Ray - you are absolutely right, little difference at idle. But I did fear my BCP needle was a little bent, so that had to be eliminated.
I found a little time today, and put in the red spring, and fresh needle. I'm still idling at 3000rpm !! The throttle is closed and the choke is 100% off, but I believe the supercharger is sucking so much air, the carb piston is rising.
Seems my original damper spring is 2.75oz - the red one I've fitted is 4.5oz. the strongest one I can get is a green 12ox spring. If that doesn't bring the idle speed down, I'll either need a miracle or a major rework.
I'm confused now. If the throttle is closed, as in 100% closed how is the air getting in past the butterfly? The piston will only rise if air is getting past the butterfly. Keen to know the answer to your problem now.
EDIT. Stupid question probably but that particular carb is suitable for a suck through supercharger is it?
This isn't mine, but my throttle butterfly looks like this. A brass disc in an ali housing - I wouldn't call it air-tight, but should stop >95% of the air passing through the carb.
I've got a pretty strong throttle spring, so it should be staying like that.
I've based my design roughly on the Moss supercharger kit That uses an MGB B-series engine, a Shorrock supercharger, and a suck through HS6 carb.
Hence my choice of carb, and a lot of other design decisions.
Exercising my GoogleFoo - I've found somebody running a similar carb on a turbocharged 1200cc Datsun, They had to put in a beefy damper spring, and BCA needle - quite similar to some of my options.
I'm learning a lot at this stage of the project. But that is the whole point, it isn't just a car, or just a restoration, it is an excuse to dip into engineering and knowledge that is wonderfully fulfilling.
Have you tried just spraying some wd40 around to rule out an air leak anywhere? Basics I know but sometimes we look for the complicated solution when we're breaking new ground for ourselves.
Have you tried depriving the engine of air after it starts and see what happens? With the air filter off you have a nice flat intake which you can block with your hand and a stout cloth or preferably a number plate. We used number plates on the old diesels with no throttle housings when they ran away as they sucked so hard it was scary. Just wondering if the supercharger is sucking so hard it is drawing air past the throttle spindle if there is play in that. From memory it is just a brass spindle in an alloy housing and when the housing wears the spindle flops about. There is an element of adjustment (not much) to centralise the butterfly so for all the time it takes I would be tempted to take your carb off and shine a light through to see how much light if any gets past the butterfly. Any air leaks after the carb should not lift the piston as the air is bypassing that.
Just wondering if the supercharger is sucking so hard it is drawing air past the throttle spindle if there is play in that. From memory it is just a brass spindle in an alloy housing and when the housing wears the spindle flops about. There is an element of adjustment (not much) to centralise the butterfly so for all the time it takes I would be tempted to take your carb off and shine a light through to see how much light if any gets past the butterfly. Any air leaks after the carb should not lift the piston as the air is bypassing that.
Ray - you are definitely on the right track here
The throttle spindle is good IMHO. But the throttle disc is new, and does let a little "light" through. The body of the carb probably needs a little clean up, to get it fitting tighter. I'm sure it fits fine for a normally aspirated installation, but I can see how a supercharger could suck air past it a little at the moment.
I'm truly thankful for all the suggestions. I worked through them all. What surprised me, if the throttle was open just the tiniest amount - the thing would rev like crazy.
So, I looked closely at ray suggestion of throttle butterfly sealing. Shinning a torch through the body of the carb revealed the seal wasn't great.
Stripped the carb 1/2 down and set to the throat with a fine needle file and some 180 grit Abranet. Sat down and methodically improved the seal. After an hour, it wasn't perfect, but I deemed it good enough, and certainly way better than it was before.
Cleaned the carb out, and put it back on the car, and fired the engine. It immediately settled down to a really low idle - about 550rpm - brilliant !!!!!!!
I added a hair of carb adjustment, and brought the idle up to 750rpm.
As the image loader is broken currently - have a video.
I couldn't be happier, I was wondering if this would actually work, and was pondering fuel injection or a Weber - neither of which I wanted to do.
But onward and upwards. Damper springs, needles, fuel ratio and timing can all be fine tuned later. The engine idles and "blips" pretty well, and gives me a good basis to build upon.
I'll probably leave the engine like that for a bit, as the dashboard needs painting before winter sets in hard.
result. it was always going to be something pretty simple. will you be running a cold air feed to the filter? its going to ingest pretty hot air there.
result. it was always going to be something pretty simple. will you be running a cold air feed to the filter? its going to ingest pretty hot air there.
No plans for a cold air intake at the moment, I'm hoping the louvred bonnet will keep under bonnet temps a bit lower. Exhaust manifold will get wrapped in the glassfibre tape too.
Brilliant. Glad I was able to suggest a possible remedy. My 48 years in the motor trade finally paid off ha ha. Must be over 30 years since I last touched a SU or Stromberg carb.
You could possibly make a heatshield to put between the manifold and carb in addition to wrapping the exhaust.
I'd put the sandblast cabinet to good use, and stripped the paint from the glovebox lid. Then spent a couple of hours aligning the dash, and the door. This was as good as I could get it. I used the same technique as the larger panels, a couple of small holes to ensure it goes back on, the exactly same way it is fitted now.
There were some holes to fill up. The ones for the original radio had an ickle piece cut to size and held in with tape before welding. I'd drilled holes for some switches, but in an ideal world they need a flat to hold the switch vertical. I thought I'd make loads of work for myself by adding some weld, which I can then file back.
Welded, ready for grinding back. Big piece of copper on the bench I used for backing the welds, which meant cleanup on the reverse is minimal.
The Morris dashboard was made in two halves at the factory. The join wasn't tidy, so I cut a little sliver of steel, and welded up the gap.
Previous owners had fitted the wrong clock using what appears to have been a crowbar. There were holes everywhere for switches, which I'd previously welded up There were lots of holes where a cloth was tied into place between the dash and parcel shelf.
So my next task is to crack out the body filler and the sander, and try and get it ready for paint.
Post by grumpynorthener on Sept 24, 2021 10:33:05 GMT
Metal dash panels for the win in my book - you cant weld & paint the more modern vacuum formed padded vinyl type dashboards that crack & disintegrate after a few decades
Spent a bit of time grinding down my welds, test fitting all the switches, and applying some filler.
The reverse of the dash, had a little surface rust - so applied some Vactan to try and keep it under control. I then slapped on some Isopon Zinc brushing paint - largely because I had it, and it seemed a good use for it.
I'm using 2K paint for the dash, so setup an impromptu spray booth on my outside workbench. The donor dash was used to stop the masking sheet blowing around.
Slathered on loads of leftover Kapci 2K primer filler. Sanding it back against a guide coat was actually quite therapeutic considering the dash is a very awkward shape.
Morris dashboard is normally black, but I'm trying to get away from using black paint. So, I gave the rear of the dash a coat of 2K Maroon body colour.
Bottom 1/2 of the dash is body colour, here is the glovebox hung up to dry. I've also painted the steering column shroud, and a few other dashboard bits whilst I had the spraygun out.
The bottom of the dash got a top-coat. Pretty happy with the finish straight out of the gun. But I was a bit heavy handed, and got a run above one of the heater controls. But I think it'll be hidden once the controls go back in.
Tomorrow I'll hopefully get some suitable weather, and can put the grey top-coat on the dash, top of the glovebox, and the glovebox liner. If I can get that done it'll give me scope to finish the wiring and get the dashboard back in over the winter.
Great work there, that dash looks fantastic. Also, congrats' on getting the engine running and idling.
I've been watching your progress since you first posted on the other site, as I've been restoring a similar Australian spec' Farina. Your posts have been a great help, many thanks!
Great work there, that dash looks fantastic. Also, congrats' on getting the engine running and idling.
I've been watching your progress since you first posted on the other site, as I've been restoring a similar Australian spec' Farina. Your posts have been a great help, many thanks!
Thanks for the kind words tonywa glad you are enjoying the journey.
Be great if you can post up some pictures of your project.