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Vacuum advance


Sammas09
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Hello everyone. 

Ok so here's my query, 

 The previous owner of my robinhood swapped the carbs from the 2l pinto engine from weber twin dcoe 40s to weber 32/36 dgev. After the swap the vacuum advance was never connected up due to it being broken on the distributor. The engine has never run perfectly since I've owned it, which I believe is down to it not having the vacuum connected. The car does drive and is useable but I'd like to improve engine power, as it gets up to 60-65mph it runs out of pull.

Now it's off the road for the winter, I've been wondering about the vacuum port on the carb, will it have been blocked or is it a simple case of fitting a new distributor and connecting the pipe up?

Thanks everyone

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Vacuum advance is mainly an improvement in MPG and not essential for running.. At large throttle openings there is little vacuum so the slight leak from the small take off point on the carb will have little effect.

Reading your post I understand that you now have a 32/36 DGEV twin choke carb fitted.

The first question to ask is what cam is fitted as DCOE40s on thier own will not do much so the cam is probably an upgraded one, is it timed right?

Then the jets on the carb will need changeing to suit the cam and any changes to the porting work in the head.

Also the advance curve of the distributor will need checking, does the ignition advance when the revs build up?

More information is needed to say what is wrong.

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As this has an electric choke, has it been wired in correctly and does it work?  I also agree about the cam, when I bought my engine it wouldn't run properly.  I found that it had been fitted with a competition Rally cam which was never designed for road use.  I changed it and the engine runs great.

Edited by cb750
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to check the choke is working remove the air filter and you should see the choke butterfly closed when cold. Turn the engine on and as it warms up you should see the choke butterfly open. If it doesn't it ain't working.

as above though if you have a strobe light connect it up and raise the revs and you should see an increase in advance. A tipex pen is useful for marking the timing mark so its easier to see.

Edited by agent_zed
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If you were running twin 40’s and FR32 you would be very near the max airflow the engine required.

40’s can only accommodate a 33mm venturie and are only used on a relatively standard engine.

twin 45,s allow venturie up to 38mm, you probably need 35 to 36mm venturies for an FR32 cam.

you will need to get whatever carbs you put on the car rolling road tuned to make it work

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According to Dave Andrews, Weber 40s can take a 36mm choke, 45s can take up to 40mm.

http://www.s262612653.websitehome.co.uk/DVAndrews/webers.htm

I changed the cam on my pinto first, to an fr32. I then changed from a 32/36 to 38DGAS which was a big improvement,

but when I fitted twin 40s with 36mm chokes the engine really came alive.

Even with a 32/36 it should pull to well over 100 (only on a track). Make sure that the vacuum into the engine/carb is blocked off it its not connecte to the dizzy

Make sure that the second choke is actually opening, if it is I'd recommend a RR session to get the ignition and jetting right.

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  • 1 month later...

Ok new day, new problem. 

Car wont start. 

So i hadent even got round to swapping the distributor as ive been away for a while, but the other day i decided id give the car a run. Its always started easily enough before but now :(.

So car sat for roughly 2 month, nothing done to it but it has sat for this long before and always started again. 

Things ive checked...

1)spark. Cleaned all connections and checked the spark. It has spark. 

2)fuel. Drained old fuel and added new. 

3)battery. Nearly new battery i left on charge overnight. Fully charged. 

4)timing. Lined engine up tdc, nothing changed. Marks still line up. 

The engine (2l pinto) is just turning over. It makes no attempt to start. 

Any one any ideas what the problem could be? Am i missing something stupidly simple thats stopping it from starting? Any help appreciated thankyou! 

 

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After trying to start engine take spark plugs out and see if they are wet. If not it's odds on to be a fuel problem If they are look to the electrics.

If dry plugs try carb, not too sure but you may have a fuel cut off valve that may be stuck or not connected. Can also see if fuel being fed into intake if remove air filter and see fuel while someone else turns engine - word of caution beware of backfire or will loose eyebrows or worse - smart phones or camera a good alternative!

If wet plugs it's pretty likely to be electrics so check again, if running a dizzy check the spark gap etc.

Good luck.

Jim

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A trick that works with old tractors sometimes is to put the spark plugs under the grill on the cooker to get them up to optimum operating temperature. Not with the wife's toast obviously. Has it got the mechanical fuel pump or is it an electric one? If dry plugs check for fuel to carb. Can't be much if it was running and you haven't tinkered with it since.

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Plugs are wet after attempted start. I have also taken air filter off and can see fuel whilst it is turning over... 

As you say it cant be much wrong as it was working fine last time i tried it and have not touched a thing since. 

Ill give all the electrical connections another going over and try again... 

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  • 3 weeks later...

Engine starts again! 

It was a combination of dodgy electrical connections and new sparks plugs needed. Thanks everyone for the advice. 

I've swapped the distributor and just need to do some test runs then tweak the timing, engine already ticking over much smoother than before. 

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