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timing/pinging
https://slantsix.org/forum/viewtopic.php?t=43925		 Page 1 of 1
Author:  aypee 6 [ Mon Mar 07, 2011 4:27 pm ]
Post subject:  timing/pinging
G'Day guy's
Does this timing curve sound right.
Static 14deg at idle (1000rpm)
0deg at 1200rpm
18deg mech to 3500rpm for a total of 32deg. No vacuum advance.
Problem is engine pings at around 3000rpm even if I reduce timing to 10deg static for a total of 28deg at 3500rpm.
Comp is now 9.8:1
cam 245@050 straight up
465 holley std jets (57), 2.5 pv due to low vac from reduced timing.
3.23 rear
904 auto with 2700 stall.
running 98 ron (aus)
Cheers Steve.
Author:  SV162 [ Mon Mar 07, 2011 4:57 pm ]
Post subject: 
I'm no expert when it comes to advance curves, but 0* at 1200rpm seems unusual. Your initial would be OK, I run mine at 14* and your total should be OK too, mines at 31*
Just for comparison, here's what mine does.
Static-500rpm
3*-800rpm
5*-1250rpm
8.5*-2000rpm
Total Crank 17*-4000rpm
My engine does ping on a very hot day but only at around 3 - 3500 if I'm accelerating hard in top gear from around 60mph. I don't think my comp would be far off yours, but I'm only running on Premium fuel which is 95 RON.
How much vacuum do you have at idle and at 3000rpm? your power valve may not be opening causing your engine to lean out and making it ping.
Author:  aypee 6 [ Mon Mar 07, 2011 9:52 pm ]
Post subject: 
Cheers SV162
I think I'll jet up on the secondary circuit and see what happens. A present I have to get my throttle blades drilled so I can use my idle circuit, as I am on primary and this is causing carb to be lean before powervalve kicks in. What rear jetting/plate do you have for your secondaries.
Cheers.
Author:  SV162 [ Mon Mar 07, 2011 10:54 pm ]
Post subject: 
Try adjusting your secondary idle before you start drilling any holes. You may find just opening up the secondary plates a little bit more might give you more adjustment on the primary idle.
I'm running a 350 2BBL now, I got tired of trying to get the tune right with the 4BBL. I was using a 390 Holley with a secondary plate, which was a 56 jet.......I think.
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