• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

SU HS6 Carbs overflow leaking...........

Share this page

R

RossL

Member
Country flag
Offline
I have a set of HS6 carbs on my TR6. There are a few drops of fuel coming out of the overflow/vents after driving the car.

I've rebuilt them and adjusted the float levels. I'm now about 1/16" higher than spec. The TR6 has a mechanical fuel pump.

I am going to install a fuel pressure regulator.

What pressure should I set it to for the SU's?

DSC01155.jpg


DSC01159.jpg
 
Instead of a regulator,you could just shim your mechanical pump out from the block a bit to shorten the stroke that the lobe is able to push the pump arm.
It would take a bit of experimenting to find out the thickness of shims you need to achieve the 3 1/2 psi but it would save the extra complication and potential problems with a regulator.
Just my humble oppinion good luck............

Mark
 
I think this thread got lost in cyber space
 
If your pump is a stock mechanical, you have other problems. The stock pump should not do this.
Ross Post on the TR. forum
 
DNK said:
If your pump is a stock mechanical, you have other problems. The stock pump should not do this.
Ross Post on the TR. forum
Click to expand...

Hi Don,

Since the TR6 didn't come with SU's I thought I would get more feedback here.

Ross
 
Lots of SU guys in the TR section too.
Not that these lads are slouches.

Just MG guys
 
DNK said:
Lots of SU guys in the TR section too.
Not that these lads are slouches.

Just MG guys
Click to expand...

Though at least he had the good sense to go where the accurate knowledge is first. (harumph) :jester:
 
2p:

The description is "a few drops after running"... could it be due to combination of slightly higher float setting and heat expansion of the bowl contents after things are up to operating temps?

Although a LOT of folks use those "dial-a-pressure" regulators, IMO they're unreliable and downright diabolical. A good regulator is made by Holley, albeit a bit pricey. The SU's should be okay with up to around 4PSI. Lower is better.

If you don't have Viton tipped needle and seat, get 'em.

Why is the float level set higher? Which metering needles are in 'em?
 
DrEntropy said:
2p:

The description is "a few drops after running"... could it be due to combination of slightly higher float setting and heat expansion of the bowl contents after things are up to operating temps?

Although a LOT of folks use those "dial-a-pressure" regulators, IMO they're unreliable and downright diabolical. A good regulator is made by Holley, albeit a bit pricey. The SU's should be okay with up to around 4PSI. Lower is better.

If you don't have Viton tipped needle and seat, get 'em.

Why is the float level set higher? Which metering needles are in 'em?
Click to expand...

I do have the Viton tipped needle/seat.

When I said the float was adjusted higher, I was thinking of it upside down. I guess it may have been more accurate to say "lower". The float is adjusted about 1/16 over spec, measured from the lip of the float bowl to the bottom of the float.

Since the pictures were taken I installed an ARE heat shield. It did not make a difference.

I should also note that for this test, I have been driving the car much harder than usual shifting between 4500 and 5500 rpm (traffic permitting)...........since I'm running a mechanical pump I assume it's putting out more pressure at these RPM's.

Yesterday I fitting dial regulator, the car would not run when dialed at 2-3 pounds. At 5 pounds it ran well and I did not see anything coming form the vent/overflow.

I have to do a few more test drives to be sure.

I have to assume the dial regulator is not so accurate.................
 
Listen to the Doc, even if he is a Lotus and MG guy
grin.gif
 
Sounds as if you've sussed the issue. If you intend to keep that "regulator" (it really just restricts flow, doesn't much alter pressure), tape it or otherwise secure it to the setting... they have been known to "self-adjust" and in some (racing conditions) instances self-disassemble... just a word in yer ear.
 
Doc, have you ever seen a stock pump put OUT to much pressure?
 
Electric ones, nope. The AC mechanical ones will vary with RPM, tho. If it were mine, there'd be an electric one in it... converted all the Lotus cars over to either an SU or Facet, Spider currently has a Carter. Much more consistent, IMO.
 
I've got a real nice carter he can have.
Never been used
 
Carter P60504? :smile:
 
No, I think it's a 4070. That's the one the Weber folks suggest . They say it works best for not over taxing the DCOE's
 
I've the 60504 in the Spider, been there about four years now. No issues.

Oh, and 40 DCOE's.
 
Not.
 
Back
Top