Setting up a 32/36 Weber on a Pinto engine

[gouldsborough7]

Guys
Now I have fitted a 32/36 Weber to my 2 litre Pinto, I am having problems in setting up the carb to run well throughout the rev range. The camshaft is a 270 Piper, which is a mild-tune for un-modified engines.

Originally, the engine had a 38 DGA Weber from a 3 litre Grannie, and for thos who might have followed my messages on this, it was a bit of a pain for regular road use. So I took the plunge and bought the model the engine had originally, brand new, from Fast Road Cars. The guy there is very helpfuly, but so far I haven't resolved the snags.

When I first ran it, I had to screw in the mixture screw to only half a turn from fully-home position, instead of the usual 1-2 turns. As an experiment, he said to swap the idle-jets over Primary to/from Secondary. These were 60 primary and 50 secondary size.

To cut long story short, I've swapped over the jets from the 38 Weber, and now am running with 45 Primary and 50 Secondary. The tickover is better, and it cruises OK at speed, but there is a dreadful flat-spot at around 1,000rpm. This makes for a piggish problem in traffic.

Has anyone established satisfactory idle-jet sizes on a 32/36? I think the 45/50 combination is per Haynes, but they are not always correct?

I'm also wondering about the accelerator pump, and whether it is pumping enough fuel into the primary choke at the right moment. It might account for the flat-spot, when the engine almost dies is the clutch is let out slightly too harshly. Usually means that revs have to be nearer 1,500rpm to guarantee success.

Cheers
Mike

[dogoncrazy]

Re: Setting up a 32/36 Weber on a Pinto engine

Mike
Experienced problems with my pinto engined Cabrio over the last few days[probably as a result of deciding to sell]
To cut a long story short it started to stall at junctions etc and slightly lumpy tickover.
Investigation showed no change to idle speed when No 4 plug lead removed. Have done all the usual -changed plugs /ht leads etc. Last night put Colour tune into No4 and in dark garage could barely see any ignition until revs increased, not so on other cylinders as all nice 'bunsen' blue even at idle.
Thinking at present that maybe exhaust valve leaking/ burnt on that cylinder, which brings me to your problem -is all correct with yours as attempts to 'tune' carb may well be in vain if you were to have similair prob
Should also maybe say that a compression check on mine didn't really show a problem.
Will post a follow up once I have the head off!

[gouldsborough7]

Re: Setting up a 32/36 Weber on a Pinto engine

Alan
I have been in discussion a few times with Fast Road Cars (who sold me the 32/35 Weber), and it would seem that the most likely reason for the 'flat-spot' is an air-leak.

As a precaution, I have replaced the HT leads, the dizzy cap and rotor arm, as their history was unknown, and was a worthwhile exercise for a modest cost of about £23.

I am currently running the carb with the primary idle-jet I changed from 60 to 50, i.e. leaner mixture. This allows me to set the mixture screw back to 1.5 turns from fully home position. The standard 60 needed the screw to be turned until it was about the 0.5 turns position, and it still ran badly. The tickover now is reasonable, and it starts & cruises OK, but it has a flat-spot at about 1,000rpm, suggesting that it wants more fuel, yet I have had to install the leaner jet.

The joint between the carb and manifold had a new sandwich-type insulation gasket. The guy said to install it 'dry' without any compound, making sure all was clean - which I did. At the time, I did'nt double-check the 'flatness' of the manifold flange, which I might do now. Nuisance to take off the carb again, but worth the effort. Might resort to a smear of deluxe blue gasket compound as a belt&braces idea.

I didn't originally double-check the manifold to head gasket area, which I might still do. Some of the bolts are difficult to access, especially near the battery which is shoe-horned into a tight space. Bit of a chicken&egg situation there - which was installed first - manifold or battery!

Ignition timing and dizzy advance & retard is another area to explore soon.

The reason why such problems were not so apparent with the 38 Weber ex Grannie, was possibly that it was slurping so much fuel into the engine that it masked flat-spots etc. Starting it was always a gamble, and occasionally was necessary to have plugs OUT and drying routine before going on a journey - pain!

Will keep this site advised of progressm and hopefully a result asap.
Cheers
Mike

[gouldsborough7]

Re: Setting up a 32/36 Weber on a Pinto engine

As promised, this is a possible finale of my weber problem. Having checked out all likely air-leak areas, and experimented with idle jets, , I moved on to the Ignition. I had already replaced the HT leads, dizzy cap and rotor, so this only left the ignition timing. I know the dizzy itself could be duff in the advance/retard area, but taking this to pieces was at bottom of my list - unlikely culprit I thought. Having driven the car for about 2,500 miles since purchase, Ignition timing was not an area I expected to find anything too wrong.

My old strobe light was passed it best, so I bought a modern 12 volt induction type, which gives a much brighter light - don't have to turn off the garage lights to see it working. Bingo!! With vacuum pipe temporarily clamped, the initial advance was only 2 degrees BTDC. Haynes says 8 degrees for a 2 litre Pinto. Did the adjustment, and put back the original 60 primary idle jet, with mixture screw about 1.5 turns from home. Big improvement. Unclamped the vacuum pipe, and went for a short run, doing some fine-tuning of mixture & tickover in convenient lay-by. Couldn't quite get rid of the flat-spot, but definitely better. The tendency to 'run-on' when turning off the engine was improved also. Amazing what a few degrees makes!

Not sure if the 8 degrees if the optimum figure with a 270 Piper camshaft. Going above 8 degrees made the engine rev a little more. Left the adjustment at 8 for time being. Will ring Piper to ask the question.

Has anybody got any know-how on this? Is 8 degrees OK for a 2 litre Pinto?

Cheers
Mike

[Dane_Rescueman]

Re: Setting up a 32/36 Weber on a Pinto engine

Hi Mike.

Your Piper 270 has a period of 268°. For this you are looking at around 10° to 12° BTDC for the static timing. Make sure that your maximum advance, at say 4000rpm, is no more than 38° to 40° BTDC (Vacuum disconnected of course). If your engine is not an unleaded one you may have to retard by a couple of degrees to avoid pinking under load. With this camshaft performace may improve with a sport dizzy without the vacuum retard. Small adjustments plus trial and error is the way forward!
I have put a similar cam (Kent FR30) in my refurbished Pinto and this needs the 10° + to idle properly. I get about 38° advance at 4000rpm on the Bosch injection dizzy (no vacuum fitted). The only downer with this sort of static advance in a Pinto is that starting can be more difficult as sometimes the first couple of ignitions tend to impede the starter. I find cracking the throttle helps.

I hope that this has been of use to you!
Good luck.

[gouldsborough7]

Re: Setting up a 32/36 Weber on a Pinto engine

Thanks Dane, that's interesting.
Funnily enough, I rang Piper just a few minutes before reading your note. They wouldn't comment on the ign timing aspect at all. Too many variables the guy said! I asked whether in principle an extra few degrees on the standard Ford figure of 8 was possible. He had no comment except to say "put it on a Rolling Road, and check for best power output". Say goodbye to £100! No thanks!

Not sure at this moment what dizzy I've got, except to say I believe it not to be the original, and its got a vacuum pipe. The vac is definitely working, as the strobe light shows the timing moving back and forth on the crankshaft pulley with variations in revs. Must admit that I hadn't checked this with the pipe clamped off. I was thinking of going for 10 degrees basic, but have not had time to experiment as yet, and left it at 8.

Regarding the vac tubing - I thought I would get a new one, for the sake of £2, and my local motor factors sold me one with the tiniest of bores. The original was possibly about 4mm inside diameter, whereas the motor factor's one was about 1mm! Not sure what difference this would make. Think I might stick to the larger tubing.

I sometimes notice also that the starter-motor appears to lack power to turn over the engine. Almost as if the battery had gone down on power, or the compression was too great for it. Perhaps another quirk of a tweaked camshaft? Would be surprised if the previous owner went for high comp pistons.

Cheers
Mike

[dogoncrazy]

Re: Setting up a 32/36 Weber on a Pinto engine

Back on all 4 cylinders! Don't think valves were seating correctly on that cylinder - carbon build up back of valves possibly as result of valve stem seals shot. Anyway all valves out , cleaned up, relapped ,new gaskets ,retimed etc -RESULT

[Dane_Rescueman]

Re: Setting up a 32/36 Weber on a Pinto engine

Mike,

That starting symptom can occur with tweaked camshafts and their advanced ignition settings. I get a bit of that. It is as if the battery is too low to turn the starter over. I suppose that I could fit a beefier starter but if I crack the throttle open a bit at start, the ECU senses this opening, and , due to the lack of revs, retards the ignition enough for an easy start. It then idles fine!

[danny_nelson]

Re: Setting up a 32/36 Weber on a Pinto engine

Mike,I would still look at manifold to head. This is where most leaks take place if it is that.
Regards
Danny.

[gouldsborough7]

Re: Setting up a 32/36 Weber on a Pinto engine

ECU, Dane? Don't have the luxury of one of those! Old-fashioned carburettor system on mine, but I do have a bolt-on electronic ignition that does away with contact points. No obvious reason to suspect that as yet.

Yes, Danny, I have been eyeing up the pros & cons of taking off the manifold. I think I have even got a new gasket in my collection of inherited bits & pieces. However, there is one bolt in particular that will be a real S*D to undo, because the battery is in the way. To remove the battery, it looks like I will have to remove the manifold - a bit like the old "hole in my bucket, dear Liza" song.

Anyway, for the time being I will experiment with the 8-10 degrees timing idea. The current wet weather is not helping this at all. Have bolted on the hardtop, but that doesn't keep you dry in a lay-by twiddling with mixture screws etc!

Cheers
Mike