SLROC Forum

3.5l V8 Carbs.

How can i check if the vacuum advance on the dizzy is working? (I don't have a vacuum tester)
If it isn't how do I identify which dizzy I have as I don't see any markings to get the correct rpelacment?

take the cap of (dizzy cap)  then get a length oh tube fit on vacume advance  then suck put tongue over the end of tube  if dizzy mechanism moves back the vacume bit is goosed  the vacume bit is replaceable
regards tom

Cheers Tom

Nothing moved, nor did I get suction back.
Now to identify the correct part number.

Assuming it's a lucas 35D, Link below might help with identifying exactly what type it is (part way down the page).

http://www.v8engines.com/electrics-1.htm

if it is a Lucas 35D, the unit you need will be the one linked to below.

http://www.simonbbc.com/ignition-spares/lucas-35d-distributor-replacement-vacuum-advance-unit

Best price I've found.

Jack

Cheers Jack

Hi, I have a 'spare' distributor in the garage, If you are handy for Wishaw, I could let you try the vacuum unit if that would help?

Your vac advance won't suddenly cause rough running. Both dash pots filled with oil, balanced and mixtures correct? Cap leads and rotor arm quality items and under 2 years old? Plugs under a year old?

Dash pots were low on oil. This has been topped up.
New sparks and gaps checked. New Coil, New fuel pump.
Running in the dark no sign of sparks tracking off the dizzy or leads. Dizzy and rotor look good.
Lumenition ignition
Seems to be blowing from exhaust manifold.
Pull one plug cap at a time and you can hear it loose the cylinder.
Engine turns over and easily starts with choke. Once warm it will now tick over, with a bit of choke. Sounds to low a tick over speed.To get some high revs is a balance of choke and throttle, but carfull not to kill the engine.
I was going to clean the cabs and check the diaphragm in the Strombergs.

What type of rotor arm is fitted? Riveted or moulded?

Colour/brand of the leads, plugs and coil? I've tried all the the alternatives before and now SimonBBC is the only place doing the full dealer quality ignition parts now and the price is much better!

I would suggest your carbs need tweaking first to get a decent mixture. Check for air leaks on the inlet side of the engine. Do both carbs suck hard against your hand when you close over them and does the engine subsequently stall with the intake sealed off?

Exhaust leak is worth fixing but probably not the cause.

Carbs are quite possibly gummed up, I've had issues with Shell fuel leaving residue in the filter bowls after reacting with the ally so worth cleaning out before trying to tune. You will need to balance both carbs as well.

Hope that helps

cheers

Carbs are currently off for cleaning. Not sure if it was like it before or onremoval, but the gasket for carb to engine was shot.
Both diaphragms look ok. First bowl was spotless, yet todo 2nd bowl.

HT leads are grey. Make unknown.
Rotor is.....
Coil is by InterCoil I think is the name. High performance option.

Should the carbs have a fuel return line?
Got the manual and tools to balance & tune the carbs.

Plan to check timing and compression at the weekend.

Shot gasket will explain the need for choke to make it run.

Yes there should be a fuel return, usually heads out the front of the carb and down the drivers side back to the tank.

Sounds like you may get some good results once back together!

So why would the fuel returns be blanked off. Any advantage here?
Vacuum advance is US so carbs will be sucking air through it.

Manual for Stromberg CD carbs is different to my CD carbs.  So that don't help much

Can you get a picture up?

Does the engine run better with the vac advance hole covered on the inlet manifold?

Had a good day today.
I can confirm my vacuum advance is duff. readings of 50psi . A working one gave readings of 180 - 200. so a high compression engine.
Leaking at manifold is crack manifold.
By rotating the dizzy the engine is running much better. Vacuum pipe blocked off. It would appear the advance / retard system has seized with the timing out a few degrees.

Will give it a few runs and monitor situation. Why would the fuel return pipe be blocked off?