speedtigger

iTrader: (16)

I have seen it before too, but I don't remember a specific incident where I have fixed it to share with you.

I bet Mark or Yeti over on The Bullet would have some insight. They are some level of genius on Holleys.

ZONES89RS

iTrader: (25)

Mine did that the other day. Used to do it some times on the camaro but this was the first time on the mustang.

APillow

iTrader: (3)

Bump for a novice question...

How do you control the ridiculously high idle timing? At 700 RPM I'm at 5.7 MAP pressure and 34 degree timing. Set base 20 degrees timing + 14 off the MAP.

Idled fine, just seems high to me...

Thanks!!!

speedtigger

iTrader: (16)

If you prefer a lower idle timing you can use a "ported vacuum" source on your carburetor. I you have a Holley, that is typically like the picture below:

APillow

iTrader: (3)

Ported Vacuum!!! That has got to be the ticket then. Right now I am just running off the manifold.

Like this:



Ok, I have a Street Demon I'll check on what port is applicable are report back.

speedtigger

iTrader: (16)

The engine is more efficient at idle, will have more vacuum and will have better throttle response with more timing. So, 30+ degrees at idle can be good. Where this much timing can be a problem is idle consistency. For example, if you experience too much RPM drop when putting the car in gear or engaging an A/C compressor etc., using a lower idle timing and more throttle opening at idle can help reduce this. But as the idle timing gets lower, the emissions and gas smell will typically go up. So, it is a trade off.

APillow

iTrader: (3)

Thanks for the help! I'll post a picture later, but I am proper now on MAP hook-up... Granted I think there are multiple people here running off the original setup I had - direct manifold. Not being familiar with MAP function, I followed their lead incorrectly.

I'm going to re-map timing and MAP tonight. Driving it too work today I think I need more regular crank timing than 28. Keep MAP at 12 for now. I say this because I'm still running rich IMO. Then again the Demon 625 is still out of the box settings for enrichment, which maybe too rich for a "tight" new LS rings on vacuum. Sucking too much

jerr6

iTrader: (1)

so the MAP should be connected to ported vacuum? i dont have the MSD box. i use the Daytona. this is interesting to me because i think i need more timing at idle or at least want to try it. but i need a laptop to do that.

APillow

iTrader: (3)

I cannot speak for Daytona, but it sounded like they had 10 preconfigured curves for a lot of different situations. Way more "no laptop" friendly than MSD IMO.

jerr6

iTrader: (1)

they do. i use the most aggressive one. i just want to try more timing at 1000rpm or idle

stinkybutt

I don't like to use ported timing on high compression motors. In my experience when running lots of initial timing and you tip in the throttle you get more timing because the vacuum goes up above the butterflies. So because you must be under some load and your vacuum signal is increasing you are adding timing witch could cause some slight knock. Ported timing was used by oem to reduce nox at idle and low rpm.
On another note I've built a bunch of 6-71 blown engines and used a vacuum advance distributor.Because of low static compression they love extra timing at cruise and idle. There's no reason that a boosted engine can't run lots of timing when not under boost. I'm always giving local speed shops flak for selling non-vacuum adv. distributors to their customers. It seems most don't know or understand what engines want. I also use vacuum advance on boats. Lets the engine idle down low for engaging drive without that dreaded clunk.

Don't get me started on carb tuning and power valve #'s. Seems most carb kits come with 6.5. I like 10.5 or even 12.5 on street cars with mild cams. This gives better tip in response.
Long time Tigger.
I'm looking forward to tuning my 660 center squirters on my LS3 280Z. I want to prove that they will run well on the street.

Aleck

LQ4BU

I'm heading out to the garage now, gonna mess with my MAP settings and see what happens. I'll report back later tonight!

Doug G

Once I got my AFR gauge and did a little tuning, my vacuum went up about 1-1.5 points.
Maybe due to closing the butterflies some, adjusting the IAB's, adding timing, and cleaning up the AFR some.

BUT....My timing is still locked and no MAP timing added

LQ4BU

Good to hear!



OK, sorry for not getting back on here earlier, but here goes....

I still have some tweaking to do, but so far the results seem to be great once I added the MAP sensor. The idle obviously went up, and the off idle throttle response seems much much more snappy than before. In the past, when I had the MAP sensor zeroed out, my timing was was at 18° until 1800 rpm, then it jumped to 28° and stayed there all the way through 7000 rpm. With those settings, I could cruise at 40 mph, mash the pedal, kickdown to 1st gear and the car would slightly break the drag radials loose as it accelerated after it kicked down. Now....when I do the same thing, after setting up the MAP sensor, and with the additional timing, the car actually breaks the tires loose before it kicksdown, just from the initial mash of the pedal, due to the increased throttle response. It actually feels like night and day now. The initial throttle response is pretty amazing. I didnt think I would actually FEEL such a difference. Big thanks to Speedtigger for this post!

I'm only adding 6° right now which equates to 24° idle and 34° during light load cruising.

My question now though....how much timing is too much under said situations?? Is 34° plenty safe enough to not even worry about it under light load conditions?

Doug G

Having a similar motor (LQ4/LS3 combo) I started at 32* and went as high as 38* (but seen specs on the plugs after that pass) with 34* giving the best 60' and 36* giving best ET/MPH.....I settled on 34-35*.

Now with all this talk lately, I will be trying lower timing just to see if I may have missed something starting at 32*..... Someday when I get back out

LQ4BU

Same here....I ran my car for the longest time at 32° because I saw some gains. But I never thought it would keep picking up by dropping the timing more.

With my setup now, at full throttle, my total timing is still 28°.

turbodarryl

iTrader: (4)

are y'all using the standard 2 bar map sensor?, part number?

speedtigger

iTrader: (16)

I am using map sensor GM #16249939. I think it is 2 bar.

turbodarryl

iTrader: (4)

Thanks, going to give this a try.

Doug G

Stock sensor here also (2-bar) from 2005 Silverado 6.0L (you may find cheaper replacements from your local parts house ?)