Pinch on main bearings

[Keith Clements]

Drummond phoned me yesterday and gave me the encouragement to continue my quest. The previous day a neighbour arrived to help in the oil rig test. So thanks guys for keeping me from going stir crazy. Most of what we called summer has been in the garage. Now we have some sunshine and I can enjoy the cars.

Drummond did say that he has fitted an oversize camshaft manufactured by Bill Lock and had the block line-bored 20''' oversize. The cam journals were ground to size as it is easier to do this accurately than line boring.

[Drummond Black]

I have followed this topic with keen interest over its long saga and would now like to add my input from experience and results from the current engine in the Jupiter. I built this engine tfor the Javelin in 1997. It was run - in on the trip to JAVELIN 50 at Bradford ( What a weekend ) I kept accuate notes of all checks, dimensions, modifications etc during the rebuild and this has been worthwhile as I can now recall correctly any data.

I started with a reasonable sound pair of blocks ( Crankcase number 23084 ) The camshaft bores were slightly worn but not evenly. The centre bore showed had slightly more were than journals 1 & 3. This makes sense if you look at the width of each camshaft journal. They are as follows.
1) 1.125 inches wide 2) 0.812 inches 3) 1.093 inches
All journals have a standard diameter of 1.500 inches.

The centre camshaft bearing has nearly 30% less bearing area and I put the extra wear on this journal down to this fact. Like Leo I investigated the possibility of sleeves. There is virtually no possibility of grinding the camshaft bearing journals below the 1.500 dia as this would interfere with the cam radii. The block in this area lacks " meat " to allow a proper sleeve to be fitted. About this time Bill Lock was having Replacement Camshafts made and he had a few done with slightly oversize journals ( about .020 ins ). The possibility of having a few thou bored out of the block to allow the fitting of one of these shafts made sense. I approached a local engine reconditioner in Falkirk as to the feasibility of line boring the block and he could not envisage a problem. We approached the job as follows :-

1. I assembled the two halves to the correct torque settings and prepared a drawing with correct dimensions to the bore centre in relationship to the crankshaft bore. ( 4.4140 inches )

2. They made a jig to clamp the Jowett block onto the table of the line borer.

3. The idea was to line bore the Jowett block back to a true diameter BUT only remove the minimum ammount of metal. The final diameter was a bore of 1.5125 Dia.

4. The oversize journals of thr new camshaft were then ground down to give it an accurate running fit in the block.

Leo is correct when he states that ALL camshaft oil feed holes come off the same main oil gallery ( All on one side off the shaft. ) I decided to add extra oil feed holes from the other oil gallery which would feed oil to each side of the camshaft. This was possible on bearings 2 & 3. I could not find a safe route to add an additional oil hole to journal 1 due to extra drillings in the area. I have recorded adding holes of 3mm Dia ( 0.125 ins ) to feed journals 2 & 3.

Keiths comment from Ben Shaw regarding OIL FLOW I feel is correct. The oil feed holes in the Jowett block chop and change diameter many time as you follow its path from the pump to their final destinations. Many restrictions were inadvertantly built in ( Some were then re-looked at in the series 3 blocks so Jowett were aware of the pitfall )

I calculated each bore and drilling and the relevant cross-sectional area so as to attempt to reduce or remove as many as possible.

I started at the oil pump. The base (new ) and the pump body and gears were lapped to allow a max end float of 0.002 thou. The base was fitted WITHOUT a gasket. The banjo bolt at the pump was opened out to 11.1 mm dia ( area of 96 sq mm ) and the 6 feed holes opened up to 5.5 mm dia each ( total cross sectional area of 142 sq mm ) To other end of the oil feed pipe as it enters the block was opened up to 11.5 mm dia ( 103 sq mm ) as was the feed hole going into the block. The short vertical feed hole in the block and the feed hole in the rear timimg case casting were both opened up to 11.00 mm dia. ( area 95 sq mm ).

I fitted a modern spin off oil filter and all flows and bores were checked for unrestricted flow. As the oil flow splits to each side of the block from this point the diameters were rediced accordingly to give a flow from 8.10 mm ( area of 51 sq mm ) All oil holes in the block and crank shaft were cleaned out properly.

Apart from all the other aspects of a rebuild new tappets, rocker bushes and rocker shafts were fitted.

The engine wes fitted with fiesta pistons and ground heads resulting in a compressian ratio of 9.5 : 1.

Current oil pressure is a full 60 psi at 2,000 rpm and over and this drops back to about 25-30 psi at tickover when hot. It has done just over 20,000 miles since rebuild without problems.

I have another block and modified camshaft ( already line bored ) awaiting rebuild and all the above will be built in.

I hope the above has not bored the pants off you all but it is a current topic.

Drummond

The banjo bolts on the oil cooler feed and return pipes were also increased for flow.

[Drummond Black]

Pat asked if anyone had considered metal spraying ? YES I did consider this approach as I have a lot of experience in this area and all the equipment in the workshop for both cold and hot spray. Had Bill not come up with with the oversize journal design then I would have went down this route.

The king pins in the Javelin have been reclaimed using this method. I sprayed them with an aluminium bronze, turned them to size , and then made stainless steel bushes which were pressed into the stub axles. No wear has taken place after some 50,000 miles.

I have also reclaimed the crankshaft pulley wheel where the front oil seal on cuts into the rear diameter. THIS HAS ALSO BEEN VERY SUCCESSFUL.

Water pump spindle have also been reclaimed with success.

DB

[Keith Clements]

Draw your attention to my observation of open pipe flow pressure of 15 to 20 psi through 3/16 in pipe. This suggests that the sum total back pressure of ALL the bearing surfaces is greater than this and the flow is really quite small. I am actually not very confident of this observation!

[Keith Clements]

Javelin did 100 miles today. No problems. Oil pressure is now 80psi cold(25C) at 2000rpm. Seems to be going up!
When hot at 85C, oil pressure is 50psi at 2000rpm, 25 at 1000rpm and only 10 at 600rpm.
Water temp stays at 75-80C most of time except standing in traffic when it rises to 85C. Cools down within a couple of miles at 60mph. Note there is no mechanical fan. New aly transfer pipes supplied by Bill Lock are installed. These double the pipe cross section from head to block.
Note finned aly sump (also supplied by Bill) aids cooling.
85C thermostat fitted and electric fan thermostat set at 75C.

[Mike Allfrey]

Dear Keith, Leo and Drummond,

All I can say is Wow!

When I built the Jupiter's current engine, I used a camshaft from Bill Lock and, it being oversize at the journals, had the crankcase line-bored to clean up. I should mention here that the joint faces of the crankcase had been skimmed before torquing together. Including the five 1/4" top row bolts.

The crankcase was skimmed to rectify oval main bearing bores. The engine reconditioner informed me during initial inspection, that the centre camshaft bore had worn more than the front and rear pair. The wear was found to be side to side - not at the top.

Getting back to Leo's search for 1.500" bearing shells, they would be great, but where to find them? Has anyone tried the catalogues for stationary engines, motorcycle engines or even the aircraft engine listings?

Wot's this aboot a finned ally sump from Bill? Have I missed something along the way? How much? Is one available?

Kind regards to all,

Mike Allfrey.

[Leo Bolter]

Hi all.

I have risked the dreaded RSI for the cause by trawling through a current .pdf Automotive Bearing Catalogue in a attempt to locate the magic “1.5 inchesâ€

[Mike Allfrey]

Dear Pat,

If my memory is correct, 0.0035" was milled from each joint face. At this, the oil pump drive gear mesh was OK as was the timing cover dowels fit. The balance pipe is also OK, 0.007" extra pinch should not hurt it too much.

Regards to all,

Mike Allfrey.

[Keith Clements]

I am not happy with the 10 psi when hot either; but pressure comes up at 1000 rpm. I only hope that there is enough flow to keep the engine going for the next 600 miles. This will give me chance to weld up the other block!
I am happy with the 80 psi cold; the blow off was set to about that in the test rig.

[Keith Clements]

Picture of aly sump in Gallery
https://jowettnet/forum/download/file.p ... &mode=view

[Mike Allfrey]

Dear Keith,

Thanks for the offer of viewing on the gallery.

I have forgotten where I put my password so will try later.

Do we really need passwords?

Regards,

Mike A.

[Forumadmin]

You can change your password to something memorable; but please make it not easy to guess. Go to My Account (top right tab) then select Change Password in left panel. Of course I will need to let you in to do this if you have forgotten. Send me an email. Security on the Gallery site is important.