440 cam questions

[ZR91]

Sent: 6/8/2007 10:19 PM

Hi,

Can anyone recommend a cam for the 440? So far, I am leaning toward this one from Comp Cams :

21-220-4 XE250H

HYDRAULIC-Very strong torque excellent mileage, smooth idle   Hyd. Hyd. 600 to 4800 21-220-4 XE250H 250 260 206 212 .432 .444 110º

After the intake/carb/headers/ignition it will now rev to 5,500 rpm (as opposed to only 3,200 before)

However, it runs around 3,000 rpm at cruising speeds, and will rarely rev much higher. Am I correct in choosing a cam that is designed for torque & fuel economy?

I think this will work with the supporting modifications already completed, but would appreciate any advice.

Thank-you,

Jay

[denisondc]

Sent: 6/9/2007 4:56 AM

My personal view is that the original 440-3 cam, cut for a torque peak of about 2800-2900 rpm is the best - for torque and fuel economy. The 'torque peak' in this case really means a very mild curve, with lots of torque from 2200 up to 3400. Unless you plan on driving a lot at highway speeds in 2nd gear you wont be using rpm above 3400 much. Even climbing the continental divide in Colorado we never saw above 3500 in either 1st, 2nd or 3rd. As far as I know, the best fuel economy will be with the engine turning as slow as possible, and with the torque peak close to that rpm. I dont think a final drive ratio lower than the 4.56 or 4.88 they came with would help either; because our RVs dont have lock up torque converters. So there is plenty of loss in the TQ at the lower rpm. Changing to a manual transmission would be the only answer that I know of. However..... each time we drive our Winnebago in small towns in Mexico, or on the Metro Interstates (around Houston, Dallas, Wash. D.C. Atlanta, etc), I am Very Glad to have the 727 auto tranny.
The only thing I personally would plan on to maximize mpg would be a distributor rebuilt by an expert. I could probably get better mileage by running my fuel mixture leaner, but that would make my exhaust manifolds more likely to warp/crack.

[Surfinhurf]

Your tq peak should be about 500 rpms above your cruise speed.  If your tq peak is at your cruising speed,,you are done,,maxed out, and this is where your engine will be using ALOT of gas.  The problem is that you are cruising at 3000+ rpms,,like all of us.  The 4:56 or 4:88 ring and pinion was needed in the 70s because the big blocks of the time were not very efficient,(only 195 to 220 hp and 300ftp tq) and needed the higher RPMs..  If you are rebuilding your 440, removing the smog bs, improving spark and fuel delivery, cam etc, you should be able to get close to 300hp 400 fps tq.  This should supply enough hp/tq to be able to reduce your cruising rpms.  This will improve MPG's and drivability.  The 440 hits its peak at about 3000 rpms, your cruise speed should be about 2500 rpms.  Rebuild your engine and then drop your Ring and Pinion to a 3:73 and you wont believe the change.

Good Luck

HURF

[jkilbert]

Also many of the 440-3 engines were actually classed as industrial not automotive engines. I know that mine has never been changed or taken apart but found that common 440 parts like spark plugs wouldn't work. We checked the casting numbers and found that its a 440 usually used in generators and other constant speed applications. So I got really luck when he cleaned out his garage of leftover parts from when he built a 440 for his Coronet. Now I have heads, intake,cam and a lot of other toys. Now I just need the time to work on it