Roller cam opinions

[Marc]

The engine
520 cubic inch Hemi, 10.5 to 1 compression

What do you think of a roller cam that specs at .613 lift and 255 duration @ .050 intake and exhaust? Streetable, or a little too much?

I think the big cubes will tame it down, but how much?

[jelsr]

I think it will be streetable judging from my car. It's a flat tappet setup with 252I & 257E @050 and a lot less displacement. It will idle under 1000 and pulls like a bear at 3000. The idle does have the Detroit Diesel lope to it though. Your extra inches should mild that down a bunch. I wouldn't consider it a "daily driver" streetable but streetable none the less.

[Marc]

My car IS going to be a daily driver though.
Would the roller cam be "virtually" smaller than a same dimension flat tappet? Would the displacement tone the cam down a fair bit, would it be noticeable?

Anybody have any comments?

....DartGT66 ?!?!

[Best Machine]

Marc
What is the lobe seperation of that cam?

www.BestMachineRacing.com

[Marc]

108 degrees lobe separation

[Best Machine]

Marc
I have found with large CID mopar engines that lobe sep`s of 112 to 113 make more power and have a better idle, My car a 80 mirada with a 500CID wedge has ran 10.47 @ 131 mph with a .600 hyd roller 262 268 @ .050 with a 113 lsa and will idle at 900rpm in gear. I think the size of the cam you have picked is OK but would recomend a lsa over 111.

www.BestMachineRacing.com

[Marc]

I didn't actually pick the cam, Ray Barton had it made at Comp Cams.
You're car is a hydraulic roller? The cam I am enquiring about is a solid roller- would the characteristics be the same?
I went to your site, your Mirada sure reminds me of my 1980 Cordoba LS...

[Best Machine]

Marc
A mech roller can make more power than a hyd because you can put in more ramp speed. As far as the characteristics, I feel a mild mech roller and a hyd roller are the same, Its when you start increasing your dur @ .200 the mech roller starts making more and the hyd stops do to the limits of the lifter,It cant handle the spring press required with the higher .200 numbers. The cam in my car is very streetable and I wouldnt consider it a all out drag race profile. I have made over 100 drag strip passes and have put about 600 street miles in the last 3 months. I dont know that I would use it as a daily driver with MPG under 5, Even with pump gas I would have to fill up sometimes two time a night. Im not saying the Barton cam wont work, I just think its old school. I have been working with Strightline Performance on some wide lobe sep cams and have found more power and driveablity without giving up anything.
Chuck

[Marc]

I'm not sure I would categorize the cam grind in question as "old school"?

I'm building a car to DRIVE, and the engine I am looking at has that particular camshaft in it. I am looking at changing it unless someone can convince me otherwise.
The engine is presently single Dominator with 10.2 to 1 compression and made 750 HP on Barton's dyno.

I will toss the single Dominator and run a stack injection set up converted to multi port EFI by Rance Baxter. I have a feeling the cam may be too big (A) for vacuum signal needed for the EFI to work properly and (B) for drivability/reliability.
I can come up with guess after guess myself, I want other people's guesses to balance my own!

It seems alot of Cam manufacturers roller grinds have larger lobe separations with their BIGGER cams, the more drivable grinds are down around 108 degrees - unless I'm misreading?

Also- your .050 duration is slightly larger and your cubes are slightly smaller, I'm not sure the numbers are big enough to represent much of a difference though? Will the Hemi react to the specs the same way a wedge will, or is the valve geometry going to figure in somehow?

[vanishPt]

I have a 527 hemi with Indy single plane, Nuytten 850 DP. 10.6 al heads, comp cam 244 duration and 544 lift. Hyd .
Car idles easily at 850 in gear ( 11" converter). 8" vac. at idle.
Car runs 11.45 at 123 at 3800 lbs in full street trim. Bfg 275 drag radials. When i freshen mine up i may go with 'The next size up" roller. probably the same duration , but a lift in the .57 range.

[Marc]

I take it you find the car totally streetable? How would you characterize the cam? Any way to explain it to me in WORDS? lol

Is it street driven? If so, what gears are you running?

I take it you had a small hooking problem? LOL

[FuryusVIP]

The Burton Cam might be a really nice piece, he is the Hemi Guru. But the 108 lobe centers are a little tight. Tight is a relative term. It seems anything around 112-116 lobe centers will make street driving a LOT easier, it will have a lot of vacuum around idle. You may even want to try calling Scotty Brown @ Straightline performance.www.racemufflers.com his contact number is on the site. He is working with me to improve my performance on my SportFury, it currentlly uses a Crower Roller .647/.627 108cl 262/268@.050, we are looking at something in the .590/.600 with a wider lobe center to give it much more mid range torque. Looking to get 11.90's out of 2 tons this year!

The current cam make very little vacuum @ idle, something like 7"hg, but it idles @900rpm. Mine is a 440 .060 wedge with INDY S/R heads,11.5 CR, Indy Dualplane, 950 HP Holley. it only made 570hp/550tq on the dyno, but that was on a hot day. Current converter is 4,200[ 3,500 in '02] 4.56 gears in the Dana[ 3.73 in '02] Currentlly weights 4,500 and runs 12.99@106 with a 2.14 60ft. [just a little tire spin. Ok, a lot] I shift at 6,500 now, looking to shift at 6,000. Car is driven on the street a LOT.

2 cents worth. Ok maybe more.

You got nothing to lose, just the price of the call.

[IMG]C:/noxim/71sfpics/71lr3qtra.jpg[/IMG]

[DartGT66]

I used a 260/.575" roller in a 440 wedge, and it was really tame. I believe with your bigger displacement you'll have no problems with that cam at all.

[vanishPt]

My car is 99% a street car. I put almost 7000 miles on it last year. I use a 3.91 gear, but I also have a GV overdrive. With drag radials , my average 60' was 1.9

[Marc]

Vanishingpt, is your car a hydraulic or hydraulic roller?

Do you find the cam is really mild?
How tall are your tires?

[vanishPt]

a flat tappet hyd. , tires are 27.5 " the engine idles pretty smooth

[Jims451]

I'm not a Hemi guy, but it sounds very streetable considering your 520 CID and 10.5:1 compression.

My 11:1 Compression 451 wedge uses a 251/251 on 108 LSA Ultradyne roller and it is pretty decent on the street, but it does idle like you know it's there, at 800-850 RPM. This slow idle RPM does create a problem with low engine vacuum, that makes power brakes marginal (I should get a vacuum resivor.)

With your 10.5:1 compression, I would not go any smaller in cam size or you may not be able to run pump gas. A smaller cam might make too much cylinder pressure for pump gas.

My cam was a off the shelf compromise, and I would like to change it to a slightly larger split duration cam with a bit wider Lobe Seperation Angle. The wider LSA will reduce overlap, helping the idle quality.

[Marc]

I have no power brakes, I think it should be OK, the only thing I worry about vacuum quality for is the EFI system.

If you say your 251 @ .050 roller in your 451 runs decently on the street, I would think a 255 @ .050 in a 520 would be a safe bet?

[Jims451]

I think so
The valve lash eats up a bit of duration also.

[phoenix]

What is the required/suggested valve spring seat pressure called for by the manufacturer of the camshaft, this is usually a good way to "gauge" the streetability of the cam in regards to how long it'll live in the rigors of a daily driving. "street Roller" grinds typically want around 160lbs. on seat, while faster ramp race rollers can call for225lbs. or more. Rest assured, you run a race type roller at 225 lb. seat pressure on the street as a daily driver your gonna have a oilpan full of broken lifters in your not too distant future with ANY CENTERLINE. If the cam requires high spring pressures to keep the lifters "on the profile" then it's probably not intended for street driving, BUY a STREET ROLLER MECHANICAL CAM that's meant for street driving.
Good luck

[KM]

Marc,
I have a 471" Hemi with 262/264 .580/.560 Mech cam (no roller) and to my liking it is too tame !!

I´m thinking of changing it to a mech roller something like you are thinking.

Have you asked from Rance what he thinks about it. He should know EFI´s....

Let me (us) know what you decide and feelings about it when it´s done......whatever you decide to do !!

Thanks,
Ki

[Marc]

Ray Barton built it as a "street engine" with a trip to the track once in a VERY blue moon, if at all.
Rance said he thinks the cam is fine, but to try the engine with the EFI as is before commiting to a cam change.
SO.
I put a deposit on it, and will pick it up within the next couple months.

[TL]

wow

[TL]

hey, was just thinking. Need someone to deliver that thing to you? Run it in a little for you? Body work on my Challenger is comeing along nicely. Should fit right in.

[Marc]

LOL

Actually...... it WOULD save me the $1500 gas bill driving out....
It WOULD save me the 3000 mile trip there AND the 3000 mile trip back...
It WOULD also save the two weeks off work I would need to take....

What year Challenger?


I'm hoping to pick it up in February!