A couple of engine carb

[kstrutt11]

Today I took the carbs off my +2S130 (twin dellortos) to enable me to clean up and paint the engine block, fix some oil leaks and tidy up the wiring and fuel lines which were all flaping around loose under the carbs.

I have found a couple of things

Firstly the ports in the cylinder head are very smooth virtualy polished, is this normal or has someone been tweaking the engine?

Secondly A couple of the thackery washers on the bottom of the carbs were broken and overtightened, how do you guys set the lower ones up is it a case of a messing around with a mirror and feeler gauges or is there a simpler way?

[paddy]

A couple of the thackery washers on the bottom of the carbs were broken and overtightened, how do you guys set the lower ones up is it a case of a messing around with a mirror and feeler gauges or is there a simpler way?

I use a mirror and judge it by the appearance in comparison with the top ones.

Some say they do it blind and judge the gap with their fingernail.

I've never tried a feeler gauge but I guess it would be pretty awkward in the space available and that level of precision isn't really called for IMO.

Paddy

[simonknee]

Use the thread pitch as a guide. Do the new thackery washers up completely - so there are just tight. Then back off by number of turns/flats to the desired amount of gap. With the studs used for a Weber head this is neatly 1 turn. You can use the studs that you can see to get a feel for just tight and check that the back-off is producing the correct gap.

Once you can do this you can throw away you feeler gauge!

(props to Keith for this)

[512BB]

I concur with everything that Paddy writes. The 40 thou gap is not critical, but dont do them up any tighter than that. Also, do not do all the top thackarys up to spec and then the bottom, or you will pinch the O rings unevenly. Do both top and bottom up evenly. And to get your eye in on 40 thou, practice doing up 1 thackary on a different application so that you can see what it looks like.

Use all new thackarys and new carb O rings, and you must use nylocks, not plain nuts, they WILL come undone.

Leslie

[512BB]

Hmm, not sure about doing the thackarys up tight Simon, and then backing off. I would have thought that you would flatten them some by doing that.

Leslie

[neilsjuke]

I have a steak knife ground Square on end to make a 40 thou gauge hold in the washer tighten with 1/4 drive socket set till it grips and back of until it falls out.
Neil

[billwill]

Rob Morley fitted rubber thackery washers to mine the last time he did up the engine.

I just do them up by 'torqing' to them. you get used to the amount of final torque needed on the top ones and just 'feel' the same final torque on the lower ones.

[kenny]

Yep, I didn't think anyone still used Thackery washers now, unless they wanted to keep the car period

I've fitted these below on all my DCOE engined cars and it is very easy to "gap" the unseen ones.

http://www.fastroadcars.co.uk/shop/inde ... ductId=105

Cheers,
Kenny

[rgh0]

I follow the Dave Bean Recommendation and always found it good advice.

1. Do not use the metal thackery spring washers on the top carb studs as the load and vibration on them causes them to break. Use the rubber style which does not suffer from this failure.
2. Do not use the rubber style on the bottom carb studs as the fuel and oil around this area causes them to deteriorate. Use the metal thackery spring washers as they tend not to break like when used on the top studs

cheers
Rohan

[kstrutt11]

Ok, Thanks gents I have ordered new washers and O rings already, I didn't know about the rubber ones but that said the metal ones have been on there for the last 14 years / 25000 miles with no problems apart from the overtigtened lower ones.

Yesterday I cleaned everthing up, it looks like someone had undersealed the engine compartment so I scraped this off, and re-painted as much as possible (one day I will need to remove the pedal box and do around there as well). I also cleaned and painted the engine block with grey garage floor paint which seems heat proof and the right colour, hopefully this will help spotting the oil leaks.

The wiring is all tidied and clipped as is the brake line. For the fuel pump (which was an facet electric one wedged under the carbs resting against the lower rad hose and very close to the steering column) I have decided to fit it in the nose where the coil orignally was clipping the line along the chassis over the steering rack, and via a filter into the pump. It will then go into the pressure regulator and onto carbs all with new rubber fuel lines. I will also add an inertia swith in the fuel pump power line.

All in all it should be much neater and safer.

Any thoughts on the head are they usually rough cast in the ports or polished?

Kevin

[types26/36]

For the fuel pump (which was an facet electric one wedged under the carbs resting against the lower rad hose and very close to the steering column) I have decided to fit it in the nose All in all it should be much neater and safer.
Any thoughts on the head are they usually rough cast in the ports or polished? Kevin

Would that be safe fitting the fuel pump in the nose from an accident point of view?
I think the modern thinking is to leave the inlet tracts rough as its suppose helps with atomization of the fuel/air mixture.

[rgh0]

The inlet ports where orginally rough cast, if they look polished or smoothed or machined in any way then the head has probably been ported at some stage. This could be good or bad depending on whats been done and why and how it matches your usage and engine setup.

cheers
Rohan

[kstrutt11]

I did think about the safety aspect of having the fuel pump further forward, but it is only just in front of the radiator and I came to the conclusion that keeping it away from the ignition sources in the engine compartment probably outweighed the risk, I also fitted an inertia switch so it turns off in an accident.

The porting is interesting, as we disccussed once before the engine was originally painted a maroon colour which some people suggested was the colour BRM engines were painted. It is only used as a road car now and it drives smoothly with good power, when I take the cam cover off to paint that I will have a look at the cams to see if there are any identifying marks on those.