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Picking a cam when also weighing auto VS a manual trans....

Kern Dog

Kern Dog

Life is full of turns. Build your car to handle.
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In 2014, I pulled out a fairly stout cam from my 440/493 because I was looking to make the car more comfortable on the street.
It was a Lunati solid flat tappet with the following specs:


Oct 5 2014 110.JPG


I was using the same 1.6 rocker arms that I still have.
I had it installed 4 degrees advanced and degreed. The car ran really strong. It actually had decent manners too. It was the idle quality that bugged me. At the time, I was running a 727 with a loose feeling 10" converter built locally. Part throttle performance was soggy. I also had a Gear Vendors overdrive unit and coupled with the converter, freeway performance was soft until I floored it. The combo was great at WOT but felt loose at any other time. I didn't like the shakes at idle in gear so I set out to smooth out the rough edges.
I pulled the GV overdrive and also changed to a better quality 11" converter. Drivability improved at part throttle and cruise but the shaky feel at idle in gear still got to me. I later switched to the Mopar Performance 284/528 solid cam.
Idle vacuum went way up. The idle in gear is much smoother. Power is good but noticeably lower than before.
I'm looking to do a conversion to the popular Tremec 5 Speed. This got me thinking.
I saved that Lunati cam and the lifters are in order. It is very tempting to swap it back in to get back to that snappy performance. The Tremec trans will mean I won't have the "in gear at idle" shakes.
Oct 5 2014 104.JPG


The compression is approx 10.17 to 1. I have ported Edelbrock heads, RPM intake, 2" headers and have 3.55 gears in but also have some 3.91s I can use.
I have heard that a manual trans allows you to go a bit wilder with the cam and still have decent street manners.
Opinions?
R T 9.jpg
 
I think you'll get opposing opinions.

I personally feel like a manual transmission lets you get away with having more cam. Letting it idle at a higher rpm with no load helps the idle quality and makes it more tolerable without the spongy torque converter feel. The opposing argument is that the car will buck at lower rpm while driving. You might not be able to run the car under 1800 in gear at any speed.

I had a combo like that. I simply down shifted and it did not bother me at all.

That is a big cam
 
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..........and, you didn't ask........but the two camshaft you have are pretty much at the opposite ends of the spectrum. There is probably a cam that gets you a better balance. But I wouldn't do anything until you make the transmission change.
 
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Kern, the Lunati is a fairly big cam. So you had it installed at 102* installed intake centerline? My bet is that the converter you had was not quite right. A 493 should be able to handle that Lunati cam fairly well with good carb tuning and using manual brakes. Seems like a manual trans would make things easier.
 
Kern, Not that this is what you are looking for but on both of my cars I have the poly engine and tranny mounts.
I can't stand the Shakes and Vibrations they cause on the street. What are you running for mounts ?
 
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Kern, that is a fairly big cam for the street with specs that really don’t match “Nice Manors” for most people looking for a driver. A lot depends on what one is willing to live with. A camshaft that has a more street friendly feel isn’t going to give the best low and mid rpm performance. One of the keys is to widen the centerline. This is a low end torque killer. It’s most apparent on small blocks vs a big block and yours stroked to 493 will make tons of torque next to a small block. I’m not sure how you will like the feel of it.

Anither thing is the ramp of the cam lobe. An aggressive lobe adds to the lumpy sound and feeling. Your 1.6 rockers are aggravating the issue slightly. While technically it should be making more lower with an aggressive lobe, the Dyno read out doesn’t tell you how it actually reacts in car, driving it and on you, yourself.

A manual trans can get away with more cam and is frequently advised to run such. The thing is, there is no converter. Which actually helps over a manual in around town driving conditions or track launch. A properly done converter these days are really awesome and hard to tell what kind of stall it has until you mash it. They drive around town like stock and hit the track like a monster. A manual typically needs more cam and rear gear to equal an automatic on the track.

If you don’t mind a bit less torque from the idle to about 4000 (considering your current cam specs above) a wider centerline and a more street friendly cam lobe is what your after.
 
A car built around the idea of “street/strip” is almost by definition a compromise.
That carries throughout the entire combo.
Converter, gears, compression, intake manifold, carb.......and as you’ve discovered for yourself...... the cam.
The one that drives better makes less power.

Most of the time there is no real “right” or “wrong” parts......It’s all about finding the correct balance for how you want the car to be.
 
You mentioned that when you changed to the more "Civil" cam, your vacuum
went way up. You didn't say weather you had manual or power brakes. If you
have power brakes could you stop the car O.K. with the Lunati? When you change
to the manual trans, you get rid of alot of problems but you still have to stop
the car. I personally like an automatic, and so I have to wrestle with stall convertors
and gear ratios and cams (and vacuum). Everything's a trade-off.
 
I'd think the 108 LSA messes with the idle quality more than anything.

And this is kinda off the subject but I'm curious---I wonder at what 'advertised' duration Lunati rated that cam. "Usually" a solid's advertised duration is up around .020 but that one, based on the numbers is very very close to my Comp solid, except yours has a tad less lobe lift, and you have 10 more degrees @.050.
Oh! And mine is ground on a 112 LSA.
My duration @.050 is 251. Advertised (@.020) is 282 and because I'm a horr with the degree wheel I also checked at .006" of tappet lift, and got 315--even though I've been told the .006 duration is kind of a meaningless number on solids.
In other words I wonder what the duration of that Lunati is @.020.
 
Darter6 said:
Kern, Not that this is what you are looking for but on both of my cars I have the poly engine and tranny mounts.
I can't stand the Shakes and Vibrations on the street. What are you running for mounts ?
Click to expand...
The mounts are rubber.
I've tried a few different cams in this engine. I did not pick the Lunati myself. A guy at FABO suggested it way back when I was trying to stop the detonation problem. It didn't help with the knocking but it did run strong with race gas. I added thicker head gaskets and the knocking stopped. I had the Lunati in at the 106 centerline as directed but later, I advanced it to the 102.
 
zyzzyx said:
You mentioned that when you changed to the more "Civil" cam, your vacuum
went way up. You didn't say weather you had manual or power brakes. If you
have power brakes could you stop the car O.K. with the Lunati? When you change
to the manual trans, you get rid of alot of problems but you still have to stop
the car. I personally like an automatic, and so I have to wrestle with stall convertors
and gear ratios and cams (and vacuum). Everything's a trade-off.
Click to expand...
I have power brakes. When I had the Lunati cam in, I used a vacuum pump.
 
Like beanhead said, the tight LSA will affect the idle and vacuum no matter auto or manual. The 360 crate motor in the Dart has a 108° LSA (big cam for the ci) and with the Tremec in neutral it shakes at idle like a farm tractor with about 10" vacuum. The Dart has manual disc brakes.
I wanted to Coronet to have a smoother idle, plus it has pdb. The Hughes cam is ground on 110° LSA and idles smooth with 15" vacuum at 850 rpm. It's running a 3000 stall converter built by Frank Lupo at Dynamic; amazing converter, great street manners but launches hard at stall.
BTW, I'm with you on the Tremec; mulling converting the Coronet over. The Dart is a blast to drive, I drive it more on longer trips than I do the Coronet because of the 5th gear.
 
The overdrive isn't just about fuel economy. The reduction in rpms has a great effect on noise and vibration. The Gear Vendors unit I had was only a .78 ratio but it made a big difference in how the car felt at freeway speeds.
 
I guess like a lot of people, once you get used to a level of power, sometimes you just want more.
 
^^^^^^Can't keep our foot off the accelerator !!!
 
Kern Dog said:
I guess like a lot of people, once you get used to a level of power, sometimes you just want more.
Click to expand...

That cam is too big for what you are trying to do. The Mopar 528 is a great street cam in a stroker engine. I've run that cam in a few different engine combinations and it really works great. You can go a little bigger than the 528 and make a little more power but the Lunati cam that you had was way too big for what you're trying to do. Talk to Dwayne and have him spec you a cam. I think you could go a few degrees bigger than the 528 and still have decent intake vacuum at idle and enough low rpm torque so you don't have to slip the clutch at every stop light.

I have a 5 speed in my Coronet and a 727 in my Duster. I've found that the 727 allows me to run a little more radical cam since the correct converter will act as a buffer. If the cam in my Coronet gets too big then the car becomes unpleasant to drive around town at low speed.
 
I wish I had an overdrive. Just Friday I took a run down the freeway (not a common thing for my car) to Kingsburg to meet a friend for lunch. With my 3.73s and 28" tires 3000ish RPM gets me to 65-70 and these nutbags were all over my ***, in an area where roadwork had us necked to one lane. So I'd let them suck hydrocarbons for a bit while they weaved side-to-side, trying to see if I was the front car...and then I would smash the gas and leave everyone in a dust cloud. This thing just takes off, even from that speed. But then I'm winding at 4000+ and that just seems like a mean thing to do to my engine...so I'd back down. The jackwads would eventually catch up, and then, I'd do it again. It was fun. But I wish I had an OD.
 
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Kern Dog said:
I guess like a lot of people, once you get used to a level of power, sometimes you just want more.
Click to expand...

It’s hard to go back.

As long as you’re willing to live with whatever the negative aspects of the power level you want are........ it’s all good.

One of my friends installed a 6 speed manual in his 71 Charger....... that made the car much more “usable”.
Still has 4.10’s in it........ but it’s no problem cruising along at 70-75 now(.63 OD).
 
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PRHeads said:
It’s hard to go back.

As long as you’re willing to live with whatever the negative aspects of the power level you want are........ it’s all good.

One of my friends installed a 6 speed manual in his 71 Charger....... that made the car much more “usable”.
Still has 4.10’s in it........ but it’s no problem cruising along at 70-75 now(.63 OD).
Click to expand...
Wow a .63....I'd set my combo up with 5.13s if I had a .63!:p
 
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