Author Topic: Flathead V-8  (Read 142463 times)

Offline keith5700

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Re: Flathead V-8
« Reply #600 on: June 22, 2016, 10:31:34 AM »
George, do you pre-heat the engine before trying to start it?
the only way I could get the v8 and the v10 to start the first times was to pre-heat the water to about 50c.
I now have a heating element built into the water tank and always heat the engine before running.
I haven't programmed the Megasquirt for cold starts yet, its bad enough getting v10 to start at all!
Good luck.

Offline gbritnell

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Re: Flathead V-8
« Reply #601 on: June 22, 2016, 12:53:36 PM »
Hi Roger,
This is a full pressure oil system. It has a pump driven off of the rear of the camshaft just like the full sized engine. The oil supply is only in the deepest part of the pan and the rods never get to it like a splash system. When the engine is turning over in the lathe there is no vacuum signal at the crankcase breather tube. The lifter valley has four .156 holes drilled through to the crankcase to vent any pressure that might arise but the engine never starts so there is no blow-by pressure at this point. As crazy as it might seem it is possible that it is spraying so much oil around inside that the rings can't wipe it clean. I have other engines with oil pressure systems and have never had a problem with them so this is an unknown.
Kieth,
I haven't tried preheating the engine prior to starting. I have never had to do this with my other engines, V-8, Holt, six, V-twin etc. so I never gave it any  thought.
Hopper,
I have given some serious thought about what you say. Having worked on engines, both car and motorcycle, over the years and read about combustion chamber design for both 2 and 4 cycle engines there could be some validity, even in model size, in this regard. I currently have 2 sets of full heads and another set of just the combustion chamber side laying on my bench. Like I said I have a pile of extra parts.
Thanks everyone for your suggestions. Believe me I take all of them seriously at this point.
gbritnell
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Offline Mosey

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Re: Flathead V-8
« Reply #602 on: June 22, 2016, 01:47:36 PM »
George,
Please disregard my questions coming from the rank beginner.
I am thinking of putting studs instead of bolts in my engine because the bolts may ruin the threads in the block from taking it apart so many times.
I wonder if there is a handy way of performing a leakdown of my cylinders to find and fix my poor compression? Presently I am using a large rubber syringe to pressurize the combustion chambers, getting 45 seconds of leakdown, pumping in thru an adapter in the sparkplug hole.
Regards and stick to it.
Mosey

Offline gbritnell

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Re: Flathead V-8
« Reply #603 on: June 22, 2016, 02:33:50 PM »
Hi Mosey,
I'm not saying that some sort of leak-down apparatus wouldn't work but for our work on small engines I'm not sure if the reading would be accurate enough to mean anything.
I have miniature compression gauges that I have made and they at least give an indication that the engine even has compression. I have a threaded adapter that goes into the spark plug hole. It is drilled through and then counterbored leaving a seat right near the very tip. A spring loaded ball bearing is inserted into the adapter as a check valve. You need the check valve right at the tip otherwise you're reading some of the volume of the adapter.
Onto this adapter I screw a very small pressure gauge to get my readings. While spinning the engine over the throttle needs to be wide open.
The usual way of checking an engine's compression is the old seat-of-the-pants method. Turn it over and if it feels like it has resistance coming up on compression you're good to go.
gbritnell
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Offline Roger B

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Re: Flathead V-8
« Reply #604 on: June 22, 2016, 03:47:29 PM »
" As crazy as it might seem it is possible that it is spraying so much oil around inside that the rings can't wipe it clean. I have other engines with oil pressure systems and have never had a problem with them so this is an unknown."

This was the direction I was thinking in. I can't imagine that you have suddenly become unable to make good fitting pistons, bores and rings so the next step was to look for too much oil reaching the bores  :headscratch:
Best regards

Roger

Offline Mayhugh1

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Re: Flathead V-8
« Reply #605 on: June 22, 2016, 07:04:19 PM »
George,
I'm not sure I would link the oil control to the no-start problem. I don't think it is at all unusual for the engine to pump oil into the combustion chamber while being spun with an external source. I've seen this on all the engines I've built even though I knew the rings are good. Without combustion pressure to push the rings against the cylinder walls any oil that finds itself above the oil ring eventually works its way into the combustion chamber. Windage will wash each cylinder walls with varying amounts of oil depending on a multitude of factors and the amount of oil pumped into the combustion chamber will likely vary among cylinders. I'd quit focusing on the oil, rings, etc.
With respect to the no-start, you've looked at all the common issues that normally plague us on bringing up a new engine of a known design. Since yours is a brand new design there are more out-of-the-box things to consider. From the symptoms you describe, I think I would wonder if the flame might be getting extinguished before it has a chance to fully propagate throughout the combustion chamber. Widening the plug gap maybe by 50% or more and dumping much more energy into the spark may help launch the flame front. Pre-heating the engine may also help sustain the flame during starting until the engine is broken in and its friction decreases. Spinning the engine during start-up much faster than you already are may also help. Ron Colonna found the cranking speed to be his no-start problem in his one-of-a-kind Novi. At least these are a few 'easy' things to try if you haven't already thought of them. -Terry

Offline Tennessee Whiskey

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Re: Flathead V-8
« Reply #606 on: June 22, 2016, 07:20:31 PM »
" As crazy as it might seem it is possible that it is spraying so much oil around inside that the rings can't wipe it clean. I have other engines with oil pressure systems and have never had a problem with them so this is an unknown."

This was the direction I was thinking in. I can't imagine that you have suddenly become unable to make good fitting pistons, bores and rings so the next step was to look for too much oil reaching the bores  :headscratch:

George,  I wonder if Roger and Terry may both be correct.  Have you built "too good of a pump" Can it be producing too much pressure for everything else to keep up?    I've seen broken springs and stuck relief valves do weird stuff in 1:1 scale

Cletus

Offline steamer

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Re: Flathead V-8
« Reply #607 on: June 22, 2016, 09:33:24 PM »
Check to see if you're pulling oil into the intake somewhere......a hole drilled too deep?.....a bad gasket?.....wouldn't take much
'
I'm having a hard time believing it's coming by the rings....not with you making the parts, and after all the engines you've made.....

Cast a weather eye...maybe even pull the manifold off and crank the pump......It just could be something dumb like that...

Dave
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Offline sid pileski

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Re: Flathead V-8
« Reply #608 on: June 23, 2016, 04:57:32 PM »
George-

I've followed your build with great interest. I know these damn little things can be so frustrating!!
Especially with the level of care you put into your work.

Just an odd thought. What if you were to replace the current oil with a synthetic two stroke oil?
Or, god forbid, drain the oil completely, just to see if you can get it running?
I've build singles wiith open cases and just assembly lube that run for minutes at a time. (I'm certain you have too).

Heck, even full scale engines not under any load will run for who knows how long. I remember HotRod magazine doing
a test on, IIRC, and LS1 engine with no oil to see how long it would last.

Offline Art K

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Re: Flathead V-8
« Reply #609 on: June 23, 2016, 08:41:08 PM »
George,
I can't say that I have any tidbits of knowledge to add. But some of the things that have been mentioned are well thought out and worth checking into. I have on doubt that you will sort it out, and we'll soon be listening to that V8 purrr...
Art
"The beautiful thing about learning is that no one can take it away from you" B.B. King

Offline gbritnell

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Re: Flathead V-8
« Reply #610 on: June 24, 2016, 03:48:47 AM »
Hi Sid,
Believe me I have thought of that! I'm going to continue experimenting until I find a solution. I'll keep everyone informed.
Thanks for all the replies.
gbritnell
Talent unshared is talent wasted.

Offline Mosey

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Re: Flathead V-8
« Reply #611 on: June 24, 2016, 02:28:50 PM »
Udo Gietl, the father of Superbikes, and brilliant engine builder, broke in his R90S BMW engines with no oil in them. Yup, completely dry. These engines won the Daytona Superbike race in 1973-4. I don't know how long he ran them dry, but it could eliminate the oiling/starting problem. Just a thought.
Mosey
« Last Edit: June 25, 2016, 02:30:00 PM by Mosey »

Offline Mayhugh1

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Re: Flathead V-8
« Reply #612 on: August 02, 2016, 06:50:42 PM »
George,
Have you been able make any more progress on your Flathead? Edison once said that learning about the things that don't work is as much progress as learning about the things that do. - Terry

Offline Don1966

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Re: Flathead V-8
« Reply #613 on: October 06, 2018, 06:09:16 PM »
Hi George just wondering if this engine has ever been completed and that I may of missed it.

Don

Offline Doc

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Re: Flathead V-8
« Reply #614 on: October 06, 2018, 07:17:45 PM »
George,
Have you been able make any more progress on your Flathead? Edison once said that learning about the things that don't work is as much progress as learning about the things that do. - Terry

I do like that saying! I always said if you can't admit you made an error you will never learn ( I worked with a guy that never made and error always some one else fault) I can say I don't miss him he was a real pain to deal with.
  But to me half the fun in this hobby is finding out what will not work and discovering  things that by all right shouldn't work but do.