@macdrew77 If you have too big of a cam in there and want to go milder on the cheap, the 360 cam would be a fine choice. One step bigger than a stock 318 cam without the rough idle and low rpm drivability issues you already have.
Torque cam for 318 2bbl
- Thread starter macdrew77
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New cam, new lifters!
nm9stheham
Well-Known Member
Got it... makes a lot of sense. Would under $200 do it for you? The concern on the 6900 with a stock 318 bottom end is that it will drop the low RPM torque to well under stock levels. The 302 heads' smaller chamber help but nor enough to make up for the 278 duration of the 6900. It really does not match up to your stated operating goals.
BTW, you do know you 100% need new lifters with a new cam? If you use the old one, they will eat some lobes, with nearly 100% probability.
macdrew77
Well-Known Member
Yeah I knew about new lifters with a new cam. I'd say my budget is $150. Didn't realize the SUM 6900 had a duration of 278... more than the factory 4bbl cam. Not sure if that's what I'm looking for after all
nm9stheham
Well-Known Member
OK, well, I can't quite do it for you at $150 LOL. If you don't mind, I'll poke the Lunati Voodoo 10200701 at ya once more. Get some stock standard lifters (2011's) and stick with the stock valve springs. $137 for the cam at Jegs (last week). 258/265 durations at .006" lift which I think will be as short or shorter than the durations at that lift for the stock cams (since they are measured differently). The lift is better but still under the limit for the retainers and guides/seals for the stock heads. It will float more easily with stock springs at high RPM but that does not sound like your operating region anyway.
Lunati's notes on this cam:
"Best mild performance cam. Works well in EFI applications with performance chip. Makes approximately 19" vacuum at idle. Great for performance marine and heavy towing applications. Great street rod cam. Slightly noticeable idle, works with stock converter, A/C, power brakes and stock springs in most cases."
As said, this is a fast rate cam so take care with break-in and ZDDP levels. Using stock springs will help any cam survive more easily.
Lunati's notes on this cam:
"Best mild performance cam. Works well in EFI applications with performance chip. Makes approximately 19" vacuum at idle. Great for performance marine and heavy towing applications. Great street rod cam. Slightly noticeable idle, works with stock converter, A/C, power brakes and stock springs in most cases."
As said, this is a fast rate cam so take care with break-in and ZDDP levels. Using stock springs will help any cam survive more easily.
Take this with a grain of salt as I have NO small block Mopar experience, but I use the old 204/214 cam in my Mustang's 289 (280/289 advertised duration), and I run 2.79 gears and a stock converter. I have 9:1 compression and 18-19" of vacuum in neutral, 15" in drive at 600 RPM. I have also run a Comp 252 with 252* advertised and 206* at .050 in the same engine. You guessed it...the same vacuum numbers. I have never felt that it's weak on the low end. It's not fast, but it's got pep, certainly more than a stock cam would.
Maybe it has something to do with the fact that the old grind has a wider LSA or something, but even the cranking compression numbers were similar. I wouldn't be afraid to run the 6900 just because of the advertised duration. Once again, however, I'm just some dude in the garage, so don't take my word as gospel.
Maybe it has something to do with the fact that the old grind has a wider LSA or something, but even the cranking compression numbers were similar. I wouldn't be afraid to run the 6900 just because of the advertised duration. Once again, however, I'm just some dude in the garage, so don't take my word as gospel.
nm9stheham
Well-Known Member
I only wish I could LOL... I don't have any old TRW cams info.
The engines in this era respond to the same things....so I'd not dismiss SBF info just out of hand. Interesting on the vacuum numbers.... look at the overlap between the 2 cams. LSA certainly has a lot to do with that. But, others factors like carb leakage and PCV setup can factor into vacuum levels, so it is not a 100% definitive test per se as to the cam differences. I'd be curious to know what your 289 has for actual compression ratio. The SBM's typically come in at .75 points below the marketing numbers, give or take. The OP is going to be right around 8.1:1 true SCR numbers even with the smaller 302 heads. (He would be helped to put in the Mr Gasket 1121G head gaskets at .028" thick, but would still be at 8.5-ish.) A whole point makes a big difference in how it will behave at low RPM's; you can feel a quarter of a point.
And what we can't 'compute' is the subjective aspects of this.... lots of guys like to rev a lot LOL
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You're absolutely right about subjectivity. I had my machinist cc one chamber of my heads, and I did a rough calculation based on that number and the other information I had. I did NOT do any more than a cursory deck height measurement because this is just a street car that I drive about a thousand miles a year. So I'd say that my 9:1 compression is within a couple of tenths either way depending on the deck height. As far as comparing the two cams I've run in this engine, I didn't change anything but the camshaft in the engine, along with checking pushrod length. I was trying to figure out some valve noise I had, which is why I changed the cam and lifters.
AJ/FormS
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Consider this
You can buy many different cams of a given .050 duration. This duration is a strong indicator as to at what rpm the power is gonna come in at,and a smaller indicator of the power the engine might make. But power comes with rpm, so increased duration at .050 speaks to power at some higher rpm.
But consider this; Any particular .050 cam spec can have many different advertised durations. What happens between the advertised events and the .050 events all affect the low-rpm, from idle to about 3000rpm,where the vast majority of a streeters time is spent.
But it gets worse, not all cams are measured from the same advertised lift point. Some are from .008tappet lift, Some from .006 or .004 or who knows.
And at these small openings there can remain many many degrees. And the more there are, the later the intake valve actually closes. And the later it closes the higher the piston will be when it finally does close. Two things happen with that very late closing intake event.
Firstly; the piston, at low rpm pushes some of that recently inducted mixture, back up into the intake manifold, thru the still open intake. This itself does a couple of things; A) it lowers the intake vacuum, and B) messes up the idle AFR,the transition AFR,and can make it hard to tune, and C) makes the engine lazy to respond to throttle.
Secondly; When the intake finally closes is when compression first begins. And this affects your actual effective compression ratio. If you start from a low static-compression ratio then you end with a lower Dynamic and an even lower effective ratio at these lower rpms. And that makes a really lazy engine. At least until the Rpms get up. As the rpm gets up, the time for the intake charge to backup into the intake is reduced, and so the Effective Compression ratio climbs a little higher. By somewhere between 2000 and maybe 2400/2600 depending on the combo, reversion back into the intake has greatly diminished, and the intake vacuum will have peaked. Now your Dynamic compression rules the show. But again, if the Dynamic is still in the basement, then you will have to wait for the power to arrive at some later rpm after the torque peak. With a stock teener this happens pretty early, maybe 2800rpm or earlier even, But every aftermarket cam you stick in there will alter the rpm of peak torque, usually raising it.
This is why you have to increase the rear gear to catch the power and not have to wait until 40 miles per hour to find it.
This is also why you have to keep pace with the stall speed, cuz the bottom end is going away.
Ok so that cheap [email protected] cam(or whatever cam) with it's really long clearance ramps, starting from who knows where exactly, could cost you a new set of gears and and a new hi-stall Convertor.
And it gets even worse.
There are two popular types of cams,( flat and roller) each with two types of lifters (hydraulic and solid)...... and none of them are directly comparable, one to another, as to power,performance,or idle quality.
When it comes to low-compression teeners, on the street,on a budget;choosing a cam is a very complicated deal, to make a successful fun combo.
Unless you already have a 2800TC and 4.10s, then it don't matter anymore.
You can buy many different cams of a given .050 duration. This duration is a strong indicator as to at what rpm the power is gonna come in at,and a smaller indicator of the power the engine might make. But power comes with rpm, so increased duration at .050 speaks to power at some higher rpm.
But consider this; Any particular .050 cam spec can have many different advertised durations. What happens between the advertised events and the .050 events all affect the low-rpm, from idle to about 3000rpm,where the vast majority of a streeters time is spent.
But it gets worse, not all cams are measured from the same advertised lift point. Some are from .008tappet lift, Some from .006 or .004 or who knows.
And at these small openings there can remain many many degrees. And the more there are, the later the intake valve actually closes. And the later it closes the higher the piston will be when it finally does close. Two things happen with that very late closing intake event.
Firstly; the piston, at low rpm pushes some of that recently inducted mixture, back up into the intake manifold, thru the still open intake. This itself does a couple of things; A) it lowers the intake vacuum, and B) messes up the idle AFR,the transition AFR,and can make it hard to tune, and C) makes the engine lazy to respond to throttle.
Secondly; When the intake finally closes is when compression first begins. And this affects your actual effective compression ratio. If you start from a low static-compression ratio then you end with a lower Dynamic and an even lower effective ratio at these lower rpms. And that makes a really lazy engine. At least until the Rpms get up. As the rpm gets up, the time for the intake charge to backup into the intake is reduced, and so the Effective Compression ratio climbs a little higher. By somewhere between 2000 and maybe 2400/2600 depending on the combo, reversion back into the intake has greatly diminished, and the intake vacuum will have peaked. Now your Dynamic compression rules the show. But again, if the Dynamic is still in the basement, then you will have to wait for the power to arrive at some later rpm after the torque peak. With a stock teener this happens pretty early, maybe 2800rpm or earlier even, But every aftermarket cam you stick in there will alter the rpm of peak torque, usually raising it.
This is why you have to increase the rear gear to catch the power and not have to wait until 40 miles per hour to find it.
This is also why you have to keep pace with the stall speed, cuz the bottom end is going away.
Ok so that cheap [email protected] cam(or whatever cam) with it's really long clearance ramps, starting from who knows where exactly, could cost you a new set of gears and and a new hi-stall Convertor.
And it gets even worse.
There are two popular types of cams,( flat and roller) each with two types of lifters (hydraulic and solid)...... and none of them are directly comparable, one to another, as to power,performance,or idle quality.
When it comes to low-compression teeners, on the street,on a budget;choosing a cam is a very complicated deal, to make a successful fun combo.
Unless you already have a 2800TC and 4.10s, then it don't matter anymore.
Slantsix64
Well-Known Member
255 or 258 duration and 302 heads equals a lot of torque
I agree. After you spend the money and do all the work, you'll find that the stock cam works best with a stock, 2 bbl engine.
macdrew77
Well-Known Member
Lots of great discussion in this thread, thanks guys. Yeah if I can find a stock cam in good condition ill pull the trigger. Also ill be sure to measure my compression ratio when I tear into this thing shortly.
MopaR&D
Nerd Member
I have a stock 5.9L Magnum roller cam I'd give you for super cheap (like $20) but that doesn't help you much lol... needs roller lifters too and those are $$$.
I had a 318 2-bbl cam at one point but I threw it away years ago, if I still had it I'd give it to you for free... post a Wanted thread in the classifieds section I can almost guarantee SOMEone on here has one. I'd actually go for a 360 2-bbl or even 4-bbl cam (NOT the E58/340 cam) those are still super mild.
I had a 318 2-bbl cam at one point but I threw it away years ago, if I still had it I'd give it to you for free... post a Wanted thread in the classifieds section I can almost guarantee SOMEone on here has one. I'd actually go for a 360 2-bbl or even 4-bbl cam (NOT the E58/340 cam) those are still super mild.
dartfreak75
Restore it, Dont part it!
If a stock cam is what you want PM me!
dartfreak75
Restore it, Dont part it!
I saw this and thought of you this would be a great choice for a budget build like ours. It's very similar to the summit 6900 with just a tad more duration. Includes lifters and springs for 160!
Dodge Plymouth 318 360 340 270H perf camshaft cam lifters springs Habla Espanol | eBay
Dodge Plymouth 318 360 340 270H perf camshaft cam lifters springs Habla Espanol | eBay
Sorry no. Still too big for a torquey teen. @SSG_Karg has a 280 in his teen and he says it doesn't come on until 3000 rpm. He's got J heads so lower compression. 318's are so easy to over-cam if you want low rpm torque.
dartfreak75
Restore it, Dont part it!
It fits the budget. I wouldn't consider a @50 duration of 209 over caming. I may be wrong I would be more worried about the slow ramps lowering the dcr along with the 114 lobe separation could hurt the bottom end but I bet it would make a screamer after 3k.
macdrew77
Well-Known Member
I'm currently leaning towards a new 360 2bbl cam from rockauto
dartfreak75
Restore it, Dont part it!
Fyi the melling is the same as the the summit 6900
I see the Ebay cam is advertised as a 270H which made me think it was a Comp Cam but described later as a Elgin cam. That's why it's so cheap I bet.
You know, the old Comp RV cam was a 268°/454 and many guys said it was borderline too big for a teen.
Manufacturer's Part Number:20-212-2
Part Type:Camshafts
Product Line:COMP Cams High Energy Camshafts
Summit Racing Part Number:CCA-20-212-2
UPC:036584500124
Cam Style:Hydraulic flat tappet
Basic Operating RPM Range:1,500-5,500
Intake Duration at 050 inch Lift:218
Exhaust Duration at 050 inch Lift:218
Duration at 050 inch Lift:218 int./218 exh.
Advertised Intake Duration:268
Advertised Exhaust Duration:268
Advertised Duration:268 int./268 exh.
Intake Valve Lift with Factory Rocker Arm Ratio:0.454 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio:0.454 in.
Valve Lift with Factory Rocker Arm Ratio:0.454 int./0.454 exh.
Lobe Separation (degrees):110
Computer-Controlled Compatible:No
Grind Number:CRS 268H-10
Manufacturer's Part Number:20-212-2
Part Type:Camshafts
Product Line:COMP Cams High Energy Camshafts
Summit Racing Part Number:CCA-20-212-2
UPC:036584500124
Cam Style:Hydraulic flat tappet
Basic Operating RPM Range:1,500-5,500
Intake Duration at 050 inch Lift:218
Exhaust Duration at 050 inch Lift:218
Duration at 050 inch Lift:218 int./218 exh.
Advertised Intake Duration:268
Advertised Exhaust Duration:268
Advertised Duration:268 int./268 exh.
Intake Valve Lift with Factory Rocker Arm Ratio:0.454 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio:0.454 in.
Valve Lift with Factory Rocker Arm Ratio:0.454 int./0.454 exh.
Lobe Separation (degrees):110
Computer-Controlled Compatible:No
Grind Number:CRS 268H-10
Sounds good at idle but watch the tach when he jabs the gas. Slow to accelerate until it gets to 3000.
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