Wheelmang

Rebuild of a 1926 DB 4 Cylinder

Recommended Posts

I know on Dodge 4 cylinder engines like mine the plugs are not over the valves.  They are also not over the pistons either which is a nuisance sometimes when it would be nice to be able to judge TDC.  Again the question of plug reach is probably more relevant on other engines.

 

Ray.

 

 

  • Like 1

Share this post


Link to post
Share on other sites

Thank all for the help. As far clearance I don’t see how there will be an issue. Looks like you could shave at least .125 (not a typo) before any clearance concern. Hope to start this project in the next couple of weeks and will post pictures and progress. Thanks again for all the info.

Paul.

Share this post


Link to post
Share on other sites
36 minutes ago, Wheelmang said:

Thank all for the help. As far clearance I don’t see how there will be an issue. Looks like you could shave at least .125 (not a typo) before any clearance concern. Hope to start this project in the next couple of weeks and will post pictures and progress. Thanks again for all the info.

Paul.

 

Hey Paul,  you need some metal left to keep the water in!🤣

 

Best of luck.

 

Ray.

Share this post


Link to post
Share on other sites

Finally started the rebuild that hopefully I can finish by September. WARNING - Nasty pictures follow along with a few questions.

I was ready to pull the engine (Surprisingly after only about 4 hours of dismantling. Gotta love the simplicity of these vehicles) and decided to do something unusual. I read the mechanics instruction manual. Can someone please confirm that in order to pull the engine I need to pull the transmission and in order to pull the transmission I need to drop the rear end? REALLY?  😒

As you can see the crank shaft is pretty much toast.

No gouging in the head although there were pieces of piston on top of the block. Did not see any damage to the top of the block.

The area in the block above the damage in the oil pan is slightly deformed and cracked. My welder friend says no problem fixing that.

The cylinder appears to be salvageable. The wall has no visible deep scores. Mostly what is seen in the picture is from where I wiped it down with a rag. I am guessing it will need at least .030 oversize. Guessing it will be best to take all four to the same size?  

How is the camshaft removed?  The instructions say something about a plug that requires a special tool. Also it needs to have .002 clearance? 

Thanks all for looking and commenting.

Paul

OilPan.JPG

Rod1.JPG

Rod2.JPG

Piston1.JPG

PistonRod.JPG

Crank2.JPG

CylB.JPG

CylF.JPG

Share this post


Link to post
Share on other sites

Yes, you do need to pull the rear axle back enough to drop the prop out of the torque tube (if you don't have an open prop) so you will have to drop the springs.  You will probably have to take out the battery box as well. Also the exhaust and the brake rods.  If you try to remove the engine from the gearbox in situ there is a risk that you will damage the clutch.  This is because the front cross member will not allow the engine to come out straight.  It will need to be tilted and an acute angle to clear it. 

 

The camshaft is located by a taper plug in the side of the block.  On 2 unit 6 volt cars this plug is hidden behind the generator.  Make up a simple puller.  It may be tight  but should just pull out.

 

It would be a false economy (in my opinion) to only bore one cylinder.  Get them all the same.  When you replace the con rods make sure they are modified to take fully floating gudgeon pins and cir clip retainers.  The original bolt clamping is probably the weakest design flaw in the engine and  has been the cause of many failures.

 

While you are getting the replacement crankshaft crack tested take the trouble to have the head and block crack tested too for peace of mind if nothing else.

 

Ray.

Edited by R.White (see edit history)
  • Thanks 1

Share this post


Link to post
Share on other sites

Got back to work today and dropped the rear end and tried to pull the trans. The cross member is unbolted and the trans is back far enough that the back of the engine is almost at the firewall. I cannot get the engine to separate from the trans. Any ideas anyone. Almost seems like the output from the crack is stuck in the pilot bearing.

Share this post


Link to post
Share on other sites

Have you removed the two thin metal supports either side of the throw out bearing?  The clutch pedal needs to come off and throwout bearing fork lifted out. I found it easier to leave the clutch on the flywheel. Note how the clutch plates wear grooves into the pins. If you are trying to pull the clutch with the trans the clutch plates might be snagging on the pins.  Don't try to replace these by the way as the heat required to remove them can crack the flywheel.  I smoothed out the grooves and applied a little grease. 

 

Note there appears to be no means of lubricating the pilot bearing in the flywheel.  Mine was dry as a bone and caused clutch drag.  I replaced it with a sealed bearing. ( It is often the case that sealed bearings are lacking sufficient grease.  I would suggest you carefully prise off the cover and pack the bearing.  The cover should snap back into place)  Also renew the brass bushing in the end of the input shaft.  The trick for removing this is to tap in a thread and screw in a bolt .Use a puller or slide hammer. 

P9100064.JPG

P9100066.JPG

Edited by R.White (see edit history)
  • Thanks 1

Share this post


Link to post
Share on other sites

Thanks Ray: "Have you removed the two thin metal supports either side of the throw out bearing?" I looked and looked but did not see anything else that could be removed. I presume these are accessed through the hole in the top of the bell housing? Thanks for the pics and info. 

Paul

Share this post


Link to post
Share on other sites

Yes, looking in through the opening  there should be two square headed bolts.  remove these and the supports will slide off either side and you can lift out the throw out bearing fork.  

 

For future reference; when replacing them be careful not to drop them into the bell housing...  Don't ask me how I know this!!!🤪

 

Ray.

Edited by R.White (see edit history)
  • Like 1

Share this post


Link to post
Share on other sites

Engine is out. Fat hands in a small place, broken cotter pins, frozen clutch pedal on shaft took four hours. So much for my simple comment earlier. Remainder of dismantle will likely be over the weekend. Just thinking that the throw out bearing may need replacing. (See video clip.)

I expected the bearing to slide off the output shaft but it appears it is pressed on?? Edited by Wheelmang
Move video (see edit history)

Share this post


Link to post
Share on other sites

Believe it or not, the throw out bearing on these clutches is supposed to move around...   I thought the same as you and ordered one only to find it was no different.  The throw out bearing is held in place by a large spring clip. Prise this off.. then the bearing unscrews.

 

Ray.

Edited by R.White (see edit history)
  • Thanks 1

Share this post


Link to post
Share on other sites

Amazing that that much movement is built in. Thanks for the post Ray - I was already trying to find a replacement. 

Share this post


Link to post
Share on other sites

I can't remember if it has been covered before but with the top removed from the gearbox you can check for wear.  Straight cut gears will of course always be noisy but the cause of excessive noise is usually found to be wear of the sliding gear surfaces and the main shaft.  You may well find that the gears actually "wobble"on the shaft.  The worst offender is likely to be the small gear nearest the front.  As this takes all the input thrust it can be severely worn.  If the teeth are badly pitted or even broken then it is a good candidate for replacement.  I don't think new ones are available except for early cars but I was fortunate enough to find a good used one. I tried to build up the bearing surface of the gear/ shaft but without success so I imagine  if you need to get these hard chromed it would be expensive. Even with new bearings (sealed) and a replacement gear my transmission is noisy in first and second - but top (which is direct) is quiet.

 

Ray.

Edited by R.White (see edit history)
  • Thanks 1

Share this post


Link to post
Share on other sites

A small progress update - The throw out bearing is removed per Ray's instructions.

TB1.JPG.76ef70da770d5437cbcc007c5d66dae8.JPGTB2.JPG.214cc669cf1db921472857cafab1e8d1.JPG

The clutch plates did not just slide off and it looked like solidified grease in the pilot bearing was the culprit.

The cam shaft plug was threaded, so a washer on the head of a bolt along with working my way around the plug with gentle pressure on a pry bar was successful. pressure from a pry bar removed it quite easily. 

CamPlug1.JPG.26abefa5fdc1b88b3198d5bf561793ac.JPG

And a question - The only marking I see is on the cam gear. I did not see anything on the cam itself. How is the correct position of the gear on the cam determined?

I almost removed the gear from the cam before realizing this.

254088225_Camgear.JPG.c61073587417fdaf5dc7ca31ced2a3e7.JPG

The two "0s" on the cam gear line up with the single "0" on the crank gear OK. (not shown in picture)

Hope to get back to considerably more progress this week. 

Share this post


Link to post
Share on other sites

That is right. I should have mentioned there is a risk of loosing the valve timing and with various different camshafts around these days you can't rely on the workshop manual settings.  The crankshaft gear has no markings on it so you would be well advised to make your own so they align with those on the cam gear.  Be very careful if it is a fibre gear.  

 

Ray. 

  • Thanks 1

Share this post


Link to post
Share on other sites

Engine is at the speed shop for a dip tank cleaning then off to the welder. Does anyone know if the 3 main bearing crankshaft from a 12 V engine is the same as a 6 Volt? (Hope so or I may be looking for a crankshaft) Also looking for confirmation for original specs for the following (car #A716963)

- Crank - 1.750 on mains and 1.625 on rods. What is the minimum diameter for crankshaft rod journals?

- Pistons - 3.875 

Thanks all

 

Share this post


Link to post
Share on other sites

The 3 bearing crank will not fit your engine.  I would suggest if you need a replacement crank it might be better to source a complete other engine.  The 5 bearing engine is a significant improvement over the 3 bearing unit.  Your call I guess.

 

Ray.

Share this post


Link to post
Share on other sites

Thanks Ray. I have a plan "B" 5 main that is re-buildable but am hoping to keep the 3 main that is original to the car. I may have been a little confusing on my question. Both the 6V and 12V engines are 3 main. If the cranks are interchangeable I would like to rebuild the original. Pretty sure I will need to come up with bearing caps for at least one main if going with the 5 main engine. Assuming (gulp) the rod bearings are the same size between the 3 and 5 main?

I really appreciate all of your insight on this project.

Paul

Edited by Wheelmang
Add text (see edit history)

Share this post


Link to post
Share on other sites

MY mistake.  It shouldn't matter if you want to swap over 3 bearing cranks regardless of 6 volt or 12 volt type engines if they are both 3 main blocks.  I had forgotten that the "C" engine with 5 mains (like mine) didn't come into production until later in 1926. I have not actually done the swap that you intend so I can't say if there are any difficulties but I would have thought it would be possible, however, I don't know if the rod bearings are the same size or not.  

 

Regarding the bearings. If you need the crank reground I think you will have to get all bearings re white metalled and line bored.... Ouch!

 

O.K., I know I obtained good clearances by adjusting the shims and lapping the bearings to fit my crankshaft but the crank was hardly worn so didn't need a regrind.

 

Ray.

 

PS.  You mentioned a crack that needed welding.  It may not actually be visible but for every crack you can see there will probably be another corresponding crack in parallel.  I had a crack across a valve seat. I  had it "Cold" stitched then machined.  Another crack was frost damage in the water jacket and I repaired it myself using a professional epoxy by Belzona.  All OK so far!

 

Ray.

 

Edited by R.White (see edit history)

Share this post


Link to post
Share on other sites
On ‎4‎/‎3‎/‎2018 at 11:30 AM, R.White said:

I would look into cold metal stitching as a preferable alternative to welding or brazing.  I have had very satisfactory results using this method.

 

I couldn't help noticing the crank grind tolerance of 0.010".  The crank needs to be much more accurately ground in my opinion.   0.001 " max.

 

Ray.

If you have a +, or - of .001, the crank is already wore out. The center line MUST be kept! You can't grind a crank like that, as you would a 350 Chevy! Your +, of - should be Zero!      Herm.

Share this post


Link to post
Share on other sites
On ‎4‎/‎4‎/‎2018 at 11:47 AM, R.White said:

 

It all depends on what you want to spend!   Your engine (and almost all stock engines) came from the works without having been balanced.  If however you want your rebuild to be the best it can be then go for balancing. The most you can expect is a smoother running engine with a longer lifespan as the absence of vibration is a real benefit. Performance will still be limited.

 

Ray.

 

 

" AGREE "

Share this post


Link to post
Share on other sites
4 hours ago, herm111 said:

If you have a +, or - of .001, the crank is already wore out. The center line MUST be kept! You can't grind a crank like that, as you would a 350 Chevy! Your +, of - should be Zero!      Herm.

 

I totally agree, Herm.  What I should have said is "run for the hills".   

 

Ray.

Share this post


Link to post
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