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 Post Posted: Mon Jan 16, 2012 5:41 am 
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shrinker wrote:
Always remember to address the ignition timing used at idle etc. Timing greatly affects the vacuum and thus the blade position.


one thing i need to check is my timing . My vacuum readings prior to the conversion were, what i call a choppy, 4-6 at idle, now they are at a more constant 6 at idle.
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 Post Posted: Mon Jan 16, 2012 6:28 am 
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.086 drill ALL 4?

You still need to make sure that the front and rear butterflies are open about the same amount too. In a "perfect" world all 4 barrels would be flowing the same amount of air at idle.

How many turns out are the idle mix screws in the metering blocks?

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 Post Posted: Mon Jan 16, 2012 7:03 am 
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yes all butterflies drilled to .086, probably could have gone smaller. i do have a extra set of butteflies that i can experiment with.

set transfer slot, front and rear, to .025(plus or minus .005) prior to mounting carb.
odd thing is that this is the first time i have ever had a carburetator idle right from the start, based on setting throttle relative to transfer slot, maybe just luck on this.

idles screws are set at 1 full turn.

ok, now i have to go work, need to head sarland, al this morning

later


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 Post Posted: Thu Jan 19, 2012 3:12 pm 
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Not luck, just you tuning it right. =D>


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 Post Posted: Thu Feb 02, 2012 5:50 am 
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still have not gone to track. :-
either it is to damn cold ](*,) or rain [-( . might try mobile this weekend. that is, of course, it does not rain.


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 Post Posted: Thu Feb 02, 2012 5:55 am 
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nomad wrote:
Not luck, just you tuning it right. =D>

thanks


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 Post Posted: Thu Mar 08, 2012 6:29 am 
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well i finally made it to the track last night. car was breaking soon as i got of tbrake. noticed my fuel pressure gage during run was 3-4 psi. usually keep it at 6 psi, which it was when i got back to pits. so raised fuel pressure to 7psi and adjusted float bowls. second pass exact same thing, breaking up right of the line, this time fuel pressure stayed at 7 psi entire run.
back to pits a little discouraged. :-& . so i decided to jet it two numbers, from 94 to 96. third pass, car reacted and ran much better, still broke up a little around the 200'mark.
and of course had to call it quits for the nite, as i did not have any bigger jets. going to order some for next week. i would imagine 98 will work for my baseline next week.

sure did feel good to be back in the seat after winter season.(Not that we have much of a winter here on the coast)

my fuel afr readings when car was at wot, all three runs, was running at 11.0-11.5.
have a few videos that i need to upload, once i figure out how to crop raw data.

and of course my msd crank trigger gremlin should up last again. that will be for another discussion.

later


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 Post Posted: Thu Mar 08, 2012 9:12 am 
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themadreefer wrote:
my fuel afr readings when car was at wot, all three runs, was running at 11.0-11.5.
have a few videos that i need to upload, once i figure out how to crop raw data.

and of course my msd crank trigger gremlin should up last again. that will be for another discussion.

later


THOSE AFRs ARE SHOWING IT'S WAY PHAT? If they are "correct" that is. Maybe you've fouled the plugs? What you should be looking for is AFRs in the 12.5 to 13.0 range down track in high gear.

MSD Problem? :-k

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 Post Posted: Thu Mar 08, 2012 10:14 am 
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yes afr readings kinda of have me boggled. considering each time i jetted up the car was running much better and afr readings
were staying pretty consistent thru each run. i am pretty confident to say, that if i had a pair of 98 or 99 jets in my tool box, car would have ran flawlesslly, even though it might have been fat.

i really do not think it is ignition. the last two times the crank trigger gremilin showed up, the car was running flawlessly.
awhile back when the first time crank trigger quit. i literally pulled entire ignition system out of car and checked, tested, probed, pulled wires, etc etc. and could not find anything obviously wrong.

the car was running great the first time i used the dominator,prior to ther conversion. guess tonight i will take carb
apart and go through and check all my calibrations. as this is the only major change i have done to car since last december.

i thought for sure last night that i would have to jet carb down,


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 Post Posted: Thu Mar 08, 2012 12:46 pm 
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Ignition demand is rather low @ part throttle where cylinder pressures are low. At WFO all that changes as when cylinder pressures rise the weak link in the system will show up. That could be plugs, wires, cap, rotor and possibly even improper routing of the crank trigger wiring.

I had an MSD Digital 7 give me a fit because the BOX was mounted to close to the COIL!! That showed me a miss down track and spikes in the recorded graphs. Replaced everything except the box and coil and it still did the same s**t. Moved the trigger wires to the outside the frame rail and that didn't help either. Finally moved the box abut 2 feet from the coil and that problem went away!

Oh, and none of this showed up until I changed out a cheap set of graphite plug wires for some really "good" MSD 8mm wires?? GO FIGURE! [-(

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 Post Posted: Thu Mar 08, 2012 1:07 pm 
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i am pretty confident ignition system is up to par. new cap, rotor, checked resistance on wires about two months ago(within specs), plugs only have about 6 passes on them. all my iginition wires are routed separetly form other wires.

now that you mention coil/box relationship. reckon i need to move my coil as it is about 6 inches from box.


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 Post Posted: Thu Mar 08, 2012 1:28 pm 
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After thinking about this a bit, those AFRs can't be accurate with the engine missing as THAT will make it show rich. Once you get the miss sorted out, maybe those AFRs will change too.

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 Post Posted: Thu Mar 08, 2012 1:52 pm 
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did not think so, but then again i am just a young grashopper with afr readings. will provide an update next wednesday


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 Post Posted: Thu Mar 08, 2012 7:01 pm 
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I think it will show lean if it's missing because of the unburned oxygen.

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 Post Posted: Thu Mar 08, 2012 7:57 pm 
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themadreefer wrote:
yes afr readings kinda of have me boggled. considering each time i jetted up the car was running much better and afr readings
were staying pretty consistent thru each run. i am pretty confident to say, that if i had a pair of 98 or 99 jets in my tool box, car would have ran flawlesslly, even though it might have been fat.

That's typical of not enough vaporization brought on from lack of compression pressure and or time or incorrect fuel. When the vaporization is too low the only chemicals that actually get vaporized are the lighter end ones. Thus you have to run a bigger jet to get enough of those chemicals into the engine.
The engine would be making a high level of CO and yet may not even be using all the Oxygen. When you change jets and the AFR reading on a WB doesn't change in accordance with the jet then your in the wrong place combustion and tuning wise.


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