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More on 2 1/2 litre V8 engine bearings

tjt77
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More on 2 1/2 litre V8 engine bearings

Post by tjt77 »

Just to share some info for those rebuilding engines :- I had difficulty obtaining correct crankshaft thrust washers... my usual supplier had been out for a while.. and has stated that no oversize are available for the thrust washers at this time .
I have discovered that the thrust washers for the BMC B series 1500/1588/1622 will do the trick..(Moss Motors part no 425-550 for std size) they are same dimensions.. with the bonus of not having a flat at the outer edge.. so slightly more surface area.. they are also almost 1/2 the cost in spite of double the number of pieces..and they fit perfectly with correct clearance and no modification.... one just uses the 'upper' plain section in the daimler V8..and discard the 1/2 with the tab that fits in the BMC bearing cap..

Still no tri metal replacement bearings in sight as far as i know... may have to seek out alternatives and modify as required.. of anyone has info on readily available tri metal bearings that are same inner and outer diameters.. please post that info.. Im really not keen on using reticular tin alloy bi metal bearings in an engine known to be hard on its main and con rod bearings when usr as intended..Frankly its fraudulent to state 'OE quality' on the box of bearings that will only take 1/2 the loading of originals ..
I may try and source an old bearing catalogue and do some further research.. thank you.

Sonus
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Joined: Wed Apr 13, 2016 2:19 pm

Re: More on 2 1/2 litre V8 engine bearings

Post by Sonus »

Russ Carpenter might be doing a run of modified 1275 bearing soon. I got hold of some Glacier NOS bearings from Barry Thorne.

daimlersteve
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Re: More on 2 1/2 litre V8 engine bearings

Post by daimlersteve »

As a one off the cost of modding 1275 c/l bearings will basically quadruple the bearing purchase cost.
Jigs to suit reduce the time taken considerably.
steve

tjt77
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Re: More on 2 1/2 litre V8 engine bearings

Post by tjt77 »

A question on suitable replacement bearings that can be modified to fit :- Can anyone confirm that the BMC 1275 cc 'A plus' bearings have the same OUTER diameter as those on the the Daimler 2 1/2 V8 ?
IF they are, it should not be too difficult to narrow them down..and modify the locating tab to fit this application. As regards main bearings one could drastically improve things just by replacing the highest load bearing, and hence rapidly 'wearing' parts that show weakness on these engines , which would be :- the lower intermediate 3 shells on main bearings.. and the uppers on the con rods.. assuming that they are dimensionally correct and match existing King Bi metals as regards inner and outer diameters..
if so, the cost to improve things is not 'radical'.. the 'king' race quality bearings are actually designed for higher loads than the OEM vandervell VP2 .. seems to me the primary issue is the intermediate mains.. and 1/2 of one set of tri metal BMC mains could be modified to to do the job and fitted in combination with the normal Bi metal offerings....
as regards the locating tabs on bearing shells .. some engine manufacturers have moved away from these.. and bearings are held in by the 'crush' of housing only.. I recently replaced some con rod bearings on a VM diesel that were plain ..no tabs on them whatsoever.. (used OEM VM parts)
Ive been unable to gain any info on the metal specifications of original fasteners.. but ARP bolts have a load bearing capability in excess of 170 psi.. the ARP 654-2750 bolts are dimensionally perfect to replace the original daimler ones for main bearing caps when used with the washers supplied in the pack .. albeit without the provision to 'lock them' in place once torqued..( i use a dab of loctite on the threads) Ive been using standard grade 8 'flange bolts' for 2 the rearmost main bearing cap for quite few engines (these good for 160psi) ... no issues so far.. I also replace the oil pump bolts with high grade 12 point head 5/16" bolt and grade 8 lock washers. this is a vast improvement and one can actually get a wrench on their heads easily ( not so with the original bolts..there is just no room around the bolt head)

John Chatfield
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Location: Shrewsbury England

Re: More on 2 1/2 litre V8 engine bearings

Post by John Chatfield »

Hi Tim,
What information would you like from the old catalogues , I may be able to furnish you with it, also F W Thornton of Telford 01952 252892 ( Whom I work for so have a vested interest in but I don't want to promote on this site as I don't want to upset anyone who I may supply or purchase from ) should have new stocks of tri-metal high load bearings delivered next week or early July in most sizes... happy days
Regards
John

Sonus
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Joined: Wed Apr 13, 2016 2:19 pm

Re: More on 2 1/2 litre V8 engine bearings

Post by Sonus »

That is very good news John. Please let me know when new stock is on the shelves :)

tjt77
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Re: More on 2 1/2 litre V8 engine bearings

Post by tjt77 »

John, thank you for that info... can you post on this site as and when those bearings are in stock please ? (I'm sure a few people will be grateful to know this info)

tjt77
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Re: More on 2 1/2 litre V8 engine bearings

Post by tjt77 »

just an update on the crankshaft bearing situation :- I recently received a couple of sets of the current 'upgraded' con rod bearings for the 2 1/2 litre engines .. these are made by the ONLY commercial supplier of bearings for our engines :- 'King'..sometimes sold under the 'County' name brand and stocked by major suppliers. Due to demand, they finally have made them in 'tri-metal' format .. copper inlay on a steel backing with lead indium facing (as per original) .. so far no tri metal main bearings are available and unikely to be made due to the small demand and costly tooling ( 4 different types of bearing shell make up the set for main bearings) For those who are using full power of their engines and concerned about bearings holding up, one solution is to have a good machinist modify a set of tri metal main bearings for the 1275cc BMC 'A plus' engine to fit in the intermediate positions (no's 2, 3and 4) which will help matters considerably.. they have to be narrowed to fit and a new locating 'tab' added.. you use the only available 'king' reticular tin alloy bearings (marked 'SA') in the 'other' positions.. the main weakness has always been with the intermediate bearings which are very narrow and have small surface area, making them prone to premature wear on the load bearing lowers. (One upside to Edward Turners 'minimalist' approach is relatively low frictional power losses)
The numbers for the new production lead copper bearings from King are :- CR 821 CP with CB 803 CP / AEB 8081 on other end of box.. Original Vandvervell bearing ID numbers were VP 803 on con rods and VP 804 for mains..

daimlersteve
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Re: More on 2 1/2 litre V8 engine bearings

Post by daimlersteve »

the mini bearing is wide enough for the #1 as well.
steve

tjt77
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Re: More on 2 1/2 litre V8 engine bearings

Post by tjt77 »

Reply to Steve.. yes indeed, the front main bearing shells can be replaced with modified BMC 'A plus' ... as to whether this is a necessity or not.. unsure.. it seems to be that the problems of excess wear only effects the intermediate main bearings in 'normal' circumstances.. quite often there is almost no wear on the rear main bearing and minimal wear on the front one..likely due to greater width giving a decent surface area.. Ive noticed there often tends to be evidence of the intermediate bearings caps 'moving' and leaving distinct mark on the cylinder block where they mate .. so there is a structural rigidity issue in play.. I think ARP bolts help a little to counter the flexing .. the recomended torque for standard bolts is 30-35lbs..To combat this issue, I'm using 40-45lbs with ARP bolts on standard main bearing caps, which should be about right and is well within standard engineering guidelines for a 3/8" NC high tensile bolt.. Bear in mind I'm building engines for mostly 'road' use other then competition.. Id suggest one needs to initially replace the std cast iron main bearing caps with 'beefed up' intermediate caps if any power increase above 25-30bhp is contemplated..

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