Is the rumor about solid lift cams having worse gas mileage true? Why is this? And what are Rhodes or Rose lifters?

Yeah , for sure, it's ticking me off! Now I need a real overdrive to keepo up with all the small block Chevelles gettting 20 mpg. Darn PIG block only gets 16 without OD!!!

Just kidding. No way. If anything the solid might give better milage since it will produce more torque over a similar hydraulic grind. Most solid grinds are pretty big, or full race, and big cams wont get mpg no matter what you do.

But the smaller solid grinds now available should give just as good mpg, and might even be better than a hyd. I know that for a hydraulic cam that reaches up and touches 7000, making power, it would idle rougher AND get less highway mpg than my small solid grind, which touches 7000 with ease.

There are a few guys running small solid cams here, 69LS1, Chad Landry, and they would be best to know whether the solid was kinder in gas than the hyd. I've NEVER run a hyd cam in a big block!

16 MPG !!!

Sigh.... I'll trade you gas mileage anyday !! When I took the XE hyd out of my 432 and put the little Isky solid in it.... it certinally made more torque and the driveability improvement was very noticable but my fuel economy didnt really change much... But then we had MTBE in the fuel that got worse MPG... they finially took that out and put Ethonol in it and that's about as bad as the MTBE... economy wise....I'll bet if I had a few tankfulls of out of state gas my fuel mileage would go up 2 to 3 MPG...

Honestly out of the half a dozen solid cams I have run for the last 3 decades only one got as much as 20 MPG .... But then again 3 of those cars had 3.90 ,3.90 and 3.91 gearing turning 3500 RPM @70 MPH.... and my old short stroke engine that had ... ahem... I wont even mention the gearing...doing 4200 RPM @ 70 MPH.... old school.. Very few overdrives available back then.... Well
thats just not easy on fuel....

But Gene and Chad sure have me beaten hands down in the fuel economy dept !!

Rhodes lifters are fast-bleed lifters that collapse more at low rpm. The idea behind this is that it makes the cam lobe appear smaller to the valve, so it'll lose a little bit of duration, aiding low-end torque.

I have a small solid in my 355, a Comp XS262, and I got 17mpg on a round trip from Atalanta to Nashville running 75-80mph, without doing any tuning. I'm thinking I can get near 20 if I work at it.

Originally posted by Georgia69:
I have a small solid in my 355, a Comp XS262, and I got 17mpg on a round trip from Atalanta to Nashville running 75-80mph, without doing any tuning. I'm thinking I can get near 20 if I work at it. Hey Georgia69- Just curious what the other specs on the combo are(carb, tranny, rear-end gears)? I'm looking at the slightly larger XS268 and am curious how it handles the street driving and cruising on the expressway? Also, did you ever figure out what caused your drop in 1/4 mile time?

PS- Just curious, what kinda valve springs(pressure) are you running with that cam?

I run a Holley 650 double pumper, #4779, 3.42 gears, and a 200-4R overdrive tranny with a B&M Holeshot 2400 lockup torque converter. I haven't been back to the track yet, but I have worked on upgrading my ignition and fuel systems, and I plan to go to the track Saturday night. Hopefully I can do some good. I think you'll find the XS268 plenty streetable, the XS262 idles darn near like a stock cam, and pulls smoothly right from the bottom. The springs I run came stock on my AFR180 heads. Specs from their website:

1.450" OD Hydraulic Dual Valve Spring, 120 lbs. on seat, .550" maximum lift, AFR #8020

I don't know if it was going from a 286 @ .006 230 @ .050 110 LSA .639 lift hyd. roller to a 287/291 @ .020, 256/260 @ .050 .643 112LSA solid roller, but my gas mileage has dropped by half.
I get about 5mpg now, less if I accelerate to speed quicker than normal cars. This is with vacuum advance..
I have a feeling my converter is a little out of whack, but..
just again, this is a personal observation.
I'd think a same duration/lift solid v. hyd with a stick behind it, yeah the solid is more efficent and would do better.

matt

Mike, I had forgot you went to the small XS line. I was going to add to my last post, wait until guys have some drive time with the XS series of cams. Thought Harold said they were designing a series to compete with XS with his unique profiles.

Al, if I keep having fuel quality issues, won't be able to run the timing needed for 16mpg. E.g., had to dosconnect the vaccum advance and ran a bit fast on a trip back from Lebanon Valley NY last year and could only muster 11mpg, down 8 degrees in timing and +300 rpm over cruise rpm.Fresh Sun94 at the next fuel stop, I reconnected vac advance and ran at only +200 rpm above cruise and got 14.5mpg. Very sensitive to timing and rpm.

I hear ya Gene... Around here 91 octane unleaded is the best we can get.. unless you get actual race gas but thats out of the question for my everyday type use...Mine wont stand over 10 deg initial unplugged and likes 8 even better.

I havent messed with the lash yet and come to think of it I still have them set abit tight from the breakin ..what two years ago ?? !! ..maybe I'll lossen them up to where they are supose to be and see if it runs different... my guess is it will... probably wont make a mileage difference tho..... When Calif mandated MTBE several years ago that change alone cost me 2 mpg with my last 327...jetting and timing changes didnt help abit with it...it was gone and wasnt comming back. graemlins/clonk.gif

Still have mine set -4 from Harold's spec. Like it tight.

Guy's, it's documented that ethanol AND mtbe both cost us about 2 to 3 percent mileage b/c the stuff is lighter and has less energy in it then striaght run gas..

As for a good little-bitty solid cam, I can't say enough about the great, but VERY old, Little Duntov, 097 cam that I ran in my old junk 301!!

BTW, Georgia, How does the XS262S wrap up AND how high will it go??

The old -097 cam would go as high as my points would allow it which when they were new and I had double spring ones was about 7,500rpm before she would lay down and I would just back off her AND hit her again..

I'm thinking very seriously about a small solid cam for my 283 but wantmore grunt then the -097 cam put out. So I figure either the XS256S or the XS262S solid cam would give it to me if both will still rpm like I want..

Pat K. say's the old -097 is more like a 270 cam then it's advertised 287...

pdq67

I was gettin 18mpg with my 239/247 @.05 lunati solid. 355, TH350, 3.23 gears, 3000rpm stall.

And I was runnin a tad rich. The way the stall stalls, all the online calcs made my 70mph vs RPM = about a 3.82 rear ratio.