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greg1.4
25-01-08, 03:42 PM
just wondering how far the dizzy timing should be advanced when running twin 40 carbs and highlift cam on a 1300 sr..

i have it advanced 15 deg to get it to run really well..below that it gets quite lumpy and doesnt pull so well..

15deg is a bit much so might bring it down a little as the engine has got a serious rattle now..

i am running semi synthetic oil, should i put thicker stuff in?

the rattle seems to come from bottom end, we have replaced the big end bearings/shells..

anybody have any idea on what the rattle could be?

cheers

Greg
Adam
25-01-08, 04:04 PM
When does it rattle? It may be detting due to excess ignition advance.

Theres no "set advance figure", it needs be on a rolling road where it can be adjusted, and then the operator check the results.
garyc
25-01-08, 05:19 PM
What is the distributor number? at what RPM is it being set at 15 deg? I suspect the idle mixture is all wron at idle. As said get it to a RR. Have you got the vauccum advance running?
greg1.4
25-01-08, 09:42 PM
yes the vaucum is working..

we set the timing when it was at 1500 rpm..

it seems to rattle really bad when you rev it..
Adam
25-01-08, 10:20 PM
Timing should be set with a warm idle, and vacuum disconnected.
Wheres the rattle coming from? Probably worn valve gear if its nothing like a heat shield etc.
_JH_
26-01-08, 12:03 AM
I agree with what garyc is getting at. I'd set it to the standard figure at idle [is it 10 degrees? it's been a while lol] and adjust the idle mixture to get it running better, then see how it drives. If not, RR is your answer.
garyc
26-01-08, 07:52 AM
I'd also check how much advance you are getting at 4500 rpm too.
greg1.4
26-01-08, 10:09 PM
ok..it seems to pull really well when it gets to 3500 or 4000 rpm..

and the timing was set with a warm idle..

car goes fine..just rattles whe she gets warm..i am going to get it back to standard timing and see..
garyc
27-01-08, 05:13 PM
Has it got an aftermarket cam in it or is it just a std one??
greg1.4
27-01-08, 08:40 PM
enem 300 deg camshaft
garyc
27-01-08, 09:28 PM
Speak to these guys http://www.h-h-ignitionsolutions.co.uk/ its highly likely your dizzy will need modifying + a trip to the RR. Keep us posted on the results.