Going to change cam

[Alex]

I have narrowed down my setup and it is time to change the cam. Currently I have a cam with 478 lift and 292 duration (.214 @ .050)
I want to go smaller to get some MPG, I currently hit under 8.
My idle is to rough and I dont hit the magic spot (RPM) while crusing.

Anyone out there running something smaller than this. I want my cam to come into it at about 1000 rpm's not 2000. And I dont care about anything above 4500 rpm's.

And please dont just say any "RV" cam. These are not all the same. I am looking for someone who actually uses a small "RV CAM" to comment. Please post grind numbers and brand names!

302
289 heads with larger valves than stock with roller rockers.
2100 2bbl
stock intake
32 inch tires
and gearing that is a little low but ...

 

[2badrotties]

I think your duration is too long. Somewhere around 270 would work a lot better. That cam would not be classified as a four wheel drive or RV cam with that much duration. There are a lot of knowledgeable people here and I'm sure that by tonight you will have a bunch of recomendations. Through a lot of engine builds from really mild to VERY wild , I have had very good luck with Crower cams. Also had good luck with Lunatti cams. You must have heard of that company " Comp Cams " - don't buy into all their crap. If Crower can't hook you up , nobody can. Dave Crower himself has talked to me on the phone a number of times and I just don't think " Mr. Comp Cams " would do that.
When building My Mustang , it started a 15 second car and every year I spent a little more and went a little faster. NEVER did they sell me a cam that didn't do what I needed it to do right up untill it ran mid nines. They have some very good hyd. roller cams as well. Their service is fast and they are friendly. Call their tech line for the help you need.

 

[Alex]

Thanks 2bad, Personally I am hope I can find a grind that will work in the "Cheap Cams" listing. You know the "House cam.

 

[broncnaz]

your best bet is to call the cam companies and see what they recommend. your cam is not all that big but it is near the upper limit of a 4x4 cam, you may not have enough compression to make it run right. I'm currently running if I remember right got to find my cam card one of these days a crane cam p/n cra-363931 with 266in 274 ex dur. and 456/472 lift operating range 1600-4000 rpm with a cruise rpm from 2200-2800 rpm required comp ratio 8.75 or less. I get 12-15 mpg city/highway and usually average about 13 running 3.50 gears with 33" tires no overdrive and a single plane intake I could probably pick up at least 1 mpg gallon with a dual plane.
Do you have headers on your Bronco ? if not that maybe causing some of your lost MPG you've have increased the air intake and exhaust capability with the cam. small block fords are know for not having very good flow on the exhaust side of the engine and need all the help they can get. With your current size of cam aftermarket intake, carb, and headers are a must. even with the cam I'm running they are highly suggested to get the full potential out of the cam. with 32" tires and low gearing you should be close to the cruise Rpm of you current cam

 

[Alex]

Yes I have headers, and the gearing is stock leftovers from the 3 speed setup, but now it is a c-4 so that may have messed me up some. I really should go out and see what the gearing is. I forgot. At highway speeds it feels like it is lugging some, may just be my perception. The motor should be close to stock compression as I just went with a basic piston that came with the rebuild kit. BUt with the smaller carb and a new fuel pump, no leaks I should hit ten for gods sake! I mean my tires are wide but I dont think you would pick up any more than .5 mpg with a pizza cutter?

Looking at the "Summit" and "Jeggs" site I see few cams for really low RPM power. I did see on in there that came on at 800 RPM's! Of course now I cant find the dam thing.

Man I would kill for 13 mpg! Or at least change cams to try to get close! ;D

 

[2badrotties]

If you want to try a cheap cam company try Chet Herbert Cams in California. They sell everything. Engine parts, gaskets, all types of stuff. I tried one of their cams once , a 740 lift solid roller and I used their lifters too. Didn't have a problem with anything from there. I also bought my Manley valve springs there for about $60 less than anywhere else. I'll bet you can get cam, lifters, springs, retainers , keepers for less than $150. They know what they are talking about. Try their tech line. Don't know their number, call information.

 

[broncnaz]

I would say that you probably dont have enough compression to run that cam thats why its dogging out. I would go with 2Bads suggestion go with something with around 270 dur. Your final gearing didn't change with the C-4 its high gear is still 1-1 just like the 3sp the only thing that may cause some problems is a slipping torque converter but I dont think thats the problem.

 

[Original77]

I am running a Melling MTF-1. Good low power and a constant 12-13 MPG. Heres the website with the numbers.

Melling Cam Website

 

[Alex]

Hmm, at first glance the MTF-1 is close to the grind I have now?

I think I need to find a cheap cam in that 270 duration, or less. What about gross lift numbers?

I hate to call the manufacturer because in reality they all have the "perfect cam for your application". I really dont want a sales pitch right now, just end user comments.

Thanks guys

 

[broncnaz]

A cheap cam is exactly that cheap, most cams will be close in price its going to be around $150 any way you look at it. check this link to crane cams they have some good info may help you choose something. like I said before I'm using the 266 grind pretty happy with it so far you may be able to use the 270 grind with no problems if you have the 58 CC 289 heads your comp ratio should be close to 9-1 dont worry about lift numbers duration has more effect. lift should be under .520 on the type of cam your looking for anyways http://www.cranecams.com/master/apps/ford9.htm

 

[bronco-billy-66]

LIFT?

how much lift can you get away with on the non adjustable valvetrain?

 

[ManTruck]

I also run the Melling MTF-1. Its been in for about 1500 miles now and I am very happy.

I have the stock type of carburation, stock intake, 4.10 gearing, stock heads from a 69 302. All of this equates into good low end power and a decent response at hiway speeds. The economy is something I cannot speak intelligent about. Most of the miles have been put on after flat towing it to my off road activities.

 

[broncnaz]

Re: LIFT?

how much lift can you get away with on the non adjustable valvetrain?

Usually anything under .520 will work but you still need to check for coil bind, rocker slot to stud clearance, and make sure the rails on the rocker arm dont push the spring retainer down letting the keepers pop out thus dropping a valve. you will also need to check valve to piston clearance. the cam manufacture will usually let you know if it will work on a stock engine.
I would change over to an adjustable valve train with any 270. dur and up cam.