carb dilema

[arcturus]

so started PV up first time since fire and carb re build, found fuel spewing out after lots of head scratching and trying to set float level correctly I managed to sort that out. I removed the float lid from the other carb so as to make comparisons and found that the lids were different so no comparison possible. took a guess at the level by eye balling it. Cant send photo to burlens foe explanation as to the difference (they re built the carbs originally when i first acquired the PV) Pic's attached below. Would welcome any comments The carbs are SU-H4.

[Ron Kwas]

arcturus;

I'm no HS4 expert but I could easily see variations in production and replacement parts being the explanation for you differences...

One thing I do note, which quite bothers me, is on the picture is the very steep angle at which float arm contacts valve shuttle on left Bowl Lid...if that is the one which overflowed, I can suggest the cause of the overflow was that steep contact angle caused shuttle to jam against valve wall instead of moving along it to close off fuel flow...do you see what I mean?...force is to side of shuttle NOT along its axis...bend float arm to correct, while keeping float height at shut-off correct also...

I just realized that what I thought was shuttle is a float arm stop...so disregard my previous, half-cocked info...just make certain fuel system post pump is clean (a post-pump filter can't hurt), floats are adjusted to shut off fuel at correct height, and valve shuttle slides freely in valve body!

Good Hunting!

[blueosprey90]

http://mgaguru.com/mgtech/carbs/cb116a.htm

http://mgaguru.com/mgtech/carbs/cb116b.htm


I didn't read the links, but I'd start by trying flatten out the fork on the left.

If all else fails, I can perhaps send you a substitute float cover. I'll have to dig around to see what I can find, but I have some partial H4 carbs in the basement.

[arcturus]

It's the float angle which bothers me. A problem waiting to happen. I definitely think that the rear float bowl needs to be changed. It would take some tricky bending of the float arm to bring it parallel with the needle.

[blueosprey90]

You should be able to pull the pin and pull the fork off for straightening. Look at the second link that I attached, as I think it shows how straight it should be.

https://youtu.be/82YNx-RkGNI

[Derek UK]

It looks like you have one of each of the 2 types of float chamber lid mentioned in the second of the MGAGURU article, note the height of the posts for the pivot pins. Both should work if adjusted correctly I guess but it would be best to have them both the same. Fifty/fifty guess that the one with the taller posts is the later one. I think Burlens should have matched them when they did the rebuild. Rebuilds are expensive but they should correct and update as part of that IMO.
Oddly, one has a tickler and the other one doesn't. The blank one is listed as a type T8 (your burnt one) but the others, depending on diameter are T1, T2 and T4.

I can take your picture with me to Beaulieu on 1/2 September and show them. The have a big stand with technical staff there. But. I think you should send the pic to them and ask for an explanation. Include your rebuild invoice number. I expect you have been to their contact page and found that you can't send pics (you mentioned it) but if you can find someone locally with a Fax machine you might be able to send it that way.
If I can help, email me off list.

[arcturus]

Thanks Derek The rebuild was over two years ago but they should have a record. I used their contact page yesterday to ask for an email address and they replied today with a customer services address so i will be contacting them later and attaching pic's. It does seem strange that they had two different lids. I remember now that at the time they said that the carbs Which i sent them were too badly worn and they sent a pair that they had on the shelf.
Never rains but it pours. Fitting replacement air filter today and the threaded holes were slightly too far apart so that the bolts couldn't pick up the thread. whilst trying to make them fit one of the captive nuts inside broke off and now I have another two week wait whilst they send a replacement.

[Derek UK]

Interesting that you say that Burlens sent you back a different pair as I have a pic of your original carbs taken from the top and I thought that they had identical lids and I did wonder if you were using different ones. Where the supposed tickler should be there are just black holes so I guess the underside of those is blanked off.
Ron, these are H4 and not HS4. Quick ID is that the HS4 lids have 3 fixing screws around the edge and inside the floats swing on a hinge The H4 has a single central fixing and the float is a donut which goes up and down on the lid fixing bolt.

[arcturus]

This is what i received from burlens
Sept 2014 how time flies!

[Ron Kwas]

Derek;

Thanks for clarification! As I stated...I'm no H4 (or HS4) expert, just applying some good basic info...I'll leave it up to the more experienced to get specific...

Cheers