Jump to content

How to manage HIGH COMPRESSION ?


ron hausmann
 Share

Recommended Posts

I find it hard to believe you could raise a 1918 engine's compression ratio to where it won't start and run on today's regular gas. Original compression ratio, probably about 4.5:1. If you did every trick in the book you might get it up to 5.5.

 

Of course a fresh engine is going to be harder to start, but if the starter, battery and wiring are in top shape it should start no problem.

 

As a last resort you could put a starter switch by the hand crank, turn on the starter and give it some assistance.

  • Like 2
Link to comment
Share on other sites

On ‎8‎/‎30‎/‎2019 at 12:36 PM, Walt G said:

Rusty, the 1931 Plymouth model PA that I had as my first car in the early 1960s had rubber engine mounts , I had to have them replaced as they had hardened and deteriorated. Chrysler called them "floating power" and that was prevalent in their advertising from day one, and they even had a special separate sales piece to explain to perspective customers what it was. So those rubber mounts were on the first cars sold which I am guessing started in the latter part of  1930 .

WEG

 And your 31 Franklin had rubber engine mounts in the rear. Series 15 parts book lists that type frame for all Series 153, except Speedster and Pirate models. 

 

Paul

Link to comment
Share on other sites

How high ? "A lot", doesn't help us help you.  I've raised 5.1:1 compression engines to 7:1 and it made no noticeable difference to the starter motor, even before the motor was broken in.  If you can't measure actual compression ratio with a graduated cylinder, then compression test numbers can be converted close enough to know if it's really high enough to give an educated guess that that's giving the starter motor grief.

 

Have you tried hand cranking with the plugs out, like Cheezstaak asked ?

 

Were the rings file-fit type and someone didn't file them to the proper gap ? Seen that bind up an engine that it was insisted that the pistons had the right clearance, (but no one thought to ask about the rings).

 

Were the main bearings align bored, or not ? If they don't line up with the exact same center axis - even with the correct clearance at each bearing - it will make it tough to turn the crankshaft.

 

Paul

Link to comment
Share on other sites

  • 1 month later...

All - thought I would put closure to this thread on compression and electrical.

    Dumb me !!! I replaced all cables with new 00. Cables but while doing do, figured out the problem. I had the 6V grounded directly to the starter bolt. What I failed to understand is that the starter is bolted only to the clutch housing cross piece which, on a Kissel, is an aluminum casting, not steel. So the entirety of everything was grounded ultimately to aluminum. 
      I’ll start it tomorrow. I grounded it now to the cast iron engine block.

      Dumb Ron 

Link to comment
Share on other sites

1 hour ago, ron hausmann said:

All - thought I would put closure to this thread on compression and electrical.

    Dumb me !!! I replaced all cables with new 00. Cables but while doing do, figured out the problem. I had the 6V grounded directly to the starter bolt. What I failed to understand is that the starter is bolted only to the clutch housing cross piece which, on a Kissel, is an aluminum casting, not steel. So the entirety of everything was grounded ultimately to aluminum. 
      I’ll start it tomorrow. I grounded it now to the cast iron engine block.

      Dumb Ron 

Aluminum conducts electricity with much less resistance than does iron. ...bob

Link to comment
Share on other sites

BTW many house with aluminum wiring also had fires (mainly caused by aluminum's tendency to flow under very high pressure which resulted in resistive connection. It cost me $200 extra when I had my house built back then for all copper wiring.

 

That said I would not be concerned about a large casting.

Link to comment
Share on other sites

On 8/30/2019 at 6:02 PM, ron hausmann said:

Alot

 

Ok, in case you don't know, when you do the compression test the engine must be spinning quickly, so you should either use the marine battery or open the cups? or remove the plugs to reduce the compression in the cylinders you are not testing. 

 

I can assure you that if you have around 160 psi of compression or more, you will have at lest some detonation even on 91 octane, so this will need to be addressed. You may even have some if the compression is as low as around 145 if it has a short duration cam.

 

Also, if it does it cold as well as hot, it may turn over a little easier if you retard the initial timing a little, by maybe around 3 degrees and try that as a test only for now.

 

Edited by barnett468 (see edit history)
Link to comment
Share on other sites

On 9/1/2019 at 7:32 PM, Rusty_OToole said:

Original compression ratio, probably about 4.5:1. If you did every trick in the book you might get it up to 5.5.

 

 

 

10 minutes ago, barnett468 said:

 

Ok, in case you don't know, when you do the compression test the engine must be spinning quickly, so you should either use the marine battery or open the cups? or remove the plugs to reduce the compression in the cylinders you are not testing. 

 

I can assure you that if you have around 160 psi of compression or more, you will have at lest some detonation even on 91 octane, so this will need to be addressed. You may even have some oif the compression is as low as around 145 if it has a short duration cam.

 

Also, if it does it cold as well as hot, it may turn over a little easier if you retard the initial timing a little, by maybe around 3 degrees and try that as a test only for now.

 

 

Compression testing is done with all holes open.

 

160 psi ? Not on any flathead. Read and heed our great friend Rusty'. These 'teen machines were designed to run on gasoline of about 40 octane. Way I learned it, cranking compression pressure  is LOWER with LONG duration "bumps", all other things being equal. Long duration camshafts have more overlap. They are particularly suited to higher revs, where fluid dynamics rule for increased volumetric efficiency.

 

Did we ever learn the results of the Kissel's compression test ?   -   Carl 

  • Like 1
Link to comment
Share on other sites

To check all your electrical connections, use a VOA meter and perform a voltage drop test at each connection including your grounding system back to the battery. If you have a voltage drop higher than .2 volts when cranking, the wire or connection is most likely  the problem.

Link to comment
Share on other sites

1 hour ago, C Carl said:

 

 

Compression testing is done with all holes open.

 

160 psi ? Not on any flathead. Read and heed our great friend Rusty'. These 'teen machines were designed to run on gasoline of about 40 octane. Way I learned it, cranking compression pressure  is LOWER with LONG duration "bumps", all other things being equal. Long duration camshafts have more overlap. They are particularly suited to higher revs, where fluid dynamics rule for increased volumetric efficiency.

 

Did we ever learn the results of the Kissel's compression test ?   -   Carl 

 

i just used 160 as a reference.

 

compression is reduced the more advertised duration a cam has because the intake valve closes at a later point. the overlap and lift can also affect it but that's a very lengthy subject. the dynamic compression is a more accurate reference for when detonation etc will occur.

Link to comment
Share on other sites

Yes. Also exhaust can stay open a bit longer for more effective scavenging. With properly tuned intake and exhaust, volumetric efficiency can exceed 100% across a given rpm range. And dynamic compression is dependent on manifold pressure and the operating torque, or perhaps more accurately, Brake Mean Effective Pressure, (BMEP). Detonation  can occur  at any point of the power stroke. As you say, this is a complicated subject, and it can be difficult for a non-engineer like myself to wrap my head around it.    -    Carl 

Link to comment
Share on other sites

  • 2 weeks later...

     Well With the new 00 cables thruout, and grounding the system directly to the steel block instead of the aluminum clutch housing, the engine cranks very well and continuously until the battery starts to give way.
     So my problem, which is now cured, was either a) too small cables for a new 6v, b) connections not properly tight,  or c) grounding to aluminum instead of steel. Not sure Whitch of these factors was the guilty culprit, but the malady now has been cured. 

     Thanks to all of you for guidance and ideas. 

     Ron Hausmann P.E. 

  • Like 1
Link to comment
Share on other sites

Good to know you figured it out. Probably inadequate cables,  less likely bad connections unless they were loose. After all this was a 'new' engine.  Grounding to the  clutch housing should not be a factor, if the clutch housing is bolted to the engine.

 

Is it starting like a new car now?

Link to comment
Share on other sites

As I mentioned the problem with aluminum is not is conductivity but the issue of keeping the connections tight. Only way I know to explain it is that under pressure Aluminum is liable to flow and must periodically tighten the connections or they become loose/resistive and that generates heat. To a lesser extent, lead (battery posts) does the same thing.

Link to comment
Share on other sites

On 10/29/2019 at 2:29 PM, ron hausmann said:

     Well With the new 00 cables thruout, and grounding the system directly to the steel block instead of the aluminum clutch housing, the engine cranks very well and continuously until the battery starts to give way.
     So my problem, which is now cured, was either a) too small cables for a new 6v, b) connections not properly tight,  or c) grounding to aluminum instead of steel. Not sure Whitch of these factors was the guilty culprit, but the malady now has been cured. 

     Thanks to all of you for guidance and ideas. 

     Ron Hausmann P.E. 

 

If the connections were clean and only lightly tightened, they would easily have a good enough connection, in which case the culprit would have been that one or both of the cables were too small or an original cable with a weak connection on the end fitting was used.

Edited by barnett468 (see edit history)
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...