BJ8 Float Level

[Lin]

I understand, and I think I agree with the observations about the desirability of equal fuel levels in the float chambers/jets in the SUs, but here is what I don’t understand: There is just no way that in the assembly of our cars, that the workers checked fuel levels. Instead, I expect that they simply bolted up carbs to the inlet manifold with float forks adjusted to 7/16” (or 5/16” if you want to believe that 7/16” has just been a perpetuated error). Somebody “may” have equalized the drop of the jets from the bridge, but it is more likely that they equalized the number of turns of the jet adjustment screw. Finally, I assume (I know that is always dangerous), although I do not have first hand knowledge since I never drove a brand new Healey, that the cars ran well off of the show room floor. If that is the case, are we making too big a fuss over the pursuit of precise tuning of our SUs?

This observation is a sincere question, and certainly not a criticism of those who have contributed to this Forum thread.

Lin

 

[vette]

I understand, and I think I agree with the observations about the desirability of equal fuel levels in the float chambers/jets in the SUs, but here is what I don’t understand: There is just no way that in the assembly of our cars, that the workers checked fuel levels. Instead, I expect that they simply bolted up carbs to the inlet manifold with float forks adjusted to 7/16” (or 5/16” if you want to believe that 7/16” has just been a perpetuated error). Somebody “may” have equalized the drop of the jets from the bridge, but it is more likely that they equalized the number of turns of the jet adjustment screw. Finally, I assume (I know that is always dangerous), although I do not have first hand knowledge since I never drove a brand new Healey, that the cars ran well off of the show room floor. If that is the case, are we making too big a fuss over the pursuit of precise tuning of our SUs?

This observation is a sincere question, and certainly not a criticism of those who have contributed to this Forum thread. Lin

 

[steveg]

I understand, and I think I agree with the observations about the desirability of equal fuel levels in the float chambers/jets in the SUs, but here is what I don’t understand: There is just no way that in the assembly of our cars, that the workers checked fuel levels. Instead, I expect that they simply bolted up carbs to the inlet manifold with float forks adjusted to 7/16” (or 5/16” if you want to believe that 7/16” has just been a perpetuated error). Somebody “may” have equalized the drop of the jets from the bridge, but it is more likely that they equalized the number of turns of the jet adjustment screw. Finally, I assume (I know that is always dangerous), although I do not have first hand knowledge since I never drove a brand new Healey, that the cars ran well off of the show room floor. If that is the case, are we making too big a fuss over the pursuit of precise tuning of our SUs?

This observation is a sincere question, and certainly not a criticism of those who have contributed to this Forum thread.

Lin

The difference between tuning and super-tuning.

 

[Lin]

Gotcha!

 

[vette]

The difference between tuning and super-tuning.

You are very right Steve.

 

[John Turney]

"Although my float levels in both HD8s were the same at 7/16", the fuel levels in the jets were way different."

I'm curious as to why the fuel level in the jets would be so different if the fuel levels in the bowls are (presumably) the same. I suspect that violates some law of physics or hydraulics.

The only way that makes sense to me is if the floats are different weights. Unfortunately, I don't have an accurate scale to measure the float weights.

 

[John Turney]

The difference between tuning and super-tuning.

Correct!

 

[steveg]

I understand, and I think I agree with the observations about the desirability of equal fuel levels in the float chambers/jets in the SUs, but here is what I don’t understand: There is just no way that in the assembly of our cars, that the workers checked fuel levels. Instead, I expect that they simply bolted up carbs to the inlet manifold with float forks adjusted to 7/16” (or 5/16” if you want to believe that 7/16” has just been a perpetuated error). Somebody “may” have equalized the drop of the jets from the bridge, but it is more likely that they equalized the number of turns of the jet adjustment screw. Finally, I assume (I know that is always dangerous), although I do not have first hand knowledge since I never drove a brand new Healey, that the cars ran well off of the show room floor. If that is the case, are we making too big a fuss over the pursuit of precise tuning of our SUs?

This observation is a sincere question, and certainly not a criticism of those who have contributed to this Forum thread.

Lin

Doubt if the factory did any of the stuff we're doing and the cars ran just fine. SU probably set the float levels, centered the needles and screwed the jets down 3-1/2 turns and shipped them out to Abingdon. A bin of front carbs and a bin of rear carbs. Mick on the assembly line grabbed one of each and bolted them up.

 

[Michael Oritt]

Lin/All--

Though I agree it is improbable that much fine tuning was done at the works I think it is likely that basic tuning was done at the dealers prior to delivery.

I wonder if anyone has access to an original retail invoice and, if so, whether there was any charge for "Dealer Prep"

 

[steveg]

Lin/All--

Though I agree it is improbable that much fine tuning was done at the works I think it is likely that basic tuning was done at the dealers prior to delivery.

I wonder if anyone has access to an original retail invoice and, if so, whether there was any charge for "Dealer Prep"

I thought "Dealer Prep" consisted of unloading it off the transporter.

 

[John Turney]

I thought "Dealer Prep" consisted of unloading it off the transporter.

I think they also washed the salt water off.

 

[Bob_Spidell]

"... I expect that they simply bolted up carbs to the inlet manifold with float forks adjusted to 7/16” (or 5/16” if you want to believe that 7/16” has just been a perpetuated error) ..."

I've always used 7/16", and noted that setting kept the flat part of the float lever parallel with the bottom of the float cover. I think a greater or lesser setting might tend to jam the float needle in its 'barrel.'

 

[John Turney]

"... I expect that they simply bolted up carbs to the inlet manifold with float forks adjusted to 7/16” (or 5/16” if you want to believe that 7/16” has just been a perpetuated error) ..."

I've always used 7/16", and noted that setting kept the flat part of the float lever parallel with the bottom of the float cover. I think a greater or lesser setting might tend to jam the float needle in its 'barrel.'

That may depend on which kind of float lid and lever you have. According to Joe Curto (https://joecurto.com/su-float-bowl-covers) there are two types for HD8s. I have the later type.

 

[vette]

A bin of front carbs and a bin of rear carbs. Mick on the assembly line grabbed one of each and bolted them up.

I like Mick, I like Mick,

QUOTE: Though I agree it is improbable that much fine tuning was done at the works I think it is likely that basic tuning was done at the dealers prior to delivery. UNQUOTE.

I'm thinking back in the day the people at the Dealers probably wanted to put a little more personal interest in the cars before they let them go. But today, I suspect the attitude would be, 'Don't breather on the dang thing until it is back here for its 1st service interval .... or sooner.' :rolleye:

 

[steveg]

I like Mick, I like Mick,

QUOTE: Though I agree it is improbable that much fine tuning was done at the works I think it is likely that basic tuning was done at the dealers prior to delivery. UNQUOTE.

I'm thinking back in the day the people at the Dealers probably wanted to put a little more personal interest in the cars before they let them go. But today, I suspect the attitude would be, 'Don't breather on the dang thing until it is back here for its 1st service interval .... or sooner.' :rolleye:

They'd at least have to drive them from where they were offloaded to the showroom. If they started and ran OK, I'd think that would be it.

 

[steveg]

Followup: For several months, I ran my (HD8s) car with the float levels set such that the fuel level in the jets was 3/16" down. 5/16" float levels delivered this. The car ran fine in our mild S. Calif. climate.

Last week I switched back to the approved 7/16" float levels, irrespective of how far down in the jets this made the fuel level.

Using my dual Air/fuel Ratio gauges and my dual Exhaust gas temp gauge, can report there was no change in either from the change in float levels.

 

[John Turney]

That's interesting Steve. So by setting the float level at 5/16" you get a bit further if your fuel pump dies, with no change in fuel/air ratio.

 

[steveg]

That's interesting Steve. So by setting the float level at 5/16" you get a bit further if your fuel pump dies, with no change in fuel/air ratio.

I didn't see any difference. Was never comfortable with the 5/16" setting because I never found an authoritative source favoring departing from the factory setting.

The assertion that 7/16" is a "perpetuated error" is baseless without authoritative documentation.