Vikram's 1960

Started by 94touring, May 15, 2016, 11:55:37 AM

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Vikram

Thank you Michael, that definitely seems like a potential issue especially after some research.

Here is a video I found of a weber 40 on a mini at idle:
https://www.youtube.com/watch?v=5a1ViLGCbDI

and here is mine at "idle":
https://www.youtube.com/watch?v=wKdYjpRmeMM&feature=youtu.be

It looks like mine is putting in the same amount of fuel as the first video when it had the throttle open. Since my throttle is not stuck, it really could be the choke. The choke does move freely, but that might not reflect what is actually happening on the inside. Should I be looking at anything in particular? I will open up the choke circuit tomorrow.

MPlayle

From those video clips, it definitely appears your throttle is stuck wide open.  If you watch them, the one at proper idle clearly shows the butterfly valves closed except when he revs it.  In yours, they appear always wide open.

Try disconnecting both the choke cable and throttle cable.  This should allow the basic springs to return the choke and throttle to return/settle at their idle positions.  Then look to see if the butterfly valves are closed.  (Car does not need to be running.)

Take note of the linkage positions when in the idle positions.  These need to be the positions when the choke and throttle cables are connected and in their "idle" positions as well.


Jimini II

I have not read the whole thread but spray the intake gasket to check for an air leak.
When the carb is removed and the idle screw backed off check to see that the butterfly's are completely closed, easy to do by holding it above your head and looking for light coming through them. If so they may have been installed incorrectly loosen the 4 screws and re tighten them with the butterfly's closed.

Vikram

Thanks for all the replies, problem has been found.
It was as indeed all of you said earlier. I originally had the issue of the car dying on me, and I was compensating by adjust the idle speed screw that would hold the throttle open slightly. I had no idea that such a small opening would have such a large effect. Instead of adjusting the throttle, I should have adjusted the floats so that the bowl wouldn't keep emptying which was killing the engine.

Now that I have adjusted the floats and backed off the idle speed screw, the car does now idle but it's not a reliable consistent idle. The bowl is still emptying but at a slower rate, and I can keep it alive by blipping the throttle. I have pretty much run out of float adjustment, so I need a needle that allows fuel into the bowl at a faster rate, and that will fix the problem.
Thank you for all the help, and I'm a bit disappointed in myself for ruling out a previous issue that was never actually solved. 

MPlayle

I don't think it is the float needle that regulates how quickly the float bowl is refilled (or rather kept filled).  It is more the flow rate and pressure from the fuel pump.

What fuel pump are you using?  If the original mechanical pump, it may not provide sufficient flow rate (gph) for the carb.  Also make sure the fuel pump pressure is in the "ideal" range for the carb in use.  Too much pressure and the float needle cannot close off the fuel when the float bowl is full and you get overflow or flooding.  Too low a rate and the carb consumes the fuel faster than the bowl refills.

Example: SU (and some Weber) carbs require a low pressure pump (2.5 - 3.0 psi), but depending on the carb and engine may require a higher volume (gph) pump.  The small Facet or Mr. Gasket electrical pumps (such as the Mr. Gasket 42S pump) give the correct pressure (2.5 - 3.0 psi allows the float needle to be able to close off the flow when full) and a high enough flow rate (42 gph) to quickly refill the bowl as needed.

The Mr. Gasket 42S was an ideal pump for the Weber 32/36 DGV carb sometimes used on Minis.

Vikram

#330
The 42S is the exact pump that I have on the car. The bowl is being drained faster than it is being refueled and I don't think I have enough travel in the floats to just reach the right amount.
Edit: the 42S has a flow rate of 28 gph apparently, 2-3.5 psi

gr8kornholio

Do you have an inline fuel pressure gauge?  It was highly recommended when I switched my toyota 22r over to a weber.
I am the GR8KORNHOLIO! Are you threatening me?

Saussie Aussie 1965 Australian MK1 Mini.
"Beavis" - 07 MY/MY MCS, B/MY Konig Daylites, JCW sideskirts, TSW springs, TSW lower rear control arms -- Exploring the country with new friends since 11/09.

Vikram

#332
No I do not have an inline pressure gauge or regulator. I'm going to call Pierce Manifolds and see if they have any advice.

Edit: After calling Pierce Manifolds, the tech said that the larger the needle and seat, the faster it would refill the bowl. He said that each increment in size would result in roughly a 30% change in flow rate. I currently have a 200 or 2.00 mm needle in the carb, and I have the option to go up to a 225,250 or 300.

MPlayle

Interesting.  Looking up the 42S specs finds a mix of ratings.  All sites show the 2.5 - 3.0 psi, but some list it as 28 gph and others as 42 gph.

Since the tech at Pierce indicates changing the float needle and seat size will change the fill rate, I would increase the needle and seat.  I would recommend going larger than the minimum necessary to solve the problem, such as up to 300 versus the other two sizes.


MiniDave

I agree with Michael, going "too big" is not possible, as the float will rise and the seat will block the flow no matter which size you get.

I think you're on your way to solving this once and for all, and look how much you've learned!   4.gif
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

Vikram

Great, 300 is on the way. Will update when its here

Vikram

Got my new parts in today.

Removed the carb and exhaust manifold today, removed the old gasket along with the gummed up and worn studs. Replaced them with new Stainless Steel ones along with new nuts. For the gasket, I ordered 2; the conventional one and the reinforced turbo gasket. I installed the latter just to see how it performs as it is both thicker and looks a lot nicer. While that was all off, took the opportunity to clean the old oil off the back of the engine from the leaking rocker cover.

It was about to rain, so had to call it a day there. Tomorrow the new rocker cover gasket goes in along with the larger needle and seat for the weber. Won't be able to run it tomorrow as the rocker cover will be bedding in, so that will be on Friday. While its setting, the front of the engine will be cleaned, along with some much needed cable management. More to come...

MiniDave

Rocker cover bedding in? I sometimes let the glue set up for an hour or so.....BTW, I put a nice coating of grease on the side that faces the head, that way you can get it off again to retorque the head or do a valve adjustment without tearing the gasket.

What you're doing looks terrific.....I think you're on your way to getting it sorted now!  77.gif
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

Vikram

I'm using the thick silicon gasket. I read on the mini forum to use rtv on the rocker cover and attach it to the gasket, but it needs a day to firmly adhere. I did hear the grease trick that you mentioned Dave, and I will definitely be doing that.

MiniDave

You don't need to with the silicone gasket....it won't stick to the head anyway.......

I bought one of those but they really only work with the stamped steel rocker covers like yours and I have a cast aluminum one on my car, so I haven't gotten to try it yet.
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

Vikram

I believe my cover is plastic....I hope it works!

MiniDave

I've never seen a plastic one, maybe the later cars had them.
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

Vikram

Engine is from a 93 rover, so I guess so.

Vikram

Rocker cover was stamped steel, not plastic.
Turns out there was no gasket, just sealant between the cover and the head. New silicon gasket installed. Some wire management too. Firing it tomorrow.

MiniDave

#344
Sealant instead of a gasket? I've seen that work ok between two very smooth surfaces, but not on one with a gap like on a valve cover!

You should definitely have fixed your oil leak with the silicone gasket!
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

Vikram

Installed the new needle and seat, adjusted the floats. Car will now idle at 1.5 k rpm, however after blipping the throttle the revs will fall before climbing back up to 2k. It will idle at 2k for 15 seconds or so before eventually returning back down. Adjusted the throttle linkage to ensure that the butterflies were closing. Sprayed brake cleaner around the inlet manifold and the carb and the inlet manifold gasket and there was no noticeable change in rpm.
Revs nicely through, and the high spring return rate makes the rev fall quickly too. Sounds great.
I do have an overheating issue. I've fiddled with the timing and that seems to make no difference. Pumped the lower rad hose by hand and even ran it with the rad cap off, and its still over heating. The top rad hose gets hot after a while, so that means the thermostat is working. Dan installed a new water pump before it came up here, so I doubt that's the issue either.
No milky fluid on the rocker cover cap, so probably not head gasket. I was also running with a fan in front of the car, so there was some airflow. Thoughts on either of the 2 issues?
Here is the link for the video: https://youtu.be/eE7dfAFcKfE
(starts with a little difficulty, might need to advance the timing slightly)

MiniDave

Looks like you already have the aluminum radiator, so....

Are you sure it's overheating or is the gauge just reading hot? Could be incompatibility between your new gauge cluster and the old sender.
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

Vikram

I'm using the 52mm aluminium rad off eBay so I shouldn't be having issues. If you remember, I broke my original sender in Dan's shop and I had to find a replacement locally. Now I'm not sure if that is the correct one and it might be reading hot. Engine does feel rather hot tho...
I'll get the proper sender in to be safe. I'll fiddle more with the idle, it's really close

MiniDave

If someone has one, those infra red/laser thermometers give a good indication of whether it's really hot, but if it's not pushing out water it's probably not overheating.
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

94touring

Well I don't recall it overheating when I initially got it driving on the road.  I drove it a solid 5 miles with no issues.