13 replies to this topic

[Minigman]

I have a mk3 so twin bolt subframe and want a more period carb than a HIF44. On a 1330cc with 276 cam, stage 3 head etc etc.

Thinking of fitting a HS6 in place of the twin HS4s as I can’t get them running properly, and can’t throw any more money at rolling roads (spent about £300 so far)

Are all HS6 equal?

Any clearance issues?

Can you just bolt any of them straight into a decent manifold or are some better more suited than others?

Edited by Minigman, 27 February 2020 - 10:40 PM.

[robert.hedges]

What's the issues with the twin HS4?

[nicklouse]

No they are not all equal. The last ones were more like the HIF design with the ball bearing slider.

I would still HIF it.

[Minigman]

No they are not all equal. The last ones were more like the HIF design with the ball bearing slider.

I would still HIF it.

Nick, I thought there were clearance issues with the HIF44 on a twin bolt subframe?

[Minigman]

What's the issues with the twin HS4?

Basically can’t be fuelled correctly.

Been to two rolling roads, had various needles, had needles reprofiled and I’m still running rich and then lean above 4000rpm.

[blacktulip]

Hi mate, there are no issues with clearance as long as you fit a shallow depth inlet manifold like the mg metro one. I had this set up in my old 1971 and it cleared the bulkhead by around 5mm. The chance of it hitting the bulkhead is zero as the remote linkage acts as s great engine steady.

[Minigman]

Hi mate, there are no issues with clearance as long as you fit a shallow depth inlet manifold like the mg metro one. I had this set up in my old 1971 and it cleared the bulkhead by around 5mm. The chance of it hitting the bulkhead is zero as the remote linkage acts as s great engine steady.

Mine is ‘74 so rod change. I was thinking of the maniflow manifold. Any ideas if this clears?

[imack]

I think if the carbs got the later waxstat type jet you're likely to have clearance issues.
Shame you can't get the twin hs4's set up properly because they are a nice when tuned correctly.
Peter Baldwin did mine in 2016 and they've been great since.

[blacktulip]

Not sure on those. The only ones I had trouble with was a howley and those unknown cast alloy cheap looking ones which were too long. The mg type was perfect plus I could use the port rings to make sure it was dead inline.

[robert.hedges]

What's the issues with the twin HS4?

Basically can’t be fuelled correctly.

Been to two rolling roads, had various needles, had needles reprofiled and I’m still running rich and then lean above 4000rpm.

I take it you've already looked at the spring and dash pot damper?

[Minigman]

What's the issues with the twin HS4?

Basically can’t be fuelled correctly.

Been to two rolling roads, had various needles, had needles reprofiled and I’m still running rich and then lean above 4000rpm.

I take it you've already looked at the spring and dash pot damper?

Yes. It’s had different needles, new springs which replaced the already new springs. It’s had about 4-5 hours on two different rolling roads. They were new carbs (as in brand new) 1200 miles ago.

[Alex_B]

How competent are the rolling roads? If they're more accustomed to using a laptop rather than re-profiling needles by hand then that might be your problem. 

Rich down low isn't difficult to sort, lean at top could well be your fuel pump not supplying enough if your needle isn't the problem, what pump are you running? I would struggle to see why the HS4 couldn't be tuned to run your engine properly, they are very capable carbs and provided they are matched correctly then they should be able to be tuned and work nicely. 

Also I would be questioning the rolling roads if they are charging you yet unable to provide a correctly tuned car, after all unless you are tuning it and using their equipment then you're paying for a service that hasn't been fulfilled? 

[Cheeser]

It would appear that you could easily spend a fair amount of money getting an HS 6 set up properly. GOOD rolling road is the best solution in my opinion. I have used Slark near Bristol airport very successfully setting up twin Hs4s, also a friend with a mini van has used Tipton Garage near Sidmouth to set up twin Hs4s and been very satisfied. Both these RR are relatively close to you. Hope this helps?

[Minigman]

It would appear that you could easily spend a fair amount of money getting an HS 6 set up properly. GOOD rolling road is the best solution in my opinion. I have used Slark near Bristol airport very successfully setting up twin Hs4s, also a friend with a mini van has used Tipton Garage near Sidmouth to set up twin Hs4s and been very satisfied. Both these RR are relatively close to you. Hope this helps?

One of the RR I used already was Slarks which told me a 276 cam would always be too much of a compromise to get HS4s to work well.

I’ve heard good things about Tipton before so may give them a go next. Slarks are just doing my gearbox at the moment following my wrecked idler gear bearing, so it should be back on the road soon.