Lotus Elan and Lotus Elan Plus 2 Forums

Hi Guys,

Back to a bit of engine assembly after a bit of a hiatus. Difficult to spare the time whilst working full time (for an automotive manufacturer) and also trying to manage two kids under 12 on a week about basis and school holidays!

I was checking out fitment of the Burton's modular water pump kit I purchased and noticed a potential trap for young players. The depth of the recess in the intermediate plate to allow clearance for one of the front block oil gallery plugs is only 1.8mm compared to 6.2mm for the original Lotus plate. This means that if the plug stands at all proud from the face of the block (which they usually do somewhat) there is potential for the plate to not seat fully against the face of the block thereby creating an oil leak.

I have purchased oil gallery plugs from both QED and Burtons. The QED ones are longer and sit proud by 3-5mm from the face of the block (similar to OEM). The Burtons ones are shorter, penetrate deeper and sit below the face of the block. I prefer the QED ones for all positions except the one affected by the intermediate plate design as there is less likelihood of partially blocking a perpendicular oilway. The perpendicular oilway at the affected position sits deeper than the others and is unaffected by the Burtons plug as I checked by inspecting with a torch the adjacent main bearing oil feed.

So the moral of the story is that if you are suffering from oil leaks from your Burton's modular water pump front cover check that your oil gallery plug is flush with the block ! Pictures of the issue attached. Block (with fitted QED plug on LHS and Burton's plug on RHS), Burtons intermediate and Lotus OEM intermediate plate compared.

Note as any further items of interest that may assist others with their engine assembly arise i will post them here.

Before you go any further check that the plugs are actually 1/4" NPT and not 1/4" BSP as both of these companies have managed to supply me with the incorrect ones from time to time.

Thank you promotor. Looking at the oil gallery plug thread on this forum I well understand the issue now.

Comparing the 3 plugs we have:
1. The QED plug is 12.7mm long and threads seem to be BSP not NPT. Screws the correct distance into the block however so no risk of blocking off oilways. Sticks out too far for Burton modular cover, OK with standard Lotus cover. Mixing NPT and BSP threads not ideal but probably still OK if using Loctite 569 sealant.

2. The Burton plug is 10.3mm long and threads are NPT like original. Something seems to be wrong with the amount of taper however so they penetrate too far into the block creating a risk of blocking the perpendicular oilways. No risk of blocking off oilway when used in front RHS position only.

3. The OEM plug is 9mm long and perfect in every way (of course). I've had a Eureka moment with this which I'll post on the original oil gallery plug forum.

Pictures of all three plugs below for reference. From left to right we have QED, Burtons and Ford OEM.

It's just not acceptable that these companies are supplying the incorrect plugs!

Wherever possible I re-fit the original Ford NPT plugs as I know they work well and do so without sealer. Otherwise I go to an air-line product supplier for my plugs.

The thread is definitely 1/4" NPT as I have the original Ford engine manuals that cover the Twincam/crossflow/pre-crossflow range and it specifically quotes that thread. These are the manuals that replicate the micro-fiches found in Ford main dealers.

What is amazing is that Burton have in the past supplied the incorrect plug to go with their water pump, and the water pump is designed to be used with low profile fitting plugs (ie like the genuine Ford ones were) - to say that they are confused is an understatement!

I have had the correct type, not the correct type, the correct type, and not the correct type the last four times I ordered these from them - I just don't buy these plugs from them as it's the easiest way to be sure.

I don't think I've had the correct type supplied in an order from QED.

To be clear the front cover will not stop an oil leak if the plug doesn't seal - that's not its purpose. The plugs purpose is to stop the leak - if it doesn't the front cover will leak no matter how well the front cover sits on the cylinder block.

Two other additional problems to check for with the Burton timing case:
a) Check the backplate is straight in all directions using a steel rule
b) Do a full trial build with the timing case, chain, sprockets and cylinder head - I found the chain, when tensioned, fouled the inside of the outer cover on the coolant passage, due to mal-position of the casting core during manufacture. This required fettling to fit.

Burton were deaf to my rants with them about wrong plugs and timing case manufacture! However once sorted and installed it works fine and is oil tight.

My understanding is the correct thread is 1/4 NPTF (gas tight) rather than 1/4 NPT.

englishmaninwales wrote:
My understanding is the correct thread is 1/4 NPTF (gas tight) rather than 1/4 NPT.

Agreed.

Thanks guys. I'll check all these points as I continue with my build. Those 1/4" oil gallery plugs are still available new direct from Ford under part number 87837-ES2 (same part number from the 1960's is still in the system!). Cost me $AUS 6.00 each for next day delivery.

The 1/8" transverse gallery plug is now obsolete from Ford. Last known part number was E650411-S72 and last used in late 90's early 2000's Ford Transits.