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Author Topic: 130-F9-190  (Read 3889 times)
Anders Dinsen
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« on: July 08, 2009, 08:44:37 pm »

After a week in the mail, new jets arrived on Monday and main jets are now down from 140 to 130. Emulsion tube still F9. Air jet reduced to 190 to be on the safe side.

Difference in performance is obvious: Where it used to drop off over 5000 rpm, it now produces full torque all the way to 6000 and above! This is how the Holbay cam should perform.

I did a quick run down my local motor way yesterday, and I dare say the performance is absolutely satisfactory. With the engine still "taking off" at 3000+ rpm, but rev'ing freely up 3000 more, the car can really do some serious "pulling". Still accelerating hard 150 km/h in fourth, I don't dare guessing on the top speed!

No work is done until the paperwork is done, as they say. And that applies here too: I have to go back to the rollers now and finish the tuning. I've got a few more air jets to play with to get the very top end absolutely right, but so far my car has never felt better than this! Smiley

I've got no photos this time, so you'll have to do with your imagination Wink

However, here's a link to my jetting chart with the entire jetting history. I may write some notes about it at some point as my comments probably need some explanation. After all, the chart also reflects the "learning process" I have been going through (not to mention the problems I have had):
http://tmp.dinsen.net/murena/jetting.html

/Anders
« Last Edit: July 08, 2009, 08:46:46 pm by Anders Dinsen » Logged

'82 Murena 2.2 prep 142
'01 Grand Espace 24v
'08 Smart Fortwo 0,8 cdi
roy4matra
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« Reply #1 on: July 17, 2009, 02:00:19 pm »

Difference in performance is obvious: Where it used to drop off over 5000 rpm, it now produces full torque all the way to 6000 and above! This is how the Holbay cam should perform.

I did a quick run down my local motor way yesterday, and I dare say the performance is absolutely satisfactory. With the engine still "taking off" at 3000+ rpm, but rev'ing freely up 3000 more, the car can really do some serious "pulling". Still accelerating hard 150 km/h in fourth, I don't dare guessing on the top speed!

Well done.

You don't need to guess at the top speed Anders.  With your high fifth gear, we know that if it is performing well it should do 220 kph at least!

Roy
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Anders Dinsen
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« Reply #2 on: July 17, 2009, 10:00:32 pm »

Thank you very much, Roy. Unfortunately it still seems to run too rich as this photo of the spark plugs shows:



This photo is taken after town driving, which explains the carbon despite the middle and top being correct (or at least much leaner than they were on the rollers). The idle jet was 50F9, so I have changed it back to the 45F8.

But, as everyone can see, there's something wrong on the two middle plugs. I currently suspect a small airleak around the o-ring spacers on the middle carbs. The manifold is obviously not designed for the particular spacers I'm using and the inner o-ring is potruding slightly over the edge. I have a hissing noise in the car at certain (small) throttle openings, which I have at some point been able to eliminate by tightening the spring washers on the carbs. Since the carbs are not supported from the underside, the four studs in the top row are carrying the whole load. With time and vibrations, the spring washers ("thackeray washers") seem to soften up a bit, causing a leak. I have to check that now.

Interestingly, however, the 45F8 works rather ok. Perhaps a little too lean, but not much. Switching emulsion tube to F16 has improved it however.

So current setup is:

Idle: 45F8
Main: 130
Emulsion: F9
Air: 180
« Last Edit: July 17, 2009, 10:02:47 pm by Anders Dinsen » Logged

'82 Murena 2.2 prep 142
'01 Grand Espace 24v
'08 Smart Fortwo 0,8 cdi
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