Vacuum advance needed or not?

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21st January 2008, 11:08 PM
Taz

Agree with lonerangie - I thought LPG likes a heap of advance upfront, something like 20deg or more, and then upto around 28deg at max revs. So no vacuum advance is likely to have a greater impact on LPG economy
23rd January 2008, 01:20 PM
mcrover

Quote:

Originally Posted by Bradtot

Thanks for the input.
If I replace the hose without this restrictor in I can suck and watch the dissy base plate move just as I think it should.(I must have super lungs:eek:)
If I suck on the restrictor fron the end that has "carby' marked on it I can let it sit on my tounge and it will not leak, meaning its blocked , restricted etc.
If I suck on the end marked "dist' I can suck right through it. That is why I thought it was some sort of valve.
This was not put in when I converted it to gas it was already there. I am sure I have done the same thing before years ago and the base plate did move, so maybe its now become blocked?
I will let u know if there is any improvement as I havent driven it since I have taken this thingy out of the loop.
Regards
Brad:cool:

Just a different set up than I know of, normally they are loaded up with a fair bit of spring pressure so it takes a fair bit of force to move it, cant remember off hand what the last one I tested was so I cant say much more than that.
24th January 2008, 06:57 PM
Tank

Quote:

Originally Posted by mcrover

Just a different set up than I know of, normally they are loaded up with a fair bit of spring pressure so it takes a fair bit of force to move it, cant remember off hand what the last one I tested was so I cant say much more than that.

If you cant move the vacuum advance plate by "super sucking" then it is probably siezed up, suck it and see, Regards Frank.
24th January 2008, 11:03 PM
Bradtot

Update I tried really hard to suck on the end of the one way valve thingy and had it stuck on my tung for a while and it held, I sucked even harder and I could just get it release and let air through it, so it does work but I feel its way to hard to overcome the resistance before it lets through some vacuum.
I have now driven the Rangie with just a pipe from the plenum to the dizzy, and I know the dissy plate moves when I just suck on the tube normally, and its much smoother and appears to have slightly more go. When just on coasting feathering the acc pedall all seems smoother, dont know if I am imagining it or what. I am going away this weekend so I will monitor the consumption on both gas and petrol.
Also I heard no pinging at all on gas and just a small amount under load on petrol Timing is set at 14 deg btdc static.
We shall see when I get back the results.
Thankyou all for your comments very much appreciated
Brad
25th January 2008, 10:58 AM
Scouse

I've found the same problem with mine.
I recently fitted my spare 3.9 HC engine after an unfortunate incident with a bit of water & couldn't believe the fuel economy difference - it would have to use 1 1/2 times my old 3.5 LC engine.

I investigated the vacuum advance & found it wasn't working as in your 1st post. I then found that the "restrictor" was blocked so I took the one off my 3.5. That was the same.
No matter how much vacuum I applied, it wouldn't get past the restrictor to operate the vacuum advance.
I have removed the restictor now & have no problems with pinging at all - so far so good anyway.
25th January 2008, 01:32 PM
Bushwanderer

Quote:

Originally Posted by Scouse

I've found the same problem with mine.
I recently fitted my spare 3.9 HC engine after an unfortunate incident with a bit of water & couldn't believe the fuel economy difference - it would have to use 1 1/2 times my old 3.5 LC engine.

I investigated the vacuum advance & found it wasn't working as in your 1st post. I then found that the "restrictor" was blocked so I took the one off my 3.5. That was the same.
No matter how much vacuum I applied, it wouldn't get past the restrictor to operate the vacuum advance.
I have removed the restictor now & have no problems with pinging at all - so far so good anyway.

I Scott, I'm pleased to see that you have gotten the RR back on the road.

Best Wishes,
25th January 2008, 02:41 PM
Scouse

Quote:

Originally Posted by Bushwanderer

I Scott, I'm pleased to see that you have gotten the RR back on the road.

Best Wishes,

It was up & running the next weekend :D.
I'll post up the gory pictures later :twisted:.

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