RPM beat me to is but I beat Gabba
I ordered Crane Cam kit with the adjustable vacuum advance (that was discussed in this thread) and had this fitted. I cheated though and had a shop do it for me as they have all the timing and tuning gear.
Anyway, I gave the shop TKO's timing figures and that is what we used. With the adjustable vacuum advance, this was wound fully in and then wound out two complete turns. I am not sure if this is enough yet or not, but there is no pinging.
I took the car for a spirited drive post the re-curve and here are my thoughts and what I noticed;

1. Engine idle felt more free, like a sewing machine running calmly. Sounds weird, but I noticed a difference at idle.
2. On acceleration, I feel that it winds up pretty nicely now.
3. When doing 55-60 and I punched it, I noticed the jolt into the seat. Usually at 60mph, the car would still have some pull, but this was a lurch and a jolt.

All in all, yeah I think it has woken up the 289. If I had the money, I would have loved putting it on a dyno before and after.
Thanks for the guide here fellas and for the encouragement to make this modification. Thanks for starting this post Gabba!
2.

Last edited by Stevo (8/20/2019 5:12 AM)

TKOPerformance wrote:

You can always try adding more by bumping base timing, but what I found on these low compression 289s is that I could never get one to ping, at least on decent gas.  The ethanol is even more detonation resistant than the octane rating would imply, because ethanol is really had to ignite without a spark.  I run 89 octane in mine, and I could probably get away with 87.  I could never get it to ping under any circumstance with 93 or 89 (I used to run 93 like an idiot before I realized it just didn't need it).  I even had the timing WAY off at one point, but still no pinging.  I think if you could dyno it though you'd see the improvements stop about 40-42 degrees and then it would start going backwards.  At some point you're introducing ignition too soon on the upstroke and the engine starts fighting itself because the mixture has burned before TDC, and now the energy left to push the piston back down is reduced from optimal. 

I would definitely say that mine is more agile now. Winds up quick and you really feel how light these cars truly are. I am not sure I would want much more HP in this thing after this mod.

Stevo wrote:

TKOPerformance wrote:

You can always try adding more by bumping base timing, but what I found on these low compression 289s is that I could never get one to ping, at least on decent gas.  The ethanol is even more detonation resistant than the octane rating would imply, because ethanol is really had to ignite without a spark.  I run 89 octane in mine, and I could probably get away with 87.  I could never get it to ping under any circumstance with 93 or 89 (I used to run 93 like an idiot before I realized it just didn't need it).  I even had the timing WAY off at one point, but still no pinging.  I think if you could dyno it though you'd see the improvements stop about 40-42 degrees and then it would start going backwards.  At some point you're introducing ignition too soon on the upstroke and the engine starts fighting itself because the mixture has burned before TDC, and now the energy left to push the piston back down is reduced from optimal. 

I would definitely say that mine is more agile now. Winds up quick and you really feel how light these cars truly are. I am not sure I would want much more HP in this thing after this mod.

WOW!!!!!!!^^^^^^^^^^
6s6
 

TKOPerformance wrote:

Yeah, give it some time

He'll want 1-3/4" long tube headers and a snotty cam before its all over...

This is only stage 1 of the sickness...

Ha, ha... Oh man, here we go!
Sadly, this thing called money (or lack of) really cramps my style though

Stevo wrote:

TKOPerformance wrote:

Yeah, give it some time

He'll want 1-3/4" long tube headers and a snotty cam before its all over...

This is only stage 1 of the sickness...

Ha, ha... Oh man, here we go!
Sadly, this thing called money (or lack of) really cramps my style though

Pay the mortgage, buy new cylinder heads...is this really a decision?

Like I said, sickness...
 

TKOPerformance wrote:

I wouldn't change it.  GT40 heads shouldn't need a ton of spark lead.  Vacuum advance has to be tuned by driving and adjusting.  Static numbers on a stationary engine aren't going to get you anywhere because that's not what vacuum advance is for.  An old rule of thumb is set the can to add another 10 degrees at 2,000 RPM, but that's an extremely oversimplified way of looking at it.  I'd add vacuum advance until it pings then knock it back until it stops, reducing it by about 1 degree for a safety margin. 

Just remember clockwise is LESS advance, counterclockwise is more. 

I'd also try to get the mechanical advance in sooner with lighter springs.  You want it all in by 3,000 or even a bit less.

TKO , the comp cams manual says rotate all the way clockwise for full vaccum advance, reduce by two turns counter clockwise rotation , to reduce spark knock... lol another thing wrong in this manual?

https://youtu.be/rRPBlhToqrA

So now it’s marked also on the vacuum advance how it operates so I am not confused next time if I need to adjust .. the setting I left it on is 6 turns clockwise , basically half way!



If you look closely it’s connected to manifold vaccum at the base of the carb.  Idle is reset, The car is ready for a test drive .. !

Total timing set to 36 degrees.

Last edited by Gaba (8/23/2019 7:09 AM)