340 cam for 318

[PRH]

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.

 

[toolmanmike]

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.

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.

 

[273]

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.

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).

 

[RustyRatRod]

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.

You seem fixated on the 340 cam. Go for it. It's the only way you're gonna learn.

 

[Baggs]

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?

 

[273]

Here's a lsa shootout

 

[Baggs]

You seem fixated on the 340 cam. Go for it. It's the only way you're gonna learn.

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

 

[1MeanA]

As with many things there is no free lunch ie there are always compromises and no 'best'. I thought this test demonstrated that. So the question is, what compromises are you willing to make?

https://www.hotrod.com/how-to/camshaft-shootout-lobe-separation-angle-tested-explained/

ps I see 273 just posted something similar 2 minutes before I did

 

[RustyRatRod]

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

I wouldn't necessarily recommend a "newer" grind. See @toolmanmike's quote.

 

[Baggs]

I wouldn't necessarily recommend a "newer" grind. See @toolmanmike's quote.

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.

 

[RustyRatRod]

Grind #54 would be a decent one. They will grind to whatever LSA you need for no additional charge, so put it on a 108.

Hydraulic Camshaft Specifications

cam and camshaft specifications

oregoncamshaft.com

 

[273]

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
RPM	BASE	MOD 1	MOD 2
2,000	292
2,500	287
3,000	287	338	336
3,500	272	335	340
4,000	248	326	330
4500	218	309	319
5,000	188	285	296
5,500		250	258

HORSEPOWER SUPERFLOW 901 DYNO-TESTED AT WESTECH
RPM	BASE	MOD 1	MOD 2
2,000	112
2,500	137
3,000	164	193	192
3,500	182	224	227
4,000	189	248	252
4,500	186	265	274
5,000	179	271	282
5,500		262	270

 

[RustyRatRod]

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.

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.

 

[fishmens67]

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

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.

 

[junkyardhero]

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?

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:

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

here's the timing chain:

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

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.

 

[cookietruck]

Here's a lsa shootout

I always wonder how these shootouts would play out if they installed both cams at 108 or 106.

 

[Baggs]

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.

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.

 

[66fs]

Does anyone know what lift that duration is measured at?

There is no standard for advertised duration. Some will tell you, most do not.

 

[RustyRatRod]

There is no standard for advertised duration. Some will tell you, most do not.

Especially Mopar Performance. They don't want you to know anything other than what they advertise.

 

[RustyRatRod]

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.

I wouldn't use a modern grind here. No way on a 100% street driven car. Have fun with it!

 

[Dartswinger70]

"Retarded" I like that word almost as much as "doo-doo" ...

 

[toolmanmike]

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.

Sounds like fun. That 3.91 doesn't hurt a thing performance wise.

How far did you advance it?

 

[340six]

Especially Mopar Performance. They don't want you to know anything other than what they advertise.

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.

 

[PRH]

If you’re not totally lost yet…….
Here’s some more stuff to absorb:

Cams for 318's

 

[cookietruck]

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.

[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

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.