High Compression Head Review

[johnneilson]

Ron did just fine in my opinion, the most important decision was based off His utilization of the vehicle. Not that He may change it later on, it suits the purpose now.

Combustion efficiency has many factors, timing only plays a part and must be managed to minimize detonation. Fuel alone will not cure it (octane) and the combustion chamber shape is critical. Modern technology of such provides much higher engine speeds and more conservative timing settings.

John

 

[Y-Blockhead]

As far as going with a Mitchell. You might want to look at some of the other alternatives out there, F150, T5, etc. Mitchell does NOT have a first gear synchro and you need 2 separate boxes to get overdrive and Syncro and they are at least $1k over the others.

With the Mitchell O/D you can shift down if you wish by putting the Mitchell in neutral, down shift the transmission and re-engage the Mitchell. So you really don't need synchros in the transmission, the O/D has synchros. The main reason I would install a Mitchell transmission is to get better gear ratios.

Around town I just use 2nd low and high, unless I have to start off on a hill then I shift to 1st.
But we are getting off the subject...

 

[Model A Ron]

In your opinion, which everybody has one. I like the difference in performance with the mods I have incorporated.

I am happy for you as well. The most important thing is to do what you feel is right for your car and being happy with your decisions. Last time I checked this was still a free country but that is quickly changing.....also a different discussion on a different forum.

 

[Model A Ron]

With the Mitchell O/D you can shift down if you wish by putting the Mitchell in neutral, down shift the transmission and re-engage the Mitchell. So you really don't need synchros in the transmission, the O/D has synchros. The main reason I would install a Mitchell transmission is to get better gear ratios.

Around town I just use 2nd low and high, unless I have to start off on a hill then i shift to 1st.
But we are getting off the subject...

This is exactly the reason I am getting the Mitchell. It is shipping this week and I feel the 5.5 Head will compliment it quite nicely. I just hope my limited Model A experience will allow me to grasp such a complicated concept as having the additional shifter in the car lol......Satire again my friends

 

[Hitman]

I'm glad the original poster is finally happy with a high compression head.

I have to agree with Brent and a few others, there is a lot of misinformation in this thread and similar threads. When someone asks how can they drive 60 mph all day, and the responses vary from transmission type, spark rod set to 9:00 and leave it, put a centrifugal advance distribution in, and run the mystery oil!

Changing out parts is not the simple solution. These things are simple, and forgiving machines. There's too much over thinking, without the understanding of how it all comes together and works. Like the T5 transmission comment, do you know how many variations of the T5 transmission exist? Dozens!

Just be careful with the information, especially considering this will be searchable and will probably come back up years from now, with a new question from a new person trying to learn. If I followed the timing advice in this thread alone, I'd be overheating, and would kill my gas mileage during every trip.

 

[CarlG]

I have the 5.5 head, 97 carb, F150 ******, 3.78 rear, 550R19 tires. Perfect combination for MY type of driving.

 

[ryanheacox]

One other thought to prove my point. These vehicles and their engines were designed for Ladies to operate them. As a general rule, these Lady drivers did not understand the fundamentals of spark timing location, nor how to fine-tune the Carburetor's GAV, or other facets of operation. A Lady could operate her Model-A by leaving the spark lever in one location from starting to driving without a single issue nor any harm to the engine.

And she could start out in 2nd gear and leave it there for around town driving.


Back on topic, glad you're happy with the 5.5 head. I like mine too. No change in top end performance (stock head did 65, so does this one) but a noticeable improvement climbing hills.

 

[BRENT in 10-uh-C]

Well I took everyone's advise and drove my car along with as many Model A's that I could to help decide on what High Compression Head to get.

First off the most performance I had the opportunity to test drive was the Lion Head. This was the most power by far however it does not look stock and to be honest I was not looking to build a race car with an engine that looks modern. My vision was to drive my Model A at a constant 55 to 60mph when needed without turning the engine to fast and keep it looking stock.

Next was the Snyder's 6 to 1 and 5.5 to 1 heads. I had the opportunity to test drive both on Stock Model A's. In my opinion and remember everyone has one....I could not tell a difference between the two.

I installed the head early Saturday morning and since then I have logged 100 miles on it. I now notice that it pulls much better from about 20mph all the way up to 55/60 mph. The engine is still turning to fast in my opinion to go a constant 55/60 but with my soon to get Mitchell OD it should have no problem.


I highly recommend the Snyder's 5.5 head and if your on the fence I hope this helps you decide.

With this first hand experience, (Not HEARSAY) I made the right decision for myself. I was simply giving my opinion after driving cars with both heads. See my quote below from my original posting:

Unfortunately I could not tell the difference. If I were going for high performance based on my experience I would have went with the Lion Head however that was not the direction or vision I have for my car. We are talking about a Model A hear not a tricked out Mustang.

But what do I know? I am just a guy in my late 40's who just learned how to change my oil......for some on hear I need to point out that this is Satire

Ron, I guess where I feel this is misleading to others is that you are making recommendations based on a statement that you tried both cylinder heads and there is not any difference between them. You also suggested that people should purchase the 5.5 head based on your testing. Many will never take the time to read thru all of your posts to understand that your 'seat of the pants' testing was done driving different automobiles, ...with different body weights, different camshafts, bore sizes, weather conditions and different roads. Adding to that, you have approximately 100 miles of drive time on your own cylinder head prior to making this recommendation that others should buy a 5.5 head. Is this overview synopsis close to being accurate, ...or have I missed something?

.

 

[Y-Blockhead]

This is exactly the reason I am getting the Mitchell. It is shipping this week and I feel the 5.5 Head will compliment it quite nicely. I just hope my limited Model A experience will allow me to grasp such a complicated concept as having the additional shifter in the car lol......Satire again my friends

Ron, I think you will love the Mitchell. I have a '30 Town Sedan which is little chunkier than your Phaeton. Only engine mods over stock are 5.5 head (6.0 was not available yet), mild cam and Marvel Schebler carby.

The "three shifters" make people wonder at car shows...

 

[alexiskai]

Is this overview synopsis close to being accurate, ...or have I missed something?

I think you have missed something, but it doesn't really affect your point. The "review" is essentially an argument-from-authority. The OP says:

1. I was deciding between the 5.5 and the 6 head
2. A test drive of different cars gave me no useful information
3. Paul Shinn recommends the 5.5
4. Therefore I chose the 5.5
5. "I highly recommend the Snyder's 5.5 head and if you're on the fence I hope this helps you decide."

As you point out, it's the jump from #4 to #5 here that raises eyebrows. There is no stated rationale for the decision except the appeal to Paul Shinn as an authority on cylinder heads.

 

[Jack Shaft]

Paul Shinn..isn't he the guy who did the mitchell install video? Where they supported the weight of the car with concrete cinder blocks?

 

[alexiskai]

Paul Shinn..isn't he the guy who did the mitchell install video? Where they supported the weight of the car with concrete cinder blocks?

He did do one, but they use normal jack stands in the video – maybe you're thinking of a different one?

 

[Benson]

Maybe it was the famous video where they dragged the car with a tow strap around and around the parking lot for a long time because they claimed that all "Rebuilt" engines with Babbitt bearings were always tight until they were run!

The present version of that video looks totally unlike the original!

 

[Y-Blockhead]

Maybe it was the famous video where they dragged the car with a tow strap around and around the parking lot for a long time because they claimed that all "Rebuilt" engines with Babbitt bearings were always tight until they were run!

I think that was the Hagerty rebuild video where they towed the Model A to start it.

Why don't ya'll see who else you can rag on today?

 

[Benson]

Just saying ...

If nobody says anything about Bogus information posted then the new guys will think that it is true story that you must drag a car around to start up a rebuilt engine.

 

[AL in NY]

Tod (who posts here) makes a stock looking 7:1 Winfield crowfoot head. You may want to check that out.

 

[Jack Shaft]

Maybe it was the famous video where they dragged the car with a tow strap around and around the parking lot for a long time because they claimed that all "Rebuilt" engines with Babbitt bearings were always tight until they were run!

The present version of that video looks totally unlike the original!

Its called 'burnishing'...drag it around till the babbit gets so hot it finds its place

 

[JayJay]

I think that was the Hagerty rebuild video where they towed the Model A to start it.

I watched that video and I was a bit dismayed to see them do that and hear them state that all rebuilt engines are so tight that you need to do that. OTOH, when I was a kid we always did a first start on all our engines (rebuilt or rescued) at the house of the friend that had the longest and steepest driveway. That way we had lots of distance to get the bugger started by compression. If it didn't start, tow it back up and try again.

JayJay

 

[Model A Ron]

And she could start out in 2nd gear and leave it there for around town driving.


Back on topic, glad you're happy with the 5.5 head. I like mine too. No change in top end performance (stock head did 65, so does this one) but a noticeable improvement climbing hills.

Thanks. I found my top end to be the exact same as well at 65 but the hill climbing is a huge improvement from from the stock 4.2 to 1 head.

I think the 6 to 1 head is very good as well and I know it performs better than the 5.5 with additional modifications. I have Babbitt bearings and have no intention of doing any additional performance modifications so the 5.5 head was right for me. No need for me to go higher as the 5.5 meets my needs.

Ron

 

[JimZ]

Thanks Ron for your recommendation. Your advice has helped me decide to go with the 5.5.