340 cam for 318

-
B

Baggs

Well-Known Member
Joined
Dec 12, 2024
Messages
77
Reaction score
54
Location
Oakdale, Ca
In my first thread, I’ve decided to just square the deck and get it to 9.58 height.

This 318 will be 8:1 SCR

But in that thread talk of a 340 cam on a 318.

Doing some Google says the earlier 340’s were 10.5:1 SCR. Later ‘70’s were 8.5:1.

I also noticed much different cam specs on both.

I’d assume, but want to verify, used the ‘73? cam with my SCR?
Thanks,
Mike
 
if you're buying a new cam for a low compression 318 there are LOADS of better options than a 340 cam.

can it be done, yes.

also, there's only two 340 cams: 68 4spd cam and then the other one. which is... wait for it... also the 360 4bbl cam!
 
I would not. The 73 cam is the same as the 69-72 cam. They are ALL the same except the 68 4 speed cam. It's way too big a cam for the 318 at that compression. Although plenty of people have done it for decades, it's not a good match.
 
Well, okay. I can measure can lift, won’t worry about the rest. All I recall was the shop telling me “like an RV grind” cam card is long gone.
 
Melling SPD-22

Merry Christmas

Screenshot_20241214-163328_Gallery.jpg


Screenshot_20241214-163530_Gallery.jpg


Screenshot_20241214-163723_Gallery.jpg



☆☆☆☆☆
 
Just for the math, I assume that I have 1.5 RA ratio ?

Been living in the SBC world for a long time.
 
Baggs said:
Just for the math, I assume that I have 1.5 RA ratio ?

Been living in the SBC world for a long time.
Click to expand...
That's what they're specced at, yes. That's not what they'll measure. lol
 
The reason we're sayin a hard pass on the 340 cam is one reason. Its wide lobe separation. That's a huge no for a low compression engine. You want a narrow LSA for low compression. Opening and closing the valves more quickly keeps cylinder pressure up. The last thing you need with a low compression is a wide LSA. You'll end up with a dead dog.
 
290° of duration is a bit much for a 8/1 Teen as well. That Melling cam looks like an old school grind. It reminds me of an old Crane. Lots of duration, not much lift.
Click to expand...
 
Wow! $347 for that Isky HFT cam.
We’re not in Kansas anymore.

Before I spent that, I’d look into seeing how much the old 360 2bbl cam is.
 
PRH said:
Wow! $347 for that Isky HFT cam.
We’re not in Kansas anymore.

Before I spent that, I’d look into seeing how much the old 360 2bbl cam is.
Click to expand...
You ain't kiddin. Ain't none of um cheap anymore. Gone are the cams for 29.95. lol
 
PRH said:
I think the .454/.454, 216/216-110 summit house cam is under $200.
Click to expand...
What's the LSA on that one? I searched "108" lsa and that one was not among them.
 
PRH said:
I think the .454/.454, 216/216-110 summit house cam is under $200.
Click to expand...
That's actually on a 110, so it's not too bad. I'd stab it in maybe 2-4 degrees more than the cam card and let er rip.
 
Last edited:
junkyardhero said:
also, there's only two 340 cams: 68 4spd cam and then the other one. which is... wait for it... also the 360 4bbl cam!
Click to expand...
Bingo! The knit time I have seen something different is when the smog years came into effect hard, ‘76, ‘77, etc….

MoPar would equip the cars with 4bbl carbs and use a 2bbl cam. There are various amounts of 2bbl. cams out there.
 
PRH said:
Wow! $347 for that Isky HFT cam.
We’re not in Kansas anymore.

Before I spent that, I’d look into seeing how much the old 360 2bbl cam is.
Click to expand...
Thing is, can you even GET the 360 2bbl cam anymore? I "just bet" the industry has consolidated all the stock cams the same.....and with our luck, they are all the stock 318 2bbl cam.
 
RustyRatRod said:
What's the LSA on that one? I searched "108" lsa and that one was not among them.
Click to expand...

It’s 110.
Had one in a 360 i pulled apart to rering. Ran good, would probably act like a somewhat hot cam in a 318. Mine was in at 110 or 109, cranked 185psi and idle vacuum was 13-14”.

Would def install at 104-106 in a lower compression motor.

I think that cam is the same as the crane 272.
 
Last edited:
cookietruck said:
It’s 110.
Had one in a 360 i pulled apart to rering. Ran good, would probably act like a somewhat hot cam in a 318. Mine was in at 110 or 109, cranked 185psi and idle vacuum was 13-14”.

Would def install at 104-106 in a lower compression motor.

I think that cam is the same as the crane 272.
Click to expand...

@Baggs - What is the rear ends gear ratio and tire size? The cams mentioned below work well with 2.94 to 3.55 gear ratio pretty good.

The weird thing with Chrysler is for a long time there is a gap between the 3.55 to 3.91 ratios. The 3.73 went missing in the early days. It’s available though.

If your gear ratio is at 3.23/3.21 or numerically lower, I would not use a larger cam and the stock converter. Read on below.

The Crane is a 272 (216@050) .454 on a 112.
This cam has a mello idle, easy driver, a basic upgrade cam that works well in a stock engine with or without bolt on’s. Exhaust manifolds or headers, 2 or 4bbl carbs.

I used the split cam at 216/228 (272/284) .454/.480 on a 112 in that old project Duster I started in with a decade plus ago to try and show how just simple bolt on parts can really improve a low compression 318. The Duster did end up managing some high 14 1/4 runs on a ‘79, low 7.8-1 compression long block 318 & 3.23 gears on stock tires.
 
You must log in or register to reply here.
-

Back
Top