Which carbs

[qim]

Hi

 

here I am again

 

I have a TR3A 1959, which I bought in 1977 and as far as I am concerned it is pretty original.

 

I wanted to have the carbs overhauled and bought a kit, which appears to be the wrong one.

 

Apparently, the late TR3As (from 1959) came with tthe same carbs as the early TR4. is that right?

 

having come to that conclusion two different firms give me different versions of the carbs. Are they SU H6 or SU HS6 ?

 

here are some photos:

[boxofbits]

Hi

 

From the photos looks like you have HS6 carburettors. The float lids differed between versions in that the H6 had a central bolt to secure the float lid and the HS6 three screws. There are probably a few other differences but that is an accurate identifier as far as I am aware.

 

Regards

 

Kevin

[Lebro]

TR2's used H4 (1½") carbs, TR3's on to TR4's use H6 (1 3/4"), TR4a's used either strombergs, or HS6.

 

The ones in your photo are HS6, so not original, however they are better carbs, & I would stick with them.

(I use HS6's on my '56 TR3)

They may have been purchased from Cox & Buckles spares a long time ago (as were mine) as they were doing them at a V good price.

 

Bob.

[Dave Larnder]

Hi Member

 

They are HS6´s, as the view below the carbs is the dead give away.

I have them on my TR3A with a TR4 manifold, and as Bob says, stick with them they are better carbs.

 

Dave

[John390]

Bob, both my 1964 TR4's have strombergs!

 

Cheers John

[qim]

Thank you all!

 

Next question:

 

The car used to run very well until I had a daughter... It meant some 15 years without any use, other than going round the block 2 or 3 times a year. I've just had them tuned and the ticking over while stopped sounds good, but at a certain point when moving it starts missing a bit. Without knowing much about carbs, I suspect that as the pistons rise under increased rpm one of them (at least) starts sticking due to dirt accumulated over the years.

 

I was going to overhaul them but got the wrong kit and mow decided that maybe all I need is to clean the pistons and put in new needles.

 

Do I also need springs?

 

Thanks

[Lebro]

I would start by just cleaning every thing.

Don't mix the parts from the two carbs up, & when re-assembling take some time to ensure the jets are centered.

& use 20 to 30 grade straight oil in dashpots

 

Bob.

 

P.S.

John.

I'm not sure exactly when the change over was, but the point is no TR3 ever had HS6's

Edited May 24, 2016 by Lebro

[qim]

Thank you Lebro

 

I used to service the car when I was 30. Now, at 70 I don't touch it and leave it to a mech. Problem is few mechs know what they are doing here!

 

Do you think I should invest in the springs before the carbs are disassembled?

[Lebro]

Not unless you have a good reason to think there is something wrong with them.

 

Bob.

[qim]

Could it be that they start calibrated but as the piston is forced up the springs act differently for being unused for so many years (other than the very occasional run round the block)?

[Lebro]

Well I don't think so, but others may disagree.

The usual reason for the pistons not going down properly is either the jet not being correctly centered, or simply build up of grime in the piston / housing area.

 

Bob.

[TR 2100]

The HS6 has a shorter body to allow a longer, and better 'flowed', inlet manifold.

 

Not so sure the shorter body carb on the shorter squared manifold is desirable.

 

As has been pointed out, in the early days of the Register, Pete Cox was selling

HS6 cars at a very favourable price, plus there weren't the same readily available

carb rebuild options.+

 

AlanR

[BlueTR3A-5EKT]

Well I don't think so, but others may disagree.

The usual reason for the pistons not going down properly is either the jet not being correctly centered, or simply build up of grime in the piston / housing area.

 

Bob.

+1

 

The piston springs are worth renewing if you consider they are visually not a pair.

 

Special note: If these are C&B cheepo HS6 carbs the needle may be a BIAS/spring mounted type. They had special needles made with a SM profile but a bias fitting. If that is the case you could be 'steeped in the proverbial' as I am not aware of any stocks of the bias type SM needle being available. Way to check is Unscrew the three screws that hold the dashpot lift the piston and needle assy out - touch the needle - does it move a bit from side to side as if spring mounted? If so it is BIAS type. If it does not it is a FIXED needle.

The ways round it if it is a BIAS type are :-

1. Source a pair of pistons and dashpots that will accept the fixed SM design needle as original. - my solution when I needed them.

2. Create SM needles in bias needle seats with araldite/knurling/super glue. - lots of fun that one.

3. Search the needle profiles for a bias type wit the same profile as a fixed SM that fit the 0.100" jet <<Link to Minty Lamb http://www.mintylamb.co.uk/suneedle/

BIAS type could be BAE or BAB or BDB - Your standard original FIXED needle is SM

4. Buy these < http://rover.ebay.com/rover/0/e11011.m43.l1120/7?euid=e5b4864cf31e49c694d363b7128a45b5&bu=43178097180&loc=http%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2Flike%2F112005059077&sojTags=bu=bu >

 

Cheers

Peter W

[Lebro]

To check if the springs are the same strength find a rod / pole of any material which the springs fit over, then compress the two springs towards each other. if they are the same then they will "shrink" in length at the same rate.

 

Regarding the C & B HS6's mine came with fixed needles.

But last year I was making up a pair of HS4 carbs for a friends TR3A (fitted with a TR2 engine) I purchased a "pair" of them at the autojumble at last years Malvern IWE. When I examined them more closely I realised that they were not a pair, just 1 LH carb, & 1 RH carb from different origins.

One had a fixed needle, & the other had a sprung one. To sort this out I made up an insert to go in the sprung one, a press fit, to accept the fixed needle.

 

Bob.

[ianc]

Like many others, I bought a pair of brand new HS6 carbs from Pete Cox "just in case" in 1970/71 - too good a bargain to miss at £25. They had fixed needles.

When the car was being rebuilt in 1992, Neil Revington fitted these carbs in place of the H6s, and all that was required was replacement of the needles to suit the modified engine - the setting-up by genius Peter Lander on his rolling road in Gillingham (Wiltshire) took about an hour - another bargain!

Ian Cornish

[Kiwifrog]

+1

 

The piston springs are worth renewing if you consider they are visually not a pair.

 

Special note: If these are C&B cheepo HS6 carbs the needle may be a BIAS/spring mounted type. They had special needles made with a SM profile but a bias fitting. If that is the case you could be 'steeped in the proverbial' as I am not aware of any stocks of the bias type SM needle being available. Way to check is Unscrew the three screws that hold the dashpot lift the piston and needle assy out - touch the needle - does it move a bit from side to side as if spring mounted? If so it is BIAS type. If it does not it is a FIXED needle.

The ways round it if it is a BIAS type are :-

1. Source a pair of pistons and dashpots that will accept the fixed SM design needle as original. - my solution when I needed them.

2. Create SM needles in bias needle seats with araldite/knurling/super glue. - lots of fun that one.

3. Search the needle profiles for a bias type wit the same profile as a fixed SM that fit the 0.100" jet <<Link to Minty Lamb http://www.mintylamb.co.uk/suneedle/

BIAS type could be BAE or BAB or BDB - Your standard original FIXED needle is SM

4. Buy these < http://rover.ebay.com/rover/0/e11011.m43.l1120/7?euid=e5b4864cf31e49c694d363b7128a45b5&bu=43178097180&loc=http%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2Flike%2F112005059077&sojTags=bu=bu >

 

Cheers

Peter W

 

These carbs look very simular to the HS6's I have fitted on my 3A with the vaccuum advance on the rear carb instead of the front carb, I run BBW bias type needles in mine a bit richer at the higher stations than SW but seem to work well. I did try BDM but they seemed to be a bit weak maybe because of the waxstats Minty lamb will give you a good idea of which needle to choose. My HS6's were NOS Marina 1800TC jobs so have the wax stat still attached

 

cheers

 

Alan

Edited May 25, 2016 by Kiwifrog