Special getting closer...

911hillclimber · Post by **911hillclimber** » Sun May 02, 2010 8:39 pm

Thank you for the idea.
Used to have one ages ago and worked well.

If I can get the basic thing running then it will go to the rollers for fine tuning.
Not sure i would be able to see the end of the Colourtune 'plug' way down in the 911 heads?

pncarrerars · Post by **pncarrerars** » Mon May 03, 2010 9:41 am

Sorry, I meant that you could use a colourtune to diagnose the current missfiring rather than for fine tuning. You should be able to determine exactly which cylinder(s) are missfiring & whether it is lean/rich mixture or ignition related.

I found on a 911 that the deep plug hole helped as it is dark & easier to see the combustion colours. Needed to use a mirror though as my head is too large to fit between the engine & the bodywork.

Pete

Barry · Post by **Barry** » Mon May 03, 2010 11:36 am

Yes, I wondered about a Colourtune: very useful things particularly when you just want a rough idea of what's going on.

Did you say you've done a compression check Graham?

Have you had the PMO apart, just in case there's anything in there?

In a way, you have a lot going for you, in that one bank is fine, so you are very limited as to things that are unique to the 'poor' bank, and that one cylinder in particular: dizzy cap and it's own lead (have you tried a test sparkplug with, say 1/4in, gap?), but not king lead. It should easily jump this. You know that the rest of the ignition is O.K. as the other bank is good, and that applies to timing as well. If the compression is within 10% or so of it's neighbours, then that would be close enough to run the cylinder well enough at this stage, I'd have thought. Is there any reason that the cam timing or valve clearances could have changed? Mind you, if the compressions are the same as the other side, that would imply that you were close enough at this stage I suppose.

I understand your frustration, I famously went a VERY long way around the houses trying to get my blue 911 to rev beyond 5K. Suffice to say, the engine went in and out several times (I'd just rebuilt it, so wasn't sure about my cam timing, or whether the Solex cams I had used were suitable), different carbs, all sorts of fuel system mods, fitted MSD to replace the CDI: loads and loads and loads of things. In the end it turned out to be the tacho taking too much current from the ignition. Wouldn't have been so bad, had I not advised Ian Donkin of exactly the same thing several months before. Pulled off one wire, and away it went

.

I had a friend who's motto was 'it's only a hobby' in these situations, sage advice, except that in his case it usually followed a massive tantrum in a 3 yr old stylee

.

911hillclimber · Post by **911hillclimber** » Thu May 06, 2010 6:42 am

I've been working in Stockholm for the last 3 days so far more relaxed about it all now.

It is simply dissapointing such a thing is happening after so much done.

The carbs are near new and from the jets I've taken out all is clean.
I have been asked to check the fuel supply and pressure, but as the engine runsa hard at 6000 rpm can't be too much wrong there?

The colour tune is a good idea, a window into each cylinder. The offending cylinder should show darkness and a flash of combustion quite well I hope. Just need to find one.

The compression test is next on the list to make and try.

As said; the one bank is perfect. That does say most of the ignition is right, the system, the dist cap/rotor etc.

The plug tops are to get changed to some spares I've have for 2 decades in a box.
I have a spare lead but not a copper wire but fibres instead.

SO
One cylinder (maybe 2 or 3) all on one side? Would be strange is all are down on compression and the other side ok. Could be one though.

Test will show that to be true or false

Plug lead/cap: Substitution will prove that (though tried ages ago)

Colour tune for an in-sight on the 4/5/6 bank.

Cam timing on the one side? Goes too well at 6000rpm/232 bhp

Exhaust valve clearances all ok on 4/5/6 bank (measured).

Have to get the 911 ready tonight for the run to Barbon Manor hillclimb in the Lake District on Sat, but will have sunday on the car to make my way down this list.

Thank you all for the help!

hot66 · Post by **hot66** » Thu May 06, 2010 7:12 am

911hillclimber wrote: The carbs are near new and from the jets I've taken out all is clean.
I have been asked to check the fuel supply and pressure, but as the engine runsa hard at 6000 rpm can't be too much wrong there?

my 2.4S was running crap at low revs , but still pulled pretty strong at high revs ........ in both situations the fuelling was leaning out ....... might be still be worth checking even if it is just so you have eliminated that as a potential problem

911hillclimber · Post by **911hillclimber** » Thu May 06, 2010 6:28 pm

Hillclimbing the 911 this saturday in the Lake District, so play will resume on sunday.

Went to Halfords and bought a nice new Colour tune and a nifts set of 4 spark plug/ignition testers that snap over the plugs and flash when a spark travels!

Put 3 on the one side and then run the engine. The red light will flash in a sequence, but if the sequence is interuped, then the spak didn't make it.

I am going to re-route the fuel line to how the 911 is, one tube into the one carb, through and loop to the rear of the other. Anyone have any instructions for setting a filterKing flow regulator please?

I can't help but think this is a spark problem to one or two cylinders.

I might even be patient and do one thing at a time

Gary71 · Post by **Gary71** » Thu May 06, 2010 6:30 pm

Changing one thing at a time may help you find route cause, but following proper fault findings methods is no fun is it!

911hillclimber · Post by **911hillclimber** » Thu May 06, 2010 6:44 pm

True Gary!
Dive in and tweek the bloody lot!

I don't realy care as long as it will sort itself out.

Mike911scrs · Post by **Mike911scrs** » Fri May 07, 2010 9:35 am

HI 911hillclimber
I have full ign' parts if you would like to borrow them; dist', coil, dist' cap, leads and 6pin CD box with wiring, could drop off at Barbon or I am just off the J36 if you would like to call in.

regards mike

911hillclimber · Post by **911hillclimber** » Sat May 08, 2010 8:51 pm

! Thank you Mike!
Just got BACK from Barbon! We left on fri noon so I've missed the email...

The 911 hotrod ran a dream today. Had a really good class battle with Simon Butterworth in his orange Boxster, but he pipped me on the very last run by a few tenths.

I was ahead all the way by a few 1/100's of a second till then.

Still, not too bad for a steel 3.2 engined old '73T.

It is a day like today that makes me so doubtfull about this Lola Porsche. The 911 is just so good.

Anyway, not about to throw it in the skip just yet.

will spend the day on it tomorrow. After discussing it with the techies at the hillclimb today, seems the ignition to cylinders 4 and 5 are the target.

There are only two things:

The leads or the caps!

jwhillracer · Post by **jwhillracer** » Sat May 08, 2010 8:58 pm

911hillclimber wrote:!
Anyway, not about to throw it in the skip just yet.

Just ring JW Skip Hire inc. 01579 348***

JW

911hillclimber · Post by **911hillclimber** » Sat May 08, 2010 9:02 pm

Ha!
I recon you would fit in it now Jonathan!

You missed a great day at Barbon, we had 6 runs...because of a very unusual event in the morning....

jwhillracer · Post by **jwhillracer** » Sat May 08, 2010 10:19 pm

Are BP going to clear it up after they finish in the Gulf of Mexico?

Didn't seem to slow Trevor Willis much!

Cheers!

JW

911hillclimber · Post by **911hillclimber** » Sun May 09, 2010 6:56 am

Exactly.

I've seen FAR worse at Shelsley and the others.

FTD sat at 21.3 I think yesterday, Scott's done 20.5 so the track was fine. A slight bump where new met old tarmac just higher than the public crossing.
Could feel nothing of it in the 911 but my ar$e has always been insensitive!

I was dead chuffed running steadily faster in the 29's spurred-on by Simon being right there to 3 hundreths at one point.
My Kumho's are entering their third season and Simon's were no better.

Great tussle and very good sport between us, a real pleasure.

Real hillclimbing.

Barry · Post by **Barry** » Sun May 09, 2010 10:21 am

Just a silly idea, assuming the compression check (as you say, now got to be the top priority) doesn't lead anywhere, and don't laugh: is it possible to physically swap the carbs over?

I appreciate that you'll have to pop some long (temporary) fuel lines on, and you'll be on hand throttle (with a helper), but if you could do that (especially if the manifolds would swap too), it would absolutely and definitely rule in/out all of your fuel and air systems.

It might be a bit of a faff, but if your compressions turn out to be O.K., and it sounds as though you've already tried most options over on the ignition side of things, it would be another large chunk crossed off.

BTW, During my brief 914 ownership, amongst the many tuning issues with it, it turned out that the new inlets manifolds had been seated half OVER the cooling shroud on one side (

). It was amazing how well it ran despite this and had a very large air gap, but it certainly improved things afterwards

. Once I had sorted the ignition timing out (over 25 degrees off), and un-wound the tappet with minus clearance, it went really quite well. Went like stink actually

.