Well Belated Happy Birthday sir Dan... i didn't know you're a Libran. so your bday falls on the 1st of October beerfest !!!

Missed my birthday by 2 days!

In Bible, rope means patience.. The longer your rope,the longer your patience is. It mrans you dont easily get angry at people, which is a good trait. Just tell them they're wrong, that's good enough. sir Dan, when is your birthday, we will give you a b-day tribute.... A tribute for being patient and generous in giving advices, and for being so knowledgeable  about minis, you know averything from headlight to tailight.  

If you meant me... no worries! I'm a sailor. To a sailor a 'sheet' is a rope which controls a sail. so "full of sheet" might either mean I've got lots of rope or my sails are full of wind. (Don't go there! HAhahaah)

simple joke, duh

We know he is full of sheet

Grab yerself a coffee and some glasses! I didn't say "sheetrock stock"! I said "sheet stock", as in flat sheets of stock gasket material.
I don't use the term "sheetrock" at all anyway. To me, the proper term is "gypsum board". Some people say 'gypsum wall board', but it is used for more than just walls.
(On the other hand, it might explain Tony's plugged exhaust system.)

Dan, Sheetrock stock?  Never tried that.  I always just used gasket material with a paper punch and sissors.  Where can I get sheetrock stock?
Dogscarf

We are saying the same thing! Flow is from smaller diameter into larger diameter. Because the two are not flush, there is a small (miniscule) eddy current after the lip. Nothing to worry about. as for the gaskets, my personal preference is to go with the larger bore one - it keeps the gasket material completely and evenly compressed with nothing hanging out.

But then again, I DO over-think things. For a while I had a tired HS4 mounted onto a single carb alloy intake made for a 1.5" or 1.75" carb. With hand tools, I tapered the bore of the spacer, making sure it had a smooth-ish transition out of the carb and again from spacer to intake manifold. I also cleaned up the 1.75" opening into the manifold and some of the bends... casting flash, rough molding etc. But not polished!  When I got a new HIF-44, I made sure it sat properly too. (Made my own gaskets each time from sheet stock too!)

You have to go with what is best for your application as you have ported the head also. I am thinking maybe you may have to enlarge the ports on the 1.25" gasket.

Yes but the step is down and not up.  Therefore, there is not an intrusion or a wall for the air to hit.  What I do wonder about is which gaskets to use.  A 1.25" gasket has a 1/8" portion that is left hanging against the carb face .  A 1.5" gasket would not completely cover the the carb face but would cover the manifold.  Maybe I am making too much of this.  Thoughts?

Dogscarf

Going from 1.25 dia carbs into 1.50 dia manifold leaves a 1/8" step. It would generate a little turbulence, but general consensus it this turbulence would help blending air and fuel. "They" also say polishing the intake too much can be detrimental because flow gets too smooth.

I put twin HS4s on my 1275.
Most definately outperform the twin HS2s
Using #5 needles

There was a recent thread where a member tried uprating his carbs on his re built 1275 S, after installing the twin 1 1/2"s he dynoed it again and found he lost power over the stock HS2's. The HS4's will help with a warmed up maybe stage 2 or 3 build but for normal use the HS2's are better.
FWIW i have found the M needles work best.

Malsal,  yes, the Big Healeys had several different carb configurations depending upon the year.  The double 1 3/4" HD6 or HS6 were common.  I have a 1963 BJ-7 with three 1 3/4" carbs bored out on what were originally three 1 1/2" carbs.  Thus, I have extra 1 1/2" HS4 carbs laying around for a Mini application.  Do you think that two HS4 would be a better setup than two HS2 carbs?  I may try those at a later date.

Dogscarf

That manifold should work fine. Didn't the big Healey's run 1 3/4" carbs ?

Great, thanks Dan!  As of today I have rebuild the 1.25" carbs.  The PO had them assed up, wrong jets and wrong offset for the float bowls.  I went with an A2H needle for starters.  Anyway, I will check the line up of the new manifold.  It fits in fine and just doesn't have side to side movement.  It seems to fit just fine.  Much more contact area. It is bored out to fit a pair of 1.5" carbs but the 1.25" bolt right up to it.  I don't think there should be a difference in operation with a pair of 1.25" carbs on a manifold bored to fit either.  The ads for the manifold say it works with either carb,  Tell me if I am wrong...............  I do happen to have several 1.5 HS4 carbs laying around from spares off of 1962 Austin Healey tri-carb setups, so I could rebuild those as a potential carb setup.
Dogscarf

Dogscarf:
When installing a intake manifold with an exhaust header, you must check the thicknesses of the flanges of both pieces. They are often not the same thickness, and when you tighten the nuts, you get uneven pressure, resulting in leaks at the manifold-to-head gasket. You either have to grind/file down the thicker flanges to match or use thick washers cut away on one side to compensate. Don't "hope' it is OK.... check!

You mention the intake manifold is snug between the manifold studs. You should make sure the intake flanges aren't quite touching the exhaust flanges to allow for expansion. Similarly, the intake should slide smoothly into place with a bit of clearance to the studs; otherwise it might "weld" into place with heat and time.

There is no guarantee that the head's intake ports and studs align correctly with the manifold ports. One way to check is to make a mask or template out of stiff paper on the face of the head. (Sheet gasket material works well.) Cut holes neatly to fit onto the studs, or if you have them out or are using bolts, apply the paper and inset the bolts/studs through it. With the template in place, rub over the port openings with enough force to make a crease in the stiff paper. Mark the template for "UP" and "Manifold Side" and then remove it. Very carefully cut out the port openings exactly. (If the engine or head is out, you can use a thin scalpel or #11 Exacto blade (not one of those crappy snap-off blades) to cut the openings while the template is attached to the head by following the edge of the opening.
When you remove the template you can apply it over the intake manifold. The orientation must be the same as on the head - don't flip it. Now you can see if the ports do line up and if they are the same inside diameter. The head ports can be a little larger, but not smaller.

(You now also know how to make replacement gaskets for carbs, thermostat housings, mechanical fuel pumps etc. You just need to buy the appropriate gasket sheet material.)

OOPS!  The original manifold will not fit due to my LCB header.  Looks like I will have to use my manifold for the 1.5 inch carbs.  The latter manifold looks much better than the original anyway.  It has twice the contact area with the exhaust gasket.  It also fits snug between the manifold bolts so there is no way that it won't line up with the head.  I don't have the locating rings, the head has been ported and they won't fit anyway, not needed.

Dogscarf