thoughts on the Model A engine?

Cider Mill

Cider Mill

Senior Member
I am going to have an engine rebuilt for a town sedan I am restoring with all original parts. My question is this:

Should I go stock, touring grind cam, counter balanced crank, over sized valves, etc There are so many options!

I plan on driving this car around town and on tours that probably won't be more than 150 miles, but want to be able to go 500 miles should I choose to. Any thoughts out there?
 
We have used Stipe cams in several engines for our projects. You have several very good rebuilders around your area, Schwalms in PA and Antique Engine in IL that we have used for two. Antique Engine offers a nice package for a short block that several people we know have used and are very pleased.

What ever you decide would work on the short tours you are talking about, but once you get behind the wheel of a smooth running Model A you will be amazed how far you will want to go. Next year we are going on a 5400 mile round trip with 32 other Model A subscribers to the Model A Times! Glad to see you are planning on driving it and once you get to feeling good about the car you will be surprised how far you will go.
 
The Town sedan is a pretty heavy Model A. I had an early 31 Murray. When I had the engine rebuilt I put in a touring cam. If I was to do it again I would also add a 5.5 Snyder head for more power going uphill and change to a Stipe cam. My coupe has a 5.5 head and Mitchell overdrive and has all the power I need.
 
The best "bang-for-the-buck" is adding a higher compression cylinder head, either the Snyder 5.5 or 6.1. Next I would add the Stipe "340" cam. You can go on and on, larger valves, better carburetion , counterbalanced crank, lightened flywheel, on and on. Just depends how deep your pockets are and how much more HP you think you need.
 
I like to point out that the Model A off the factory line was capable of 60 MPH no problem. It was also considered a VERY reliable car as it was built. The primary issues in the day would be poor quality oils and fuel, poor battery and condenser chemistry, dirt roads and not so good rubber in the tires. If you read about how the cars were driven and the problems with the cars it all comes down to the above problems. All those problems are fixed today.

While all the extra things people do today to improve the engine will certainly help, it is questionable if the average guy really needs them. A well built and well balanced engine will run unlike most engines you will find in 'restored' cars today. The simple addition of a B cam and a high compression head add a lot of bang for the buck. Adding in the counter balanced crank and some of these further additions may not give you much for the cost. This depends on your driving styles and how much you will drive. Most engines bearing failures are not related to needing a counter balanced crank. Either the bearing was done wrong or the crank was done wrong. More likely a combination of both.

So take your time to understand what the factory engine will give you and understand what it takes to get back to a factory engine.

If you have not already, follow the link to:
My comments on the A

Keep in mind I am not say to keep the car stock, just what you want may not need all you are told you need.
 
Try running 55-60mph with the typical rebuilt Model A engine with poorly done "balanced" crank and too thick wrong alloy mis-poured babbit and prepare to very quickly knock out the babbit.
 
I also tend to side with the "bang-for-the-buck" value is with a new Stipe IB330 or IB340 cam over the head is for the same reason that Kevin pointed out, --that they would run 60 mph originally. Naturally if you are needing to have a stock head re-surfaced, the money that operation will cost can be applied towards the purchase of a hi-comp head and make it a better value yet if funds are tight, IMHO the cam is a better value.

With regard to the original post, a couple of things I have come to the realization of with my own personal cars is, if you are on a Model A tour and have the most powerful engine under the hood, you are still limited by the slowest car in the group. Kinda like using a Thoroughbred to give Pony rides to kids! :D The funny thing is, in all of experiences I only hear of regrets where someone wished they would have upgraded to the O/S valves, better camshaft, C/W crank, etc., etc. when they were having their engine rebuilt, ...however I have yet to hear someone say they wish they would have not spent the extra money for those things. ;)

The next thing that I have learned is for most folks it is not prudent to use babbited mains with a counter-weighted crankshaft because it is impossible to remove the rear main cap to adjust the clearances with a stock flywheel housing. In this case, either the transmission or the engine must be removed, --or the flywheel housing butchered on to get the cap off. If that extra work is of no consequence to you, then use babbit as it will offer many miles of good service if done correctly.

Good luck in whichever route you choose.
 
To me, it's really nice to not be holding up traffic so much while pulling away from traffic lights and so on. The high compression head really helps with that, and, IMO, makes the car a much more practical driver for modern conditions. If your driving is all in the country, no big deal.

On our trip to the Williamsburg, VA meet (from Michigan) several years ago, two of us had HC heads and two were stock. We all motored along at the same speed on the level, usually in the 50-55 range. In the mountains, the HC heads pulled away, but eventually the others caught up, and we all arrived together. Being the slow poke would have bugged me, but others didn't seem be bothered at all--depends on you! As far as our monthly club tours go, Brent is right about the slowest car setting the pace, but I do enjoy being able to open it up getting to and from the tour gathering site, which can be a good ways away.

I've got all the goodies on mine, and I'm one of those guys Brent referred to who is glad he spent the money.

Steve
 
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BRENT in 10-uh-C said:
The next thing that I have learned is for most folks it is not prudent to use babbited mains with a counter-weighted crankshaft because it is impossible to remove the rear main cap to adjust the clearances with a stock flywheel housing. In this case, either the transmission or the engine must be removed, --or the flywheel housing butchered on to get the cap off. If that extra work is of no consequence to you, then use babbit as it will offer many miles of good service if done correctly.

Good luck in whichever route you choose.
Click to expand...

Brent,

I am taking the liberty of editing you post down to what I want to comment on. I think you are describing the situation with a Model B engine with a counterweighted crank and a Model A flywheel housing. If a person adds counterweights to a stock Model A crank there shouldn't be any problem (please correct me if I am wrong) removing the rear main cap.

Charlie Stephens
 
Charlie Stephens said:
Brent,

I am taking the liberty of editing you post down to what I want to comment on. I think you are describing the situation with a Model B engine with a counterweighted crank and a Model A flywheel housing. If a person adds counterweights to a stock Model A crank there shouldn't be any problem (please correct me if I am wrong) removing the rear main cap.

Charlie Stephens
Click to expand...

Actually, I probably should've qualified that a tad bit. Thanks for pointing that out. Generally speaking, you cannot remove the cap even on stock Model A crank w/ counterweights added. I do not have any pix on this computer but I can post some on Monday when I am at the shop that shows this. Maybe if you have small enough counterweights (maybe half the size??) you could, ...but then they likely would not be large/heavy enough to be effective or worth the effort.
 
A few thoughts from the cheap-seats...

The Town Sedan is one of the heavier Model A's, and would probably gain driveability benefit from a little more power...

I think a good touring cam would be a "must" at rebuild time.

The higher compression head could be added after the rebuild is broken-in...

How much good would larger valves do if the stock intake and carb were retained ?

If the rebuilder can properly balance the stock crank and reciprocating components, then a stock bottom-end should be sufficient ?
 
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A 5.5 or 6 to one head and a B or touring cam and you will do fine. But most important of all is quality assembly. Everything balanced to specs. Correct babbitt and grooves. All clearances measured and fitted correctly. No shortcuts. Do the research. The performance add-ons are wasted unless the basic engine is fundamentally sound and done right. The rebuilding process is often taken for granted, and it should not be.
 
There is nothing wrong with a nice original Model A motor. Why can't we just leave them like they were made - which was pretty dam good. "To each their own" - but why do we need to make race cars out of these historic old artifacs?
 
It has been stated on this site that changes in the engine will also affect the sound of the engine. The puckity puckity sound is changed and in some cases goes away.
 
Now maybe we are starting to confuse statements. I never meant to say that a high compression head was over-kill, --or that it did not improve performance. My opinion is that if a person only has the ability to purchase one item during the rebuild, it would be a new camshaft ....and not necessarily a 'Touring Grind' camshaft. My reasoning is much like what was mentioned above about not holding up traffic or having more power to pull a hill. This "ability" comes from an engine that makes torque to pull with.

We also need to remember that the 'Police Head' option was intended to be installed on an engine that already had a good stock camshaft in place, which means there would have been no need in 1931 for a "Touring Cam" or a Stipe cam to be installed. Therefore the higher compression head was the best bang-for-the-buck in that day but today due to most camshafts being out of specs, I am of the opinion that mindset really doesn't apply in 2011.

Also, if one searches this forum they will find where it has been discussed about how reground camshafts must give up something to gain elsewhere. To regain 'lift' again on a worn cam lobe, the valve duration must be compromised. The theory about this is discussed in many threads on this forum so it really doesn't need to be repeated here again but the general mindset is that the torque band is moved up in the RPM range when the cam is reground, ...and as such, it fights against other characteristics of the Model A engine. For example, the stock carburetor is not as efficient at higher RPMs due to airflow limitations so if we utilize a camshaft that makes power higher up in the RPM band, then does one need to change to a modern carb. to compensate?

So I guess we are no closer to helping Cider Mill in choosing his engine's direction. :o

.
 
What has also been stated on the forum is that if one were to take the blueprints and specs for a Model A engine to a builder he would "think" you were building a racing engine given all the tight tolerances.
 
It is hard to say, only you know how much you want to spend and how much you want to change your engine.
At least I would think a new cam from Bill Stipe and a 5.5 cylinder head.
There are many other things that can be done, but all cost money.
 
Can you install a new cam without taking the engine out of the car?

If you installed a new cam would that be the time to do a valve job, or does the engine need to be out of the car to do that?
 
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