Dip

F

Flat32

Member
Concerned with how deep the rods dip into the oil that will be in my dipper tray so I measured. Turns out the rod dippers extend 3 13/16" below the pan rail and the dipper tray is 3 9/16" down from the pan flange without gasket. If I allow 1/16" for the gasket the dippers only dip 3/16". Is this correct??

Seems like it should be more considering the relatively short arc length of the dip and the relatively huge, deep depressions in the pan.

My initial concern was more to make sure the dippers weren't going to hit the bottom. I wasn't expecting what i found.

Thanks,

Ray:confused::confused:
 
I've never made the measurements you have.. But look at how long the dippers are.. You only want the dippers touching the oil, not the rod ends themselves.. I think its surprising how much oil those dippers can grab and how much pressure that generates..
 
Understand, the depth of the oil in the tray is deeper than the trough. The oil will build to the level at the rear of the tray before it returns to the pan bottom. Ford had a problem with this causing a fog inside the crankcase and oil creeping out the filler tube. To combat this he changed the design of the baffles in the filler twice and eventually returned to the original type so, 3 different tries before enlarging the tube to approx 2 1/4" for the 32 model. When he found the change to the tube did not work he installed holes in the tray flat so as to drop the level of oil in the tray. These holes started as 4 7/16" holes in each corner but had a fifth added soon after. When this still didn't do the job he increased the diameter of the holes to 1" which worked better and was the end of the modification. After this the V8 was modified for pressure which eliminated the need for the tray and solved the problem to an extent. Even after this, the problem plagued him and others so, the road tube was invented with an internal baffle that effectively solved the problem.
 
Last edited:
The rear edge of my tray is flat, no turned up edge. I pretty much know the engine will run with the parts as is and I guess the oil splashing around in the crankcase is a major contributor to rod oiling through the two top rod holes, but I don't know what the rpm limit is for this type oiling system and how critical the dip depth might be.

I can envision, starting out quickly the oil sloshing toward the rear and right off the tray to a substantial degree leaving the level in the depressions somewhat lower and with the refilling dependent on what runs down from the valve chamber it seems iffy to me.

I'm fairly certain there will be oil on the bearings even if the dippers didn't catch any for a few revolutions, but at around 2500 rpm overheating the bearing surfaces becomes an issue. Pressurized systems provide cooling that the dipper system can't.

Is there a min and max for dipper depth or any discussion related to it? Or is there a known rpm limit specified by Ford or found via years of experience?

I'll live with whatever this dip and splash system will allow.

It's just that I don't want to screw up with the non OEM parts combination I'm assembling.

I'd feel better if the dippers were a little longer and there was a little more rod side clearance, But I'm not about to go experimenting with a system I know so little about.:o

Ray
 
Flat32 said:
The rear edge of my tray is flat, no turned up edge. I pretty much know the engine will run with the parts as is and I guess the oil splashing around in the crankcase is a major contributor to rod oiling through the two top rod holes, but I don't know what the rpm limit is for this type oiling system and how critical the dip depth might be.

I can envision, starting out quickly the oil sloshing toward the rear and right off the tray to a substantial degree leaving the level in the depressions somewhat lower and with the refilling dependent on what runs down from the valve chamber it seems iffy to me.

I'm fairly certain there will be oil on the bearings even if the dippers didn't catch any for a few revolutions, but at around 2500 rpm overheating the bearing surfaces becomes an issue. Pressurized systems provide cooling that the dipper system can't.

Is there a min and max for dipper depth or any discussion related to it? Or is there a known rpm limit specified by Ford or found via years of experience?

I'll live with whatever this dip and splash system will allow.

It's just that I don't want to screw up with the non OEM parts combination I'm assembling.

I'd feel better if the dippers were a little longer and there was a little more rod side clearance, But I'm not about to go experimenting with a system I know so little about.:o

Ray
Click to expand...
How do you know the rear edge is flat? Have you had the pan off and looked at it? If it is it is modified in a way it shouldn't be. I am not saying it is wrong any more than drilling holes in the tray was when ford did it. If it is flat how was it done? cut off, hammered flat? You don't want to damage your OEM parts but, have a modified part that possibly could in some opinions.

As for the dippers being too short, they have run this way in motors at more RPM's and for many more years than any stock Model A engine you or most here could ever imagine.

The rods are not oiled through the holes in the top of the big end, These holes are for splashing oil onto the cylinders from the dippers . The oil is picked up at the dipper forced through the grooves to the wells at the side of the parting line and up to the holes in the top of the big end where it is sprayed onto the cylinder walls. The rods and dippers also create a fog which lubricates everything in the crankcase including the wrist pins which have 2 small holes in the top of the rod which collects this fog and lubricates the pin same way the Model T lubricated the entire rotating assembly. The T had no oil pump, no dippers, and no tubes from a reservoir in the valve chamber. These T engines will astound you with the way they will run and how dependable they are.
 
Pan is off and I have 3 B trays, no A tray for comparison. Rear edge is not turned up except for short distance at each corner where the side upturned flange comes around. Pictures posted on this forum previously show exactly what I have.

been looking on Vince Falter's website for info.

What would you say is the rpm limit for a B engine??

Thanks,

Ray:)
 
Flat32 said:
Pan is off and I have 3 B trays, no A tray for comparison. Rear edge is not turned up except for short distance at each corner where the side upturned flange comes around. Pictures posted on this forum previously show exactly what I have.

been looking on Vince Falter's website for info.

What would you say is the rpm limit for a B engine??

Thanks,

Ray:)
Click to expand...
Factory limits
Model A- 2600 RPM
Model B- 2800 RPM

Max RPM's
3500-4000 either
Some will say more but we all have our opinions.
 
James: I have not seen those (or any) figures before, can I ask the source? Not arguing, really. Just curious and asking. I regularly run in the 24-2500 range and recently tore down the A engine and the bearings are pristine.
 
James, I have not seen those, or any, figures before, can I ask the source? Not arguing, really, just curious and asking. I regularly run in the 24-2500 range and recently tore down the engine (A) and the bearings are pristine.
Jim Brierely told me he will run 4000 in a hillclimb, so I accept that as my personal redline.
I met an old timer who has some neat A stuff. He says that back in the day the hot rod guys would open up the dippers with a file. He is a retired aeronautical engineer who designed rockets for Lockheed (a real rocket scientist) and is a lifelong A man, so I decided to try it. The photos (I hope) show the before and after dippers I did this winter with a Dremel tool. I dont know how much this will help, but as Herm once said, I never heard of a bearing failure from too much oil.
He also drills out the main bearing bolt holes to 9/16 and uses close tolerance aircraft bolts. Increased clamp and stability. I was going to do that too until I checked out the price of close tolerance aircraft bolts. He must have gotten his wholesale from Lockheed.
 
Last edited:
PC/SR said:
James, I have not seen those, or any, figures before, can I ask the source? Not arguing, really, just curious and asking. I regularly run in the 24-2500 range and recently tore down the A engine and the bearings are pristine.
Click to expand...
These are numbers that have been run by me since I have been building A and B engines but you can see more here:
http://www.modelaengine.com/02.html

These are not limits but HP RPM. Max limits could vary and I know they won't be much more than these.
 
Years ago an SAE engineer did some testing on his own on a stock Chevrolet 6 with babbit bearings and dip oiling. He was trying to determine at what rpm the groove cut in the oil by the dipper would not refill between revolutions. With the oil he was using it was about 4000 rpm and the oil pressure generated at the bearing surface was 40 psi.
This was all noted in a paper he presented at an SAE meeting.
 
Pete said:
Years ago an SAE engineer did some testing on his own on a stock Chevrolet 6 with babbit bearings and dip oiling. He was trying to determine at what rpm the groove cut in the oil by the dipper would not refill between revolutions. With the oil he was using it was about 4000 rpm and the oil pressure generated at the bearing surface was 40 psi.
This was all noted in a paper he presented at an SAE meeting.
Click to expand...
I had heard the max RPM before starvation was 4000 but heard the max psi was more. 40 PSI is still plenty.
 
I have a set of rods that came out of a modified B engine that had the tray reservoir depressions cut away to be open to the sump. The dippers had been drilled out and threaded for the installation of threaded tubing that resulted in dippers that are about 1.5 inches long. The dipper tubes were machined on the ends to have angled scoops. I have no idea why this was regarded as an improvement but the bearings seem to have not suffered for this modification. Otherwise, the babbitt was poured and finished in the usual manner. Has anyone ever seen or heard of this mod?
 
ursus said:
I have a set of rods that came out of a modified B engine that had the tray reservoir depressions cut away to be open to the sump. The dippers had been drilled out and threaded for the installation of threaded tubing that resulted in dippers that are about 1.5 inches long. The dipper tubes were machined on the ends to have angled scoops. I have no idea why this was regarded as an improvement but the bearings seem to have not suffered for this modification. Otherwise, the babbitt was poured and finished in the usual manner. Has anyone ever seen or heard of this mod?
Click to expand...

It sounds like if they cut the bottoms of the windage tray away to access more oil, thats why they extended the dippers to 1 1/2 inches.

Also, the two web holes in the tops of the rods, on any X grooved rod, is for moving oil through the rod, or it would be air locked on the top X. No X grooves. no web is drilled. Herm.
 
Never heard of the mods that ursus talks about but I have seen squirters plumbed in like a Chevy is. I have run my B engine/C crank to 4300 on the quarter mile track but still think 4,000 should be the max. If you are going to run more than that, it is time to go to full pressure with a drilled crank.
 
Jim, ever seen rods that had inserts in the rod half and babbittin the cap? I have a set I removed from a running engine tho, not very well. This motor came from south Florida and had .010 shims under the main inserts (not at the parting line) and used some insert I have never seen nor could identify. This is a good advertisement for the new inserts out now. At least you can identify where the bearings came from and replace them.
 
I have seen several H&H (I think) engines with insert rods that had standard length dippers made from threaded tubes like you discribe. No mods or cuts to the dipper tray in any way.

But on one engine the threaded tubes on all four con rods had come unscrewed and were laying in the dipper tray. It made the loudest noise I ever heard a running engine make!

Engine was recent rebuild and low mileage.




ursus said:
I have a set of rods that came out of a modified B engine that had the tray reservoir depressions cut away to be open to the sump. The dippers had been drilled out and threaded for the installation of threaded tubing that resulted in dippers that are about 1.5 inches long. The dipper tubes were machined on the ends to have angled scoops. I have no idea why this was regarded as an improvement but the bearings seem to have not suffered for this modification. Otherwise, the babbitt was poured and finished in the usual manner. Has anyone ever seen or heard of this mod?
Click to expand...
 
You must log in or register to reply here.
Back
Top