The 'E' Type Forum

Hi
I am a newbie with a 67 OTS i have had for 5 months I now have a total of 20 miles on her.
As you might expect it has been one challenge after another. The current issue is uneven idle,blue smoke out of cylinder 123 exhaust side with "uneven chuffing" out the exhaust.
So..
1/ Check valve clearances-adjust
2/ check piston timing and ignition timing ,set 10" advance static-adjust
3/ check cam timing-adjust
4/ replace worn distributor with new petronics distributor( and coil )
5/ New wires plugs and caps , plugs new
6/ Rebuild frozen carbs with Joe Curto kit ,reset jet depths and needle heights
with vernier caliper, check all float settings -adjust to spec
7/ Compression 160 on all !

After all this -no change
Symptoms,
Rear carb will not balance, draws less air than the others at the identical settings,other two fine
At 1500 rpm it draws 10 cfm the other two draw 20cfm
Air leak?
check with propane ,carb cleaner etc. None found
Replace vacuum hose from intake just in case-no change
Remove intake manifold( fun- not )
Intake tracts appear oily wet and black, #1 and #2 the worst ( Plugs black sooty but dry )
valves appear to have more wet carbon build up than the rest
So
could the valve guides be allowing enough oil and air past to affect the carb balance and cause the blue smoke and " chuffing " from these cylinders?
If so , off with her head?? ( yuk )
Help!

Check the basics like the interconnecting links between the carbs. It is absolutely essential that all three cars start to open exactly at the same time and all three butterflies close completely at idle.

To set the idle you might first disconnect the above linkage and ensure that all three butterflies are closed/ against their respective throttle stops. With the carbs now on their stops try adjusting the air volume/idle screws to determine that you can adjust each one. (highly likely you can) once you have achieved/confirmed that, then you can connect the linkages and set all three butterflies to open at the same time. this takes a fair bot of patience, but when done properly makes a big difference. You also need to ensure the choke operating components are adjusted properly. if you read the workshop manual a few times it will become clear.

There are many other checks to do like confirming the carb pistons etc are free to move float chamber fuel height setting etc. if you have good compression I would spend my time on the carbs at this point and not think about taking the head off.

Just mu opinion.
Best regards
Phil D.

I agree with Phil : it would be very unusual for 2 guides to wear and not the others. The tell tale of worn guides is a puff of blue smoke on each upward gearchange ( best seen by a following observer ) or in a really bad case continuous blue smoke on the overrun. The advice Phil has given is good, and in addition have you checked the respective float levels ( and indeed the integrity of the rear needle valve ) ?

Hi,
Of course, I'm agree with Phil and Christopher for the SU.
Look at the service manual and follow exactly all the points.

Oupsss

Mich

Thanks all !
good suggestions ,although some have been tried already. Choke adjustments are verified clear of contact.
I have experience checking fuel jet levels on my MG TD H2 SU's but the jets can be dropped completely to reveal just fuel in the jet bearing. Easier to check with a vernier caliper .
How do you advise doing this on the HD8's? What should the fuel level range be in the jet bearing?
Also might it be possible that some of the oil may be due to the 20wt damper oil overflow from the freshly filled dampers causing the "wet oil" Look on the intake valve and tracts?
Odd that the car was doing exactly the same thing with frozen jets ,old fuel ,a battered distributor and cam timing out by five degrees on intake and exhaust cams.
When I matched the CFM of the rear carb at 450rpm with the other two , the idle scew was open 2.5 turns and the other two at 0.5 turns !!! Butterflys are tight fitting and I even tapped the spindle spring arms to make sure they were shut hard on the front two carbs.
Linkages were disconnected between carbs
All float needles are new viton reset to 7/16" as per manual ( gross jets removed )
I will continue to chip away at.
All advice much appreciated !
Cheers

450 rpm is far too low for a reliable idle . A normal idle would be perhaps 700 rpm . As far as fuel levels are concerned, with the jets set at a nominal 65 thou down from the bridge, I expect to be able to see fuel in the jet but not at its very top and certainly not overflowing . I think it highly unlikely that damper oil could cause wetting of the inlet valves unless you overfilled the dampers to a radical degree. None of this in any event explains your imbalance in airflow for which I can only suggest 4 causes : 1. Butterfly stagger which I believe you may already have eliminated . 2.An air leak adjacent to the rear 2 cylinders - the servo takeoff is the obvious suspect - again you have tested for this but the leaks can be insidious, and PTFE taping the thread of the spigot might help 3.A blockage in the balance passages in the manifold - these are enormous in the 4.2 and blockage could cause all sorts of untoward effects 4. a lack of suction in one of the affected cylinders - I had this from a very unlikely cause on a Rover 2000 which was that one of the buckets had a hardening defect and had worn a hollow in it so that the valve was hardly opening!

Good luck !

Not much I can add except to ensure the three needles are EXACTLY the same length as measured from the face of the damper piston. They have a tiny groove at the shoulder to mark how far they should be inserted into the bottom of the damper piston. One of mine was 2 mm too far in. It caused similar balance symptoms and black carbon deposit on the plugs to those described although no blue smoke. A mm makes a huge difference. Oh and if you remove the needles makes sense to check all three are the same profile...UM from memory but I might be wrong so check your manual.

You say you are experiencing uneven running and blue smoke. You are sure the engine is not overfilled with oil arent you?

ie bent dipstick, incorrect non "e" dip stick, wrong grade on too thin oil etc.

Have you checked the engine blow though pressure with the motor running? You could pull off the breather pipe from the inlet, you should see some fumes indicating it is not blocked.

Quite often I have seen the breather gauze fitted upside down on the breather or be clogged up.

Its always interesting to see the camshaft rotate with the engine running by removing the oil cap. You might detect excessive pressure, indicating combustion blowby.

Mich7920 wrote:Hi,


A think is stange for me. It's the inlete wich are oily wet and specialy the 1 and 2.
If you're right in the number ( the 1 is near the radiator ) check the breather pipe.
It join the support bracker just between the 1 ands the 2.


Mich

On the XK engine, the #1 cylinder is at the rear and #6 is near the radiator. The numbering is just the opposite of most engines.

Hi James
Breather just cleaned and working fine, dip stick measured ,adjusted according to posts here a few months ago . The stop had been shoved up giving a false full reading that the PDO ( previous dumb owner ) never noticed. Correct measured oil now fills 1/4 up the crosshatched section.
I may try to bring #1 ,( at firewall ) to TDC on compression stroke and apply some air pressure to the intake tract at the head and see how much air escapes the valve guide/seal. Then check #2.
If they check out fine then my problem is/was elsewhere.
Right now, thats the best plan I can come up with !
All other suggestions welcome !
Regards,
Keith

Do a wet compression reading and post here to compare against the earlier dry reading. Put some oil in the spark plug hole just before taking the compression reading. You may find the number increases.

Absolutly right Mark !!!

Thank you for making this correction in a pleasant way
It's a basic information and luckily I respected it when I rebuilt my engine. It was a long time ago but it's still inexcusable!

Mich

Heads coming off, just waiting for it to let go.
I will post the results once it is in the shop for examination.
Thanks to everyone for the most helpful input.
This is a great site with generous members !!

Shop confirms bad intake valve guides on #1 and #2. So new intake guides , positive oil seals and then some hold downs for the exhaust buckets. Then check all valves for proper angles and seats.
Meanwhile the upper cam chain was so loose , it scored the head on the intake side !!!!!
Time for a new one, its quite floppy.
I cant get the damper nut off so am considering just breaking the master link and attaching the new chain and feeding it through. Idler gears look good as do the guides.
Shipwrights disease? I'm lovin' it
Keith