yellow rose
Overnight Sensation
Well that does suck buttermilk. We need much better trade deals with Canada rather that sending all our money to China. It would be better for both countries.
1968 340 Cam Choice (Again)
- Thread starter Kendog 170
- Start date
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Well that does suck buttermilk. We need much better trade deals with Canada rather that sending all our money to China. It would be better for both countries.
Wyrmrider
Well-Known Member
go to the 318 cam thread stickie and you can see the stock cam and others with similar durations and choices of LCA's
that said true compression would help
you need to determine if you CAN close the intake earlier by shortening the duration or closing up the lobe centers
Then know that the very extra long closing ramps (for that duration) can be shortened allowing the exhaust to close earlier and close up the lca that way
as yr said the factory cam is a compromise based on warranty and the the factory valve springs
depending on how much work you want to do you can lighten up your springs with beehives and their lighter retainers
if donig the heads you can use lighter chevy valves
etc
The 268 comp is no better than the stockcam except that it is ground with a SLIGHTLY narrower lca
There are better choices than either
but the stock cam will work if your compression is what you say it is
it is a dog with less (that's IMHO of course)
that said true compression would help
you need to determine if you CAN close the intake earlier by shortening the duration or closing up the lobe centers
Then know that the very extra long closing ramps (for that duration) can be shortened allowing the exhaust to close earlier and close up the lca that way
as yr said the factory cam is a compromise based on warranty and the the factory valve springs
depending on how much work you want to do you can lighten up your springs with beehives and their lighter retainers
if donig the heads you can use lighter chevy valves
etc
The 268 comp is no better than the stockcam except that it is ground with a SLIGHTLY narrower lca
There are better choices than either
but the stock cam will work if your compression is what you say it is
it is a dog with less (that's IMHO of course)
I have the Comp XE 268 in a mild 340
And I have a love / hate relationship with it.
It makes good power and has a nice little Lope to it.
But it is noisy!!
Ticks like a sewing machine and gets louder with Rpms.
On the Freeway it drives me nuts...lol
I've tried adjusting the valves, different oil weights...etc
I go back an forth with wanting to change it.
If I had to do it over I would go Lunati Voodoo 268 for a shelf cam.
If you search the Comp cam you'll find a lot of people saying the same about noise.
I have not found anyone complain about the Lunati.
I think it maybe has to do with it being a mopar 904 lobe camshaft even though it has fast ramps too.
If I had done a little more research I would have passed on the XE 268..
And I have a love / hate relationship with it.
It makes good power and has a nice little Lope to it.
But it is noisy!!
Ticks like a sewing machine and gets louder with Rpms.
On the Freeway it drives me nuts...lol
I've tried adjusting the valves, different oil weights...etc
I go back an forth with wanting to change it.
If I had to do it over I would go Lunati Voodoo 268 for a shelf cam.
If you search the Comp cam you'll find a lot of people saying the same about noise.
I have not found anyone complain about the Lunati.
I think it maybe has to do with it being a mopar 904 lobe camshaft even though it has fast ramps too.
If I had done a little more research I would have passed on the XE 268..
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I'm also helping a friend on his 68 Road Runner.
His 383 has a Comp XR cam (roller.)
It is just as noisy as my Cam.
His 383 has a Comp XR cam (roller.)
It is just as noisy as my Cam.
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ir3333
Well-Known Member
I agree...my xe 268 did have some valve train noise but i grew to like it.
aaronk785
Well-Known Member
Built a 340 for my friends 68 cuda 3.55s, manual 4 speed over drive. We ran a lunati voodoo 262 stock intake, thermoquad, and stock manifolds. I was happy with the way it ran. A little lope and good torque even with the big gear split. It was quiet to.
fratzog lover
Well-Known Member
Bingo. Basic 360 stock build. I put a Coan 2500 unit in and swapped SG 3.23's to 3.73 Tru Trac's. That woke it up. Still wasn't the cam I should have used.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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I offer to put a stock 318 cam in it, you'll have so much scary torque you'll flip your lid. And finally get some pressure into those aluminum heads, which they are begging for. Yeah the power will peak early but with those Eddie springs you'll be able to shift it at whatever.
With a 4-speed and 3.23s, 60mph in second will be about 4650rpm , so that's thru the power peak twice and change. That will add up to a good amount of average power.
And you probably have a 318 cam just laying around. For a bit-O-fun slap in a set of solid lifters and an adjustable valve gear. Oh sorry, you said no solids,lol.
30 mph in 2.66 first will be about 3320 rpm, very close to peak torque with that little cam,maybe a lil after, so at 3200#s,and 235 tires, there will be tirespin, so hang on.
But sorry, no rumpiddy rump.
Instead, with a lil effort, you might get her to idle down to 450 rpm at 4.0 mph, so maybe you can parade her. Won't be able to with the 340 cam, except by slipping the clutch, cuz even if you get her down to 650 idle, this will still be 5.8 mph, and she'll probably get jumpy on you unless you retard the timing.
Iron manifolds will kill the overlap anyway so any 340-type cam you stick in her is not gonna give you the top-end rush you might hope for.And a slow-ramp cam is just gonna kill off some pressure... which kills torque, and by definition, power; so why bother with the aluminum heads. So while the power will be there with a bigger cam, it's kindof moot cuz all yur gonna get out of it from zero to 60 mph, is extra tirespin.
Just my opinion.
But if you also crave a low ET with 3.23s, well the 318 cam is not the one, cuz your trap speed is gonna be into the low 5000s in third gear, so you will need a cam closer to the 340 one, just with faster ramps; waaay faster ramps, to keep the pressure up.
With a 4-speed and 3.23s, 60mph in second will be about 4650rpm , so that's thru the power peak twice and change. That will add up to a good amount of average power.
And you probably have a 318 cam just laying around. For a bit-O-fun slap in a set of solid lifters and an adjustable valve gear. Oh sorry, you said no solids,lol.
30 mph in 2.66 first will be about 3320 rpm, very close to peak torque with that little cam,maybe a lil after, so at 3200#s,and 235 tires, there will be tirespin, so hang on.
But sorry, no rumpiddy rump.
Instead, with a lil effort, you might get her to idle down to 450 rpm at 4.0 mph, so maybe you can parade her. Won't be able to with the 340 cam, except by slipping the clutch, cuz even if you get her down to 650 idle, this will still be 5.8 mph, and she'll probably get jumpy on you unless you retard the timing.
Iron manifolds will kill the overlap anyway so any 340-type cam you stick in her is not gonna give you the top-end rush you might hope for.And a slow-ramp cam is just gonna kill off some pressure... which kills torque, and by definition, power; so why bother with the aluminum heads. So while the power will be there with a bigger cam, it's kindof moot cuz all yur gonna get out of it from zero to 60 mph, is extra tirespin.
Just my opinion.
But if you also crave a low ET with 3.23s, well the 318 cam is not the one, cuz your trap speed is gonna be into the low 5000s in third gear, so you will need a cam closer to the 340 one, just with faster ramps; waaay faster ramps, to keep the pressure up.
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I should say it's not all that bad in town.
My car is a daily driver, so about 95 %
Of my driving is in town 45 mph max.
The valve train noise is tolerable
But on the Freeway at 3500 rpm @ 70 mph
It's annoying, to me anyways.
I've thought about using some dynamat or something on the firewall to quiet the sound inside the car..
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