340 cam for 318

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I’m pretty sure the stock replacement cams are rated using some iteration of SAE J604.
Which is something like .006” VALVE lift, divided by the rocker ratio.
So, .004” tappet lift on something with a 1.5RR.
 
273 said:
I'd pick something like a Comp 250 or 256 over a slow ramp 340 ish cam, similar @ 0.050" and lifts, but quicker ramps with less advertised duration on 110. Or similar from other companies.
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Slam em' open and slam em' closed. The old cams made power with low lift and easy duration. The new cams have faster lobes and are more efficient by opening the valve further, sooner. You know how they work. There is a limit though. Now, let's go roller cam. More expensive but better all around.
 
Baggs said:
I looked on summit, the LSA in is 114. As I’ve been told in this forum, 106-110 is best for a low compression 318, to build cylinder pressure. Only vacuum I have will be for the distributor.
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With the few lsa shootouts out there, they seem to average like peak 3 lbs-ft per degree of lsa, so if that held true, 114 to 108 to would gain around 18 lbs-ft which is a decent gain. As you go tighter the difference shrinked, but that's just a handful of shootout's doesn't mean that's the overall trend. 110 seems to be the middle ground compromise for most cam companies for our type's of engines (/6 sbm bbm).
 
Baggs said:
I looked on summit, the LSA in is 114. As I’ve been told in this forum, 106-110 is best for a low compression 318, to build cylinder pressure. Only vacuum I have will be for the distributor.
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You seem fixated on the 340 cam. Go for it. It's the only way you're gonna learn.
 
Well let me ask this here, seems Mopar did like other manufacturers, in 71/72 the timing sets were 4-6 degrees retarded when installed straight up.
I should get a degree wheel, but won’t know what I have in it now until I get more off of it.
If my set is retarded, just get a 70? I guess, 318 timing set?
 
Here's a stock low cr 318 long block,

Base stock 2bbl with headers

Mod 1 add 4bbl and xe262h

Mod 2 carb spacer

https://www.hotrod.com/articles/mopp-0312-318-long-block-bolt-ons/

if you look a 4bbl and mild ish cam added a lot of low end torque over Base and base has headers so there would even be a bit better gains if they measured Base with stock 2bbl with manifolds.

TORQUE SUPERFLOW 901 DYNO-TESTED AT WESTECH
RPMBASEMOD 1MOD 2
2,000292
2,500287
3,000287338336
3,500272335340
4,000248326330
4500218309319
5,000188285296
5,500250258
HORSEPOWER SUPERFLOW 901 DYNO-TESTED AT WESTECH
RPMBASEMOD 1MOD 2
2,000112
2,500137
3,000164193192
3,500182224227
4,000189248252
4,500186265274
5,000179271282
5,500262270
 
Baggs said:
I did, he said a 110 LSA seems to be a good compromise. Which leads back to why I decided to not go with the 340 cam via information posted here.
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That's not what he's talking about. The LSA has ZERO to do with how fast a rate of lift a camshaft is. He was talking about newer fast ramp style camshafts.
 
Baggs said:
No I’m not, I started this thread and was soon told about newer/better grinds, LSA, etc. I just mentioned the Summit specs of it, and noted it was 114:)
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Talk to Ken at Oregon, tell him what your working with and what you're looking for, if you ask he will recommend a cam for you.
 
Baggs said:
Well let me ask this here, seems Mopar did like other manufacturers, in 71/72 the timing sets were 4-6 degrees retarded when installed straight up.
I should get a degree wheel, but won’t know what I have in it now until I get more off of it.
If my set is retarded, just get a 70? I guess, 318 timing set?
Click to expand...
if you put a cam in without degreeing it i will roll up there and kick you in the sack. straight shot to the yam bag.

the kit is only like $100 and you'll use it again.

anyway, get a 340(ish) cam and get the summit double roller timing set, it has the capability to advance it that 4~6 degrees you'll want.

here's the degree kit:

www.summitracing.com

Summit Racing SUM-G1056-16 Summit Racing™ Cam Degreeing Kits | Summit Racing

Free Shipping - Summit Racing™ Cam Degreeing Kits with qualifying orders of $109. Shop Camshaft Degree Kits at Summit Racing.
www.summitracing.com www.summitracing.com

here's the timing chain:

www.summitracing.com

DODGE Summit Racing SUM-G6603R-9 Summit Racing™ True Roller Timing Sets | Summit Racing

Free Shipping - Summit Racing™ True Roller Timing Sets with qualifying orders of $109. Shop Timing Chain and Gear Sets at Summit Racing.
www.summitracing.com www.summitracing.com

i literally just finished up a 318 build: 73 block, 68 heads w/ 340 sprAngs, thin fel pro head gaskets, 340 cam advanced, LD4B, carterbrock 625, OE electronic ignition, thru manifolds. idles smooth with a little hint of lope and absolutely rips when you jam on the gas. 65 dart w/ 391's 2nd gear is all hands on deck.

so it will work. it's just that if you're buying a new cam there's better options available at basically the same price point.
 
RustyRatRod said:
That's not what he's talking about. The LSA has ZERO to do with how fast a rate of lift a camshaft is. He was talking about newer fast ramp style camshafts.
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Pretty sure I mentioned it before, but early on when I was set straight on cams, was to use a modern grind vs 50 year old technology. I just brought up the LSA because he had mentioned it
I don’t know or speak cam-ese so I ask questions and gather the replies.
 
Baggs said:
Pretty sure I mentioned it before, but early on when I was set straight on cams, was to use a modern grind vs 50 year old technology. I just brought up the LSA because he had mentioned it
I don’t know or speak cam-ese so I ask questions and gather the replies.
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I wouldn't use a modern grind here. No way on a 100% street driven car. Have fun with it!
 
junkyardhero said:
i literally just finished up a 318 build: 73 block, 68 heads w/ 340 sprAngs, thin fel pro head gaskets, 340 cam advanced, LD4B, carterbrock 625, OE electronic ignition, thru manifolds. idles smooth with a little hint of lope and absolutely rips when you jam on the gas. 65 dart w/ 391's 2nd gear is all hands on deck.

so it will work. it's just that if you're buying a new cam there's better options available at basically the same price point.
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Sounds like fun. That 3.91 doesn't hurt a thing performance wise. :lol:

How far did you advance it?
 
RustyRatRod said:
Especially Mopar Performance. They don't want you to know anything other than what they advertise.
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They even had some sily multiply the advertised duration by a number deal to see the at 50
That worked ok. Except the time i bought a MP cam that was miss boxed at whomever they had grinding them. After we pulled it out and had a machine shop measured it we knew why it had so much RUMP, Rump, Rump and was a slug with my 323-1 gears and stock 340 converter. for such a large duration and lift.
I did use it with a larger stall and 391 gears. I learned to check the cam before use.
 
Last edited:
One of the reasons i asked about advertised duration.

For example this lunati voodoo. They call it a 253/258 cam but the .050 duration is quite similar to the factory 340 cams.

www.forabodiesonly.com

[FOR SALE] - Lunati voodoo 700 cam - .454 [email protected]

Bought this cam for a 318 in a 4x4, i think this would be an excellent 318 cam. But most likely i will build a fresh 360 so my cam choice will be different. $220 shipped in the usa. Cam only, new in box.
www.forabodiesonly.com www.forabodiesonly.com

I also pulled a summit cam from a motor to regrind. It’s basically the crane 272h but i also saw it seems to be the same exact grind as some 268 he comp cams.
So comp measured at .006” and crane at .0045” i guess.
 
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