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BT-7 tri-carb Two more questions

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1) can i get the front pipes on after i have installed the heat shield and tri-carbs?

2) should the caps on the HS4 carbs be vented?

Thanks
 
Anything is possible it just depends how flexible your wrists are and how extensive your tool collection is .
As for the carbs .
I have an original unmolested set all still in one piece in my shop for my 62 tri carb project . I will have a peek tomorrow.
 
If you mean the caps on the float bowls, yes, they are vented. The stock vent tubes are clear with an interior spring at the bend. They just bend straight down a couple of inches and stop. Some folks rout the tubes to the side, but many are left stock. Some folks omit the vent tubes entirely. I solved the periodic venting problem by switching from conventional valves to the Gros-jet ball bearing valves. If you retain the stock setup I believe Delrin (or some such) needle valves are required due to the makeup of fuels sold today.
 
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i was asking about the damper caps. i have always read that when SU carbs have that angle brace at the top of the carb, they do not use a vented cap. My caps are vented.
 
I am not sure....The assumed to be stock damper caps on the HS4s on my side shift tri-carb are not hex edge brass like the caps on many other S.U.s. They are dark plastic fluted edge affairs with a definite vent hole off center. I have seen these caps on most of the tri carbs. (but I never thought to look for the hole, I was more enthralled by the fluted edges.)
 
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Drone Dog
If your carbs have internal venting (Called dustless venting). Then you do not want vented caps.
My understand is that if you have both the piston will not raise properly and you will be chasing all kinds of mixture problems.
Hope this helps.
 
Thanks. vented are all i have seen. i was just wondering because of what i read when working on the TD.
 
Thank you Maestro Brinkerhoff, it is good to have to have the benefit of your expertise.
 
Pic of my unmolested tri carb set up . Breather holes in all the caps . 1/16ā€ ish
 

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Just like mine. Designed to be operated with thumb and forefinger. I can hear the sound they make when you check them just by looking at the picture.
 
Are all plastic caps suppose to be vented? I have HD8s, and the plastic caps had been molested. A PO glued dimes on top. I took the dimes off, but can't tell if there were vent holes.
 
This discussion about vented versus non-vented damper caps got me curious. I wrote Joe Curto and heard from him right away. I also found a website authored by a fellow who has SUs on his Volvo. The bottom line is if the dome (dashpot) is vented, then the damper cap should not be. The reverse is also true. If the dome (dashpot) is not vented then the damper cap should be, that is, it should have a hole in it. To see if your dome(dashpot) is vented, just unscrew the damper and look at the inside neck of the dome. If you see a hole, then it is vented. Check out the link to the Volvo website. He provides good captioned photos. Hope this is helpful.

https://65brick.blogspot.com/2009/04/carbs.html

Lin
 
Since my HD8s are unvented internally and have no holes, I propose to drill holes. I have a spare, junk, HD8 with a black plastic cap with a 1/16" hole, marked AUC 8114.

Could someone with a stock BJ8 confirm whether they have AUC 8114 vented caps?

Thank you.
 
My stock aud 124 HD8 carbs have auc 8112 dampers which are vented; according to the su website and other su publications i have in my possession the 8112 are correct for an Austin Healey Mark 111. The auc 8114 damper is listed on various hd6 carbs installed on other applications. Hope this helps!!

John
 
The damper for the HD6 carb is slightly shorter in length than the damper for the HD8. Perhaps someone can chime in on the impact of using a shorter (or longer) damper has on the functioning of the carb.
Lin
 
The dampers are sized to the carb - if you used an HD6 damper in an HD8 they wouldn't be submerged in oil as well and if you used the HD8 dampers in a HD6 it could prevent the piston from rising fully. BTW, the damper rods are a press fit into the caps - I have triple HD6 now but when I had twin HD8s I used brass caps because at one time I was testing heavier oil and found the rods pushed thru the plastic caps and stuck out the top which led me to pressing them into brass caps, I later went back to lighter oil but kept the brass caps because I prefer the appearance of the brass.
Dave
 
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