Go Back   The Ford Barn > General Discussion > Model A (1928-31)

Sponsored Links (Register now to hide all advertisements)

Reply
 
Thread Tools Display Modes
Old 02-09-2020, 02:53 PM   #1
kimlinh
Member
 
Join Date: Nov 2014
Location: Middlebury,Connecticut
Posts: 86
Default High compression engine life.

I am still running a stock head. I'm sure the high compression heads run better, more power, cleaner burning, etc. However that also means more load on the bearings. With a stock oil system (not pressurized), I did not want to add more load to the bearings. Am I wrong? Are you guys with the 5.5 and 6 to 1 heads noticing shorter bearing life or any other related problems?
kimlinh is offline   Reply With Quote
Old 02-09-2020, 03:00 PM   #2
alexiskai
Senior Member
 
alexiskai's Avatar
 
Join Date: Apr 2018
Location: Mebane NC
Posts: 465
Default Re: High compression engine life.

This question comes up frequently. I've never seen anyone link 6:1 heads to premature bearing failure. When you get up to 7:1 or 8:1, that's where folks start to recommend pressurized oil or stronger bearings.
alexiskai is online now   Reply With Quote
Sponsored Links (Register now to hide all advertisements)
Old 02-09-2020, 03:14 PM   #3
Gary WA
Senior Member
 
Gary WA's Avatar
 
Join Date: May 2010
Location: Clinton,WA/Whidbey Island
Posts: 3,094
Default Re: High compression engine life.

Same here no problems!
Attached Images
File Type: jpg cars.jpg (66.3 KB, 18 views)
__________________
www.whidbeymodelaclub.com
Gary WA is offline   Reply With Quote
Old 02-09-2020, 04:03 PM   #4
chrs1961815
Senior Member
 
chrs1961815's Avatar
 
Join Date: Jul 2018
Location: Spring Grove, Illinois
Posts: 613
Default Re: High compression engine life.

I have wondered this too as well but it looks like it is not a problem.
__________________
"The more things change, the more they stay the same."
chrs1961815 is offline   Reply With Quote
Old 02-09-2020, 04:50 PM   #5
Russ/40
Senior Member
 
Russ/40's Avatar
 
Join Date: May 2010
Location: Santee, California
Posts: 3,107
Default Re: High compression engine life.

Even if it lead to shorter bearing life, i wouldn't hesitate to use the 6.1 head. The contribution to better drivability in today's traffic is impressive. It's like my "A" is much happier!
Russ/40 is offline   Reply With Quote
Old 02-09-2020, 05:26 PM   #6
kenparker
Senior Member
 
kenparker's Avatar
 
Join Date: May 2010
Location: Van, Texas
Posts: 1,076
Default Re: High compression engine life.

Over 30,000 miles on a 5.9 head and she is still running strong. blue coupe.
kenparker is offline   Reply With Quote
Old 02-09-2020, 09:39 PM   #7
Purdy Swoft
Senior Member
 
Purdy Swoft's Avatar
 
Join Date: May 2010
Location: Alabama
Posts: 7,638
Default Re: High compression engine life.

've been running a 5'9 compression head for 23 years on our black 31 standard coupe with no problems . I did install a set of rebabbited connecting rods when the engine was overhauled prior to the installation of this higher compression head .
Purdy Swoft is online now   Reply With Quote
Old 02-09-2020, 11:30 PM   #8
Phil Brown
Senior Member
 
Phil Brown's Avatar
 
Join Date: May 2010
Location: Santee Calif.
Posts: 180
Default Re: High compression engine life.

It's not so much the compression as it is running with too much spark advance with the extra compression. The over advanced timing causes detonation and that's what hammers out the bearing material. Babbit and insert both will suffer the same fate.
Phil Brown is offline   Reply With Quote
Old 02-10-2020, 12:05 AM   #9
J Franklin
Senior Member
 
J Franklin's Avatar
 
Join Date: May 2010
Location: oregon
Posts: 4,136
Default Re: High compression engine life.

Your foot plays a big part in bearing wear too.
J Franklin is offline   Reply With Quote
Old 02-10-2020, 12:31 PM   #10
Jim Brierley
Senior Member
 
Join Date: Jun 2010
Location: Temecula, CA
Posts: 3,132
Default Re: High compression engine life.

What Phil Brown says is right on! I run B blocks with C cranks, and have 2 that are all babbitt and stock oiling, both have been run in my speedster. One was first run in my wide-bed for many years and miles, with a 7.5:1 Cyclone head. That one got its peak HP at 3900 RPM on the dyno, the other has been run at hill-climbs at 4100 RPM, with no problems. The theory is that the bearings ride on a thin film of oil, not directly on the babbitt. Rods do not hold up as well as mains, but are good for many, many miles.
Jim Brierley is offline   Reply With Quote
Old 02-10-2020, 12:50 PM   #11
Cape Codder
Senior Member
 
Cape Codder's Avatar
 
Join Date: May 2010
Posts: 1,025
Default Re: High compression engine life.

When I had my motor rebuilt some 11,000+ miles ago I also wanted to install a 5.9 High Compression Head on it. When I received the head it was TOO short for my liking (i.e. 1/8" in front and 1/8" in rear) so I returned it and was told I could have another. Well, the NEW? one was the same measurements, so I returned it for a full refund including shipping! Some time later, maybe a year and a half, I ordered another from the same dealer (because of the refund) and this one fit BUT both sides of the head were so badly GOUGED from what I assumed was the grinder they used to remove the slag. I returned it again, and again I received a full refund including shipping. I have to say that I dealt with Synders! I have since ordered numerous small parts from them with no problems.

My QUESTION is has anyone ordered a new head recently and been happy with it (i.e. appearance wise)?
Cape Codder is offline   Reply With Quote
Old 02-10-2020, 01:09 PM   #12
Terry Burtz, Calif
Member
 
Join Date: May 2010
Location: Campbell,CA, USA
Posts: 75
Default Re: High compression engine life.

Cast iron shrinkage from molten to solid is roughly 1/8 inch per foot, so what you are seeing is a new cast iron part that used an original part for the pattern.
Terry Burtz, Calif is offline   Reply With Quote
Old 02-10-2020, 02:38 PM   #13
Russ/40
Senior Member
 
Russ/40's Avatar
 
Join Date: May 2010
Location: Santee, California
Posts: 3,107
Default Re: High compression engine life.

Terry, I purchased a 6.1 head from Snyders around late September last year. My experience was the front of my head is just under 1/8" short of the block. No problem, as I'm not that finiky. I got what i wanted, and that is PERFORMANCE. Love it. Curious as to why it would be that short.
Russ/40 is offline   Reply With Quote
Old 02-12-2020, 11:02 AM   #14
M2M
Senior Member
 
M2M's Avatar
 
Join Date: Jul 2012
Location: AUSTRALIA/USA/EU/RUSSIA
Posts: 953
Thumbs down Re: High compression engine life.

People should reply with miles they've done not years they've had. 20+ years means little if you only do 200 miles a year on average.
__________________

M2M is offline   Reply With Quote
Old 02-12-2020, 11:22 AM   #15
Benson
Senior Member
 
Benson's Avatar
 
Join Date: May 2010
Posts: 1,978
Default Re: High compression engine life.

Don't worry about it ...



I installed a Police Head (5.2) in 1963 on an old worn out Model A engine with loose rods (which I pulled shims to tighten up) and drove it 42,000 miles.



Also during this time I used:


1. 8.25 Thomas
2. 6.50 Lion III head



Driven daily from 6,000 to 8000 feet (60 + miles a day) and from 8000 to 12000 feet on weekends. Speed was 50 to 60 MPH. These engines were not "babied".

Engine still runs fine. Just wanted B engine's extra power.

Engine replaced with rebuilt babbitt B block with "C" crank using same head. Have put 20,000 + on that one since that time.

Last edited by Benson; 02-12-2020 at 01:51 PM.
Benson is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Sponsored Links (Register now to hide all advertisements)


All times are GMT -5. The time now is 07:56 PM.