How to manage HIGH COMPRESSION ?

[ron hausmann]

All -

    I have a freshly overhauled 6 cylinder engine in my 1918 Kissel. It’s a six volt system. Head and block were milled and new pistons and modern rings installed. It ran very well then on an engine stand at my overhauler. 

    Now the engine is in the car, the engine struggles to crank, even with a brand new 700-cranking amp 6v battery, and even with two Six volt batteries in series. The batteries test fine and the starter tests fine. Very, very tight. 

     When we hook the starter directly to a 12 volt marine battery, she cranks well and starts. My mechan8c friends say that the engine is “tight” because it’s brand new and not “broken in”, and because we increased the compression by milling the head. Once started the engine runs just beautifully and smoothly at various revs.

     How can this problem be fixed? Will running the engine for hours help break in. Should we carry around or jury rig a 12 volt battery starting system on it until the engine wears in. 

     Any advice will be appreciated.

     Ronald n Hausmann P.E.

[jackofalltrades70]

Have you tried new cables and cleaning the connections very well at starter and ground?  

Matt

[Matt Harwood]

I think your friends are somewhat correct about tolerances being a little tighter than they will be after break-in, but I don't know that it would affect starting significantly. Possibly, but that would have to be a VERY tight engine. I doubt you raised the compression enough to be a factor, either--whatever it is, there were cars with more compression in the '40s and '50s that started just fine on six volts. Matt's advice is always my first bit of advice, too. Big (00 gauge) cables and clean grounds, plus an extra ground from the starter to the battery's ground point on the frame often reduces or cures hard starting on 6V cars. I used two 6V Optima batteries with new cables and good grounds and The Car Which Shall Not Be Named fired up instantly, hot or cold, and that was 414 cubic inches of V12.

 

You probably have a combination of all these issues. If your engine is freshly detailed, make sure there's no paint interfering with the grounds. Same with the frame. I think you're experienced enough as a hobbyist to know about the big cables, but if not, get big cables from one of the vintage wire suppliers (Rhode Island Wiring will make you any battery cable size and type you want). I wouldn't try to use the 12V battery as any kind of solution. It'll spin the starter pretty vigorously but it's not a solution.

 

Finally, some 6V cars just crank slowly. Every single 356 cubic inch Packard straight-8 I've ever had would crank so slow that you'd think it would never start, but they always did. My 1941 Cadillac 60S would crank until you thought it wouldn't start, and then it would fire. Every single time. You just have to get used to what is "normal" for each car, because they won't be the same, even if they're identical cars. It's just the nature of the beast.

 

Hope this helps and please keep us posted on what you find--solving hard start issues is one of the most common topics on this forum and your solution could help someone else.

 

 

Edited August 28, 2019 by Matt Harwood (see edit history)

[Bud Tierney]

From my old shade tree mechanic days "tight" engines were normal, to the point I've seen some that had to be towed  to get them started...but those weren't Classic Car Type engines but well worn beaters/drivers being (hopefull0 temporarily rehabilitated...

I'd be inclined to raise an eyebrow at a professional shop dealing with rare/expensive engines that turned them out so tight they had serious starting problems; I'd expect the shop to

run them in" a bit themselves if it couldn't be avoided...

You might ask the shop what king of voltage they used when the engine started normally in the shop...

It's perfectly true that the engine will "wear in" with driving; it's why new cars in my day came with "break-in" instructions for the first 500 miles or so, but, again, those were mass production engines, not engines turned out individually from a skilled professional rebuilder...

An excessively tight engine could experience damage before comfortably "wearing in"...

[Marty Roth]

Ron,

Do you have 00 or 000 , or welding cable?

or has someone used ordinary 12-Volt style battery cables which will NOT carry sufficient current for a 6-Volt system?

Also, I hope yoour two (2) 6-Volt batterys are wired in PARALLEL which will give more cranking Amps at 6-Volts, NOT SERIES  which would give 12-Volts

 

My early cars (at least some of them) have a pair of Optima 6-Volt batterys side-by-side in the battery box, wired in Parallel, 

and have either Double Aught, or Triple Aught (00 or 000) battery cables,

AND Battery cable ends are Soldered, not Crimped to assure proper Voltage/Amperage

 

Best of luck with your project

[Bob McAnlis]

Ron.  You should be able to use a compression tester on each cylinder to see what psi you are achieving.   That should give forum input on compression worries and either address them or focus on getting full power to the starter as others have suggested above.   

[just me]

Ron

 

Is this a problem hot or cold or both?

 

Charley

[C Carl]

Hi Ron !

Let me take a kick at this can, and add to all the above good advice. Regarding the possibility of compression ratio/pressure being a major factor here : YES, it most certainly MAY be THE major factor. But we on the forum don't have enough data yet to arrive at a definitive conclusion. Therefore I will make a best case assumption, propose an experiment, and offer what I hope is a helpful suggestion.

 

Assumption : Without knowing what your target increase in compression ratio is, let me just assume that you did superb engineering and execution in order to raise your compression. If you were able to bring a 4.X : 1 compression ratio ancient flathead engine up to 6.X : 1 (a remarkable and desirable feat), you would indeed notice the increased demands on the starter. But we don't know how much the compression PRESSURE has been raised through head and block milling, new piston design, and any + or - change by way of cam profile modification, if any. 

 

Experiment : Open 5 primer cups and the throttle, and pull the plug on the remaining cylinder. Measure the compression  and compare to one of your similar unmodified engines tested in the same way. Hopefully there will be quite a difference in pressure. NOTE : As I am winding up my long winded epilog regarding octane vs. compression ratio relationship, Bob McAnlis has anticipated this.

 

Suggestion : Use the current state of the art break in oil. Unless there has been a breakthrough in petroleum engineering since I last checked, that would be the specifically designed Amsoil product. Please look it up, and you will find an interesting and convincing read.

 

Disclaimer : I have absolutely no connection with Amsoil in any way whatsoever. 

 

 

I have written from time to time about the relationship between octane and compression necessities. In order to fully extract all the BTUs from modern 87 octane fuel, you would need a compression ratio up in the 8.X : 1 range. But I don't know any way to achieve this in 90-100 year old flatheads. You can only do the best you can with what you have. In the late 'teens, gasoline was right around 40 octane. Rather sophisticated engineering, and testing facilities with dynamometers, high pressure range manometers, etc., produced 4.X : 1 engines capable of developing maximum BMEP (call it torque if you like), from the 40 octane fuel back then. In order to achieve this level of efficiency, the power stroke must be just shy of preignition,(detonation), during its entire travel ! Yes, detonation can occur at any point in the power stroke depending on a number of factors. Now, running a 4.X : 1 compression ratio engine on comparatively high detonation resistant 87 octane fuel, will preclude this level of maximum efficiency. You quite simply can not develop the BMEP and  HP and efficiency on 87 octane fuel with an engine designed to do so on 40 octane fuel. The only way to approach the original capabilities, is to significantly raise compression. You will not be able to EXCEED the original 40 octane BMEP specs by simply doing this, and you will not want to be running maximum BMEP at all times. But it is good to have it on demand if needed. In any case, fuel, economy will increase, and your exhaust valves will thank you.

 

You remember tinkering around with timing for maximum performance : "advance her till she pings, and back off a few degrees ".

 

I hope this helps you, Ron. Of all the contributors here who I immediately turn to when I see their handle, you are at the very top. Truly fantastic work from a formally trained well organized mind, with a massive amount of hands on experience. If my humble prattlings serve any purpose whatsoever, it will have been a privilege to have done so. Thank you for sharing so much with us.  -   Carl 

[maok]

Try the larger cables. What is probably happening is that your starter needs more torque (amps) to turn the tight engine over, which in turn is dropping your battery voltage down. Lower the battery voltage, slower the turn speed of the starter.

 

PS; starter motor speed is directly related to the voltage applied, not the current/amps.

Edited August 28, 2019 by maok (see edit history)

[Guest]

Did you rebuild your starter.  When I worked in a GM dealership in the '60's we had a terrible convincing customers that if your engine need to be rebuilt your starter did as well.  

[Jubilee]

Post reminds me of the movie “ The Gods Must Be Crazy”. Overhauled a Land Rover and it was so tight the fellow didn’t dare shut it off. No parking brake. All gates at top of hills. Hilarious.

[60FlatTop]

If you have a copper cap tube to a heat gauge or copper line to a dash mount oil gauge just hold your hand on it while you crank the engine. If one gets hot you might find you have an alternate ground.

 

It is an easy test.

[Rusty_OToole]

Can you put a torque wrench on the crankshaft and find out how much torque it takes to turn it, with the plugs out? This is a measure of friction. I remember from an article years ago, about rebuilding an engine, that if it was done right it took 17 foot pounds of torque to turn the engine. Too low or too high, something was too loose or too tight, or out of line someplace. This was on a sixties Detroit V8. If you give the torque reading maybe some more experienced mechanics can tell if it is too tight.

 

C Carl looking forward to the article on compression vs fuel octane. No doubt you know, that you can lower octane by mixing some kerosene with the gas. Most low compression engines from the teens and twenties respond well to this, develop more power, run smoother and cooler etc.

[padgett]

Higher compression/octane usually needs more advance. If the crank suddenly hesitates then there is probably not enough spark advance. Other comments are great just had not seen this one.

[ron hausmann]

11 hours ago, Rusty_OToole said:

Can you put a torque wrench on the crankshaft and find out how much torque it takes to turn it, with the plugs out? This is a measure of friction. I remember from an article years ago, about rebuilding an engine, that if it was done right it took 17 foot pounds of torque to turn the engine. Too low or too high, something was too loose or too tight, or out of line someplace. This was on a sixties Detroit V8. If you give the torque reading maybe some more experienced mechanics can tell if it is too tight.

 

C Carl looking forward to the article on compression vs fuel octane. No doubt you know, that you can lower octane by mixing some kerosene with the gas. Most low compression engines from the teens and twenties respond well to this, develop more power, run smoother and cooler etc.

 

Rusty,

this car has primer cups so with them open, I have cranked it and now I will put a torque wrench on it.

ron

[ron hausmann]

All,

    Thank you for your very sage advice !!

    I will first add/change all the cables to 00 or 000 size. I have a cutoff switch in the car which might have smaller cables which would contribute to the problem .

    Then I will check all the grounding connections. It’s a positive ground car. My grounding is to the engine which was freshly painted and I’m wondering if the contacts were on partly painted surfaces. 

    We will see if these two actions help cure the problem.

    Thanks, Ron 

[Rusty_OToole]

Paint can act as insulation. You may need to scrape off the paint under the lug for best connection.

[Restorer32]

I see you resorted to the "plumbing fixture" solution to the wiring tube and carb crossover problem. We did the same on the Kissel we restored but replaced  them after we bought a tubing bender for a different project.

[carbking]

Not that it will help your situation, other than possibly a good laugh:

 

I have an early John Deere that is hand cranked. This one is early enough, Deere hadn't figured out compression release petcocks were a good idea. When I was much younger, I could crank it. Now it is parked facing downhill on a good grade!

 

Jon.

[Ronnie]

On 8/28/2019 at 8:11 AM, ron hausmann said:

I have a freshly overhauled 6 cylinder engine in my 1918 Kissel. It’s a six volt system. Head and block were milled and new pistons and modern rings installed. It ran very well then on an engine stand at my overhauler. 

    Now the engine is in the car, the engine struggles to crank,

 

I know nothing about these engines so pardon me if I show my ignorance.  From reading what was quoted above, is it possible that something that was added after the engine was installed in the car is causing it to be hard to turn. Like a generator, water pump or fan? Or maybe something about the clutch or transmission?

Edited August 30, 2019 by Ronnie (see edit history)

[60FlatTop]

My little story can from a guy who asked why his dashboard glowed red above the oil gauge when he started the car. It turned out that excess tubing was coiled near the gauge and clamped to the back side of the gauge. Due to other issues it was the only path for an electrical ground. It may have been the temperature cap tube, but the message is the same. Expect the unexpected.

 

Back in the early 1980's I taught Adult Ed nights in a High School trades shop. While explaining HVAC electrical circuits I put my meter on a white neutral wire explaining it would read zero. There was 110V. Unwinding an overhead extension cord reel we found a splice about 20' from the plug. Under the tape; two wires, black to white and white to black. "Trust, but verify"

 

 

 

 

[Rusty_OToole]

1 hour ago, 60FlatTop said:

My little story can from a guy who asked why his dashboard glowed red above the oil gauge when he started the car. It turned out that excess tubing was coiled near the gauge and clamped to the back side of the gauge. Due to other issues it was the only path for an electrical ground. It may have been the temperature cap tube, but the message is the same. Expect the unexpected.

I had a similar problem in the seventies on an Olds powered Willys hot rod. One day the choke cable got red hot and melted off while driving along.

[Rusty_OToole]

On 8/28/2019 at 9:53 PM, padgett said:

Higher compression/octane usually needs more advance. If the crank suddenly hesitates then there is probably not enough spark advance. Other comments are great just had not seen this one.

I always thought high compression required less advance? I would try timing the ignition to TDC or 1 or 2 degrees after, for easy starting. You can always adjust it again later when the engine is broken in. Later timing will  be easier on the engine while breaking in .

Edited August 30, 2019 by Rusty_OToole (see edit history)

[Rusty_OToole]

On 8/28/2019 at 8:11 AM, ron hausmann said:

The batteries test fine and the starter tests fine. Very, very tight. 

I'm curious what you mean by this, especially the very very tight part?

[Rusty_OToole]

On 8/28/2019 at 7:46 PM, 60FlatTop said:

If you have a copper cap tube to a heat gauge or copper line to a dash mount oil gauge just hold your hand on it while you crank the engine. If one gets hot you might find you have an alternate ground.

 

It is an easy test.

A 1918 car would have the engine bolted solid to the frame, no rubber motor mounts. They weren't invented for another 14 years.

[Walt G]

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

[60FlatTop]

I'd make sure some fertile mind didn't get the idea to slip a cushion in there. It has been 100 years.

 

If I saw a folded over inner tube piece foe an insulator I would imagine the proud perpetrator standing back with his thumbs hooked in the suspenders of his bib overalls admiring the job.

 

And a restoration shop searching for one.

 

Once I had a boiler operator trying to find the wooden plug that started dripping on his 40 year old boiler. It was on the low water safety cut out. Turned out to be the shipping plug to keep the float secured.

[Rusty_OToole]

4 hours ago, 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

That is the car I was thinking of, except I thought the 1932 model was the first with Floating Power (per Wikipedia). 1918 + 14 = 1932. What the hell difference does it make if it was 14 years or 12 years or 6 months, the point is, no 1918 car had rubber mounted engine. All were bolted to the frame, although some early cars used a sub frame, but it was still grounded to the frame.

 

I might add, the first Floating Power models used steel coil springs which would ground the engine. The next year they went to rubber mounts. So even if I'm wrong I'm right.

Edited August 30, 2019 by Rusty_OToole (see edit history)

[Walt G]

The difference is that I just hope to set the correct year for historical sake, nothing more - just from personal experience and observation . Accuracy that's all. Nothing to get angry over is it?  I guess your final sentence tells us all a lot as well.

Edited August 30, 2019 by Walt G
typo (see edit history)

[ron hausmann]

Rusty -

     By “very very tight” in my question, I mean the engine itself. With the Kissel primer cups open, I can crank it pretty easily, but when they are closed, it’s very, very hard for me even to rotate it; tight !

 

All -

    I thank you all again for your input. The car has no rubber cushions and should not. I’ve restored it to correct details. But I will disconnect all battery cabLes and check for paint or anything that isn’t shiney metal-to-metal.

    Also, I’ve ordered 00 heavy duty battery cables which are available from a few websites. I will replace ALL the battery cables that I have on with these HD cables as many of you have suggested.

    With these two adjustments, and a fully charged new battery, then I’ll see if she turns over better. I’ll keep you all informed.

    Thanks again. Ron Hausmann P.E.

[W_Higgins]

You mentioned having a disconnect in the circuit.  Remove that for the duration of your testing.  I've seen those, both new and old, cause resistance issues.

[C Carl]

1 hour ago, ron hausmann said:

With the Kissel primer cups open, I can crank it pretty easily, but when they are closed, it’s very, very hard for me even to rotate it; tight !

 

 

 

Well, then : as per the title of this topic, how high did you raise the compression.   -   Carl 

[ron hausmann]

Alot

[ron hausmann]

My other three driver-Kissels being readied for show next weekend. Nothing to do with this post except that these are very rare Kissel Kars also.

ron

[Rusty_OToole]

Very good information. So it seems the root of the problem is the high compression not excess friction. Do you know how high the compression ratio is? Have you done a compression test? It doesn't seem reasonable that you could raise it so high the starter won't turn the engine over. Maybe it turns over, but not fast enough? 6 volt cars used to turn slow. One like yours, might only turn as fast as a man could hand crank it. This did not prevent starting, if the timing was late enough and everything else working right. I see your engine has a very long intake pipe. This can't be good for starting, do you have to prime the cylinders when it is cold?

 

As a last resort there are special 12v-6v batteries available that start on 12v and switch to 6v for running. Basically a divided battery with Ford starter relays to switch connections. You could do something similar with your 2 6v batteries.

[Grimy]

Try a pair of 6V Optimas wired in parallel, borrow a pair to see if they improve your situation.  (If you have any local Pierce guys, they'll be a convenient source.)  The Optimas will spin Pierce 8s and 12s VERY fast, although the primary reason I run pairs in my three 8-cyl Pierces is for Reserve Capacity (RC) for long runs with lights on given 25 amp generators that fall to 17 amps once the temp regulator kicks in after 8-10 minutes.  A pair of Optimas fits easily into a Group 3 battery box and maybe a generous sized Group 2.  For judging, there is a vendor selling a mock standard battery case into which one fits the two Optimas.  From their website, dimensions of EACH Optima red-top 6V starting battery is 10" long x 3.55" wide x 7.81" tall.  Further, I never put a float charger on them--they will hold enough charge for 5-6 months to start in the spring.

 

The fast starter spin is an added benefit for me, but may be the solution to your problem.

 

I've been using Optimas exclusively for over 20 years.  They last a very long time, there is no need to fill or check electrolyte level, and the terminals don't corrode--ideal for underseat / underfloor battery locations.

 

I have no affiliation with them, just a delighted customer.

[60FlatTop]

16 hours ago, ron hausmann said:

 By “very very tight” in my question, I mean the engine itself. With the Kissel primer cups open, I can crank it pretty easily, but when they are closed, it’s very, very hard for me even to rotate it; tight !

 

Just curious if you have opened individual primer cups to see if the result changes by cylinder or number of cylinders relieved.

How many cups closed makes the difference between pretty easy and very hard? And which ones?

Bernie

[padgett]

" thought high compression required less advance?" Good question. Actually the compression itself has little to do with advance (particularly if have direct injection but that is later). The problem with higher compression is that detonation becomes more likely. To avoid detonation you go to a higher octane which burns slower and requires more advance to complete combustion at the "sweet spot", 5-10 degrees ATDC. It is the octane of the gasoline that determines the proper advance for a specific RPM (time to burn is a constant so a higher RPM also requires more advance. (Lets not get into the slower flame propagation rate as the manifold vacuum increases hence the need for "vacuum advance").

[LARRYCAROL]

You should try a voltage drop test. Attach digital volt meter, pos to engine bock, neg to battery post. Crank engine & watch reading. Should be less than tenth of volt. You can move leads around to plan point where drop ls. Same for pos side. Battery post (positive) to starter post. We used this method my vow shop for years. Old bugs would burn throttle &heater cables if engine ground was bad. We had trouble with sciroccos losing spark when cranking in cold weather also. Resitance between trans mount & trans case(ground cable @ mount) caused back feed to stop spark but starter still worked. Hope this helps.

[Ronnie]

On 8/28/2019 at 8:11 AM, ron hausmann said:

Head and block were milled and new pistons and modern rings installed.

Was the head CCed after it was milled to determine the new compression ratio?  If the ring groves are higher on the piston compared to the old pistons you may have increased the compression ratio more than you calculated.   If the work you did to the engine resulted in a compression ratio that is too high, could you run two head gaskets to lower it some?