I just spent the last few hours running cams through desktop dyno 2000. Here's my problem.

A lot of people including that famous 400 buildup have harped on how good the 265DEH comp cam is. Now when I run it with a 4bbl on a bone stock 351M with small tube headers with mufflers, using head flow data from http://www.jason.fletcher.net/tech/f.../cleveland.htm I am not getting that good of results with it. Running the 350 CFM 2bbl there is even less difference except for low-end torque. I tried the 252DEH and didn't get any better results than a plain old 260H in the rpm range that I want to run ( idle-4500 rpm). Now my questions are?

Since the 260H is a single pattern cam, will it get better fuel economy than the dual pattern cams. My experience has usually been that you gain top-end power with a dual pattern, but you gain mpg with a single pattern cam. I will not spend a whole lot of time above 4000 rpm, so that extra 10 hp that I gain at 4500 doesn't offset the 15-20 lb/ft of torque that I lose at 2000 rpm.

Secondly, do roller cams actually give the returns that the dyno shows? If so, I could run a roller cam and have very similar torque to a mild hydraulic 400 with the mpg of a 351.

I am more concerned with mpg and decent cruising power than top end raceway performance. With the 260H I can wrangle 360 lb/ft of torque at 2500 rpm, and approx 250 HP at 4000 rpm. All of this with very little mods and the stock 2bbl type carb. This is going into a moderate daily driver that needs to pass the sniffer test and be reliable as a rolex watch.

Any ideas? Or actual dyno/real world comparisons to go by?

Thanks in advance for any tips or hints. I've built quite a few engines now and I am learning that I still don't know half as much as I think I do when it comes to all this stuff.

 

Read the manual for DD2K, The roller cam setting is only used with very radical cams. According to the manual use the solid lifter cam setting to approximate the results with using a hydraulic roller cam.

For mileage make sure your vehicle is set up to operate at about 2000 rpm at cruise speed and use the 255DEH.

Overlap is the main culprit for siphoning gas thru the cylinder! -hehe

 

Roller cams are great but they are not worth the money unless you are going to match it up with 4v carb, intake, headers, compression etc.

 

Thanks. I had a hard time muddling through all those pages of stuff.

 

I have several cam articles that can be viewed in the Files area of my Home page. Using mostly factory components can make an HR cam installation much more affordable. The horsepower per dollar spent may not be the best but I think it's better than fitting longer con rods or adapting an EFI set up.

 

I haven't been impressed with the roller cam conversion I did to my old Mustang. In fact, I kind of like the flat tappet hydraulics.

 

What were the specs?