Help determining 340 cam

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CluelessMopar

CluelessMopar

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Okay guys, be kind.... I'm new to engine building/tear down :)

I recently picked up a 340 long block with 10:1 compression and I'm trying to figure out the camshaft to determine what torque converter to run... Before I purchase a dial indicator or remove the timing chain cover to determine the markings I was hoping someone might be able to shed some light on the manufacturer of the cam based on these details:

Engine was assembled about 15 years ago.
Solider lifters
Roller rockers
The gear that makes contact with the helical gear is yellow. (Sorry I don't know what this gear is called on the camshaft)

This might not be enough to go off of, but I know identifying cams in engines can be a little tricky sometime. Previous owner did not know the cam and I'm hoping to find out so I can at least set the valve lash correctly.

Here's a few pictures of the engine if that helps as well.

20220219_121009.jpg

20220219_120254.jpg
 
Grinders #'s are usually on the front face of the cam.

You can adjust your rockers based on what they are set at right now. Some MAY be looser than others but this method works OK. The milder the idle the closer the clearances are as a rule. Or you can start at .014 and go from there.

You could also pull the cam and have it Cam Doctored to get the real specs. Or ditch the TF and install a 4 speed!
 
Krooser said:
Grinders #'s are usually on the front face of the cam.

You can adjust your rockers based on what they are set at right now. Some MAY be looser than others but this method works OK. The milder the idle the closer the clearances are as a rule. Or you can start at .014 and go from there.

You could also pull the cam and have it Cam Doctored to get the real specs. Or ditch the TF and install a 4 speed!
Click to expand...
Just to clarify you're saying .014 is a good reference point to set the valve lash... then adjust more less based on the idle? And that's a cold lash correct?
 
I was expecting to see roller lifters and roller cam when u described the oil pump drive gear as being yellow which would be bronze. Kim
 
If the grinder id# are on the face of the cam. Why not remove the cam plug on the rear of the block? At the least you have a new cam plug.
 
I , me personally, would not run that big of a cam on the street.
I, me personally, already ran a 292/292/108 cam which I measured at [email protected]. I ran it in a 367 @11.3 Scr cranking about 180/185psi
I ran it with a manual trans and 3.55s
The problems were;
1) the power peak on mine was up around 5600. Shifting at 6000 then; which in First gear with 28" tires is 53mph. With an automatic, and 3.23s; that would have been ~57mph . That's all good but;
2) second gear for the 4-speed tops out at 6000=73; whereas;
for the auto, second @6000= 96mph; at 65 the rpm in Second is just 4060, fully 1540 below the power-peak of the 292 cam. Do you see the problem? Obviously first gear is fine. Just as obviously you are almost never gonna run , to shift-rpm in Second, on the street.
3) With iron heads, you cannot run 185psi,
but if you don't max out your pressure for the fuel you plan to use,
the bottom line is, that the bottom end (low rpm) is very likely gonna be a lil soft...... which forces you to run more stall then you might want to, therefore;
4) taking the above into consideration; [email protected] in my case, was a bad idea. I pulled the cam before the end if the First summer and sold it to a racer, who was very happy .
5) the cam I then installed next, was a 223/230/[email protected]; but I reduced the Scr to back off the pressure a tad. Best cam I ever had.
 
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AJ/FormS said:
I , me personally, would not run that cam on the street.
I, me personally, already ran a 292/292/108 cam which I measured at [email protected]. I ran it in a 367 @11.3 Scr cranking about 180/185psi
I ran it with a manual trans and 3.55s
The problems were;
1) the power peak on mine was up around 5600. Shifting at 6000 then; which in First gear with 28" tires is 53mph. With an automatic, and 3.23s; that would have been ~57mph . That's all good but;
2) second gear for the 4-speed tops out at 6000=73; whereas;
for the auto, second @6000= 96mph; at 65 the rpm in Second is just 4060, fully 1540 below the power-peak of the 292 cam. Do you see the problem? Obviously first gear is fine. Just as obviously you are almost never gonna run , to shift-rpm in Second, on the street.
3) With iron heads, you cannot run 185psi,
but if you don't max out your pressure for the fuel you plan to use,
the bottom line is, that the bottom end (low rpm) is very likely gonna be a lil soft...... which forces you to run more stall then you might want to, therefore;
4) taking the above into consideration; [email protected] in my case, was a bad idea. I pulled the cam before the end if the First summer and sold it to a racer, who was very happy .
5) the cam I then installed next, was a 223/230/[email protected]; but I reduced the Scr to back off the pressure a tad. Best cam I ever had.
Click to expand...
Appreciate the response... I had a feeling this was going to be way too much cam for my intended use. I'm debating putting in a Comp Cams Big Mutha Thumpr or just the regular Mutha Thumpr. I love the rough idle sound but I know people aren't too fond of them.

Also looking at the Hughes "real" Chrysler cam.
228/232
Operates at 2800 RPM.
Onky issue is they recommend 373 + gears... I'm running 355's...dunno if that's an actual issue at all.
 
AJ/FormS said:
I , me personally, would not run that big of a cam on the street.
I, me personally, already ran a 292/292/108 cam which I measured at [email protected]. I ran it in a 367 @11.3 Scr cranking about 180/185psi
I ran it with a manual trans and 3.55s
The problems were;
1) the power peak on mine was up around 5600. Shifting at 6000 then; which in First gear with 28" tires is 53mph. With an automatic, and 3.23s; that would have been ~57mph . That's all good but;
2) second gear for the 4-speed tops out at 6000=73; whereas;
for the auto, second @6000= 96mph; at 65 the rpm in Second is just 4060, fully 1540 below the power-peak of the 292 cam. Do you see the problem? Obviously first gear is fine. Just as obviously you are almost never gonna run , to shift-rpm in Second, on the street.
3) With iron heads, you cannot run 185psi,
but if you don't max out your pressure for the fuel you plan to use,
the bottom line is, that the bottom end (low rpm) is very likely gonna be a lil soft...... which forces you to run more stall then you might want to, therefore;
4) taking the above into consideration; [email protected] in my case, was a bad idea. I pulled the cam before the end if the First summer and sold it to a racer, who was very happy .
5) the cam I then installed next, was a 223/230/[email protected]; but I reduced the Scr to back off the pressure a tad. Best cam I ever had.
Click to expand...
do you use it for just street driving or a combination for both looking for a new cam for my 34 duster and this thread is helping a lot thank you
 
100% street
Depending on your intended useage, gears, willingness to run a hi-stall, etc.
low-rpm torque is king; and that starts with pressure and cubic inches.
After cubic inches has been selected, all you got; for bottom-end, is pressure.

The factory 318cars were duds for two reasons; they barely made 135psi, and they were stuck with horrible gearing. Remove those handicaps, and a 318 can be a blast.
Same goes for a 340, except the early ones already had pressure. But for a streeter that also needs to run hiway, the go-to rear-gear is 3.23s If an automatic, that usually spells a soft take-off, until you install a TC with a stall between 2500 and 2800, depending on the pressure left over after the cam is installed.
===============
Here is a bit of ; what you need to know.
Lets start with 340 and a true 10/1 Compression ratio.
And lets install the factory 340 cam; 268/276/114 in at 110, the intake valve will close at about 64* ABDC. Thus, this engine, at 800ft elevation will make about 159psi cranking pressure,with a P/V index of 126.
Pressure of 159psi is as about good as it gets for a 340, to still run on pumpgas.
But that P/V of 126 is pretty low; about what an injected 5.2M makes. P/V is a number that levels the playing field between engines of varying sizes and pressures and is a low-rpm performance indicator. So any two engines with the same P/V index are gonna perform about the same, up to about 3000/3500rpm.

See part 2 below.
 
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Personally I would recommend calling Racer Brown. He was recommended to me here on FABO and his advice was more realistic than what I got from Comp Cams, Lunati and Hughe’s. It comes down to buying a cam that fits your needs.
Racer Brown Cams
 
AJ/FormS said:
100% street
Depending on your intended useage, gears, willingness to run a hi-stall, etc.
low-rpm torque is king; and that starts with pressure and cubic inches.
After cubic inches has been selected, all you got; for bottom-end, is pressure.

The factory 318cars were duds for two reasons; they barely made 135psi, and they were stuck with horrible gearing. Remove those handicaps, and a 318 can be a blast.
Same goes for a 340, except the early ones already had pressure. But for a streeter that also needs to run hiway, the go-to rear-gear is 3.23s If an automatic, that usually spells a soft take-off, until you install a TC with a stall between 2500 and 2800, depending on the pressure left over after the cam is installed.
===============
Here is a bit of ; what you need to know.
Lets start with 340 and a true 10/1 Compression ratio.
And lets install the factory 340 cam; 268/276/114 in at 110, the intake valve will close at about 64* ABDC. Thus, this engine, at 800ft elevation will make about 159psi cranking pressure,with a P/V index of 126.
Pressure of 159psi is as about good as it gets for a 340, to still run on pumpgas.
But that P/V of 126 is pretty low; about what an injected 5.2M makes. P/V is a number that levels the playing field between engines of varying sizes and pressures and is a low-rpm performance indicator. So any two engines with the same P/V index are gonna perform about the same, up to about 3000/3500rpm.
Click to expand...
thank you that is soo much more than i thought'd get i appreciate it
 
Ezra_Duster said:
thank you that is soo much more than i thought'd get i appreciate it
Click to expand...
My computer stalled, I wasn't finished lol.
Part 2
How much P/V do you need?
Well that kindof depends on how LOW a stall you want to run. If yur running a 3000, then you don't care. But if a 2200 then the more the better.
By my experience, with a manual trans, over 160 is really nice.
Personally, having experienced over 160, I wouldn't run under 140 ever again, but I have a manual trans so there are many many times , maybe most of the time, that my engine is in that 1800 to 3000 zone. In fact, with the generous P/V, I usually shift at 2800, which drops into Second at 1740, yes my 367 is a bit of a tractor.
How do you change your P/V ?
In a given engine, there are only two ways; changing the Scr (Static Compression Ratio), or changing the ICA (the Intake-valve closing angle).

Going back to your 10/1 340 still at 800 ft, lets install a cam about two sizes smaller that has an Ica of 57* ( from 64* previously). And the pressure rises to 169, with P/V rising to 142, very nice.
Next, lets put the 340 Cam back in it, but increase the Scr to 10.5, And the numbers come to 169psi and 134 P/V; almost as nice.
Except you cannot normally run these pressures with iron heads on pump gas.

Now, lets say you switched to a cam with a more narrow LSA than the 114* of the 340 cam. Lets say a 108, how can we fudge the numbers into a pressure that we can run, with as much P/V as possible?
I'm glad you asked.
here is the factory cam showing all the events
268/116 comp/104 extraction/276ex/44* overlap/ 114Lsa/64* Ica. Next
268/120 comp/112 extraction/276ex/56* overlap/ 108Lsa/60* Ica. same cam except Lsa tightened up
So, the Ica has changed to 60 from 64 and still at 10/1 and 800ft elevation;
pressure jumps to 165psi@P/V of 135 here yago. This is about the max pressure you can run on pump gas. and even this will require a tight Quench design. But the P/V is creeping up to the magic 140 that I kindof like to see.
Now about the numbers;
the extra 4 degrees of compression, is where the pressure increase comes from.
the extra 8* of extraction, is gonna take the 340 out of the realm of gas-hog, and into the realm of having the potential of making reasonable hiway fuel economy.
Intake and exhaust are the same.
The overlap jumps from 44 to 56 which, with headers has the potential to add a big old hump in the power curve, the downside being a more narrow powerband. Do you care? No Because the increase in pressure will make up for it, as will; at under 3000, the 9 points of additional P/V, now 135 up from 126 .. This will allow you to run less stall.
So what is the downside to the 108? besides the slightly more narrow powerband; there are two;
1) the jump in overlap is gonna require a higher cruise rpm to slam the door on reversion, which negatively affects fuel economy. But with 3.23s this is NOT an issue; and unless you get an overdrive, it will NEVER be an issue.
2) the TorqueFlite has ratios of 2.45-1.45-1.00, with splits of .59/.69
That 1-2 split of .59 means that whatever you rev the engine to, on the 1-2 shift, the Rs will fall to that percentage. This 268 cam might have a powerpeak at around 5200, and a shift rpm of 5500. So, shifting at 5500, the Rs will drop to 3250, which is a powerband requirement of 2250rpm; pretty enormous. Well; that 108LSA cam is not gonna cover that, so on the shift, the engine will definitely fall off the cam, meaning, at 3250 in Second gear; she needs all the help that you can give it.......... and we did! We pumped the pressure to 165, tightened the Q to .040 or less, and if it's still too far off the pipe, just rev it to 6000, and come in at 3540; easy-peasy.

Disclaimer;
I'm NOT saying you should run a 268/276/108 cam!!
This is just a study to show you what can be done with the Ica and Scr to maximize your combo.
The 340 has enough cubes that it does Not necessarily have to be at optimum, in a streeter, to still be a lotta fun.
Finally, with alloy heads you CAN pump the pressure up to 185psi and STILL run 87E10/ Jus saying. And that will get you a boatload of flexibility in cam choices. I once ran my combo up to over 190psi@176VP, which was insanely fun. I ran that with a double overdrive, and geared for 65=1600; dressed like that, my 367 pulled over 30 mpgs, on one certain daytrip. That's what a VP of 176 will do. Those alloy heads paid for themselves in just a few years as installed on my DD.
BTW;
the 8/1, 318LA makes about 136psi@113P/V @ the same 800ft, just for comparison.
 
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That is a pretty stout cam. The one you were thinking of is much better. Go a step lower and use your 3.55’s. It’ll be a good cruiser and have good low end power.
 
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