Help Climbing Hills - new head?
 

i have a stock model a engine with a lightened flywheel and a weber carb. I am also running a 36% mitchell overdrive and an aires muffler. I am happy with the combination except for the fact that I am losing speed on hills. I like to be able to maintain at least 50 mph on the hills. The engine is also a babbit engine in very good condition.

Will a high compression head solve my problem?

Re: Help Climbing Hills - new head?
 

It would be a step towards that. I guess it would depend on the grade and length of the hill.

Re: Help Climbing Hills - new head?
 

For Power =Carburetion+Compression+Cam(breathing)
equal and balanced proportions

Re: Help Climbing Hills - new head?
 

are you sure the mitchell is a 36%? They are usually 26%

Re: Help Climbing Hills - new head?
 

A high compression head is the best money you can spend to improve torque values for a Model A. To climb hills better, improve torque.

Re: Help Climbing Hills - new head?
 

You can order either 26% or 36% overdrives from Mitchell.

Re: Help Climbing Hills - new head?
 

I concur with the head upgrade, the most bang for the buck! With the babbitt I would stay at no more that 6-1. I really like the 5.5 from Snyder's but have a 6-1 Winfield, and a 5.9 Brumfield that all work well.

Re: Help Climbing Hills - new head?
 

I cannot maintain 50 mph on any hills. But then I live at 7,600 feet elevation. I usually top hills at 30 - 40 mph. I suppose at lower elevations that might equate to 50.

I just don't drive 50 on a regular basis. It's normally 40 - 45. I prefer to putt along and enjoy the moment, and I'm very conscious of overworking the engine on hills. I ease up on the gas, and retard the spark, and try to "coast" to the top of hills whenever possible. Beware of beating those Babbitts flat by trying to maintain a certain speed.

Re: Help Climbing Hills - new head?
 

The above is so true and so important that I quote it again here for emphasis. Power here means HP, which keeps you running at the desired speed. (Torque provides acceleration.)

You need a lot of power to overcome the wind resistance on a boxy Model A at 50 MPH, plus the power to climb the hill, plus power to overcome rolling resistance. It adds up fast.

The HC head will certainly help, as others have said.

In addition to cam for breathing (you don't say which you are running), you might also need slightly larger than stock intake valves to improve the breathing and to keep everything balanced.

It also depends on the steepness of the hills you are trying to climb at 50 MPH (as others have mentioned).

You don't say what rear gear ratio you are running. With a stock rear gear, you will only be turning about 1600 RPM at 50 MPH in OD with that OD ratio, and you are probably below the peak of the HP curve. You are kind of asking a lot out of that little engine at fairly low RPM with that much OD, unless the engine and chassis are specifically built for it.

Or go out of OD and you are turning about 2200 RPM and running right around the peak of the HP curve. But then you don't get the benefit of that fancy OD.

Keeping everything balanced is the key.

Re: Help Climbing Hills - new head?
 

If that Mitchell really is 36%, it is too high for 50 mph, especially on any hill. The normal 26% to me is far more useful for most Model A use.

Re: Help Climbing Hills - new head?
 

terryh - thanks for your input. i'm confused. If the engine is not lugging, why is 50 mph too fast for a 36% overdrive?

Re: Help Climbing Hills - new head?
 

A higher compression head will help but with a 36% overdrive it probably won't completely solve the problem.The engine doesn't produce much power at low rpm. The higher final gear that the overdrive gives doesn't let the engine turn enough rpm to produce the torque that is needed for hill climbing.There is a trade off with overdrives and higher gear ratios. The higher the final gear ratio the less the hill climbing ability and low speed power.

Re: Help Climbing Hills - new head?
 

This often brings up the question: "is 4.11 to 1 a higher or lower ratio than 3.78 to 1?" :confused:
I think 4.11 to 1 is a higher ratio, but a slower speed ratio.

I now just refer to the ring and pinion as higher speed ratio, or lower speed ratio.:D

Re: Help Climbing Hills - new head?
 

At 50 mph, a 36% OD is almost lugging, and will certainly be quite a bit below the peak horse power point of your Model A. That high of gearing will be better suited to 60-65 mph. I have a 5.5 head on my Town Sedan, and a Mitchell 26%, and at 55 mph it will pull slight hills, but not much more.

Re: Help Climbing Hills - new head?
 

If the engine is not lugging why is it that you are having problems going up hills?

Re: Help Climbing Hills - new head?
 

ok, i am learning from everyones posts. thanks so much. just a clarification, i am not lugging on level ground at 50 mph but have to downshift out of overdrive to handle significant hills

Re: Help Climbing Hills - new head?
 

OK I think this will help look at the stock black lines. The problem is that your running the engine at such a low RPM that you are out of the power range to give good results going up a hill.

Re: Help Climbing Hills - new head?
 

Gee, I wonder what your point is?
If you have overdrive, its to help you go at greater speeds with a lower engine speed. Assuming the same engine, you would have to reduce the gear ratio to climb a hill, or as everyone has said, modify the engine with a higher compression head to increase torque. The laws of physics do not change with gearing, they are still there, just utilized, but in different ways.
I say go for the high compression head and utilize the increased torque to blow over the hills. It would not hurt to have a Stipes cam and larger intake ports too while you are at it.
Good Luck and happy motoring.

Re: Help Climbing Hills - new head?
 

Our driver climbs hills but not steep ones, not at all. Steep hills are our nemesis. So when we can the Stipe IB 330 cam will go in. We just put this cam in a restoration that we're doing.

http://www.fordgarage.com/pages/stipecamshaftspecs.htm

Re: Help Climbing Hills - new head?
 

I think we all have to down shift. I got a Mitchell in my car with 378s in the rear, with 650 16 tires. I just did some motor work , and put a tac in my car. to make it easier on the motor I started splitting second gear. I have not driven my car over a lot of hills but when I have I have I split second gear.my car tacs out at about 1900 at 53 mph and it seems happy there. I don't think that it likes to go much higher.