Just curious x 2

[Russell Reay]

1) I read that the muffler design is what gives the Model A its unique sound. If one were to install a Toyota 22R or Pinto, Jeep or other 4 cyl engine with the Model A muffler, would it sound the same ?

2) there are several high compression heads available. Why can't an original head just be planed?

Don't mean to be a pest, but there is so much to learn about these cars, and if I don't ask I won't learn.

[Y-Blockhead]

Originally Posted by Russell Reay

1) I read that the muffler design is what gives the Model A its unique sound. If one were to install a Toyota 22R or Pinto, Jeep or other 4 cyl engine with the Model A muffler, would it sound the same ?

2) there are several high compression heads available. Why can't an original head just be planed?

Don't mean to be a pest, but there is so much to learn about these cars, and if I don't ask I won't learn.

The stock head could possibly be planned. But the combustion chamber of the high compression heads is a more effecient shape so your results will not be the same.

Also, I don't know the deck thickness of a stock head. Taking too much off may make it too tin.

[700rpm]

Russell, you’re not being a pest. This site was built to help people with questions and problems with their Model A. Come on in and make yourself comfortable. We have all been where you are right now.

[Charlie Stephens]

Someone stopped by my house one night with what appeared to be a nicely restored Model A. He left it idling and it sounded stock. He lifted the hood and it had a 4 cylinder Chevy II engine with a stock Model A muffler attached. So the sound is in the muffler (and probably the 4 cylinder engine).

As far as planing the stock head there is not enough metal to plane enough to make a difference, you really need to get a high compression head.

Charlie Stephens

[Ray in La Mesa]

We had an A at a meet some years ago that sounded totally stock as it went through the gymkhana , turned out to have a Pinto engine going through a stock A muffler. It just idled a bit smoother.

[GeneBob]

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The high compression heads are made to be higher compression. That sounds flippant but there is more to it than planing down the stock head. The head must have relief for the piston and clearance above the valves. The higher end heads use various shapes of the chamber to improve flow from the valves to the cylinder bore and tailor the "squish" of the gasses during compression.
If you research these online, you can find pictures the different shapes that are used; Winfield, Lion Speed Head, Rocket 428, Brumfield, even Snyder's and a few others. There are a lot of interesting ideas that have been tried over the years.

[Tacoma Bob]

MMM Interesting thread. At 71 years young I have been around car stuff my entire life. Having a head milled was a real big thing back in the day. That being said, once the head was milled was additional work done to the combustion chambers??

[chrs1961815]

Originally Posted by Tacoma Bob

MMM Interesting thread. At 71 years young I have been around car stuff my entire life. Having a head milled was a real big thing back in the day. That being said, once the head was milled was additional work done to the combustion chambers??

I have never heard of someone tampering with the chamber shape on an original head of a Model A, maybe other cars. Like said before, there is not enough material to mill off to make a difference. People looking for speed saw this and found a high compression head. Aftermarket high compression heads have been available pretty much since the 1930s. Different ratios, different chamber shapes, styles. The big ones are still made today.

[bbrocksr]

Originally Posted by chrs1961815

I have never heard of someone tampering with the chamber shape on an original head of a Model A, maybe other cars. Like said before, there is not enough material to mill off to make a difference. People looking for speed saw this and found a high compression head. Aftermarket high compression heads have been available pretty much since the 1930s. Different ratios, different chamber shapes, styles. The big ones are still made today.

I'm going to have to disagree with the statement " there is not enough material to mill off to make a difference " The counterbore over the piston is about an 1/8" deep , You can mill about .100 off and still have piston clearance .
Not comparable to a high compression head but is does make a difference.
Bill

[chrs1961815]

Bill you are right, that is what I meant to say lol!! A difference yes, but not a big one.

[ETAModel]

Originally Posted by Russell Reay

1) I read that the muffler design is what gives the Model A its unique sound. If one were to install a Toyota 22R or Pinto, Jeep or other 4 cyl engine with the Model A muffler, would it sound the same ?

2) there are several high compression heads available. Why can't an original head just be planed?

Don't mean to be a pest, but there is so much to learn about these cars, and if I don't ask I won't learn.

My dad really liked the late 1960's/early 1970's Datsun pickups. He said they sounded like the model A. I know they had about 65 HP, so maybe that was why he liked them. He grew up hauling oilfield pipe and heavy equipment on the AA, so he had an attachment to the sound, I guess. The loads he hauled with those little Datsun's would make your head spin.

[J Franklin]

I once fit a glasspack muffler on my car and it sounded like a modern 4 cal car! Changed it back quickly.