high compression head

Mike

Mike

Well-known member
Good afternoon,

My head gasket is seeping between # 2 and 3 cylinders, my question if I am going to replace the head gasket I would like to upgrade to a high comp. head. My engine has babitted bearings with 6,000 miles on it, should I go with a 5.5 or 6.0 compression head? Is the 6.0 head look just like the original? I am leaning toward the 5.5

Thank you,

Mike
 
Snyders had'nt yet come out with the 6.0 when I bought mine, so I took what was available at the time, which was the 5.5. I've been very happy with it.
 
Babbite bearings will handle either the 5.5 or 6.0 heads. I would suggest, with 6000 miles on your engine, that you consider checking clearance on your main and rod bearings; the clearances may have increased as the bearings polished out from running that many miles; just a safety precaution.

Ron
 
How much more horsepower will that give an engine over a original head?
Should the engine be decked before putting a High Compression head on?
Thanks for your time.
Joe Grobleski
 
I have the 5.5 in my sedan and she drives just fine at 50-55. I try and keep her at 50, eventhough she tries to go faster. Just think what that head will do to your LIGHT truck! You may be able to cruise at 65:D.

Mike
 
Nostalgic1930 said:
didnt they run into issues with the head being to thick? and the new arp bolts not being long enough
Click to expand...

Yes: according to what I have found out is that the studs from the Model A suppliers are the right length.
The heads thickness is about a 1/16 more than they should be.

By the way Larry Brumfield had figured that by making the heads compression to 5.9-1 that would be the max for a Model A with babbitted bearings in good condition to handle just fine.
www.jandm-machine.com
 
We've ran a 5.9 head with grade 5 studs and nuts at 55 ft.lb. torque on the coupe for 15 years and 13 years on the speedster with no problem. The oinly thing was that I had to retorque four or five times to get them to hold 55 ft.lb. The last 5.9 head, I used the grade 8 bf studs and torqued to 65 ft.lb. and only had to torque twice. I really think that 65 ft.lb. torque and the grade 8 studs that are harder than the 80 year old block threads, may be hard on the 80 year old block threads. Being as I know it will work I'll use grade 5 studs the next time.
 
Cape Codder said:
How much more horsepower will that give an engine over a original head?
Should the engine be decked before putting a High Compression head on?
Thanks for your time.
Joe Grobleski
Click to expand...

I just checked the Piranio Dyno sheet and it shows the stock model A engine with the Snyder head was putting out 51.09 horsepower at 2200 rpm. This would be an 11.09 horsepower gain. I think that I've seen slightly higher rateing on other tests but dyno tests can vary slightly acording to conditions. They show the C head giving over 6 horsepower boost, add a pair of updrafts, free flowing exhaust an warmed up ignition you can easily get it up to 60 horsepower or better.
 
jackball said:
How much does the high compression head affect gas milage?
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I've never seen any figures where people did an accurate check before and after the head change. Since the 5.5 makes more power and the engine runs more efficiently I would expect a couple MPG gain with the 5.5 head. The best I can get with my 28 Phaeton (stock head) with no side curtains and driving 45 MPH on a trip is 22.3 MPG. Someday I'll install a 5.5 head and see what that does.
 
Looks like I'm the only guy that would recommend the 6:1. I ran a 6:1 Winfield on my tudor for a few years with no problems, prior to that I ran a 7.4:1 Cyclone head on my widebed for many years, again with no problems. Both engines were B block, C cranks with stock oiling and babbitt. The engine in the widebed had .050" undersize rod throws which is not recommended but worked fine. Fuel mileage will increase as compression goes up.
 
I purchased an engine from Antique Engines in Slokie, IL, and between the 5.5, I guess, is their ratio, the touring cam, and some other stuff, I JUMP to 55 mph, and too often find myself going 65 on the highway where I have to back down since I think I'm playing with fire, safety-wise.:D
 
I've been running 5.9 heads for at least 15 years. I feel that the Snyder heads are the best or only choice for a new cast iron head that has the original appearance. I wouldn't worry about the 1/16 extra height thickness. If I used one I would use the 3&3/4 length grade 5 ignition cable studs. I'll be the second to say that I would choose the 6.0. The way I see it every little bit counts, to a point. I feel that heads that are 7to 1 or close to it require more use of the spark to the point that it would hurt driveability for me.
 
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