|
Sponsored Links (Register now to hide all advertisements) |
|
|
Thread Tools | Display Modes |
12-02-2023, 09:38 AM | #1 |
Senior Member
Join Date: Jul 2023
Posts: 235
|
5.5:1 vs 6.0:1 heads
It is fairly simple to determine that increasing the compression ratio on the little Ford 4 cylinder A engine will make the car more drive able due to the additional power it will develop. But by how much? What are the comparisons to be made between the two aftermarket iron heads offered?
The low range torque curve for the 6.0:1 head was a little flatter than the 5.5:1 head, power output was negligible for the two, about 3.5 HP. For an engine with insert bearings and given that the cost for the two heads is the same, the 6.0:1 head would probably be the way to go.....But what of the exhaust note between the stock and higher compression heads? Are they the same? I know that the 10.5-11.0:1 V8s from the 60s had quite distinguishable exhaust sounds over their low compression 8.75:1 counterparts. But ignition, valve timing (camshafts), carberaturion/induction, and exhaust was also different for these old fire breathing dragons. I guess I want it to sound like a Model A, those who are using these heads, which one is it, and what does it sound like?? |
12-02-2023, 09:53 AM | #2 |
Senior Member
Join Date: Apr 2018
Location: Mebane NC
Posts: 2,356
|
Re: 5.5:1 vs 6.0:1 heads
Use the 6.5:1 Burtz head. Better cooling, more power, correct size, similar price. End of story.
|
Sponsored Links (Register now to hide all advertisements) |
|
12-02-2023, 10:22 AM | #3 |
Senior Member
Join Date: Jul 2023
Posts: 235
|
Re: 5.5:1 vs 6.0:1 heads
|
12-02-2023, 10:33 AM | #4 |
Senior Member
Join Date: May 2010
Location: Eastern Tennessee
Posts: 11,520
|
Re: 5.5:1 vs 6.0:1 heads
FWIW, an original muffler and exhaust system has different tone than what an aftermarket Aries muffler has. Yes, compression ratio affects the idle quality but is less detectable at higher RPMs. The increased compression just 'hits harder' for each stroke at idle over a stock 4¼:1 ratio. The caveat is most hobbyists today have no clue what they originally sounded like.
|
12-02-2023, 10:43 AM | #5 |
Senior Member
Join Date: May 2010
Location: Long Island, NY
Posts: 3,472
|
Re: 5.5:1 vs 6.0:1 heads
I have a 6:1 head on my Victoria and it sounds like a Model A at idle.
__________________
Bob Bidonde |
12-02-2023, 11:02 AM | #6 | |
Senior Member
Join Date: Jul 2023
Posts: 235
|
Re: 5.5:1 vs 6.0:1 heads
Sponsored Links (Register now to hide all advertisements)
Quote:
Thanks bob, that is what I was wanting to know. The Model A has a very distinctive "cackle" and I would not want to affect that. The 3.54:1 ring and pinion I recently installed is requiring a little more "twist" than is currently available prompting these considerations. I would imagine that you are realizing better fuel millage to boot. The last tank with the new final drive changes yielded 14.6 MPG.....I think we can do better... |
|
12-02-2023, 11:02 AM | #7 |
Senior Member
Join Date: Jan 2012
Location: Western North Carolina
Posts: 3,900
|
Re: 5.5:1 vs 6.0:1 heads
There is more than compression ratio to flathead head design. The air must turn to flow down the cylinder during the intake stroke and out during the exhaust stroke. The design of the squish area determines how well and how fast the combustion takes place. In my opinion, the best head designs are those for flathead Harlies and racing Briggs and Stratton engines.
__________________
A is for apple, green as the sky. Step on the gas, for tomorrow I die. Forget the brakes, they really don't work. The clutch always sticks, and starts with a jerk. My car grows red hair, and flies through the air. Driving's a blast, a blast from the past. |
12-02-2023, 11:03 AM | #8 | |
Senior Member
Join Date: Jul 2023
Posts: 235
|
Re: 5.5:1 vs 6.0:1 heads
Quote:
Yes, I would expect so Terry....I might fool them, but I remember what they sounded like....Thanks |
|
12-02-2023, 11:03 AM | #9 |
Senior Member
Join Date: Oct 2018
Location: Prescott, AZ
Posts: 130
|
Re: 5.5:1 vs 6.0:1 heads
|
12-02-2023, 11:08 AM | #10 |
Senior Member
Join Date: Jul 2023
Posts: 235
|
Re: 5.5:1 vs 6.0:1 heads
|
12-02-2023, 11:29 AM | #11 | |
Senior Member
Join Date: Oct 2018
Location: Prescott, AZ
Posts: 130
|
Re: 5.5:1 vs 6.0:1 heads
Quote:
FWIW, other than "sounds like a Model A at idle", I am going to disqualify myself for the "does it sound noticeably differently at other throttle positions?" I have a Weber carb and cast iron exhaust header with Aries plain steel muffler. Other than idle sounding the same (to my ears) as an original 4.2:1 setup, it seems to sound the same under lower rpm load with the characteristic "cackle." At cruising speeds, IMHO, seems to have an overall smoother sound. This is of course subjective as I have never heard my Model A drive by. Last edited by AzBob; 12-02-2023 at 10:51 PM. |
|
12-02-2023, 11:48 AM | #12 |
Senior Member
Join Date: May 2017
Location: Denver Area
Posts: 433
|
Re: 5.5:1 vs 6.0:1 heads
I went with the Snyder's 6:1 a few years ago and liked it. It is a good head. I have since gone with a Lion III head and I think it is smoother than the Snyder was.
If I were starting from scratch now, I think the Burtz may be the way to go. Higher compression and better water passages would be the deciding factors. We have come a VERY LONG WAY from the 1930's gasoline and engine rebuilds. Take full advantage and improve the efficiency of your engine. |
12-02-2023, 01:35 PM | #13 |
Senior Member
Join Date: Nov 2010
Location: Anchorage, Alaska
Posts: 9,115
|
Re: 5.5:1 vs 6.0:1 heads
I have the Snyder 5.5 head with a cast iron header and Aires muffler (not stainless) and it sounds like a Model A.
__________________
Alaskan A's Antique Auto Mushers of Alaska Model A Ford Club of America Model A Restorers Club Antique Automobile Club of America Mullins Owner's Club |
12-02-2023, 01:52 PM | #14 | |
Senior Member
Join Date: Mar 2012
Location: Ohio
Posts: 1,973
|
Re: 5.5:1 vs 6.0:1 heads
Quote:
|
|
12-02-2023, 06:47 PM | #15 |
Senior Member
Join Date: May 2012
Location: Fredericksburg, Virginia
Posts: 764
|
Re: 5.5:1 vs 6.0:1 heads
Snyders 6.1 on mine and it too sounds like a model A should at idle.
|
12-02-2023, 07:44 PM | #16 |
Senior Member
Join Date: Jun 2014
Location: Land of Lincoln
Posts: 3,131
|
Re: 5.5:1 vs 6.0:1 heads
I have a Synders 6.0 -1 head, 330 touring cam, larger intake valve’s, and Aries plain steel muffler. All of the old timers comment your A is so quiet, I’am not old enough to know if it sounds like stock, Aries says there made to Ford specs , retard the timing lever and it will cackle ! and adjust the idle at a slow idle.
__________________
Don't force it with a little hammer tap, tap, tap get a bigger hammer tap done |
12-02-2023, 10:29 PM | #17 |
Senior Member
Join Date: Jul 2023
Posts: 235
|
Re: 5.5:1 vs 6.0:1 heads
All very useful information, thanks fellas.....
|
12-03-2023, 11:14 AM | #18 |
Senior Member
Join Date: Jan 2012
Location: Western North Carolina
Posts: 3,900
|
Re: 5.5:1 vs 6.0:1 heads
My current Model A does not sound like the Model A's of my youth. But nothing does because of my bad hearing.
__________________
A is for apple, green as the sky. Step on the gas, for tomorrow I die. Forget the brakes, they really don't work. The clutch always sticks, and starts with a jerk. My car grows red hair, and flies through the air. Driving's a blast, a blast from the past. |
12-03-2023, 11:38 AM | #19 |
Senior Member
Join Date: Jul 2023
Posts: 235
|
Re: 5.5:1 vs 6.0:1 heads
|
|
|
Sponsored Links (Register now to hide all advertisements) |
|