SU HS4

[wilkpauled]

Does anyone know if HS4s could be fitted to the TR7? I know the HS6 is the standard, but I have the chance to get an inexpensive pair of HS4s from someone in the neighborhood. Possible or just not a good idea? What about the intake manifold?

[mak]

You could use a manifold from an Dolomite 1850 and try to work out which needles you need. Main issue would be that the amount of petrol/air getting into the engine would be less. (hs4's I think have two mounting holes whilst hs6's have 3.) Quiller triumph in the UK sell alloy hs4 carb mounts for the 1850.

[wilkpauled]

Thanks for the info. I was thinking maybe enough gas wouldn't get through. I should probably stick with HS6s if I'm going to get rid of the Strombergs.
Paul

[Hasbeen]

Paul, why do you want to get rid of the Strombergs?

I have SUs on my 7, & love them for their simplicity, but when our
local Triumph expert saw them he wanted to know why I went to the
trouble.

He told me they get just as much power fron the Strongbergs, as they
can with SUs, & claims better throttle response from them.

Hasbeen

[bmcecosse]

You would be well rid of the Strombergs! SUs are far better/easier to work with. HS4s will be fine - lose a little bit of top end power, but be honest - how often do you run with your foot right on the floor. If the price is right - go for it.

[wilkpauled]

The main issue with the Strombergs right now is that there's a nasty little petrol leak coming out of the vacuum pipe on the front carb, underneath (used to be attached to a little pvc tube going to a fuel trap and then out to the distributor or the egr valve, I've never been able to figure out how that system functioned since someone snipped it off a long time ago). And this after a rebuild too. So... it's frustrating.
But I have an old Triumph mechanic still kickin' around in the area working on it, and he thinks he's found the solution by cleaning out the manifold with a carb cleaner additive he's been running through the system. He says there was a lot of buildup in there and that it was forcing fuel backwards and then out the pipe--his theory, at least. We'll see if he can fix it. I'd sort of run out of theories, so I'm letting him play around.
Of course, I'd just like to get the car rolling, and I'd keep the Strombergs a bit longer if he can get it to go. But he also said SUs could be an option if it's not the intake manifold plugged with junk after all--telling me straight out that Webers would be too expensive, which I've sort of realized. So I've been looking a bit.
We'll see what happens. Thanks for your input.
Best,
Paul

[bmcecosse]

The 'manifold gunk etc' story sounds highly unlikely !! Get the SUs ready - far better carbs anyway.

[Hasbeen]

Are you sure the carb is not flooding?
Have you checked the fuel pressure? It should not be over 2 PSI.

Hasbeen

[wilkpauled]

I told him to adjust the fuel pressure--since it does have a regulator on it-- but he said that the pressure would be regulated well enough just by the action of the needle and the seat. Maybe he's a crackpot--I have my suspicions.
Thanks for the continued interest--I need all the help I can get with this one.
Paul

[Hasbeen]

Paul, its the fact that the needle & seat can't handle more than 2
PSI, that causes the trouble, if the pressure is too high.

Perhaps you should try another bloke.

Hasbeen

PS. I assume you have cleaned the carbs, & replaced any worn needles
& seats.

H

[wilkpauled]

Yep, they were cleaned and rebuilt, seat and needle were both fine. So, maybe it is really just a question of the fuel pressure.
Again, thanks for all the ideas. I'll get this resolved one way or another. She's such a nice little car when she runs well.