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Thread: Lucas vacuum advance DIY repair

  1. #1
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    Lucas vacuum advance DIY repair

    Hey all, I noticed a few of us have been having vac advance issues lately including myself. With nothing to lose since mine was cactus I thought I'd have a crack at fixing it, and it worked all of a sudden I got all this HP back. It's great and a simple fix which I found online, dosnt take much time and best of all it's virtually free.
    First get your vac advance out, simply 2 torx screws you may need to turn your dissy to get to them. If you do make sure you mark your dissy location or have a timing gun handy to reset the timing later.
    If you press down gently on the arm from the advance it will release from the weights inside the dissy.
    So there's not much to them, the body's basically been pressed together and thats what we need to open. Take a photo of the arm so you can put it back together in the same direction.
    You need a piece of timber with a hole ideally about 20mm smaller that the VA, I didn't have a hole saw that big on me so I just made what I had work.
    Start by cleaning any gunk out of the fold and find a good spot to start prying. I used a sharpened flat screwdriver to get it started, don't be afraid to tap the screwdriver with a hammer to get a start. I used a combination of some small vice grips and a flat head screwdriver, work your way around it until it all loosens up. There's no pressure behind the spring so it's not gonna come flying out at you.
    Once it's apart set the spring and body aside and focus on the diaphram. Have a look at for any tears and holes. Hopfully it's just got a couple of pinholes if so clean the diaphram and fill the holes with silicone or similar. If your diaphram is like mine and torn in a few places it could be trickier to get it back together. Their simple to pull apart only 1 small screw just take note of the washer location and diaphram direction.
    I'm thinking making a new one from a piece of rubber and some heat would be very easy to do. But I had a can of plasti dip on hand so that's what I used. I gave it about 6 coats overall and it come up great, unfortunately I went a bit overboard in some spots but it functions perfectly.
    Stay tuned for part 2, reassembly.
    Cheers Jim

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    Reassembly,
    After your silicone or plasti dip has dried it's time for reassemble. Put the diaphram back together the same way it was, make sure the large washer has the lip upwards. Reinstall your spring and put the body together, you will have some resistance from the spring.
    Now go back to your block of wood and sit the VA in the hole, now ideally you will have a few different shaped hammers I couldn't find my panel beating hammers so I used a claw hammer and vice grips. Holding the VA so the lip you have to close is upward gently tap a few spots from an angle to hold it together lightly. Now before its all tight turn the arm to the right location, you will be able to turn it later but you may undo the screw in the end.
    Whilst holding the VA firmly down with a small square hammer tap all around the sides of the lip working your way around a few times, try and get the sides as tight as possible. Next tap the lip on the angle closing the lip downwards on the body, the with a small cold chisel tap the last of the lip flat down. And that's basically it for the Vac advance pretty simple, I sucked in the hose before reinstalling and I couldn't get any air through. Once I find my hammers in going to neaten the folding but it works just fine the way it is.
    Next reinstall the vac advance, if your lucky you will be able to fish the pin into the hole. If not take the cap off, GENTLY! GENTLY! pull the rotor arm off and unscrew the baseplate. Fish your way until you get the pin through the hole in the arm, and screw the VA back onto the dissy. While you have the base plate off put a drop of oil onto the weights and a drop into the shaft. Reassemble your dissy, fire it up unplug the VA and check the ignition timing.
    Plug the vacuum advance hose back in and enjoy all that extra torque and HP you forgot you had!
    Most of this is picked off the web but I thought it would be good to open a thread for it.
    Hope it helps some one out there!
    Cheers Jim

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    I've been working at the ass end of sunbury the last 2 weeks. Definetly a difference getting up bulla hill, and heaps better at holding 100ks. My plasti dip seemed to work but it feels like it could be better still, the spring seems really hard maybe it's worth putting a slightly lighter spring in so it advances easier. Putting my finger over the vac hose it didn't seem to have anywhere near enough pressure to pull the spring.
    I done some searching and found some fuel pump diaphram material, I'm gonna buy some and when I re do the folds I'm going to try and build a new diaphram. If it dosnt work I'll put the original one back in. Also thinking of making a press to lock the 2 pieces of the vac advance together.
    Cheers Jim


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    Thanks James. A very intelligent & workmanlike approach to this repair job.



    Plastidip. $20 a can at Autobarn atmo. Never heard of the stuff, but maybe that is because I have lived a very sheltered life.

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    Quote Originally Posted by 4bee View Post
    Thanks James. A very intelligent & workmanlike approach to this repair job.



    Plastidip. $20 a can at Autobarn atmo. Never heard of the stuff, but maybe that is because I have lived a very sheltered life.
    No problem at all! Saw a few videos online of some old cars from the 30's that you can't get parts for he fixed the pinholes with silicone. The plasti dip came from a toymota forum, the guy plasti dipped his diaphram in his FJ. It's good stuff it's invaded the automotive industry as a paint job you can peel off.
    I'll definitely be buying a sheet of the proper material and having another crack at it. I'll post it up when I do!
    Cheers Jim

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    Made a few calls to try and find some diaphram material locally, the tools at auto barn didn't even know what a vac advance was.... called every carb, turbo, and brake repairs I could and got the same answer...."hahaha good luck" most of them very helpful at least putting me onto the next guy... I was suggested to try some tyre tube so that's what I'll do if I don't buy some material online.
    Cheers Jim

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    Quote Originally Posted by LRJim View Post
    Made a few calls to try and find some diaphram material locally, the tools at auto barn didn't even know what a vac advance was.... called every carb, turbo, and brake repairs I could and got the same answer...."hahaha good luck" most of them very helpful at least putting me onto the next guy... I was suggested to try some tyre tube so that's what I'll do if I don't buy some material online.
    Cheers Jim
    LPG converters are a good source of thin oil resistant rubber sheeting, maybe your local wreckers might have some really cheap.

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    Quote Originally Posted by bee utey View Post
    LPG converters are a good source of thin oil resistant rubber sheeting, maybe your local wreckers might have some really cheap.
    Thanks very much I'll have crack. I possibly found some localy he needs to check in the warehouse later on. Pretty much looking for a nitrile coated nylon material that's the best Ive found, it's pretty obsolete now only a few specialists I've found that rebuild VA and their up north. Plasti dip seems to work well but it's not very even around the edge which could possibly cause a leak in the future, but experimenting for now at least the VA is easy to open now Lucas vacuum advance DIY repair
    Cheers Jim

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    Found some $10 for a square foot! Not bad at all he's even gonna drop it off for me, the fella has horses near me so bonus! Looks like be making diaphrams for everyone Lucas vacuum advance DIY repairLucas vacuum advance DIY repairLucas vacuum advance DIY repairLucas vacuum advance DIY repair

  10. #10
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    I was doing a restriction on the driver's side screen washer this am & thought I'd give the pipe a suck....... $&^#@(*% Wish I hadn't now, 'cos the VA appears to be leaking. (not the original one) All joints ok so it seems it will be a another little job to do now.

    You are pretty good at putting a hex on my Discovery from afar, James.

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