803 rebuild progress

[bmcecosse]

Yes - I agree this could be the problem.

[JOWETTJAVELIN]

JJ,
Go back to my post at the start of this thread about the size of the hole in the filter as measured by our Swiss collegue. That could be your problem. He mentions the original filter hole was only 1.5mm whereas replacements were measured at 2.5 to 3.5mm. This causes a pressure drop and I could very well believe him. Measure the hole in the filter you have installed.
Regards
Declan

Thankyou, I knew it was something to do with the design but had forgotten about that.

[JOWETTJAVELIN]

OK, to finish this thread here are some photos of the engine in situ, note that this car is still running on the original engine.

Over 200 trouble-free miles have been covered so far, and on trying the engine for the first time it fired straight up! There are one or two things still left to do; some fine-tuning of the carburettor to correct a poor fuel consumption and a bad oil leak (which I know the cause of, and am mildly annoyed about).[frame][/frame]

You can just make the number out (274434):
[frame][/frame]

[frame][/frame]

Hopefully this power plant will propel the car to 100,000 and beyond![frame][/frame]

National Rally 2013 here I come!

Oxford or bust!

[brucek]

If you set off now, you should be there by June!!

Nice rebuild though - hope it carries you for another 80,000

[bmcecosse]

I strongly advise you fix the low oil pressure - get the correct filter.

[JOWETTJAVELIN]

Thanks for the comments.

BMCE I don't know what you mean by the 'correct oil filter'. I am using the one supplied by all the Minor specialists for the 803. Do you mean a NOS Tecalemit or Unipart one such as those from Club Spares?

[bmcecosse]

Yes - the one with the smaller hole. Either that or figure out a way to reduce the hole size in the one you have. Would be interesting to temporarily remove the filter and plug the orifice to see how the pressure reacts then when hot.

[Declan_Burns]

Yes - the one with the smaller hole. Either that or figure out a way to reduce the hole size in the one you have. Would be interesting to temporarily remove the filter and plug the orifice to see how the pressure reacts then when hot.

I agree with Roy. If the pressure increases and if you want I can contact Rolf Corbat on your behalf and find out how much he charges for his restrictor if you cannot source the correct filter. A club member over here did fit it and mailed me that it was a success.
Regards
Declan

[JOWETTJAVELIN]

OK I'll update when the time comes for a filter change.

[bmcecosse]

Don't wait too long - that pressure is worryingly low......

[Declan_Burns]

Info from Rolf Corbat,
The restrictor costs 12€ incl postage sent to me in Düsseldorf from Switzerland and if anybody wants one I will the forward on at postage cost ~1GBP to UK addresses. Next batch ready in approx. two weeks.

Regards
Declan

[JOWETTJAVELIN]

Thanks v. much Declan, I will be in touch with you shortly about this.

[Declan_Burns]

There are a few questions coming in from other members so I have translated the second page of Rolf's article (see link at the beginning of this thread)
Quote:
It should be clear to everybody that when driving mildly at engine speeds below 2500 rpm, there is not enough oil pressure to lubricate the bearings of all the moving parts. The solution to this serious issue lies in inserting a simple restrictor with a 1.5mm hole which fits in the original block thread. This corresponds to the original filter arrangement and works without a problem.
Pictures from left to right
1) Restrictor side view showing cross drilling-max height 11mm.
2) Restrictor front view showing Allen key fitting and 1.5mm hole.
3) Attaching the restrictor with an Allen key to the original block.
4) Insert restrictor with an Allen key until fully home
5) Measure the depth with a depth gauge-it must be at least 14mm.
6) Filter cartridge with too large a hole-in this case 3mm.
7)--
8] Fit filter and secure with a jubilee clip.
9)..

I make these restrictors from a stainless steel M8 Allen screw. The outside thread is recut to match the block thread 7/16" UNF. The cross drillings ensure there is enough oil flow in the block.
Unquote

I hope this helps answer the various questions coming via PM.

I would just like to add some comments I received from Rolf this morning.
1)The photos show the actual installation sequence
2) With the restrictor installed the pressure and flow are independant of the filter manufacturer and variations in the hole from supplier to supplier.

He has sent me the article in the original format and I will do a full translation and make it available to anybody concerned over the Christmas period when I should have more time.

Regards
Declan

[stevey]

Great stuff.

Many thanks for doing this, look forward to the translation.

[Declan_Burns]

I finally got around to finishing the translation.
Sheet 1[frame][/frame]
Sheet 2[frame][/frame]
Regards
Declan

[JOWETTJAVELIN]

I fitted the restrictor (a straightforward job) and have recorded the following before/after readings. Note that this engine is fitted with the much better 1098 oil pump, and the first set of readings were obtained using SAE 30 running-in oil, and the second set using 20/50, both Morris (Shrewsbury) lubricants.

BEFORE:

Idle - unless the idle speed was set higher than usual a reading of 5 psi was common. Increasing the tickover gave 20 psi.

30 MPH - 55 psi

40 MPH - 50 psi

AFTER:

Idle - setting the slow-running screw to a normal tickover a figure of 20 psi is the norm.

30 MPH - 55 psi

40 MPH - 70 psi

45 MPH - 70 psi

As can be seen the change in readings is marked and the restrictor is doing its job. The greatest changes were at road speeds in excess of 35 MPH and idling/crawling in traffic. The oil pressure warning lamp has barely come on since.
I would strongly recommend that anybody running an 803 engine buys one of these restrictors.

My grateful thanks to Declan Burns for bringing this modification to my attention and his translation of the original text, Rolf Corbat for producing the restrictor, and all of you who have commented on this rebuild offering advice, criticism and support.

[stevey]

Excellent!! hopefully mine will read something similar when its done. And yes a big thanks to Declan Burns and Rolf Corbat.

[Declan_Burns]

Thanks for the nice comments and I'm glad this mod is working. Rolf has been informed accordingly.
Regards
Declan

[bmcecosse]

Well done and a very useful discovery. I do however think that some of the improved readings will come from the now 50 grade oil rather than 30 grade..... But thats not to take away from the new restrictor which looks like an essential part to have if you can't get original spec filters.

[David53]

I have finally had time to fit the restrictor to my 803. I can see what you mean about the hole size on the filter -it was huge compared to the restrictor. The gauge on my car is the same as an MM, not terribly accurate but the pressure seems a little better than before (readings with a hot engine)

Idle = 20 psi

Pulling up hill in IRS gear = 60 psi

45-50 mph in top = 55-60 psi

Previously she would always sit around 50-55 psi once warmed up Thanks again Declan for getting the restrictor for me all the way to Australia

Just re reading Jowetts post - doesn't the relief valve prevent the pressure from exceeding 60 psi?