Hughes Cam?

[daren44]

I'm thinking of this winter and next year already. I'm thinking of a new cam. I'm currently using a Comp off the shelf cam, .450 lift. Hughes says that their cams provide faster rates of lift, etc, etc., making them better. Anybody out there use a Hughes cam and have an opinion on it? I race at a 3/8 mile asphalt track with tight corners. Torque off the corners is important. Thanks.

[Rich33]

I race a smaller dirt track with tight corners, a 7.30 final and 89 inch roll-out on the tires. I used to run the old purple shaft 284/484 cam with good success. But, a couple years ago I built another 360 with more compression and a hotter cam. The result was that my car was a dog on restarts and slower off the corners. The cam was a MP solid for a 3/8th's track, can't remember the number off hand. I changed back this year to that old purple shaft and the engine came alive.

I checked on the Hughes grinds as well and they all seemed pretty big in comparision to what I had been running. I'm sure that they work, but I wonder how much gearing change I'd have to do take advantage of it. My 7.30 final is pretty tall already.

What's your final now and tire size?

[modracr41]

I just got my motor back from Dave, and his camshafts are ground to take advantage of the larger lifter diameter a mopar has over a chevy. They act more like a roller lifter with respect to the fact that you can use a more radical profile with no ill effects.
I have one of his shafts and I love it. I can pull the chevy guys off the corner and all the way down the straights. I can't swear it's all the stick, but it sure helps.
I had an isky stick that had a chevy grind on it before, and this one makes gobs more torque than that one ever thought about.
Just my two cents, and ...................See ya at the track!!

[daren44]

Thanks for the input. I've got a 3.91 rear gear and I run the trans in 2nd, for a final of 5.67. Tires are 85.5" diameter. I've been running a milder cam, similar to the purple shaft, compared to the chevy guys. I can't complain about power, and they all think I've really got some horses under the hood. That's what I was curious about, is the cam being ground specifically for the larger lifter bore a worthwhile improvement? The hughes is expensive compared to a shelf cam.

[sanborn]

Daren, it's like everything else in racing, it all depends if you want to go faster.

You will notice two things about a cam ground for the larger diameter lifters. One, it will give a stronger signal to the carb boosters off the turn because of the larger area under the lift curve. And secondly, if you use a split duration camshaft(like Hughes does) you will see an increase in upper end HP. One of the problems with stock type heads is the exhaust flow is weak compared to the intake; because, the stock type heads are not designed to turn the RPM we frequently want to turn a race engine. So, split duration helps to evacuate the combustion chamber of spent exhaust gasses more fully and a purer incoming mixture can then be drawn into the combustion chamber for the next power stroke.

One of the things you will notice when changing camshafts is the carb jetting may require some adjustment-usually slightly leaner(surprise??) when going to a camshaft ground for the larger diameter lifters and split duration.

[jelsr]

I'm using a HEV5056BS in my Super Stock on dirt, 451, 5.57, 90" tires. It starts waking up in the 26-2800 range and is at full boil at 3-3100. Bear in mind that displacement tends to make big cams more docile. It will pull hard to 7000. The transition is rather abrupt but I am running small (1-3/4) and long (41) primaries. Will probably try larger pri's next year.

[340duster1]

I run a hughes cam in my 360 magnum in my street/hobby stock. I don't have the specs handy but it was a .557 lift hyd roller. They did a bit of a custom grind because my car is carbureted (not EFI) most of their magnum cams go to EFI engines. I am building another magnum engine this winter and I would not use any other cam. I gave them the engine specs and let them pick a cam. I won the feature the first time out with the new engine. I would highly recommend Hughes. And If I ever build another flat tappet engine I would use them as well.

[340king]

Darren, I think cam selection is one of if not the most important thing you can do to improve the output of your engine. The proper selection depends on many variables, but you can find the range in cam size fairly easy with only a few variables. I use the Engine Pro program from Patrick Hale's Race Systems Analysis in AZ. I have found that the program lends itself to figuring out cam size quite easily. All that is needed is bore, stroke, actual compression ratio, rod length, carb size, head flow, intake flow factor, cam type (ie solid flat, hyd. roller, solid roller), duration @ .050". I play with the duration at .050" until I reach a point where HP and TQ both drop off with increasing duration. This is the maximum cam size to consider.

This part of the selection deals only with the engine and ignores what the chassis wants. Matching the cam to chassis/track is where the trial and failure come into play. The perfect cam for the dyno may not be the perfect cam for the chassis or track. Like Rich mentioned above. The bigger cam he had may have made more peak HP on the dyno compared to the old Purple Shaft, but it didn't work as well on the track.

Here are some things to consider. Track design. The track design requires a stop and go type of driving. This in turn requires an enigne that produces torque and hp over a broad rpm range. Typically, this would require a tigher lobe separation angle, like 104° to 106°. What are you running for exhaust? Stock manifolds really hurt exhaust flow on what is normally anemic flow to begin with. Splitting the duration as Sanborn mentioned can help reduce intake reversion caused by too much exhaust pressure in the chamber when the intake valve opens. This is especially important if you run the tight lobe separation listed above. Is this a restricted engine? In other words do you run a two barrel or four barrel? That can make a difference on how much split in duration is required and the lobe separation that will produce the best power. Remember, we are looking to produce the most area under the torque curve for a given rpm range.

I know, I know, ask a guy for the time and he tells you how to build a watch. In theory, the Hughes cams enjoy an advantage. Selecting the proper one to maximize that advantage is where the challenge is! The more you can tell the cam manufacturer about the conditions your engine runs under, the better the cam he can recommend for yo

[daren44]

Thanks for the input guys. 340king, my experience has been that cam manufacturers go for the biggest duration they can get. I've been running a very mild cam and it has made a lot of horsepower. I local racer suggested this cam to me. I called several different cam manufacturers and gave them all the same info and they always came up with a LOT more duration. Local experience is worth a ton, but I think the manufacturers are selling dyno horsepower, not track results. The cam I was running was only 218/218 duration with 110 lobe separation and .450 lift (per lift rule). Everybody else was suggesting cams of 230 duration and larger. I don't care how lopey the engine sounds in the pits, I care what it does on the track. I'm trying a 225/225 108 cam right now. Have't ran it more than a couple laps yet, so I haven't made a determination. Thanks a bunch.

[Billydelrio]

I realize that most cam grinders use lobe profiles made for a Chevy application, but what about the grinder that makes the Mopar purple shaft that is "engineered for Mopars." Do they take advantage of the larger lifter diameter? I could go out to the barn and do some measuring, but all that stuff is piled under, so I will take the easy way out and just ask yall.

Sanborn, One of these days I will get back to work on that 318 I started a few years ago. It is on the bottom of that pile I mentioned in the upper paragraph.

Billy

[RedEye]

http://victorylibrary.com/mopar/mpcam-tech-c.htm

That’s a list of MP cams that were “cam doctored”

They’re not all that “slow”…and the originals were designed by some of the folks who’s put the big tappet bore in the motors in the first place.
They’re also a fairly (<--sarcasm) bright group of guys…most notable Hoover and Racer Brown who found lift had a direct relationship to power…and tried to place valve timing where it would do the most good.

Less is More

The main trick when it comes to “Chrysler Special” cams is to pick duration numbers a little back’ards to what a lot of people are doing. Look for less at .006” rather than more at .050”…sounds the same at first…but instead of looking…for example…for a 280 grind that’s 240 at .050” look for a 240 at .050” grind that’s less at .006”…say 270.
If you think about it the earlier we open the intake…the longer in RPM it’ll take to overcome reversion from the piston that’s still headed up…so if we can pinch some of that opening event ‘til later we can keep the same opening from .050 up and make power less abruptly…or smoother…the faster cams typically have more lift and will make more power.
The exhaust side offers a little different dynamic as we’ve got a “blowdown” and “pushout” event…and we’ve been pretty happy lately with slowing the exhaust lobe down to keep the two connected…in fact some stuff has been an odd looking 15 degree split in duration and .025” difference in lift.
Anyway we’re starting to get smarter about where and when to apply valve action…rather than trying to blast