Oil Filler Cap, Gap to Bonnet, and Improving Breathing ?

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rfs1957
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#1 Oil Filler Cap, Gap to Bonnet, and Improving Breathing ?

Post by rfs1957 » Mon Sep 17, 2018 4:45 pm

Would some kind souls measure how much room there is above the top of their oil filler orifice and the bonnet ?

Looking to produce adapter rings to enable the Monza-type caps to be fitted and as my car is in bits .......

Image

The Monza cap sits 33mm above its base, against my original cap's 15mm.

I've seen them fitted but don't know just how much of a tight squeeze it is ......

My personal interest is in the 3.8 but dimensions from later models would be welcome too.

Image

Image
Last edited by rfs1957 on Thu Sep 20, 2018 4:00 pm, edited 1 time in total.
Rory
3.8 OTS Cream 877393 Built May 28th 1962
1978 Mini Van
(plus bevel and belt single-cylinder Ducatis)

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#2 Re: Oil Filler Cap - and gap to bonnet ?

Post by 288gto » Mon Sep 17, 2018 5:38 pm

Rory,

Have a look at Darren’s restoration thread
I know he did the same thing to his and if you haven’t already seen it. I know when I spoke to him there weren’t any clearance issues.

http://forum.etypeuk.com/viewtopic.php?f=8&t=6087

I’d measure mine for you but the bonnet is off the car. :scratchheadyellow:

Simon
Simon
1969 S2 OTS

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#3 Re: Oil Filler Cap - and gap to bonnet ?

Post by PeterCrespin » Mon Sep 17, 2018 10:29 pm

I turned down an old screw cap, leaving a spigot just deep enough for the Monza (from a long-gone Matchless race bike) to fit as good as flush against the cover. I aligned the flip top 'bulge' fore and aft to minimize height but I think rather than being lucky it didn't foul, there was plenty of room. The highest point is the tip of the two inboard cam cover acorn nuts at the front. I placed a metre-long builder's level back from there and recall the cap being well below the imaginary line. Of course, I get my kicks these days from having cam covers with no oil filler provision of any kind and no dipstick either :bigrin:
1E75339 UberLynx D-Type; 1R27190 70 FHC; 1E78478; 79 S2 XJ12L; 97 XJ6L

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#4 Re: Oil Filler Cap - and gap to bonnet ?

Post by ralphr1780 » Tue Sep 18, 2018 7:57 am

Sorry for asking, :shrug: , what are the advantages of fitting such a cap?
Ralph
'69 OTS + '62 OTS - Belgium

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#5 Re: Oil Filler Cap - and gap to bonnet ?

Post by PeterCrespin » Tue Sep 18, 2018 4:29 pm

It's pretty.

You can't absentmindedly lose the cap.

It's still pretty.

You only need to press quickly to release, not unscrew a hot cap at a petrol station.

It's very pretty
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#6 Re: Oil Filler Cap - and gap to bonnet ?

Post by christopher storey » Tue Sep 18, 2018 4:33 pm

Beauty is in the eye of the beholder, Peter

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#7 Re: Oil Filler Cap - and gap to bonnet ?

Post by JagWaugh » Tue Sep 18, 2018 5:32 pm

Peter, you forgot:

It's a justification for owning a lathe.
It's pretty.
It's a justification for owning a lathe.

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#8 Re: Oil Filler Cap - and gap to bonnet ?

Post by rfs1957 » Wed Sep 19, 2018 9:02 am

Peter, can you put a picture or two of the D type breathers up ? What source or adaptable part is good for similar period-credible hose adaptation stroke union for adding additional breather pipes, and who thinks this is anyway unnecessary and a waste of time ?
Rory
3.8 OTS Cream 877393 Built May 28th 1962
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#9 Re: Oil Filler Cap - and gap to bonnet ?

Post by PeterCrespin » Wed Sep 19, 2018 8:12 pm

Here's the real McCoy - GBP500 each inc VAT https://www.bighealey.co.uk/jaguar/jagu ... aight-port. Plus 180 incl for the flanges/tubes. About 1200 anyhow. You can't have too much breather unless you want to establish crankcase vacuum or meet emissions, but 1100-1200 squid is a lot of money to save small pumping losses. On a big single or 360-degree parallel twin or boxer (and some V-twins) these losses are significant. On a 180 degree twin or multi-cylinder, less so. Still, it looks 'racey' and Jag used this system on all Ds and Lightweight Es. Some people even think it means a wide-angle head and who am I to pop their balloon?
Image

I did invest about 500 for my D-Type from another source, but for a road car I went for a DIY option and made another solution: Old covers plus 200 worth of bits. Note, the ones on the engine have not been milled yet to get the alloy half moons flush with the gasket face for use on a big valve head:
Image

I had half a dozen twin-breather towers for the left cover cast using a pattern not shown and the transverse breather tubes/flanges cast using the red wooden one. This has the cover flange boss that welds to the cover cast integral with the tube and flange that's bolt to it. This was to ensure perfect alignment when drilling breather and fastener holes, prior to sawing into two parts at the point where the flange meets the boss. Sadly (but harmlessly) the cut was made by the foundry at the 'wrong' place, leaving a bit of boss on the flange but this will be trimmed off.
Image

Image

The twin breather tower has two standard tube size pipes protruding (7/8"/nominal 22mm), which are very snug fit and angle back with convoluted alloy/paper breather tube attached, for that 'works team' look :roll: . The pipes have a 120-degree kink and can be rotated to fold close to the cover, before holding firm with gasket goo. You can just use short tumps of straight pipe and let the breather tube take the bend. The transverse tubes and flanges can be made of tube and sheet metal, which is more original or you can buy from Denis Welch and align the holes yourself. The transverse connection here is oil-proof rubber hose, not alloy breather tube. The picture shows left to right: steel tower tubes before trimming, the 'works' transverse fittings and hose, fabricated steel transverse fittings/flanges and 120 degree brass plumbing fittings that could be soldered to a flange or used as breather tower tubes once slipped over a short copper stump into the tower. The standard S1 breather has a 0.5" ID. These conversions more than triple that with 2x 0.8"

Image

The final picture shows my S2 with its crossover, to demonstrate clearance for the tower. Even with the black lid in place the bonnet still shut, so although my engine mountings are due for renewal, you can see the clearance where the tower would be.

Image

Finally, for those who have asked, here's a very fuzzy picture from the shipper (CARS, nr. Bury St Edmunds) of the D-type slung together for shipping, pending disassembly, final riveting and rear skinning/painting/completing.

Image

To recoup my outlay a bit, I will sell the three spare breather towers, each with enough tube and 2x brass 120-degree fittings to make the two breather pipes. The Denis Welch tube set that cost me about 180 inclusive, would sell for the VAT-free price. If we have a lister with foundry connections, they could use the wooden transverse pattern to cast more, and turn a spare tower into a pattern to make more of those. Contact me off list, I suppose.
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#10 Re: Oil Filler Cap - and gap to bonnet ?

Post by Heuer » Thu Sep 20, 2018 9:38 am

rfs1957 wrote:
Wed Sep 19, 2018 9:02 am
and who thinks this is anyway unnecessary and a waste of time ?
I am all for making useful changes but I think this is a pointless exercise for a road car. I had a problem with the engine in my OTS generating too much crankcase pressure which caused the rear rope seal to fail. Bear in mind this engine produces 280bhp and 340lb/ft. The simple solution was to fit a dual breather:

Left hand side:
Image
Right hand side:
Image
Twin outlets:
Image
Exits:
Image

Difficult item to photograph as it sits behind the header tank. Mine came from CMC. Worthwhile if you have a high performance engine and 'open' trumpets.
David Jones
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#11 Re: Oil Filler Cap - and gap to bonnet ?

Post by rfs1957 » Thu Sep 20, 2018 11:19 am

Thanks for going to such lengths, Peter, and for your suggestion, David.

One is tempted to conclude, as this post began with the filler-cap, that it is the filler-cap orifice that might actually constitute the ideal spot to incorporate extra ventilation ....... maybe cam-spray precludes that location.

As to rope-seal failure being caused by crankcase-breather issues, is this speculation or established ?

Sample size ?

My own experience examining single-cylinders (the worst case ?) and vee-twins on a dyno was always that their breathers were remarkably non-wheezy or busy, and that open, closed, or bigger made zero difference to power output.
Rory
3.8 OTS Cream 877393 Built May 28th 1962
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#12 Re: Oil Filler Cap - and gap to bonnet ?

Post by Heuer » Thu Sep 20, 2018 12:50 pm

It was Andrew Turvey at CMC who diagnosed the rope seal failure after 8,000 miles and concluded it was due to the crankcase pressure generated by my particular engine with 9.5:1 compression and trick cams. He felt the standard vent was of insufficient diameter and could become blocked (and I assume this is your thinking). They developed the dual outlet breather specifically for high performance and race engines so suggested that I fit one. They were only £50 each plus the cost of the corrugated tubes so not exactly a cynical marketing ploy! As to total sample size I have no idea but CMC thought it worth making the mould and getting the castings made so there must have been quite a few cars affected. I have since covered 40,000 miles with no further problem.

Not sure if CMC still offer the dual outlet breather but someone with your experience/skills could fabricate one and test it out. A lot easier than buggering about with machining cam covers. If the mod is insufficient for your needs you could always then move over to the faux D-Type eye-candy system. About the only thing I would do differently is to add an alloy oil catch tank for the sake of the environment (obviously) but also to track how much oil is being exhausted.
David Jones
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#13 Re: Oil Filler Cap, Gap to Bonnet, and Improving Breathing ?

Post by rfs1957 » Thu Sep 20, 2018 4:06 pm

CMC don't have any of these any more but are interested in having another go.

I really like the decanter-tower type that's fitted to mine, and wondered if it wouldn't be possible to modify a breather casting (or make another ?) that would actually carry a pair of these ?

There must be a reason why the D-type breather boxes effectively discourage the oil from just running out down the pipe ..........

See my dreadful Paint-Chopped and flipped picture.

Image

Is this total nonsense, in that it would be phyiscally impossible to fit for reasons of space, routing etc ? I can't judge as everything's in a million bits.

Pass judgement please.
Rory
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#14 Re: Oil Filler Cap, Gap to Bonnet, and Improving Breathing ?

Post by Heuer » Thu Sep 20, 2018 5:51 pm

Don't see the need for the oil traps, they are only going to get gummed up. Just run two pipes straight out - simple and clean. The original gauze (or baffle on the first 500 cars) is still there to trap and return as much oil as possible to the circulation.

This is the system used on those very early cars which is a single pipe version of the CMC version:
Image

Competition Department prepared E-Type's with stub intakes (and therefore no manifold connection) used the C8048 breather housing and flexible pipe. This is from the 4.2 that was Competition Department prepared:
Image

If they thought that arrangement was good enough no reason to think the dual outlet housing will be anything other than ideal. More photos in the Competition Fit thread: http://forum.etypeuk.com/viewtopic.php?f=4&t=7464
David Jones
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#15 Re: Oil Filler Cap, Gap to Bonnet, and Improving Breathing ?

Post by PeterCrespin » Thu Sep 20, 2018 8:26 pm

FWIW Rory, that device would be better than stock, but present a total of 264 mm2 X-sectional area, versus the 314 mm2 that is the ID of the main breather tube from the cover. So if you are concerned about back pressure alone, just wind the alloy baffle off the base steel stump and fix a 1" hose to that.

Pete
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#16 Re: Oil Filler Cap, Gap to Bonnet, and Improving Breathing ?

Post by 288gto » Thu Sep 20, 2018 8:43 pm

Hi Rory,

Only a thought. What about the larger XJ6 S3 breather? Rather than keeping it black you could polish it. I might even have one I can post to you to experiment with. You could still fabricate some alloy tubing and polish it to replicate the look of the original but just a larger bore?

Link to one on E bay

https://m.ebay.co.uk/itm/JAGUAR-XJ6-SER ... SwVxdbjlnw

Back to the filler cap area I suspect splash might be a problem as Darren did initially develop a leak from the actual cap seal not the adapter sleeve. I think he replaced or modified the seal .
Simon
1969 S2 OTS

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#17 Re: Oil Filler Cap, Gap to Bonnet, and Improving Breathing ?

Post by PeterCrespin » Fri Sep 21, 2018 3:49 pm

"What about the larger XJ6 S3 breather? Rather than keeping it black you could polish it. I might even have one I can post to you to experiment with. You could still fabricate some alloy tubing and polish it to replicate the look of the original but just a larger bore?"

And if Sir finds the XJ6 part a little, ahem, 'constricting', Sir could always try the V12 version on the left. Not for those of a nervous disposition....
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#18 Re: Oil Filler Cap, Gap to Bonnet, and Improving Breathing ?

Post by rfs1957 » Tue Sep 25, 2018 9:23 am

This is the CMC part, available for £78 inc VAT.

Might have been tempted if it had been polished .......... but it can wait for now.

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Rory
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