340 Cam Kits which ones work with a stock block

[68 Coronet RT]

Some notes working backward

Abody bomber

268H is a safe grind, good torque but not great torque especially with a lower compression motor

look when it was designed and what gas was available

The Summit is better than buying exactly the same thing from Edelbrock, Elgin is even less expensive

an even older design than the 268 H I'd do a regrind first Like the stock cam it has really long seat timing for the amount of lift or duration at 200 Needed compression back in the day and that has not changed.

Agree with crackeback – but I do not buy cams for the sound

and the 218 was a strawman till real data shows up- just for discussion- I can even agree with Rumble about that

72Dart r has a good point use as much lift as you can but no more- and put it in correctly as advance or retard changes valve clearances

what is a small cam? Short at .200 IMHO we can use limited lift by rolling the nose over while still have the valve open a bunch where it counts where the piston is really moving

Duration is simple more duration moves up the torque curve- how much low end do you want to live without?

Excellent post rumblefish360

68CoronetRt Purpleshafts are better than most out there but they are pricy and lobes are dated

one reason is that there are better springs today- and better heads if you use head flow to help spec a cam The stock 340 cam has VERY LONG RAMPS and as you say not much lift

any idea what your cranking compression is--- stock heads, thick gaskets now? Any idea what your compression really is?

thanks for the tip about Competition components- not in my database

I'll post some in the range you are looking at later today but IMHO you are not ready to make a choice



a Note on CRANE

nm9sheham

The reason that the crane 268 is milder is that it is! Crane measures duration .004 off the basecircle whereas Comp measures at .006 so a 268 Comp is BIGGER than a 268 Crane

and Engle and Isky measure at .008 (or more in IskyMegacams) and MOPAR (which is completely different)

They are not aggressive ramps even for the Chevy lifters they were designed for

What they are is that they are SMOOTH for the time they were designed- Harvey Crane was ahead of the game as to jerk etc (at least as far as advertising it) and was in fact less hard on the valve train than Clay Smith, Howard and some others we could mention- Isky made (and still sells the same thing) cams that were easy on the valvetrain by stretching out the duration (just like the factory did)

That's why Isky Megacams rev well and are reasonably stable when over revved

so you gear low or a more modern grind will eat you off the corner- and change your springs

Wyrmrider/Crackedback
I was going to wait till tomorrow to do a compression check but since it's so crappy outside I went ahead and pulled all the plugs. This is what I have, mind you this is a stock block X head motor that's never been apart. Cylinders 1,5,7- 155, cylinder 3, 150 cylinders 2 and 4- 150, 6 is 148 and 8 is 155 so the compression doesn't look all that bad.
Crackedback after talking to a buddy of mine he told me that the .284/.284 .484/.484 would be to much so I'm still looking but I have been on Hughes Engine website and submitted a form with all the info they requested for a Cam kit and I did the same with Howards Cams. I'm also going to talk to a guy by the name of Dwayne Porter who is a very good mopar guy and I'm waiting for a call back from Scott Brown from Competition Components. One way or another I will get the right setup

 

[autoxcuda]

If I knew what was in the car as far as a converter it would be different as far as what I would put in it. I would hate to drop it then only find out what I bought new is what's in there. This is my first automatic. My other mopars were 4 speeds, What mods are you talking about to the heads for springs ? If you are talking changing the springs I don't need to pull the heads to do that. The cam kit I had in my 440 RT I had to change the springs and I have the tools to change them on the car that's not a issue and I would rather change them as this motor in my Dart has never been apart it's all original as is the interior and all the sheet metal. The cam I had in my RT was from Straight Line Performance which is now Competition Components, the cam had Lobe lift .335 intake and .335 Exhaust, Valve lift was .503, Adv.Dur 270 In 284 EX, [email protected] 226 In. 238 Ex. LBC 108 IN. 116 Ex. It was a adjustable hydraulic lifter set up with new springs and rockers. It really ran good but you could not tell there was a cam in it unless you got close with the hood up and you could here a little clatter from the lifters.

So....

68 Coronet RT, Would you would be happy with the same idle and performance increase over stock on your 340 at that Straightline Performance/Competition Components ??

Would a Comp XE268 ground on a 112 centerline give about the same mellow idle??

Couldn't he run the stock 340 HiPo spring (if tested ok) and rockers with that cam, correct??

 

[68 Coronet RT]

The cam kit that the Coronet had worked very good but I'm looking for a idle a little more choppy over stock. The coronet idle was very mellow

 

[Wyrmrider]

I would not run 50 year old valvesprings
For some reason Howards has not gotten back to several posters lately- let us know your experience
I suspect Howards is now grinding Hughes cams instead of Engle
Howard has one off the shelf cam
543 lift 271duration on the intake 224/234 @.050 112lca in at 108- compares favorably to the comp XE-HL grind
if you wanted it choppy squeeze the lca down to 108 as suggested above
Evidently Competition has Comp grind some of their cams - let's see what they come up with
I do agree that the MOPAR 484 is too big especially that your compression is not high
You did notice that it is about 10 degrees bigger than the others it's more like a 290 class cam
Duane Porter knows what he is doing
best advice
go here and fill out
Street Performance | Jones Cams
if keeping your lift in the half inch range Lunati 10230703LK (there is also the 60302)
it's a 268-276 .494 lift so you can compare the intake lobe to those comp 268 chevy grinds

 

[lil red]

I emailed howards regarding cam selection about 2 weeks ago, took a couple of days but they did respond. Good bunch, they also immediately responded to a couple of emailed questions i had regarding their selection, seemed knowledgable

 

[Wyrmrider]

good to know
two posters at B Bodies Only were maybe too impatient
I agree with your findings

 

[rumblefish360]

The 284/484 will definitely give you a choppy idle. It should be in the 240-242 range at .050. If you do buy that cam , DO NOT get one other than the 108 LSA model. In a stock 340, grab a degree wheel and install it at 100-102 ICL.

Put plenty of initial timing on it and it will be decent down low.

If you don't already have the cam, look for something other than a MP grind. There are plenty of similar grinds from other companies out there.

CB, not to split a hair with but isn’t that @.050 a bit low for that cam? iirc, (LOL) isn’t that closer
To the 280/480?, I thought (lol again) the 284 was about a 244@050, otherwise, I so agree.

Couldn't he run the stock 340 HiPo spring (if tested ok) and rockers with that cam, correct??

Yes but there old. If they were replacement springs, as in OE
I’d say yes.

543 lift 271duration on the intake 224/234 @.050 112lca

A much more favorable cam that I’d rather install. LCA exempt.... but would work as mentioned and asked about by the oe poster. I have a similar @050 cam in a hydraulic roller in the wife’s 360. Very nice.

 

[Wyrmrider]

I have the 484 at 238, 239 and 241 possibly operator error or MOPAR changing vendors

IN 68 Coronets case squeezing the Howard down to 108 gives him the choppy idle with more overlap AND allows him to get the intake closed earlier with his not super compression
He just designed a Whiplash...
now if that is the right size to begin with...
also examples
285 555
271 543 shown above
271 518
267 506
263 498
252 475
measure twice- cut once

 

[68 Coronet RT]

I would not run 50 year old valvesprings
For some reason Howards has not gotten back to several posters lately- let us know your experience
I suspect Howards is now grinding Hughes cams instead of Engle
Howard has one off the shelf cam
543 lift 271duration on the intake 224/234 @.050 112lca in at 108- compares favorably to the comp XE-HL grind
if you wanted it choppy squeeze the lca down to 108 as suggested above
Evidently Competition has Comp grind some of their cams - let's see what they come up with
I do agree that the MOPAR 484 is too big especially that your compression is not high
You did notice that it is about 10 degrees bigger than the others it's more like a 290 class cam
Duane Porter knows what he is doing
best advice
go here and fill out
Street Performance | Jones Cams
if keeping your lift in the half inch range Lunati 10230703LK (there is also the 60302)
it's a 268-276 .494 lift so you can compare the intake lobe to those comp 268 chevy grinds

Wyrmrider
What ever cam kit I decide on I plan on changing the springs, I don't know the exact mileage on the car but 50 year old springs got to go maybe if I decide on a mechanical flat tappet I will have to do the rockers anyway

 

[crackedback]

If you want an idle it needs to be on a tight LSA and can be low on lift so that part of the equation doesn't even matter.

232-235 on a 106 would chop it up and low lift would allow for a single spring and sub 500 lift. You mention that the 226 at 050 cam in the 440 was soft on idle, you need to step up the duration and tighten the LSA to get a choppy idle. People suggest cams with a lot of lift and that's not necessary for what you appear to want.

 

[crackedback]

CB, not to split a hair with but isn’t that @.050 a bit low for that cam? iirc, (LOL) isn’t that closer
To the 280/480?, I thought (lol again) the 284 was about a 244@050, otherwise, I so agree.

Going of memory for at .050 numbers
292 = 248
284 = 241
280 = 237ish
268/276 = 228/230

The last two might be off by a degree or two.

This guy want a choppier idle. Simple to get, won't require bigger valvesprings and none of the 268 grind cams on the market are going to get him there based on the 440 comment. Little more .050 and a tight LSA will get him what he wants with lift less than 500. No adjustable rockers or anything fancy required.

Back to the rocket surgery!

 

[Wyrmrider]

yep
squeezing down the LCA gives the choppy idle - more duration more chop
but also plug fouling and harder to tune the carb
more lift (or more duration @200 with a rolled over nose if lower lift is desired) gives more power
early intake close is must with low compression
if you want it driveable- big seat duration makes it mostly strip only with low compression- loose converter and low gears

the recollections above about durations of DC cams seems close
The seat durations varied more than the .050 depending on what vintage and who was grinding the cams
I think the early ones were Camcraft- I talked to the master maker many years ago-knowledgable
touched them up with a file and stone just like I saw Potvin's Bill Jenks do in the 70s I think they were doing the masters for production cams too

 

[rigger3006]

mopar 284/484, comp 901 springs and you will definitely need a different converter, im using the hughes 3000,works great

 

[Wyrmrider]

rigger go back and read the whole thread
I'm sure it does work great and a MP 484 on 108 has been suggested but this is a daily driver work truck
btw compression seems just about perfect for what OP wants to accomplish

 

[rigger3006]

rigger go back and read the whole thread
I'm sure it does work great and a MP 484 on 108 has been suggested but this is a daily driver work truck
btw compression seems just about perfect for what OP wants to accomplish

maybe you should go back and read 1st post, its a car with 391s

 

[AJ/FormS]

Looking for a good cam kit for my stock block 340 with stock exhaust manifolds and stock intake but willing to change the intake if need be. What I'm looking for is a cam kit that will give me the nice cam sound but don't want to sit at a light and rock and roll, want to be street able. I know I will have to change springs and rocker arms and lifters not an issue. Car does have a 2 1/2 " TTI exhaust system all the way with dyno max mufflers. She is a automatic with a nice shift kit but not sure about converter. Rear end has 3:91 posi.

I have no idea what's in the car for a converter, what ever is in there was there when I purchased the car last year. Do I really want to drop the tranny to change the converter, if I was going to go to the track every weekend I might but I have no intensions of going to the track. Just play around on the street so no

It's a stock block X head motor with a production date of 6/22/67, stock compression 10.5.1

The stock 340 cam has a Intake lift of.429 and exhaust of .444 according to my service manual. The cam I'm looking at is a purple shaft with a Intake and Exhaust lift of .484 or a cam from another manufacturer with something very similar

Wyrmrider/Crackedback
I was going to wait till tomorrow to do a compression check but since it's so crappy outside I went ahead and pulled all the plugs. This is what I have, mind you this is a stock block X head motor that's never been apart. Cylinders 1,5,7- 155, cylinder 3, 150 cylinders 2 and 4- 150, 6 is 148 and 8 is 155 so the compression doesn't look all that bad.
Crackedback after talking to a buddy of mine he told me that the .284/.284 .484/.484 would be to much so I'm still looking but I have been on Hughes Engine website and submitted a form with all the info they requested for a Cam kit and I did the same with Howards Cams. I'm also going to talk to a guy by the name of Dwayne Porter who is a very good mopar guy and I'm waiting for a call back from Scott Brown from Competition Components. One way or another I will get the right setup

The cam kit that the Coronet had worked very good but I'm looking for a idle a little more choppy over stock. The coronet idle was very mellow

Average cylinder pressure of 152.5, which you call; "so the compression doesn't look all that bad", by itself is barely Ok for whatever is in it now. The only thing that is saving your combo is the 3.91s, and possibly the TC as we don't yet know the stall.
So whatever cam you chose it is gonna have to be custom, and you are gonna have to figure out first, one of the following;
1) your exact compression ratio, or
2) the exact ICA of the current cam,
3) both would would be ideal.
From those numbers you can build a cam.
Without those numbers anything you put in there is a gamble, and is likely to turn your bottom end to slush, mandating a new TC. And then your fuel economy will take a dump as well.

Unless your low cylinder pressure is already the result of a big cam.
So I highly recommend a LeakDown test to prove the numbers are NOT due to leakage.
Without some kind of idea as to what's in there .... IMO, you could be setting yourself up for an expensive disappointment.
From what I'm seeing, that engine is already a candidate for being a soft combo.
Those early 340s in stock-tubbed As,with street tires,are tire fryers all the way thru first and a good ways thru second to something like 60 mph,often even higher. How does yours compare?

 

[68 Coronet RT]

Average cylinder pressure of 152.5, which you call; "so the compression doesn't look all that bad", by itself is barely Ok for whatever is in it now. The only thing that is saving your combo is the 3.91s, and possibly the TC as we don't yet know the stall.
So whatever cam you chose it is gonna have to be custom, and you are gonna have to figure out first, one of the following;
1) your exact compression ratio, or
2) the exact ICA of the current cam,
3) both would would be ideal.
From those numbers you can build a cam.
Without those numbers anything you put in there is a gamble, and is likely to turn your bottom end to slush, mandating a new TC. And then your fuel economy will take a dump as well.

Unless your low cylinder pressure is already the result of a big cam.
So I highly recommend a LeakDown test to prove the numbers are NOT due to leakage.
Without some kind of idea as to what's in there .... IMO, you could be setting yourself up for an expensive disappointment.
From what I'm seeing, that engine is already a candidate for being a soft combo.
Those early 340s in stock-tubbed As,with street tires,are tire fryers all the way thru first and a good ways thru second to something like 60 mph,often even higher. How does yours compare?

Don't know for sure what the TC stall is, I'm assuming what ever came from the factory. Is there a number on the front if I rotate it around I can see ?
Not sure on the ICA, if you are talking Cam c-line it's 114 and Installed C-line it's 112 according to my book.
Negative on the big cam it's the factory stock cam
When I did my compression test I let the gage sit on each cylinder for a good five minutes to see if there was any leakage and the gage barely moved.
The guy I bought the car from told me the car originally had 3:91's sure grip but he swapped them out for 3:23's, sure grip I didn't like the performance at all with the 3:23's so I put a 3:91 Richmond gear set in. That woke it back up, she pulls really good but I think it can be better.

 

[AJ/FormS]

Don't know for sure what the TC stall is, I'm assuming what ever came from the factory. Is there a number on the front if I rotate it around I can see ?
Not sure on the ICA, if you are talking Cam c-line it's 114 and Installed C-line it's 112 according to my book.
Negative on the big cam it's the factory stock cam
When I did my compression test I let the gage sit on each cylinder for a good five minutes to see if there was any leakage and the gage barely moved.
The guy I bought the car from told me the car originally had 3:91's sure grip but he swapped them out for 3:23's, sure grip I didn't like the performance at all with the 3:23's so I put a 3:91 Richmond gear set in. That woke it back up, she pulls really good but I think it can be better.

You cannot use a compression tester to do a LD test. The gauge has a little valve in it that prevents the air from leaking out of it until you release it. You could make your own LD tester using the compression tester and a regulator, and a shut-off valve, as I have, but most will find it easier to just get the tool.
As to the TC you can do a stall test. Start with a warmed up ready to rock engine Apply the brakes hard and start bringing the revs up in manual low gear. Watch the tach. When the brakes can no longer hold the car back, at that exact moment capture the rpm reading. That is your brake stall.IIRC the factory stall was around 2350 +/- 100
if your engine is stock and has a stock cam, yet only has an average of 152.5psi cylinder pressure, IMO, something is wrong...... What altitude are you at?
I get about 30ft above sea-level. At 10.5 Scr, your pressure should be up around 165psi. Without this pressure, a bigger hydraulic cam will rapidly lose low-rpm performance. And that will require a higher stall TC to make it fun again. There is almost nothing worse than a poser engine that idles like a funny car but can't hardly get out of it's own way.
So to help you not get into that situation the LD test should be mandatory, and then the brake stall-test would be helpful as well.

BTW, the lackluster performance with the 3.23s supports the idea that the bottom end is already too soft. At 10.5 Scr, and proper pressure,and with the factory TC, she would be a tire-fryer. Any bigger hydraulic cam without an accompanying Scr or stall increase...... is sure to make it worse.

Also; my FSM says that engine should have pressure between 130 and 175 psi, for an average of 152.5..... so you are right on the average. .....But that spec is ridiculously ambiguous, and helps to explain why the broad diversity in 340 performance.
Low-rpm performance hinges on high compression, making or breaking your street combo. If you don't have it, then you have to apply bandaids like the hi-stall or the 3.91s. If you did have it, you can use a lot less stall and a lot less gear.And go further on a gallon of gas,sometimes a lot further.

 

[rigger3006]

that seems like a pretty inaccurate way to check stall speed, i think the way the brakes are setup would make quite the difference in "stall speed".and yes i'm speaking from personal experience, not all brake systems are created equal,imho

 

[AJ/FormS]

In the field, without instrumentation, it's the best we got. Furthermore at your power level, it doesn't need to be dead-nuts accurate . We just need to the nearest 200 rpm, to be able to differentiate what you might have. It tells us a little about the efficiency of your engine, and why it's not burning up the tires, and helps to predict where it needs to go, if you up-size the cam.
It's like this; a given TC will stall differently depending on the input torque, and the output load. In a given chassis; You can take say a 904 TC from a slanty and put it on a stock 318, and it might stall 300 to 400 rpm higher. And then bolt it onto a stock 360 and see the stall rise another 200, and then onto a 340, and see it drop back to the 318 level. If you were familiar with the TC, you could tell by the stall,what engine was in front of it without ever opening the hood.
The TC is a key to unlocking off-the-line performance, because it lets the engine spool up to an rpm where the power is that you are needing to make it accelerate from a standing start, at the rate you want it to.
You can line up several TCs with a stall difference of 300 between each, and watch your take off go from; worn out nag, to hard working Betsy, to quarter-horse, to stallion, to Thoroughbred racer, with each change in TC; without ever touching the engine.
All a 318 needs is a 2800 to make it feel 40hp bigger. Then swap out the 2.73s for 3.91s and Hang on Harvey! It's like a mini supercharger.

 

[68 Coronet RT]

Don't get me wrong, before I put the new tires on I could easily spin the tires in second gear and a little in third. Since I put my new tires on 245/60/15's I haven't been out with the car because the weather here has been horrible plus I need to take it easy for awhile as I'm breaking in a new set of gears. Time will tell. There is one other way to tell on the TC, 10 mph roll in 3rd gear and punch it, tack will spike to a rpm and hold for a second have to do it a couple of times for an average. Not the greatest way but the best we can do. Tomorrow will tell

 

[Wyrmrider]

sorry rigger wrong thread
either low compression or big cam
low dynamic compression in any case
good tips on the stall tests AJ
without knowing the converter or the cam it's hard to tell which way to jump
If we were sure the motor was ok mechanically it would help
are U sure this has the stock so called 10.5:1 pistons in it
did you say or know if it still has the steel shims or are there felpros or something
If it does have thick gaskets and stock pistons real compression is in the 9.5 range
if pistons have been changed...
has it been apart? I cant remember- right Rigger

 

[AJ/FormS]

Don't get me wrong, before I put the new tires on I could easily spin the tires in second gear and a little in third. Since I put my new tires on 245/60/15's I haven't been out with the car because the weather here has been horrible plus I need to take it easy for awhile as I'm breaking in a new set of gears. Time will tell. There is one other way to tell on the TC, 10 mph roll in 3rd gear and punch it, tack will spike to a rpm and hold for a second have to do it a couple of times for an average. Not the greatest way but the best we can do. Tomorrow will tell

Was that with the 3.91s already?

 

[68 Coronet RT]

No that was with the 3:23's and the E70/14 poly glass tires

 

[rigger3006]

sorry rigger wrong thread
either low compression or big cam
low dynamic compression in any case
good tips on the stall tests AJ
without knowing the converter or the cam it's hard to tell which way to jump
If we were sure the motor was ok mechanically it would help
are U sure this has the stock so called 10.5:1 pistons in it
did you say or know if it still has the steel shims or are there felpros or something
If it does have thick gaskets and stock pistons real compression is in the 9.5 range
if pistons have been changed...
has it been apart? I cant remember- right Rigger

I hear ya, a guy can get lost in all the fun