Low Down Grunt

[firebane]

Since its difficult to search for certain keywords like "cam" and "rv" due to character limits I've done my share of reading and googling and can't really come up with any good results.

Quick rundown is that I will have the top end of my motor apart and figured its time to refresh some stuff and toss a new cam, lifters, and push rods into the truck.

With this though I have seen the Melling MTC-1 cam style grind recommended a lot and I can get this fairly cheap but I was wondering if people had any other recommendations.

The truck is a 74 lwb 4x4. I'm running 16" tires with 3.42 gears. I'll do offroading and looking for torque down low for acceleration and something mid band for passing and going up hills.

I don't know much about the block in the truck but it currently has 882 heads on it and I'll be running a aluminum dual plane intake manifold.

I'll be possibly looking into headers in the near future too.

Melling MTC-1 specs:
1500-4000 RPM Range,
278 intake/288 exhaust Adv Dur,
Duration @.050 204 intake/214 exhaust,
Valve lift 420 intake/443 exhaust,
Lobe C/L 112

 

[rich weyand]

You should look at Comp Cams 12-300-4, 12-235-2 or 12-234-2.

I think 12-300-4 has the most torque in the bottom of anything Comp makes, which is why I chose it. 12-235-2 and 12-234-2 will have have slightly less in the bottom, but more on the top. 12-300-4 rolls off around 4000 rpm, and they go a little higher.

Looking at the Melling specs, subtracting the .050 duration from the advertised duration, you get 74*. That's a slow ramp, and means you will get lower dynamic compression due to later intake valve closure, and less power and mileage due to earlier exhaust valve opening. A modern cam grind normally has faster ramps, in the 40-50* range.

 

[firebane]

You should look at Comp Cams 12-300-4, 12-235-2 or 12-234-2.

I think 12-300-4 has the most torque in the bottom of anything Comp makes, which is why I chose it. 12-235-2 and 12-234-2 will have have slightly less in the bottom, but more on the top. 12-300-4 rolls off around 4000 rpm, and they go a little higher.

Looking at the Melling specs, subtracting the .050 duration from the advertised duration, you get 74*. That's a slow ramp, and means you will get lower dynamic compression due to later intake valve closure, and less power and mileage due to earlier exhaust valve opening. A modern cam grind normally has faster ramps, in the 40-50* range.

Yeah the 12-300-4 starts at 600rpm and goes to almost 7000rpm. I will never see that high on my truck but the 600rpm is definitely a good bonus and allow the truck to get moving quicker.

I found your thread on another site talking about the -4 cam and you said others maybe good for 2 lane driving. How do you find the -4 now that you've used it for awhile when having to pass on 2 lane roads?

 

[rich weyand]

You'll never see 7000 rpm; 12-300-4 runs out of oomph above 4500. I have the TH350 governor modded for 4000 rpm WOT shifts, which puts me back at 2600 rpm, right in the fat of the torque curve. My WOT shift with 3.73:1 on 31" BFGs is 60 mph. With the stock governor, it would hold second above 60 and flatten out, and then jump forward when it finally made the shift. I went one notch heavier on one weight of the TH350 governor to move the WOT shifts down a bit and cleaned that up.

But it has about 320 lbft of torque coming off idle at 1000 rpm, and that is so nice.

12-235-2 has almost as much in the bottom, but goes about 500 rpm higher before it runs out of oomph, and does not require a TH350 governor mod. About 280 lbft of torque coming off idle at 1000 rpm.

Also, 12-300-4 will run with stock springs. 12-235-2 and 12-234-2 are higher lift, and with those fast ramps, you should probably run the Comp springs.

 

[bucket]

I had that Melling cam (installed by the PO, likely for cost) and wasn't very happy with it. Replaced it with one of the very mild Comp cams and it was a whole new truck.

 

[lusktommy]

i have a summit racing cam and lifter set... needs to be used if your interested. its a very mild cam. part number SUM-1787

 

[kickdeez]

What kind of offroading are you doing on 16" tires?

 

[firebane]

What kind of offroading are you doing on 16" tires?

I'm not sure if your being sarcastic or just not knowing.

But 16" tires are just fine for offroading and are cheaper and far more plenty than 15" tires these days.

 

[kickdeez]

I was kinda joking with you. I am definitely not in the "know" on this small tire offroading. I would love to be enlightened though. There is a distinct advantage to having large tires where I wheel my trucks. Ground clearance below the axles is paramount when it comes to rock crawling and trail riding in my neck of the woods.

Sorry, didn't mean to derail your thread. I was very curious about the small tire size, and wasn't sure if it was a typo in the original post.

 

[rich weyand]

He wrote 16" tires. I suspect he meant 16" wheels.

 

[MadOgre]

He wrote 16" tires. I suspect he meant 16" wheels.

LOL. What the heck would you do with 16 inch tires? LOL. GO_KART?

Hey rich what size valves are you running on that engine with the cam you like so much ?

 

[firebane]

I figured being on a truck forum people would know the difference LOL.

16" tires on a big ole heavy truck wouldn't get any movement.

 

[MadOgre]

I figured being on a truck forum people would know the difference LOL.

16" tires on a big ole heavy truck wouldn't get any movement.

Could probably do burn outs like nobody's business!

 

[firebane]

Could probably do burn outs like nobody's business!

The real question is would the pumpkin be dragging?

 

[MadOgre]

The real question is would the pumpkin be dragging?

Yep might have some ground clearance issues heh?