How common is oil restrictor to Rockers

[silverfox4]

Hi All,

Just did a full engine rebuild and wondering if there is too much oil going to the rockers. This then collects in the PCV and flows back into the intake.

Observation one is that the valve cover baffle is a bit makeshift, so have made some simple drain modifications there. The other is maybe there is excess oil reaching

the rockers and misting. At this point It is likely too soon to subscribe to the "remove PCV and use draft tube" solution.

So am wondering how many folk use an oil restrictor under the pedestal? Was the external oil feed a competition alternative or a lack of oil solution?

 

Cheers,

Alf

[RogerH]

Hi Alf,

the oil supply to the rocker shaft is metered by the end bearing on the cam shaft - so effectively that is a fairly/stable oil supply.

The rocker cover should have a plate covering the exit to the PCV thus restricting the escape from the engine,

 

If the PCV appears to have excess oil floating around in it then it is probably the PCV going pear shaped.

 

I removed my PCV, to prove what was going on, and fed it into a catch tank. After a few thousand miles there is no oil in the catch tank

So I would suggest that the PCV was drawing oil out of the engine rather than the other way round.

 

The external supply may not be a good move. It could easily supply too much oil and deplete the oil flow around the crank etc.

Generally the external mod is not required.

 

Roger

[Motorsport Mickey]

"So am wondering how many folk use an oil restrictor under the pedestal" ....I did a 2mm hole in a bush.

 

Was the external oil feed a competition alternative or a lack of oil solution?...neither - just a marketing ploy.

 

I did a bit of competition and over 6 years with a 4 cylinder TR never had a problem with the standard rocker oil distribution without any exterior feed.

 

Mick Richards

[silverfox4]

Thanks Roger and Mick,

 

I wondered why external feeds were used - doesn't work for me.

I will focus on the PCV and see what's up there, maybe a new diaphragm needed first.

 

Many thanks again,

Alf

[RogerH]

Hi Alf,

if a replacement diaphragm doesn't do the trick then contact Marco (Z320 on this forum). He has some neat ideas on making it work better,

 

Also make sure that the inlet form the rocker is the lowest point in the PCV (like a sump)

 

Roger

[ctc77965o]

I think I mentioned here before that I had persistent preignition problems on my TR in the early 90's which I eventually traced to the Moss Oilfeed kit and the oil mist getting thru the PCV into the induction system. After discussions with Moss they modified the kit to add a restrictor...but I just gave-up and removed the oilfeed...deciding that slow rocker shaft wear was a lesser evil than reduced power, high oil consumption, and smoky exhaust.

[silverfox4]

Thanks Dave. I see no merit in an external oil feed . In stock trim, there seems to be more than adequate flow, to the rockers (maybe even too much), and Mick's experience noted above supports this view. There are frequent suggestions of excess blow-by/crank case pressure contributing to this situation. I stand to be converted, but I am not convinced of this yet.

 

First step is PCV service and another look at the baffle design in the rocker cover,, but can possibly see a 2 mm restrictor on the horizon.

 

As is, it makes for a very messy top end with tuning issues and lack of crispness- it should not this way!

will pick away at it

 

Cheers,

Alf

[Drewmotty]

30 years ago I welded up the bleed holes on top of the rockers to restrict the volume of oil being fed into the area and force the oil to escape between the rocker bushes and shaft. Its still the same with the same shaft and bushes.

[AlanG]

Hi All,

Just did a full engine rebuild and wondering if there is too much oil going to the rockers. This then collects in the PCV and flows back into the intake.

Observation one is that the valve cover baffle is a bit makeshift, so have made some simple drain modifications there. The other is maybe there is excess oil reaching

the rockers and misting. At this point It is likely too soon to subscribe to the "remove PCV and use draft tube" solution.

So am wondering how many folk use an oil restrictor under the pedestal? Was the external oil feed a competition alternative or a lack of oil solution?

 

Cheers,

Alf

At Saturdays engine seminar at TRGB Gary /Jason mentioned that there was more than enough oil supplied to the rockers without modification. The only times they came across an external oil feed was if the rear oil gallery supplying the rockers had become restricted and the external oil feed fitted as a cure.

Alan.

Edited March 19, 2018 by AlanG

[RogerH]

At Saturdays engine seminar at TRGB Gary /Jason mentioned that there was more than enough oil supplied to the rockers without modification. The only times they came across an external oil feed was if the rear oil gallery supplying the rockers had become restricted and the external oil feed fitted as a cure.

Alan.

Hi Alan,

I can see less knowledgeable people going to the expense of fitting the external feed to bypass a blockage if time was pressing.

It would make more sense to remove the camshaft and clear the blockage.

With the head off and the cam out it is a straight drilling from top into the cam rear bearing bore.

 

Roger

[AlanG]

I think the inference was that it had not been recognized that there was a restriction, just inadequate oil supply.

Alan.

[silverfox4]

Thanks for the feedback and dialogue, which certainly serves to confirm that there is more than adequate flow to the rockers. The plan at the moment is to prepare

a 2 mm restrictor just in case.

FWIW, the motor is clamped to a bench at the moment so it can be run at our leisure to look at these issues before spring - regretfully it can't be run under load,so we have to take that

into consideration)

 

Alf