Tuning PMO Carbs with a difference?

[911hillclimber]

Sounds a bit 'old banger' but other carbs on others do the same, most are now on injection in the paddock, few of us Old School players left. Maybe I'm too fussy.

Took the plugs out today in preparation of starting the engine.
First time out of the engine for 6 years. All nice light even biscuit colour, so not much wrong with the mixture. All gaps 22 thou. Very hard to remove, corrosion maybe just setting in.

Points were a tight 0.4mm, so eased them open to 0.4mm They have never been checked or changed since Bob put them in. Faces are perfect, but dragged some folded 600 paper through them before re-gapping.
Hope to start the engine this week and check the balance and any leaks. Other than that, brakes flushed through with fresh DOT4, so season preparation close to being done!

[neilbardsley]

£110+vat is a bit painful. I've now remember the chap I used near you that was very good. BHP performance.

https://bhperformance.business.site/

However, I did a lot of work on balancing my 4 carbs before I went. His main input was getting the air/fuel mixture good through the range. Have you considered using a tool (or 2) like this?

I think is requires have somewhere on the carb to attach the hose to

https://motorcyclepartswarehouse.co.uk/ ... r-kit.html

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[911hillclimber]

Yes, seen the bike carb balancer, aimed ar the4 pot Hondas.
BHP worth a look, close asyou say.
Thank you.
G.

[MikeB]

Graham

I would say your carbs are spot on re running in the over 2000 rpm range. You are talking about a minor balancing / idle circuit adjusting to cure the low down pops. At least on the PMOs you can check your float levels by looking in the little windows. With the car idling when warm and the filters removed you should be able to see which pot is spitting back. You can twiddle with the mixture/air screws screw to see it that helps on that barrel, but it's only the idle circuit, which is not where your horsepower is going to be made. Am sure you have the PMO set-up sheets, if not I can send them. I set my Webers up with a single balance gauge, so it can be done.

I think Johnny is right, it's time to upgrade the ignition. You have various options, but ultimately if you want to ensure the best performance no matter what you fit you'll need to do a rolling road session to confirm the best performance with a custom advance curve or you can probably get 85-90% and do it by ear and the butt computer on a hill, but then you are just losing competitive track time. I'm sorry but it's probably time to spray the WD40 on the old wallet

[Jonny Hart]

Points were a tight 0.4mm, so eased them open to 0.4mm They have never been checked or changed since Bob put them in. Faces are perfect, but dragged some folded 600 paper through them before re-gapping.

Never checked, crumbs! On a points 911 distributor, even the smallest of gap changes can see timing changes of several degrees. More than enough to lose quite a few horses..

You absolutely need to re-check the ignition timing after any points adjustment or cleaning.

I get the impression from your posts that you might perhaps regard ignition as witchcraft and best left alone, however it is the single most important aspect of any engine.

[911hillclimber]

Spot-on.
Carbs and ignition are Witch Craft in my eyes (and hands), always have problems on anything that uses them.

In my defense though; it is a hill climb car so a run is about 40 seconds, and I do 5 of those a weekend.
9 weekends a year, and I run the car for 10 years, so that's about 5 hours in 10 years.

Most leisure cars would do that in a day.
So, it kept on working, and I've changed the plugs twice, the cap and rotor twice, points never since Bob fitted them, but rebuilt the engine twice due to stress and strain of over-revving.

I need to sell an unused toy first to make me feel less wasteful and take the plunge...

[911hillclimber]

Not wishing to be annoying here, but decided on a cheap 1/4 way house improvement to the existing engine.

The dist is being fitted with a simple Hall effect points replacement module and sports coil retained (3 ohm) as fitted by Bob.
Silicon ignition leads and to the rollers local to me with good reputation (first hand from people I trust) for timing set, carb balance etc on 29 March.

I'll be there gritting my teeth watching.

This is a 3.2 stock with the Boshe Distributor # 0231169011 JFUD6, 264 bhp

I have no idea where Bob had set the timing on this set-up on his rollers in 2011. Any advice on where to kick off from please?
I know exactly were the dist with points was set, but not sure where this correlates to with the Hall effect module position.

Ben at BHP knows where to safely start and will iterate to the optimum over time, but I would like to minimise the number of runs on the rollers!

[neilbardsley]

Does the timing change much with when adding electronic points? Here is an article from Bruce Smith don't remember if he mentions a timing change

http://sparkingplugs.com/3.html

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[911hillclimber]

Not at all sure, but the rollers should get it sorted.
Tyres now in the garage, booked in for the 29th, first day of local freedom!

[Jonny Hart]

I hope it's not the 'Hall effect module' with the plastic collar and the rattly magnets....

[911hillclimber]

No, it is more than that, just my description from the Dark Days.

I'm not prepared to sink a lot of money in this car right now hence this cheap 'advance'.
It is more about getting the carbs right as the sparks.
The 2 races I had last year were lack-lustre and the car lacked it's sparkle, maybe this will bring some of it back.

[911hillclimber]

Naked and afraid! The car and me respectively. Off to the rolling road tomorrow for some tweaking.

[Gary71]

Looks good body on, but for me it’s that bit more special in naked form.

Best of luck on the rollers

[neilbardsley]

Will it do a run without the electronic ignition or has that been fitted already

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[911hillclimber]

I love the naked look, but not allowed in my Class..
'
The dist' now has the 'rattley-magnets, no points, and silicon leads but will be fitted tomorrow before the torture begins.
Hope it can be dialled-in pdq.
Found that someone in the USA has COPIED my livery! Cheek.