300-6 cam HELP

[IsaacCarlson]

I have been thinking of swapping cams in the ford when I overhaul it.
My idea is to keep as much mileage as I can but get some more low end grunt and a few more ponies. I have been looking at a couple of cams, but if you have ANY input please feel free to throw it in.

The first is a COMP 252.
The second is a COMP 260.

This truck hardly ever sees more than 3,000 rpm. It gets loaded heavy and can weigh 14,000 lbs without a trailer. It would be nice to have a little more pulling power when taking off uphill, which seems to happen more often than not. 1-3rd are ok, but 4th is sluggy.

[hondaguy72]

My vote would be for the stock cam, more compression with decking the block and a very efficient exhaust. Stock compression is only 8.8/1. 9.2 to 1 would work well with regular fuel or mid grade. Optimize the ignition timing as well. Almost all cams will move the powerband up which won't improve your efficiency.

[tortoise]

Look at Isky's 331-M Mile-A-Mor. Optimized for 1000-3800 RPM.

[oil pan 4]

Keep the factory cam and retard it one gear tooth.

[IsaacCarlson]

If anything, I would want to advance the timing right? I suppose I have to be the tester on this one. It wouldn't take much to change the timing and see how it works. I have been told that advancing the timing one tooth will give a boost in power AND mileage. This came from a guy who has been messing with timing for 25 years. Race cams are retarded to give more high end to the motor. I want torque, so I would advance the cam to bring whatever top end it has, down.

I think I need new valve springs, because they sound like they are floating above 3500. It sounds all garbly and rough. The motor on my sawmill did that too, until I stretched out the springs.....

[Duffman]

Find the cam with the most aggressive pattern that your engine can use (ie a roller cam is best) Lift is good, duration is bad. Change to a higher rocker ratio while there.

[smokey442]

Stock cam retarted 5 deg.-10deg. will keep the exhaust valve closed longer during the power stroke gaining additional usefull work at part throttle. Delayed intake closing reduces pumping losses slightly and cuts back precombustion pressure allowing the use of a higher CR for a given fuel octane.

[Duffman]

Retarding the cam will decrease the dynamic compression ratio, this would be good if you had a higher CR, but I doubt this engine does. I am not sure that that is the way to go?

[IsaacCarlson]

Here is what the engine sounds like. The knocking sounds like it is coming from the block. A stethescope does not tell me much.

This is why I want to do a rebuild on the motor.
It is not bad, but I want to get it taken care of ASAP. I think it is either rod bearings or lifters.

idle noise - YouTube

[hondaguy72]

Rod bearings is probably right. Hard to tell in the video.