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MG TD TF 1500 - ID'ing HS4s from HS2s without removal
|Is there an easy way to differentiate between HS4s and HS2s while the air cleaner is attached? Looks as if the MKII from Corydon IN may still have the original air cleaner. Tnx. Bud|
|The damper "bell" is larger on H4s than on H2s. I don't have measurements, but you should be able to see the difference in proportions in these photos:|
|Rob, Even though I saved the link, he doesn't show any T series carburetors. I would assume they rebuild them, but I don't see any information on them. PJ|
|Aha! HS4s have the 4 hole mounting flange, whereas HS2s only have two holes. The HS4 flange has an extra 'hump' on the edge. Maybe that's noticeable. Bud|
|>Rob, Even though I saved the link, he doesn't show any T series carburetors.|
For illustration purposes, it really doesn't matter. H2/HS2 and H4/HS4 (regardless of application) are gonna look pretty similar. So the proportions of an H2 (e.g. TD) bell is going to be about the same as an HS2, and an H4 (e.g. TD Mk II) is going to have about the same proportions as an HS4.
They do have T-series carbs. sucarbs.co.uk is Burlen Fuel System -- they /are/ SU!
A Mk II would have H4s, not HS4s. My Mk II has MGA H4s, but they're very similar to TD H4s but for being a bit longer (and having a different linkage which is easily changed.) Which mounting flange are you referring to -- intake manifold or air cleaner?
|Whoops!!! Haven't any idea why I put the 'S' in there. I'm talking about the H2 and H4 carburetors in standard and MKII TDs. Sorry about that.|
Does the air cleaner flange of an H4 have the 4 holes vs. the 2 holes of an H2? Tnx, Bud
|Bud, What carburetors are on our 1500 engines? PJ|
|H4 is on TD MKII and all TFs. Looking at Abingdon Spares' parts list I see that the floats, and float chambers are same for H2 and H4. The H2 uses the same body (AUC6080) for front and rear, whereas the H4 has different bodies for the front (AUC6030) and rear (AUC6021). Bud|
|Bud: The special H4 Mark II carbs have two bolt holes for the air cleaner manifold, not the 4 holes found in late carbs. Genuine Mark II carbs should have these numbers vibra-etched on the right sides - front: 4031/12, rear: 4031/8.|
If the carbs on a car have the four holes they are probably from another car like an MGA (I think TF carbs also had the 4 holes, but the body dimensions are different).
Bar Harbor, Maine
Here is a picture I took last year of my H4.
Don't know it's history. Don't know if the flanges were replaced or modified.
|Mort 1950 TD1851 Möbius|
|H1 & H*2 carbs have the same vacuum chamber, retained by two screws.|
H*4 & 6 carbs have the same vacuum chamber, retained by three screws.
All carbs have two bolts to retain the air filter, except late (60-70s) HS6 which have three.
The air piston must be ventilated to atmospheric pressure on the underside, so there are vent holes below the piston; these originally were just holes drilled through the carb body, under the piston.
Somewhere around 1954, it was realised that the vent holes beneath the air piston were sucking in a lot of crap, screwing up the carbs. So, starting about the time of the TDC/TF change, the air vents were moved to emerge in the clean air from the filter. This gives the 4 holes seen on the filter face of the TF-on H4. H1 as on Bugeye only had 1 air hole, giving a three hole face, as did HS2, and likely other later H2.
This change was the advent of the "Dustproof" carb, which includes the internal venting of the top of the damper/vac chamber. But, not all carbs had the full treatment, leading to the confusion about vented or non-vented dampers. There may be H4-6 vac chambers from this transition period or earlier that do not have the angular ridge that was drilled for the full "dustproof" treatment.
|But surely you can't really see air transfer holes etc without removing the aircleaner?|
|Ok! The number of vacuum chamber screws, 2 or 3, can be seen with the air cleaner on. Won't guarantee that they're the MKII carburetors, but it's a start. Bud|
|Here's a shot of my 1500 carbs. |
|Another, Looking behind the filters, you can see a hump on each side of the filter mounting flange. The two hole models don't have this hump. PJ|
|Thanks, folks. What I'm trying to do is to provide info that will help a guy with a TDC car determine if he has the MKII carburetors under its oil bath air cleaner. Bud|
|Hi Bud, here is a picture of the MK2 carbs. Note the large suction chambers with the 3 securing screw.|
|Compare with this image shamelessly stolen from the internet. Notice how much the proportions of the bells appear -- the H4s are fatter.|
|With image this time! ;-)|
|For heaven's sake - just remove the air intake and look at the front sides of the carbs. If they are Mark II carbs they will have vibra-etched 4031/12 and 4031/8.|
|Or, if they are Mk II carbs they'll have 1.5" throats. After all, that's what the '4' in "H4" means! ;-)|
|Easy guys. I'm dealing with the owner via email. He just inherited the car. Knows nothing about it. Has no tools, nor parts books. I'm just trying to help him identify what he has. At the moment I'm waiting for him to locate the Engine No. plate on the block. The car originally had TD3/21674. I'm working with him to stop activity from the overflow tubes. Bud|
|I just measured -- the bells on my (MGA) H4s are a little over 2 3/4" in diameter. H2 bells will be significantly smaller. That should be easy for him to measure.|
|Thanks, Rob. Let's see what I can do with that. Bud|
This thread was discussed between 26/12/2011 and 29/12/2011
MG TD TF 1500 index
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