Roller Cam Specs for 340

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ethan santin

ethan santin

Buck eye jim you gotta go
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Morning FABO,

I am brand spanking new to the world of engine building and am putting together a 71 340 roller this summer. The block is .60 over, X heads, shooting for 10:1 and forged internals. I really don't know what kind of horse power numbers I could be able to expect but I'm shooting for as much as I can with the set up that I just described. Sourcing roller cams for sbm's has been kind of difficult but I have finally found some options through Howards. I really don't understand exactly what cam specs mean or what kind would be appropriate for my build so I decided to come on here and ask you guys what your take's on my set up are. If you have anymore questions or comments on my set up please do not hesitate to say or ask anything, any kind of information is seriously appreciated. Thank you for reading.

Ethan
 
Gearing & Stall, what you got or more importantly what your willing to run makes a big difference, what kind of driveability you require, how you gonna use this car etc..

It don't seem you really need a roller, a solid flat tapped probably will do.
 
273 said:
Gearing & Stall, what you got or more importantly what your willing to run makes a big difference, what kind of driveability you require, how you gonna use this car etc..

It don't seem you really need a roller, a solid flat tapped probably will do.
Click to expand...
Why wouldnt it seem like a need a roller? What's the biggest difference between running rollers or flat tappets? I wanted to go a roller route because I have heard a lot about the difficulty and anxieties around breaking in flat tappets. Is there really anything to worry about when breaking in flat tappets in your opinion?
 
ethan santin said:
Why wouldnt it seem like a need a roller? What's the biggest difference between running rollers or flat tappets? I wanted to go a roller route because I have heard a lot about the difficulty and anxieties around breaking in flat tappets. Is there really anything to worry about when breaking in flat tappets in your opinion?
Click to expand...
I just mean for your probable performance level SFT give most of what you need, if you don't mind spending the extra for a roller it's not a bad choice.
 
If you don't mind spending the money roller is the way to go IMHO. I would rely on a reputable cam mfg's recommendations like Howards, Hughes, etc. They will need to know intended use, gearing, stall, etc.
 
If you go with one of those hydraulic rollers from Howards, be sure to ask if they are ground on an LA cam blank or a Magnum cam blank. The difference is the nose of the cam on Magnum's is shorter, and not made to run a mechanical fuel pump eccentric like LA cams are. I put a hydraulic roller ground on a Magnum blank in my 273, because that was all that was available during the scamdemic. I had to buy a cam snout extender from Hughes Engines to be able to run a mechanical fuel pump. It looks like a Mickey Mouse piece to me, but several people on here said they work fine. I got my cam from Bullet Cams. They ground it to specs for an old Lunati roller that I wanted for the 273. Works good so far. Made surprisingly good power for an itty bitty motor that is pretty much stock. If the fuel pump eccentric adapter lives, I'll be happy! The Howards 770525-10 looks like a pretty decent cam. Use Morel hydraulic roller lifters with whatever cam you choose. You will most likely need to get your lifter bores bushed also. Good luck with it!

:thumbsup:
 
For performance only like a run down the drag strip you only got to focus on full throttle performance and below 2500-3000 rpm ain't usually too much of a concern even higher depending on performance level plus generally you can run the gears and stall speed needed for best performance.

Now when you bring the street into it, idle, part throttle performance (normal driving), cruising rpms etc.. become a factor and deciding the balance between the two is something you got to think of, How important is streetability, how do you want your car to behave around town on the highway etc.. how much you willing to sacrifice for full throttle fun ?
 
Last edited:
JDMopar said:
If you go with one of those hydraulic rollers from Howards, be sure to ask if they are ground on an LA cam blank or a Magnum cam blank. The difference is the nose of the cam on Magnum's is shorter, and not made to run a mechanical fuel pump eccentric like LA cams are. I put a hydraulic roller ground on a Magnum blank in my 273, because that was all that was available during the scamdemic. I had to buy a cam snout extender from Hughes Engines to be able to run a mechanical fuel pump. It looks like a Mickey Mouse piece to me, but several people on here said they work fine. I got my cam from Bullet Cams. They ground it to specs for an old Lunati roller that I wanted for the 273. Works good so far. Made surprisingly good power for an itty bitty motor that is pretty much stock. If the fuel pump eccentric adapter lives, I'll be happy! The Howards 770525-10 looks like a pretty decent cam. Use Morel hydraulic roller lifters with whatever cam you choose. You will most likely need to get your lifter bores bushed also. Good luck with it!

:thumbsup:
Click to expand...
Thank you for sharing this, I have been reminded of this by many people, I will be sure to ask Howards about it.
 
ethan santin said:
Morning FABO,

I am brand spanking new to the world of engine building and am putting together a 71 340 roller this summer. The block is .60 over, X heads, shooting for 10:1 and forged internals. I really don't know what kind of horse power numbers I could be able to expect but I'm shooting for as much as I can with the set up that I just described. Sourcing roller cams for sbm's has been kind of difficult but I have finally found some options through Howards. I really don't understand exactly what cam specs mean or what kind would be appropriate for my build so I decided to come on here and ask you guys what your take's on my set up are. If you have anymore questions or comments on my set up please do not hesitate to say or ask anything, any kind of information is seriously appreciated. Thank you for reading.

Ethan
Click to expand...
What kind of driving will you be doing with the car? After that's answered we cam between the heads and the answer to the first question.
 
Application, application, application.
I'm guessing that yur building a street-driven hotrod, but you didn't say.
The cam for a streeter is quite different from one for a racer or for a DD or even for a weekend warrior.
Shooting for a as much power as possible, say500 hp, in a normally-aspirated 340streeter, is pure foolishness..........
When 300 in an A-body is already a tire fryer.
I'm agreeing with 273 above.
we need to know what car you have, what you'll be doing with it, and it's powertrain; plus how deep your pockets are, about how many miles a summer you are thinking of traveling, and even what gas you are willing to cough up for at every fill-up.

IMO
>your first decision should be; is hi-way travelling involved, do you have an overdrive, and if not, how high a cruise-rpm are you willing to put up with.
>and your second decision, if a 4-speed manual, is how slow do you need to drive it
And why-o-why 060 overbore?
> and the third is; if you can only fit 255s in the rear tubs, for a streeter, any more than 300hp is already frying most brands of street tires, to over 40 mph; the point being, 400hp will just fry the tires a lil further/or longer, unless you fix your traction issues first..... which gets expensive in a hurry.
> just for comparison
my 367 has had 3 cams in it since 1999, varying from about 330 hp to over 430hp. My favorite was the 330, and I would have been willing to give some of that away.
Absolute hp, on the street, IMO, is not the best goal. Nor is mega torque off the line unless you can harness it, but at least you can have fun with torque, and that allows you to use a more hiway friendly rear gear. To that end, I gotta say,
for me, with street gears,
I'll take 425 footlbs at modest rpm,
over 425 hp at some high rpm.......
every time.
I'm done with big cams, performance rear gears, hiway buzzzzzzz, and even the race-car rumble out the tailpipes. Done. Gimme a 300/330hp, 367cuber, with an overdrive, in a 3500pound ready to go driver and I'll want for nothing.
For me, overdrive is a game-changer and a must-have. I like 65=2400 or less; which, without an overdrive means a rear gear of 2.94s or less. Well, with a 340, that will be unacceptable off the line. You'd need about 416 cubes to make that come alive, lol.
With a GVod, you can run a 3.73 for the same 2400.
With an A518, it is 4.10s
With a Loc-Up, maybe 4.30s.
This one time I had a double overdrive in the which 65 was 1600, man you gotta hear your 340 singing thru full-length 3" duals at 1600! I think I could drive a million non-stop miles at 1600, lol.
Well, camming for 1600 is not gonna let your 340 stretch out any, lol. I only did that the one time, to prove a point.
 
273 said:
For performance only like a run down the drag strip you only got to focus on full throttle performance and below 2500-3000 rpm ain't usually too much of a concern even higher depending on performance level plus generally you can the gears and stall speed needed to best performance.

Now when you bring the street into it, idle, part throttle performance (normal driving), cruising rpms etc.. become a factor and deciding the balance between the two is something you got to think of, How important is streetability, how do you want your car to behave around town on the highway etc.. how much you willing to sacrifice for full throttle fun ?
Click to expand...
MOPAROFFICIAL said:
What kind of driving will you be doing with the car? After that's answered we cam between the heads and the answer to the first question.
Click to expand...
This is the big question. The 340 is for my duster. It is going to be a street car but I want to prioritize performance. I am willing to sacrifice *SOME* steerability for full throttle pulls. My fathers charger's 440 is what I would consider a perfect example of a street car. 3:55's, 2500 stall (i think, we dont remember it might be bigger then that), and its running a flat tap comp 21 223 4 duration@.505 224 intake 230 exhaust and Intake .477 and exhaust .480. It still hasn't ran, still waiting to break it in so I don't know what the drivability is like on it but he predicts that it will be fairly streetable
 
ethan santin said:
This is the big question. The 340 is for my duster. It is going to be a street car but I want to prioritize performance. I am willing to sacrifice *SOME* steerability for full throttle pulls. My fathers charger's 440 is what I would consider a perfect example of a street car. 3:55's, 2500 stall (i think, we dont remember it might be bigger then that), and its running a flat tap comp 21 223 4 duration@.505 224 intake 230 exhaust and Intake .477 and exhaust .480. It still hasn't ran, still waiting to break it in so I don't know what the drivability is like on it but he predicts that it will be fairly streetable
Click to expand...
What rear gears and stall you willing to run? the deeper (3.91-4.88) and higher stall (3000-4500 rpm) the bigger the cam you can go, stall is more important than gears, you can get away with being a bit under geared but if your only willing say a 2500 rpm stall then your talking fairly mild.


A 440 with a 224 cam 2500 rpm stall and 3.55 is fairly mild.
 

AJ/FormS said:
Application, application, application.
I'm guessing that yur building a street-driven hotrod, but you didn't say.
The cam for a streeter is quite different from one for a racer or for a DD or even for a weekend warrior.
Shooting for a as much power as possible, say500 hp, in a normally-aspirated 340streeter, is pure foolishness..........
When 300 in an A-body is already a tire fryer.
I'm agreeing with 273 above.
we need to know what car you have, what you'll be doing with it, and it's powertrain; plus how deep your pockets are, about how many miles a summer you are thinking of traveling, and even what gas you are willing to cough up for at every fill-up.

IMO
>your first decision should be; is hi-way travelling involved, do you have an overdrive, and if not, how high a cruise-rpm are you willing to put up with.
>and your second decision, if a 4-speed manual, is how slow do you need to drive it
And why-o-why 060 overbore?
> and the third is; if you can only fit 255s in the rear tubs, for a streeter, any more than 300hp is already frying most brands of street tires, to over 40 mph; the point being, 400hp will just fry the tires a lil further/or longer, unless you fix your traction issues first..... which gets expensive in a hurry.
> just for comparison
my 367 has had 3 cams in it since 1999, varying from about 330 hp to over 430hp. My favorite was the 330, and I would have been willing to give some of that away.
Absolute hp, on the street, IMO, is not the best goal. Nor is mega torque off the line unless you can harness it, but at least you can have fun with torque, and that allows you to use a more hiway friendly rear gear. To that end, I gotta say,
for me, with street gears,
I'll take 425 footlbs at modest rpm,
over 425 hp at some high rpm.......
every time.
I'm done with big cams, performance rear gears, hiway buzzzzzzz, and even the race-car rumble out the tailpipes. Done. Gimme a 300/330hp, 367cuber, with an overdrive, in a 3500pound ready to go driver and I'll want for nothing.
For me, overdrive is a game-changer and a must-have. I like 65=2400 or less; which, without an overdrive means a rear gear of 2.94s or less. Well, with a 340, that will be unacceptable off the line. You'd need about 416 cubes to make that come alive, lol.
With a GVod, you can run a 3.73 for the same 2400.
With an A518, it is 4.10s
With a Loc-Up, maybe 4.30s.
This one time I had a double overdrive in the which 65 was 1600, man you gotta hear your 340 singing thru full-length 3" duals at 1600! I think I could drive a million non-stop miles at 1600, lol.
Well, camming for 1600 is not gonna let your 340 stretch out any, lol. I only did that the one time, to prove a point.
Click to expand...
To answer your bore question, I have to go .60 over, I got a really good deal on the block I have but upon further examination after buying it, many of my cylinders where different sizes. I honestly have had so many guys tell .60 over is bad idea and guys who have told me that they have had no problems at all, im not to totally worried about. My machinist has bored other customers blocks over .60 and said they run and cool fine. Now you bring up a very good question about highway travel. I will at some point probably drive it on the highway but not much at all in the grand scheme of things. As far as a driveline goes, ill probably end up running my rebuilt 904 and my 8 3/4 and sure grip which has 3:23's in it right now but will be swaping for something larger once throw my 340 in. I will probably not being messing around with any kind of overdrive because it wont be on the highway that much at all and I was actually gonna be running a 255/60 15 in the rear.
 
Last edited:
273 said:
What rear gears and stall you willing to run? the deeper (3.91-4.88) and higher stall (3000-4500 rpm) the bigger the cam you can go, stall is more important than gears, you can get away with being a bit under geared but if your only willing say a 2500 rpm stall then your talking fairly mild.


A 440 with a 224 cam 2500 rpm stall and 3.55 is fairly mild.
Click to expand...
Im still pretty indecisive. Probably a little larger then 2500 but less then 3000. For gear ratio I wanted to go 3:91 but my father said that's to big for the street and I should stick to the 3:23's I already have in the car. I thought that most guys like 3:91's for street 340's.
 
ethan santin said:
Im still pretty indecisive. Probably a little larger then 2500 but less then 3000. For gear ratio I wanted to go 3:91 but my father said that's to big for the street and I should stick to the 3:23's I already have in the car. I thought that most guys like 3:91's for street 340's.
Click to expand...
A 2800 stall is gonna put a big limit on your cam choice, probably around a 230 give take depending what you exactly want, which ain't a bad thing.
 
Ok well then, you have a legitimate reason for 60-over, I get that. and, you have given good thought to the combo.
The automatic is a wise choice.
255s will be your limiting factor, unless you address those traction issues. Your Duster will accept up to 295/50-15s on 10s, inside the tubs, even lowered, but getting them installed on the factory rear end is gonna require the exact right backspace, which will likely require custom wheels. Your other option is to buy the wheels you like, with a backspace up to 4.5inches, move the springs over, and have the rear-end narrowed to fit them, which is the solution that I chose. and even at 275hp, yur still gonna need a traction aid.
As for cams, I had a 223/230/110 high-lift Hughes/Engle cam in my 367 for several years, which, I was quite fond of. I was quite sad when it dropped lobes. However,
I ran that with alloy heads at up to 195psi, lol.
By the cars trap-speed, that combo was making ~335hp.
After that, I installed a 230/237/110 hi-lift cam, which, by it's trapspeed the Wallace says is now making 430hp. This cam lost a very large amount of bottom-end torque and at first I was very disappointed. I solved that with a lower first gear in the Trans. But the lousy fuel-economy, even with overdrive, that I could not do much with.
If I had a 340, I would likely stick with something like a 228/234/107. The split would allow you to move the cam around some without destroying the overlap cycle. The generous overlap would let you tap into a good amount of top end power. the comparably long power-stroke will get you some reasonable fuel economy. To get some generous bottom-end torque, to run those 3.23s, or even 2.94s I would install alloy heads and get the pressure up to in the window of 185>195psi, which, in my case still runs on 87E10, at full Power. timing. That's what I would do.
Except, I would run a 4-speed, cuz that's how I roll, lol.
 
Last edited:
AJ/FormS said:
Ok well then, you have a legitimate reason for 60-over, I get that. and, you have given good thought to the combo.
The automatic is a wise choice.
255s will be your limiting factor, unless you address those traction issues. Your Duster will accept up to 295/50-15s on 10s, inside the tubs, even lowered, but getting them installed on the factory rear end is gonna require the exact right backspace, which will likely require custom wheels. Your other option is to buy the wheels you like, with a backspace up to 4.5inches, move the springs over, and have the rear-end narrowed to fit them, which is the solution that I chose. and even at 275hp, yur still gonna need a traction aid.
As for cams, I had a 223/230/110 high-lift Hughes/Engle cam in my 367 for several years, which, I was quite fond of. I was quite sad when it dropped lobes. However,
I ran that with alloy heads at up to 195psi, lol.
By the cars trap-times, that combo was making ~335hp.
Click to expand...
Thank you for the recommendation, is that Hughes cam a flat tap or roller? And sorry, what do you mean by my 255's being the limiting factor?
 
AJ/FormS said:
Application, application, application.
I'm guessing that yur building a street-driven hotrod, but you didn't say.
The cam for a streeter is quite different from one for a racer or for a DD or even for a weekend warrior.
Shooting for a as much power as possible, say500 hp, in a normally-aspirated 340streeter, is pure foolishness..........
When 300 in an A-body is already a tire fryer.
I'm agreeing with 273 above.
we need to know what car you have, what you'll be doing with it, and it's powertrain; plus how deep your pockets are, about how many miles a summer you are thinking of traveling, and even what gas you are willing to cough up for at every fill-up.

IMO
>your first decision should be; is hi-way travelling involved, do you have an overdrive, and if not, how high a cruise-rpm are you willing to put up with.
>and your second decision, if a 4-speed manual, is how slow do you need to drive it
And why-o-why 060 overbore?
> and the third is; if you can only fit 255s in the rear tubs, for a streeter, any more than 300hp is already frying most brands of street tires, to over 40 mph; the point being, 400hp will just fry the tires a lil further/or longer, unless you fix your traction issues first..... which gets expensive in a hurry.
> just for comparison
my 367 has had 3 cams in it since 1999, varying from about 330 hp to over 430hp. My favorite was the 330, and I would have been willing to give some of that away.
Absolute hp, on the street, IMO, is not the best goal. Nor is mega torque off the line unless you can harness it, but at least you can have fun with torque, and that allows you to use a more hiway friendly rear gear. To that end, I gotta say,
for me, with street gears,
I'll take 425 footlbs at modest rpm,
over 425 hp at some high rpm.......
every time.
I'm done with big cams, performance rear gears, hiway buzzzzzzz, and even the race-car rumble out the tailpipes. Done. Gimme a 300/330hp, 367cuber, with an overdrive, in a 3500pound ready to go driver and I'll want for nothing.
For me, overdrive is a game-changer and a must-have. I like 65=2400 or less; which, without an overdrive means a rear gear of 2.94s or less. Well, with a 340, that will be unacceptable off the line. You'd need about 416 cubes to make that come alive, lol.
With a GVod, you can run a 3.73 for the same 2400.
With an A518, it is 4.10s
With a Loc-Up, maybe 4.30s.
This one time I had a double overdrive in the which 65 was 1600, man you gotta hear your 340 singing thru full-length 3" duals at 1600! I think I could drive a million non-stop miles at 1600, lol.
Well, camming for 1600 is not gonna let your 340 stretch out any, lol. I only did that the one time, to prove a point.
Click to expand...


Different day, same nonsense.
 
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