MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - HIF4 Jets

My HIF4 carbs from my 73B roadster are open on the bench. They were already rebuilt so I'm just replacing the float, needle and seat to try and solve the gas overflow issue.

I notice though that both jets appear to be the same, while the jets the Moss catalog have different numbers for front and rear. Also, the old pair of jets (in a box of carb parts that came with the car) are definitely labeled differently......one with a silver band and one with a brass colored band.

Both the jets currently in the carbs are black with no markings. As far as I can tell the needle holes are visually the same size on both.

Is there a way to tell if the previous owner has used the correct jet in each carb?

Thanks,
BH
BH Davis

BH, I thought a had two new jets in my spare parts, I wanted to compare them. I don't recall any difference between the front and rear jets. The B Hive shows one part number, good for front or rear. I have used B Hive rebuild kits, they weren't SU but experienced no fitting or running problems with them.

Clifton
Clifton Gordon

Clifton,

Been busy but I should have taken a monment and posted after I spoke with Joe Curto Co. this afternoon.

There is a difference.......but only in terms of the left and right direction right angle turns of the plastic input tube. There also have been some left/right universal straight down input tubes he said.

If the bottom cover won't go on you've used the wrong jet. Just that simple.

Thanks,
BH
BH Davis

Thanks, I think all I have purchased were the universal type.

Clifton
Clifton Gordon

If you have an aftermarket fuel pump, you may have too much fuel pressure, overpowering the float needles. Most low pressure aftermarket pumps put out 2-4 lbs, and the SU's spec. 1 1/2 lbs. Just a thought.
Robin Meier

Robin,

Already went through that a few months ago. I was getting 4 lbs pressure so put in a a pressure pump that I set to 2psi.

Do you think I shoudl lower it to 1.5 psi? General consensus at the time was that 2 to 3 psi would be okay.

Thanks,
BH
BH Davis

This thread was discussed between 06/07/2007 and 07/07/2007

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.