[AT] Spark Plug to Compression Tester adapter

szabelski at wildblue.net szabelski at wildblue.net
Thu Nov 19 06:53:44 PST 2020


Last night I did an internet search on “spark plug heat range” and found some charts showing the differences between various manufacturers. There were also several explanations of what the differences between heat range means, and how the heat range rating between manufacturers don’t always correlate between them since I guess there is no standard. There was also one from an engine builder website that addressed different engine designs and plug installation concerns, as well as indicating that going too hot of a spark plug could result in loss of horse power. Something you may want to consider.

Carl


----- Original Message -----
From: Jim Becker <mr.jebecker at gmail.com>
To: 'Antique Tractor Email Discussion Group' <at at lists.antique-tractor.com>
Sent: Wed, 18 Nov 2020 22:35:27 -0500 (EST)
Subject: Re: [AT] Spark Plug to Compression Tester adapter

I don't pretend to know anything about what you are working on.  Could you 
attach the compression tester in place of the compression release?

Jim Becker

-----Original Message----- 
From: Dean VP
Sent: Wednesday, November 18, 2020 12:02 PM
To: 'Antique Tractor Email Discussion Group'
Subject: Re: [AT] Spark Plug to Compression Tester adapter

Just checked the Auto Zone Web site.  With the exception of one item, none 
offered adapters for spark plug sizes greater than 18MM.  Item CP7821 has 
only one rubber adapter, of unknown size, which in the description says " 
fits all spark plugs" I suspect that too would fit a maximum of 18mm.  Even 
if that rubber adapter would seal in an 7/8" spark plug hole it would not 
work on a hand start tractor very well,  Well, unless you have three hands. 
I suspect the use of 7/8" size spark plugs in new engines went the way of 
the dodo bird several years ago.

Dean VP
Apache Junction, AZ

-----Original Message-----
From: AT <at-bounces at lists.antique-tractor.com> On Behalf Of 
szabelski at wildblue.net
Sent: Monday, November 16, 2020 5:00 PM
To: Antique Tractor Email Discussion Group <at at lists.antique-tractor.com>
Subject: Re: [AT] Spark Plug to Compression Tester adapter

The last time I did a compression test on the Cub, I rented a compression 
test kit from Auto Zone. It had a whole series of adapters that allowed for 
a standard hose to be threaded into the manifold. Don’t know what ranges the 
adapters covered. When you rent a tool from Auto Zone they basically sell 
you the tool, then refund you your purchase price when you bring the tool 
back. That way if you decide to keep it, you’ve already paid for it and they’re 
not any money. Maybe something to look into

Carl


----- Original Message -----
From: deanvp <deanvp at att.net>
To: Antique Tractor Email Discussion Group <at at lists.antique-tractor.com>
Sent: Mon, 16 Nov 2020 18:37:27 -0500 (EST)
Subject: Re: [AT] Spark Plug to Compression Tester adapter

Will doSent from my Galaxy
-------- Original message --------From: Mitchell Daly <md31043 at msn.com> 
Date: 11/16/20  2:15 PM  (GMT-07:00) To: Antique Tractor Email Discussion 
Group <at at lists.antique-tractor.com> Subject: Re: [AT] Spark Plug to 
Compression Tester adapter

Keep us up to date on your project.






Mitch
md31043 at msn.com









From: AT <at-bounces at lists.antique-tractor.com> on behalf of Dean VP 
<deanvp at att.net>
Sent: Sunday, November 15, 2020 11:31 PM
To: 'Antique Tractor Email Discussion Group' <at at lists.antique-tractor.com>
Subject: [AT] Spark Plug to Compression Tester adapter






For those of you who have tractors with 7/8” 18 TPI spark plugs and would 
like to do a compression test with the low cost compression testers kits 
sold today  you are SOL.  All the threaded as well as rubber stopper 
adapters are too small. The biggest is 18MM.
7/8” is equivalent to just over 22mm.  Doing a compression test is 
impossible on a hand start tractor with that set up unless you can buy an 
adapter from 7/8” to one of the metric adapters in the compression tester 
kit.   I just found a company Billman Company  that sells a few of those 
adapters of various sizes including one from 7/8” to 14 mm.


https://brillman.com/?s=spark+plug+adapter&post_type=product



I was thinking I was going to have to make one out of the compression kit 
rubber stopper adapter and braze it into the inside of a gutted sparkplug. 
This is a better solution in my mind.  When I receive this I will be able to 
test the compression on my Hand  start 1935 JD B. Will be able to compare 
cylinders by hand cranking, using a belt on the pulley or pulling it in 
gear.   My current guess is the compression on cylinder # 2  is about half 
of #1 by the feel on the flywheel. We will soon find out.




I also want to make sure that the manifold isn’t rusted out or leaking from 
the intake side to the exhaust side. So I made an adapter plate that fists 
on the carburetor intake side of the manifold and then drilled and tapped a 
¼” Pipe thread and installed a  quick connect air fitting.  With the adapter 
plate bolted to the carburetor inlet to the manifold I can add air pressure 
to the intake side of the manifold.  If things were perfect I should get no 
air leakage into the exhaust side but the intake valves may  open slightly 
and allow air pressure into the combustion chamber.  With the flywheel at 
TDC on #! Cylinder all the valves should be closed.  If I get a bunch of air 
pressure into the exhaust I know I have a manifold problem. If that passes 
then if  the intake  valves open  and I get no leakage out of the exhaust 
side than I know I have a good manifold and two good exhaust valves.  If I 
get some leakage out the exhaust then I probably have exhaust valve 
problems.






Have to get the B out of winter storage here and start doing these tests. I 
brought 4 restored DLTX-10 Carburetors and 4 Magneto’s along so I can 
isolate if either one of those are causing me problems.   I hope I don’t 
have to pull the head on this tractor  but my gut tells me that will be what 
happens as a result of the tests. Pulling manifolds on one of these old 
tractors is an exercise that usually ends up with 4 broken off studs in the 
head.  Broken off bolts don’t scare me like they used to but it takes  a 
whole bunch of time and frustration to get everything cleaned up again ready 
for new studs. .  Maybe for once I will get lucky and not have to do major 
surgery.








Dean VP

Apache Junction, AZ







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