at 77 mph. So, IMO, you can easily ditch that 5700rpm cam.
> now, draw a line, right across the graph at 400ftlbs. With a 360engine it will not be possible to pull the torque up to your 400ftlb line, in the rpm range that you will normally be driving, unless maybe you stroke it; even then 400@3000 is a heck of a thing for the chassis to try and deal with, and there is NO good reason to go there, as you can make the numbers down there, with gearing. That's why you have a transmission, and a Convertor..
So again; forget a long flat torque curve.
> now go back to the power peak at 5700. Do you see how slowly the power is dropping off? there is at least 300 maybe 400 more rpm left in her. Lets say a first gear outshift at 6200. With 3.55s and 27s, that is now 50 mph. In the zero to 60 contest, that only leaves you 10mph to pull in second, beginning at 3660 rpm, down around 250/260 hp, on this graph.
This is messed up.
For a streeter; You have waaaaay to much power in First gear, and are seriously choked in Second gear.
IMO, again, you would be better off with a much smaller cam, and hit Second gear much sooner.
Now I know you said "no strip racing" but
who builds a 437 hp engine and never stretches it out. What would be the point of that?

What you really need/want is another lower gear in the trans, or an overdrive, and any old SBM, at that point; Ask me how I know.



View attachment 1715845108

AJ what do you mean by “What you really need/want is another lower gear in the trans, or an overdrive, and any old SBM, at that point; Ask me how I know”?
Another lower gear? I don’t know what my trans ratio’s are in my 3 speed. What are you suggesting wrt another lower gear?

 

[autoxcuda]

Street funzies

4" stroke. Easy, cost effective, streetable. The longer stroke tames larger cams a little bit, and make them easier to tune and putter around town on the street.

Sure, other people have got to same place with other combos. But they have done lots of tuning, trial and error, have great tuning experience

 

[Dartswinger70]

Call me silly (or just old fashioned), but I really like a 3.31 stroke in my 340s... born to rev.

I was thinking the same (see my signature...)

 

[YO7_A66]

So it looks like there are some options on the length of stroke one can get in a particular crank rod piston combination. From what I gather.....the longer the stroke the more displacement BUT also the increased risk of interference on the assembly. What are the trade offs to be made? What is your experience with the amount of stroke you have used and recommend etc. Looking for a 340 application in particular.

Lets talk stroke....

""the longer the stroke the more displacement BUT also the increased risk of interference on the assembly.""

My 340 now has 4.00" stroke and a 4.090" bore. The crank and rods are from K1, and my machine shop had to clearance around the rod bolts (ARP 2000-10) which can be seen in the attached pictures.

 

[Dartswinger70]

Far out man...

 

[340inabbody]

Thanks for your inputs guys! I have a general question here. There are engine builders and machine shops, torque converter shops, cam designers, differential guys and fuel delivery specialists.

Who is the right type of professional who looks at the entire system from the weight of the car the size of the tires type of rear gear and determines the right stroke cam and converter and tune to get what a customer is seeking performance wise. I know we all have our opinions here about the individual components but at the end of the day this is a system.

 

[Dartswinger70]

Sounds like a race car builder Ed Quay, Ray Barton, S&W Race Cars....they are in my area you'd have to find one in your area or google "Performance specialists" etc.

 

[340inabbody]

Sounds like a race car builder Ed Quay, Ray Barton, S&W Race Cars....they are in my area you'd have to find one in your area or google "Performance specialists" etc.

I am not sure there is anyone here in the Phoenix metropolitan area anymore. We lost so many shops and the race track closed this year. My trap range closed as well. And I am NOT taking up golf!

 

[Unconventional]

I am not sure there is anyone here in the Phoenix metropolitan area anymore. We lost so many shops and the race track closed this year. My trap range closed as well. And I am NOT taking up golf!

I read it got kinda rowdy at the Phoenix Open Tourney the other day. Something about mud and no beer

 

[340inabbody]

I read it got kinda rowdy at the Phoenix Open Tourney the other day. Something about mud and no beer

Spoiled children not getting what they want I guess.