Triumph GT6 with Rover V8 3.5 with Weber/Edelbrock 500

[gt6-v8]

Probably been asked for before but i cant find it in posts.

I have a map fo this but its way too lumpy on idle, need to swap out my carb jets cos im running 15mpg.

I need a map for ecomomy and a map for full on race, so i can switch between the two, anyone got one?

0-60 6 seconds @ 13 mpg

Martin

[cng1]

Needing two different maps, one for economy and one for "performance" is a common misunderstanding. When you are giving it some welly you'll be in a completely different part of the map to when you are gently trundling along so a single, well set up map is all that is required.

[gt6-v8]

thanks, so all i really need to do is pay attention to the map sensor readings and back off the timing on true atmospheric, give it more after say 4000rpm than usual, and smooth it over generally.

i still need throttle response though, so cant wind it back too far. any suggestions on this? my current setup below::

cylinders=8
mapBins=10,20,30,40,50,60,70,80,90,100
rpmBins=6,12,18,23,29,35,40,45,53,60
advance0=7,18,25,27,30,32,35,36,36,36
advance1=7,20,25,27,30,32,35,36,36,36
advance2=10,20,25,27,30,32,35,36,36,36
advance3=10,20,25,27,30,32,35,36,36,36
advance4=10,20,25,27,28,29,30,33,34,34
advance5=10,20,23,23,23,25,25,25,25,25
advance6=10,19,22,22,22,23,23,23,24,24
advance7=10,18,23,22,22,22,22,22,22,22
advance8=10,18,23,22,22,22,22,22,22,22
advance9=10,19,22,23,22,22,22,22,22,22
userOutType0=1
userOutMode0=0
userOutValue0=10
userOutType1=1
userOutMode1=0
userOutValue1=20
userOutType2=1
userOutMode2=0
userOutValue2=30
userOutType3=1
userOutMode3=0
userOutValue3=40
shiftLight=60
revLimit=65

[cng1]

There's not really any such thing as "throttle response", it's just an umbrella term for all sorts of things. What I suspect you actually mean is you don't want the enging bogging down under snap-acceleration. If that is the case then the place to look is your carbs rather than your ignition system. Your ignition system (assuming you aren't using garden hose for a vacuum connection!) will respond instantly to you stamping your foot, your carbs though won't.

It takes carbs a few engine cycles for them to catch up with snap acceleration so what tends to happen is that you get an oscillation from OK to lean to rich to lean to OK as the acceleration enrichment on the carbs can't quite kick in quickly enough, hits a bit too hard a bit, the enrichment runs out and then the engine recovers. It varies depending on your exact engine/carb setup but that is the broad pattern that things tend to follow. Your ignition map can help to mask some of the hesitation and fluffiness by running a compromise between what the load site would want at a steady state and what works best with a compromised fuelling setup under acceleration. Rather than play such games you are far better off getting your carbs set up properly which will yield large gains to economy, performance and driveability. With the fuelling set up right the ignition timing can get on with doing the job that it is supposed to, rather than acting as a crutch to support poor fuelling.

[gt6-v8]

had a mess about earlier after 7 mile warm up run.

standard 3.5 v8 weber/edelbrock 500 carb

with the map disconnected and vacuum end plugged, the KPA reads 102.
the idle is still high at 800/900 rpm, dropping idle speed screw has no more effect.
idle mixture is optimal as per revs highest and back off 1/2 turn
if i wind the timing back in the live mode i can get all the way back to 0 degrees and still have an idle of 750.

to go to a reasonable advance of 10 degrees the idle is at 900rpm.
when the map is connected back in, the KPa varies wildly between 27 and 42 Kpa (hardly stable!)

i think the step-up springs may be too strong, and the carb is addding off idle fuel into the idle stage. Im going to put blue 3" Hg springs in to try it (currently has 5" Hg in it)

I also think maybe the pcv system is affecting the vacuum. (running a breather int eht right rocker and the pcv valve going to the left rocker, also have a brake booster.
Im using full time vacuum port on the carb. (not ported vacuum port)
Anyone has similar setup that works well?

[AndyGT6]

Do you have a vacuum reservoir in the vac line from the carb to the MJ, this will smooth the vac signal. There is plenty of info on this forum regarding this.

Andy

[gt6-v8]

good thinking andy, i had forgot about that adittion i must say.

I am beginning to suspect the front pulley timing marks arent correct either, so i'll be doing a dead stop check on it at the weekend.

Nice to see another gt6 by the way

apologies to all, i seem to have hijacked the ignition map thread to a general discussion - no more.

martin