Carb Identification

[Drewmotty]

Ive been looking at a friends TR4 which is fitted with TR4a inlet manifold and HS6 carbs. The carbs are not the type normally fitted to a TR4a and feature an additional connection just under the damper housing which has been plumbed direct into the rocker cover with no intermediate valve. This doesn't seem right and the car certainly runs better as soon as the connection is blanked.

The carbs also feature a recessed throttle stop which differs from the TR4a ones fitted on my cars. I'm assuming that are are a later version of the HS6.

Can anyone identify the origins of these carbs or shed any light on the extra connection?

 

[Peter Cobbold]

Andrew, That's how TR7 carbs are connected to act as a crankcase breather. The carb take-offs can be blanked and the rocker cover connected to a catch tank.

If the engine is making a lof blow-by ,eg past worn rings, I can see the engine running a bit rougher. If a hose is leaking air into the carb - a lot rougher !

Peter

[TR NIALL]

As Peter mentions above Blank them off and just use an alternative Breather from the Rocker Cover.

Those look like HS6s as fitted to 2.5s Saloon.

 

Edited October 26, 2019 by TR NIALL

[Lebro]

Cox & Buckles were selling these off at a knock down price in the 1970's, I have a pair on my '3

The part No. on them relates to being originally for an Allegro "Sport" (yes, I know !)

 

The small tubes are for rocker box ventilation, & I am using them as such with no problems.

 

 

Bob.

[Drewmotty]

Thanks for your replies gents.

Would these carbs be normally fitted with some sort of valve between the rocker cover and carbs like the TR4a?........or is there some sort of valve in the carb itself?

Edited August 16, 2017 by Drewmotty

[stuart]

Thanks for your replies gents.

Would these carbs be normally fitted with some sort of valve between the rocker cover and carbs like the TR4a?........or is there some sort of valve in the carb itself?

Not on original fitment. Though you could use the TR6 type of flame trap part number 60330A

Stuart.

[TR NIALL]

No Valve between Carbs and Cover and no Valve in Carb,,the Carb draws the fumes like a vacuum and expels them out through the Exhaust Valves down and out the Exhaust.

[Peter Cobbold]

The depression at that point in the carb is about 0.25psi so the whole crankcase will run at that small pressure below atmospheric. As gases pass the pistons they will be sucked into the carb. But so will air leaking past a leaking rocker gasket or filler cap etc. Neither will improve the mixture!

Peter