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Well my Midget made it home... Need Help!

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Re: Well my Midget made it home...

I have had seats loose in the body that leaked.
Floats failed, causing leakage.
Work out needle causing leakage.
Garbage in the seat causing leakage.
Improper float level set causing leakage.
Vent plugged causing leakage.

That vent line you showed, I would consider it too small to use to a charcoal canister, but maybe on an LBC.
Most of what I am used to for vapour recovery to a canister is 7/16" ID or so.
 
Re: Well my Midget made it home...

I put in the new float valves and like magic no more leaking.
Adjusted the floats while in there.

Was able to lean them out a few turns, will see how it drives tomorrow!
 
Re: Well my Midget made it home...

Good deal. It's always nice when it's something simple.

BTW.....do your heads have double valve springs? If not, I replaced my "old" GX springs with new ones last summer. I have everything to install them onto a regular head (springs, retainers, keepers, etc). There's nothing wrong with them....I just replaced everything when I got the valve job done. LMK if you have any interest.
 
Re: Well my Midget made it home...

mrsprite said:
LMK if you have any interest.
Click to expand...

I have interest -

On the drive to work this morning I could really tell I'd leaned out the mixture - it really wanted choke on startup but I haven't hooked it up yet. Once it got going it was fine.
Good power all the way, but for some reason the trip home has been a lot rougher than the trip in for the past several days.
Hopefully tonight it will be better.

One thing that's really bothering me now is (really two things) I can't get it to idle lower than about 2K rpm and when I shut it down I get a detonation in the exhaust. (boom)

I'd check my timing if I could get it to idle lower.

When the mixture is set rich the idle comes down to about 1000 rpm. 3 turns out and the idle is at 2000 with the idle screws disengaged.
 
Re: Well my Midget made it home...

What's happening is your lean mixture is still being pumped throught the motor after its been shut off 'cause it's idled so high. Once the mix encounters somthing hot enough.....BOOOM.
 
Re: Well my Midget made it home...

Your issues are related....the high idle causes the backfire. Try playing with the timing.....move the distributor around to see if advancing it or retarding it helps (just loosen base screw and twist). You don't really need a timing light for this, just listen for changes in idle speed.

The valve springs aren't going anywhere, so they're yours whenever you want them (we can hash out a price later). The spring seats are actually brand new.....I decided to just reuse the ones that were already installed, but the springs, retainers and keepers are all used (but still in nice shape). They'll definitely give you a few more useable RPM's.

Good luck on the carbs....just keep tweaking and eventually you'll get them figured out.
 
Re: Well my Midget made it home...

Thanks, yes I'd like the springs but I don't know what they're worth.
You can PM me if you like and we can talk it over that way.

One thing I am thinking is that these carbs are set up for a 72 - 74 MGB engine and I'm running them on "something else". So fuel metering needles are most likely not correct for this application... :jester:

Which carbs are you running with yours? HS4?
Wondering where to start to figure out what needles to install.
 
Re: Well my Midget made it home...

Nah.

Look for vacuum leaks, too, and especially throttle shafts.

I recall many moons ago we had a TR4 in that would_not_idle lower than 2K.

Bad throttle shafts bushings, scheduled a fix time, then the owner's kid ran a red light in Downtown Seattle and the car went to the scrapper.

Can be timing, but to have timing cause 2K idle one would expect it to be pinging like no tomorrow.


Dave
 
Re: Well my Midget made it home...

I will do that today.

My throttle discs are different, when I was taking the carbs apart yesterday I noticed the back one has it's hole soldered closed while the front still has the little valve in it.

Vacuum leak wouldn't cause high idle regardless of fuel mixture?
 
Re: Well my Midget made it home...

Would and will, up to the point it won't run anymore.
You DID do the shaft/plate balance before you started, right?

If the carb throttle plates are not working together, i.e. one is locked to the shaft further open than the other, no amount of tweaking will get the idle down.

Dave
 
Re: Well my Midget made it home...

That plate soldered up........one might wonder if a PO tried to get the idle down and did that in an attempt to mask bad throttle shafts?

Generally, if there is a hole in a carb or carb part, there was a reason for it.
 
Re: Well my Midget made it home...

Later cars (smoggies) came with a Spring Valve on the butterfly.

This was a pressure relief valve that is not needed.

It also adds drag to the air entering the intake, when the butterfly is open.

Some previous owners took them off and soldered them to avoid this in the late 70's.

If one was done and not the other, I would bet that the carbs are not an originally matched set.

Also, I would check for intake and vacuum leaks first, before anything else, it is cheap quick and simple.

Pat
 
Re: Well my Midget made it home...

I'll PM you later about the springs....I'll try to figure out a "value" then a price.

I am running the stock 38mm Hitachi flat top SU clones that came with the 1200GX. I am clueless about how to choose the right needle.....I let the guys at ZTherapy do that when they rebuilt them. Some day I may play around with different ones, but for now it seems to drive well in most situations.
 
Re: Well my Midget made it home...

TOC said:
That plate soldered up........one might wonder if a PO tried to get the idle down and did that in an attempt to mask bad throttle shafts?
Click to expand...

Ditto what GeeBee said, so I'm thinking either the previous owner of the carbs started the modification and did one and didn't get to the other or it's not a matched set.

I believe we did the adjustment to make sure both throttles were closing and opening in sync but I'll double check that today.
One could be just a little off - doesn't hurt to look.

I'll check for vacuum leaks right away.
 
Re: Well my Midget made it home...

You did check to make sure the butterflies closed tightly all the way around the bore when you had them off?

If the PO took the plate out to solder it, it may not be mounted right.
 
Re: Well my Midget made it home...

You are right about that - I should have held it up to sunlight but I didn't. They may not be centered - that would cause trouble.

I guess I'm getting faster at removing and replacing these now so I could pull them again.

Anyone make some kind of speednut fastener for carbs yet?
 
Re: Well my Midget made it home...

New Butterfly's are not that expensive.
 
Re: Well my Midget made it home...

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]New Butterfly's are not that expensive. [/QUOTE]

From where?
 
Re: Well my Midget made it home...

Actuallt, sunlight works, but I always back the idle stop screw clear, loosen the butterfly screws, and work the butterfly around the bore until it seats everwhere and won't move up-down-left or right anymore, hold it shut tight, and tighten (then stake) the screws.

NEVER stake them without a long drift in a vise coming through the other side or you'll bend the shaft!
 
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