Looking for a Consensus

[BILL WILLIAMSON]

When I think of using a HIGH compression head, I think of those SMALL rod & main bearings!!!
For example: Datsun inline 6 cylinder engines have HUGE mains & rod journals & was one of the few GAS engines, that were converted to HIGH COMPRESSION Diesel engines & survived AMAZINGLY WELL!!
Bill W.

[CarlG]

Originally Posted by Henry's Lady's Man

... I am tempted to do a Mitchell O/D, but then ya gotta get new wheels... Sheesh!!! ...

Why would you have to get new wheels?

[Tom Wesenberg]

I was wondering the same thing?
No need to change wheels for overdrive.

[Henry's Lady's Man]

Originally Posted by CarlG

Why would you have to get new wheels?

Well first, a lower center of gravity and better stability with 16" wheels and wider radials. I find the bias ply balloon tires of the day a little scary at 60 (my max speed downhill). The folk in our club prefer 16" radials for better handling. I never thought H Ford intended the A for anything more than cruising at 55 or less.

[Y-Blockhead]

Originally Posted by Henry's Lady's Man

I never thought H Ford intended the A for anything more than cruising at 55 or less.

Not sure I would want to go faster than 50-5 mph in a Town Sedan. Ever been out on a windy day and have a gust of wind hit you from the side?

[H. L. Chauvin]

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What would be a good guess at the probable survival rate of a typical "Senior" Model A driver, in a Model A, with a "flat" front radiator, a "flat" front windshield, and two (2) extra large front fender "wind scoops", all riding "high" above a well traveled hilly, two (2) lane back-roads-highway at 65 MPH ........ on a windy day ....... with 2016 type 18 wheelers and 2016 type young texting drivers swerving in and out and around one's Model A?

[Henry's Lady's Man]

Originally Posted by Y-Blockhead

Not sure I would want to go faster than 50-5 mph in a Town Sedan. Ever been out on a windy day and have a gust of wind hit you from the side?

Well then I have no need for a Mitchell Overdrive if I'm going to keep at 50. Our club takes fairly long tours out of state (they're going to Loveland this June, for instance).Though they swear they'll slow down for us purists, they sure left me in the dust. They were small dots on the distant horizon and no one in the caravan is to let the guy behind him drift back much. So we felt like the weak link.
What I'm going to suggest is to have two separate caravans... one for the Mod Squad, and one for the more stock crowd.The worst that can happen is they'll get to the beer first

[Henry's Lady's Man]

Originally Posted by H. L. Chauvin

What would be a good guess at the probable survival rate of a typical "Senior" Model A driver, in a Model A, with a "flat" front radiator, a "flat" front windshield, and two (2) extra large front fender "wind scoops", all riding "high" above a well traveled hilly, two (2) lane back-roads-highway at 65 MPH ........ on a windy day ....... with 2016 type 18 wheelers and 2016 type young texting drivers swerving in and out and around one's Model A?

That's about right, imo, and this club is eager to do 65 & 70. THAT is why I would feel comfortable with lower center of gravity and more rubber on the road. There's a reason they went to radials in the 60's... a much better ride.
Nevertheless, I don't have to "keep up with the Jones's". Them Jones's are probably in hock up to their cowl lights anyway.

[Mike V. Florida]

Originally Posted by Henry's Lady's Man

I just came from my Model A club meeting, and got two completely opposite opinions on buying a higher compression head. I was advised against it by two fellows, since I have a babbitt engine. They both independently told me that the higher forces would crystalize the babbitt and destroy it.
Two other guys told me the opposite. They said (and rightfully so?), that the police head (5.3:1)was used successfully with babbit for years with no problems. A fifth guy said that there have been high compression race cars with babbitt, and no big issue.

I realize people have had different experiences, or heard/read different stuff about this, so I respect ALL INPUT. "There's wisdom in a multitude of council" - (the old black book)... So I invite any input here. Thanx in advance... Chuck

I'm going to skip to the end here and not read every post. I don't think I have to because I'm sure they all say the same thing. those two guys are full of it. Even if your engine is in poor condition our "high compression" (HC)heads for the engines ain't that high.

The 90-125hp V8 engines had 6.8 to 7.2 heads on babbit. The HC heads we have for our A's are less then or equal to that.

[Henry's Lady's Man]

Originally Posted by Mike V. Florida

I'm going to skip to the end here and not read every post. I don't think I have to because I'm sure they all say the same thing. those two guys are full of it. Even if your engine is in poor condition our "high compression" (HC)heads for the engines ain't that high.

The 90-125hp V8 engines had 6.8 to 7.2 heads on babbit. The HC heads we have for our A's are less then or equal to that.

I think we have reached a strong consensus. I was a bit puzzled, since these two guys were the FIRST to advise me. It pays to go a little deeper.
Yes, I realize the Model A heads available are not REALLY very high compression, even at 7.0 . I will probably check into a 6.0. That, along with the B-cam, new pistons, rings and valves should be a big improvement. I have a good mind to leave my flywheel alone. My crankshaft is not balanced, and thus matches well with it. I'm not interested in rabbit jumps at the stoplight anyway. It's too late for me to try to impress the ladies

[James Rogers]

A high compression head won't make the car go any faster. It will increase the torque the engine produces and make hills flatten out. It will take off better and climb hills like a billy goat but won't go faster. I have run heads up to 8-1 compression on a race car with no problems. I did sell that engine several years ago and it is still being used in a tour car regularly. He uses a Snyder 5.5-1 head. Denis4X4 is correct about timing and not running too much.
I would also steer clear of the 2 guys that told you not to run one. They are fools.

[TerryH]

I have a 1930 Town Sedan, and almost 10 years ago, right after I bought it (fully restored), I added the 5.5 HC head, Mitchell OD, lightened flywheel and V-8 clutch, and cast iron brake drums. I kept the 19" wheels and Goodyear tires, everything else pretty much stock. I have been on two long tours in California, on both 101 and I-5 up to Yosemite and Hearst Castle. I also drive on shorter tours, on our local freeways, usually at 60 mph. I have absolutely no regrets over any of these mods, and have no issues on controlling my A at speed, and see no need to convert to 16" wheels. I feel that both the HC head and the Mitchell work together great in a car built for some touring and freeway driving. Here in S. California, it is very limiting not to be able to use the freeways at least some of the time.

[Henry's Lady's Man]

Originally Posted by James Rogers

A high compression head won't make the car go any faster. It will increase the torque the engine produces and make hills flatten out. It will take off better and climb hills like a billy goat but won't go faster. I have run heads up to 8-1 compression on a race car with no problems. I did sell that engine several years ago and it is still being used in a tour car regularly. He uses a Snyder 5.5-1 head. Denis4X4 is correct about timing and not running too much.
I would also steer clear of the 2 guys that told you not to run one. They are fools.

I am 100% for flattening out the hills. We've got some good ones in New Mexico. Before I tore into her, she's been climbing hills like a lame nanny goat, when the pedal's to the metal, and you're lugging & wishing for more. I think Bonnie deserves a 6.0:1 head then, coupled with the B camshaft. I will call John Cosper this week and pick his brain about lightening the flywheel some. I wasn't expecting to go faster, unless I get the Mitchell O/D, which is still a possibility. I may not want to do 70, but cruising at 55 or 60 with lower rpm is very enticing.

[Henry's Lady's Man]

Originally Posted by TerryH

I have a 1930 Town Sedan, and almost 10 years ago, right after I bought it (fully restored), I added the 5.5 HC head, Mitchell OD, lightened flywheel and V-8 clutch, and cast iron brake drums. I kept the 19" wheels and Goodyear tires, everything else pretty much stock. I have been on two long tours in California, on both 101 and I-5 up to Yosemite and Hearst Castle. I also drive on shorter tours, on our local freeways, usually at 60 mph. I have absolutely no regrets over any of these mods, and have no issues on controlling my A at speed, and see no need to convert to 16" wheels. I feel that both the HC head and the Mitchell work together great in a car built for some touring and freeway driving. Here in S. California, it is very limiting not to be able to use the freeways at least some of the time.

We've got some good stretches of original Rte 66 in our state. The club tries to tour on such backroads, but inevitably winds up on 75mph interstate. Our roads suck in New Mexico. It's not fun to hit a pothole at higher speeds, or get your left wheels stuck in a highway rut or crack. Just sayin'...
But I get excited every time I try to talk myself (and wifey) into the O/D. If I'm going to all this trouble and expense, I want her to be a smooth and fun ride for a long time. I expect Bonnie to outlive me.

[tbirdtbird]

'pick his brain about lightening the flywheel some'

so you are gonna get a counterweighted crank then

[40 Deluxe]

Originally Posted by Henry's Lady's Man

I have a good mind to leave my flywheel alone. My crankshaft is not balanced, and thus matches well with it. I'm not interested in rabbit jumps at the stoplight anyway. It's too late for me to try to impress the ladies

Actually, the stock (heavy) flywheel will get you across the intersection the quickest! Rev to about 2,000 RPM and pop the clutch. All that stored energy will shoot you across the intersection in a rapid manner!

[Henry's Lady's Man]

Originally Posted by tbirdtbird

'pick his brain about lightening the flywheel some'

so you are gonna get a counterweighted crank then

Well, I know I said I'd talk to John about it. I just want to know all the pro's and con's to both schools of thought. If there's no real advantage to lightening the flywheel other than getting up to speed faster, I'm leaning much more to leave it as originally engineered. Most in the club have lightened theirs, but it doesn't mean I have to. They like to modernize a bit too much for me.

[Henry's Lady's Man]

Originally Posted by 40 Deluxe

Actually, the stock (heavy) flywheel will get you across the intersection the quickest! Rev to about 2,000 RPM and pop the clutch. All that stored energy will shoot you across the intersection in a rapid manner!

Now THAT sounds like it's straight out of American Graffiti

[Bob Bidonde]

"Crystallizing the babbitt" is not realistic. 5:1, 5.5:1, 6:1 and 7:1 compression cylinder heads have been around since the Model T was new, and there is no stigma attached to their sensible use. I have been running a 5.5:1 cylinder head for many years without issue.

[31Tudor]

As mentioned many times here, it is not the high compression head that is the problem. I have been running a 7:1 head with babbit for 9,000 miles with out any problems, or "crystalizing of the bearings"