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TR2/3/3A latest with my H6Ss

TexasKnucklehead

Jedi Knight
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Today I thought I was going to have to reconsider using H6S's on my TR3. I thought I had an issue worked out. The rear carb bowl fouls on the firewall pass through for the heater hose. Some time ago, I made a pass through with a 90 degree bend and thought that would fix my issue. When I went to put the rear carb on today, it could not fit on the 4 bolts, because the firewall pass through was in the way. Removing the pass through is easy enough (assuming it has not been connected to the system and not full of water) but re-installing with the carb there is not so easy. The inside screw is so close to the bowl, that not even a screw driver bit will fit in there. I'll have to use a bolt, with a nut on the inside of the firewall.

But, for now it looks as I'm making progress again. The linkage is all connected, adjusted and working smoothly from the pedal. ...a few more wires, a steering column, trafficator, windshield, interior (etc) and I'll be on the road.

H6S-side.jpgH6S-top.jpgH6S-inside.jpg
 

tinman58

Jedi Knight
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Your bowls are on the wrong side. They should be to the right, standing at the right front wheel.
 

TR4nut

Yoda
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Your bowls are on the wrong side. They should be to the right, standing at the right front wheel.

With the center pull arrangement the rear carb has the bowl towards the bulkhead unfortunately.

Jerry- I'm in a similar situation and noticed the same thing. I bought a right angle fitting from Aircraft Spruce which lets me screw down the plate first, then install the carbs, then add the bulkhead fitting as a last step. But its very very tight. In my case since I haven't cleaned up a heater yet and I'm building more of a modified driver I'm leaning strongly to blanking the bulkhead fittings and forgetting about the heater for a while.
 
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TexasKnucklehead

Jedi Knight
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I'm leaning strongly to blanking the bulkhead fittings and forgetting about the heater for a while.
Randy,

That crossed my mind more than once. But I think one of the coolest things under the hood of a TR3 is that green heater valve. Unfortunately, keeping the valve also forces the use of that extension tube with 2 or 3 threads into that valve. A length of heater hose running from the extension to the other side was problematic as well. It seemed all I had to do was bump the hose, and the extension to valve was leaking. My length of hose will be inside the car, because I don't have time right now to get the heater straightened out. I want to get the wiring under the dash sorted out before I add the hose.
 
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TexasKnucklehead

Jedi Knight
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Interesting. Is there an advantage to these carbs with the opposite side bowls?

Good question and I hope some day I'll have an answer to it. Let me start with 'I don't think there is a significant performance difference between the TR3 and TR4'. You probably know the TR3 and TR4 used the same block, but slightly larger pistons/liners. The cam, distributor and carbs also changed. The carbs changed from H6 to H6S; the S for short. The intake became longer so the carb body became not as deep and not as tall. Supposedly this was to 'breath better'. I have a TR4 cam, distributor and larger pistons/liners, but the real reason I went with the H6S, is because when I brought my TR3 home, the carbs looked like this:

(for some reason I can't add a picture right now... but you may have already seen it, the one full of sand with the metal detoriated so much the piston, or anything else does not move)


and I thought they needed more than a rebuild kit could handle. After a few months, some rebuilt H6Ss and an intake came up on ebay and I went ahead and got them for a reasonable price. Was it worth the effort? We will see. Randy and I are racing to be the first in the club to have a set, and I'm sure we will be competing on a track every chance we get.
 

CJD

Yoda
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Sounds like fun! You are moving into the phase of the restoration where it finally starts to move fast. You could be racing by spring!
 

TR3driver

Great Pumpkin - R.I.P
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You guys got me wondering, so I checked. I have both an original TR4A setup hanging on the wall, and a brand new pair of HS6 carbs still in the box (sold as being suitable for TR4A). In both cases, the rear bowl is mounted to the front of the carb.
Don't recall where I got this photo, but it shows the bowl arrangement.

early SU HS6.jpg
 

TR3driver

Great Pumpkin - R.I.P
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You probably know the TR3 and TR4 used the same block, but slightly larger pistons/liners. The cam, distributor and carbs also changed. The carbs changed from H6 to H6S; the S for short. The intake became longer so the carb body became not as deep and not as tall. Supposedly this was to 'breath better'.
Just for clarity, the HS6 was only fitted to late TR4A. Early TR4 still used H6, then they changed to using ZS carbs and continued through initial TR4A production. The TR4 used the same 301466 camshaft as TR2-3A; the camshaft change was at the introduction of the TR4A.
 

Darrell_Walker

Jedi Knight
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You guys got me wondering, so I checked. I have both an original TR4A setup hanging on the wall, and a brand new pair of HS6 carbs still in the box (sold as being suitable for TR4A). In both cases, the rear bowl is mounted to the front of the carb.
Don't recall where I got this photo, but it shows the bowl arrangement.

Hi Randall,

I don't think that is correct, or I'm misunderstanding you. The float bowls on the HS6 on a TR4A are mounted with the bowl on the front carb forward, the rear carb back. The fuel line that connects the two carbs is a large C-shaped piece, that goes around the air cleaners.

-Darrell

P1010005.jpg
 
Last edited:

TR4A_IRS

Jedi Trainee
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Hi Randall,

I don't think that is correct, or I'm misunderstanding you. The float bowls on the HS6 on a TR4A are mounted with the bowl on the front carb forward, the rear carb back. The fuel line that connects the two carbs is a large C-shaped piece, that goes around the air cleaners.

-Darrell

View attachment 28768

Agree with Darrell here. My 4A has HS6 carbs and they are configured as Darrell describes.
 

HerronScott

Darth Vader
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Ditto on my 2 late TR4A's that came with HS6's.

Picture of the one that's still in original condition. :smile:

 

TR3driver

Great Pumpkin - R.I.P
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Hi Randall,

I don't think that is correct, or I'm misunderstanding you.
Ok, I'll check again when I get home. Maybe the ones on the wall are assembled backwards, and I didn't look carefully enough at the ones in the box.
 
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TexasKnucklehead

Jedi Knight
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Well, in any case, I used #10x1/2" SS allen head (3/4" will not fit in from the front) and allows enough thread on the inside for a nyloc nut and washer. The allen wrench barely fits but this is something I don't plan to be removing often.

When I got the carbs, the seller told me they were not from a Triumph, and that he had some with the rear carb bowl on the front -if it turned out I needed that. At the time I thought I was good to go... and I still do. But apparently they come both ways.

So did the TR4a have better performance? Hp? Torque? Gas mileage? There must be some reason for the change. -Still, it doesn't matter, that's what I have, and as long as I can use them, I will.

It_fits.jpg
 

mt10flyer

Senior Member
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I just ran out and took this pic. Both bowls facing forward, 1959 TR3. And don't make fun of my engine...it's a daily driver. :playful:

engine compartment.JPG
 

Darrell_Walker

Jedi Knight
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I just ran out and took this pic. Both bowls facing forward, 1959 TR3. And don't make fun of my engine...it's a daily driver. :playful:

Your engine bay looks fine! But those are not HS6s.

-Darrell
 
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