Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) What Did You Do To Your Morgan Today?

Sounds like a jetting problem to me.
Our 1985 4/4 suffered like this after I installed a K&N filter. Mike Duncan used to service that car for me and is rather an expert on carburettor engined Morgans (mine was a CVH). Mike re-jetted the carb for me and the car was transformed.

I found a jetting calculator here for a DCOE - not sure how this maps on to a DGV: https://www.carbparts.eu/calc

Could be worth checking.

Hopefully someone who actually knows what they are talking about will be along in a while.

I have had a similar problem on my crossflow 1600 4/4 (1969) with a DGV 32/36 and have not found the source of the problem despite trying a carb rebuild, new electronic ignition (accuspark) new leads, plugs, correct timing and a trip to a morgan specialist/rolling road. The fuel pressure (mechanical fuel pump) is about 4 psi. I have the standard jets on the carb:



https://weber-carbs.co.uk/product/22680-005-weber-32-36-dgv-5a-carburettor/

https://www.racetep.com/media/old-pdf/32_36DGV.pdf

Surely after rebuilding with a different cam etc, I really needs the carb (and timing) setting up on a Dyno, you don't want to risk holing a piston by being too lean in the higher rev bands

Thanks. I am bringing it to a rolling road as soon as they have time to get me in. I think I've reached the limit of my knowledge.

Well Pauly,
I had problems with a ford engine/webber carb set up and it will definitely be an intake issue. I never got to the bottom of it completely but did improve it. Check all the intake vacuum areas thoroughly. Think about the old 100E with vacuum wipers.... foot hard down and the wipers stop, cruising with a light throttle and they're going ten to the dozen! So accelerating away you are loosing that vacuum at the jet/s. jetting change's can help but will effect fuel economy. what air filter system do you have? too much air or starved will have an effect. If feeling chocked on acceleration is the accelerator pump delivering to much fuel or is it starved of air or perhaps leaking vacuum somewhere. A worn needle valve can really have an effect too!

When you rebuilt the carb did you change the jets? !973 and the brass jets do wear, the accelerator pump diaphragm might also look fine but they do deteriorate as well

I put a new accelerator pump in mine, and that did not help I'm afraid. I even tried a brand new carb, (with the standard jetting) without any success. I'll recheck the inlet. vacuum areas - it certainly feels like it should be something like that.... also tried experimenting with and without vacuum advance - no obvious effect.

CooperMan is spot on, it will defo will need re jetting and timing sorted!

In an ideal world this cam would be much smoother and nicer to drive on a pair of 40's.

In years past when the RACMSA imposed a rule that road rally cars could only run a single carb much knowledge was gained about running tuned xflows on a DGV.

You could try the following;

Air Jets: 170/160
Main Jets: 150/155
Idle: 55/55
May be a little rich on idle, if so try 50/55.

You will strugle to time a modifed xflow correctly with a standard advance curve, it will always be a compromise. The snag is they like a lot of advance at idle as much as 17 degrees, however if you set it at this you will then have a dangerous amount of advance further up the rev range. A modified distributor like the Aldon one will help, however the easiest but not the cheapest solution is a '123 IGN' programable one.

Dave: I rebuilt the carb (did not replace jets) and the new accelerator pump solved a different issue that I had. I was thinking about a new carb. There is only one vacuum opening and it is plugged. New gaskets including the manifold.

Pig: I do have the 123 programmable distributor set up at 10° to 1400, then ramps up to 32° at 3000

I'll have to check my notes to see what my jetting is now.

Thanks everyone.

Bought some Mintex anti squeal backing for my front brakes that were squealing like a pig. They are a thin rubber pad that sticks to the back of the pad, so far quiet as a mouse. Interestingly one of the securing pins had become dislodged probably due to to a weak retraining clip, fortunately I was fitting a new set so hopefully no further problems.