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WEBER conversion on my BT7


Freshman Member
Hello, originally there's a BJ8 camshaft and 2x SU HD8 on my BT7, and I I have bought a kit to convert it to triple WEBER.
I have synchronize the carbs, at idle, it's perfect, high rpm perfect, but in progression, really bad, and I think it's too poor.
Is there someone who can give me the size of his idle jet, pump jet, pump spill, main jet, air corrector, etc?


Country flag
For the progression to be spot on, the movement of all the carburettors must act at exactly the same time. Exactly! If one (1) carb leads the others, or lags behind, the engine will stumble.

How does the engine respond to these conditions:
cruise at steady speed?
cruise at steady speed with gradual throttle increase?
cruise at steady speed with abrupt application of full throttle?

Steady speed can be in third of fourth gear at 2500 - 3500 rpm, depending on prevailing road conditions.

Please note that the ignition and timing and the valve settings should be exactly set within specification before ever touching the carbs (any carbs, not just Webers).



Freshman Member
Hello, my problem is exactly :
idle is perfect
after 2000-2500 perfect
but when I startthe car in 1st, until 2000-2500 there's some small bang in the carbs
and it's the same thing in 2nd, 3rd and 4th.
It's for this I look for the settings of the other owners because I think I have a problem with this.



Jedi Knight
Country flag
Hello Randy

Not to hijack Jeepfast's post but your questions to him (below) relate to an issue I've been struggling with, although my car has SU carbs.

"How does the engine respond to these conditions:
cruise at steady speed?
cruise at steady speed with gradual throttle increase?
cruise at steady speed with abrupt application of full throttle?"

My question is, if engine is smooth under acceleration but not when cruising at steady speed, what carb issue does that suggest?



Jedi Warrior
Country flag
Not to be disrespectful, but you are in way over your head. Triple Webers are fantastic on a race motor when it has been properly dialed in on a dynomometer with experts that know what they are doing and also have a large assortment of brass, that is, main jets, idle jets, air correctors and emulsion tubes. Every engine is different and trying to get it right by trial and error is impossible if you are only driving around on the street and trying to figure out what is wrong.
Remember, every time you make one small adjustment, such as changing a main jet from a 145 to a 150, you have to buy 6 more jets. Every Weber DCOE carburetor has 2 of every jet. Multiply that number times 3 carburetors results in 6 jets every time you make a change. So if the first change doesn't solve the problem, you have to buy 6 more jets to go from 150 to 155, or 155 to 160. Or 6 more emulsion tubes to get a different fuel pattern. Or 6 more idle jets, or maybe 12 or 18. This is crazy expensive stuff. And you will never get it right without putting the engine on an engine dyno, or the car on a chassis dyno.
You may want to stay with the two HD8s. They work great and it will save you money and your sanity.


Freshman Member
Hello, thank you for your answer, money is always a problem, so I ask a question in the forum to don't buy 100 jets.
And to explain all : one of my HD8 is dead, and a friend of me give me 4 45DCOE, so the conversion is my best way.


Jedi Trainee
BoyRacer said:
And you will never get it right without putting the engine on an engine dyno, or the car on a chassis dyno.


Would never have got my quad 48's setup without getting on a dyno for half a day. Results were pleasing though as the old 800cfm Edelbrock would 'hunt and shunt' at 30mph in 4th and now we are turbine smooth at the same speed/gear AND when she's warmed up I can pull smoothly from 800rpm in 5th :jester:


Jedi Warrior
Country flag
You have been warned! The cost of fixing one SU HD8 will pale in comparison to what it will cost you to get triple Weber 45 DCOEs to ever work properly for you.
I welcome you to report back to us on your progress with these Webers over the coming years.
Country flag
I've got a compartmented box with a <span style="font-style: italic">small</span> investment in calibrated "brass;" I usually buy $200-300 worth of jets at a time!

Back in Lafayette, Louisiana, there was a guy (never really sure WHO actually owned it) with a fishing tackle box chock full of calibrated parts. It was the honor system, but he'd give you "the box" and you could use whaterver you needed, then replace the parts you kept. During the mid80s, the contents were estimated at $3000.00.

One of the most important things I did, was I ordered my 45 DCOEs with 36mm main chokes (most Healeys are running 38s) to maintain a higher velocity through the venturi. At the time I initially set these up (1985) I was running time-trials with the car, and I was aiming for immediate throttle response, versus ultimate top speed.

When I brought the car to Ohio (a mere 600' higher elevation) I practically had to start the process all over again.

Using the calibrated specs from another car with do you little to no good. I think I one time added up that there are sixty-eight (68) variables with three (3) 45 DCOEs.


Senior Member
Country flag
You have to get your Webers set up by someone who knows what they are doing, has a big selection of jet and chokes and a rolling road. I had mine set up by Chris Conoly, Mass Engineering. The car pulls like it's on Su's at low revs and keeps on going to 6000. Seriously, I'd take a trip to the UK and get him to do it for you, it cost me ÂŁ120 plus jets etc., a bargin to have a car that is now such a pleasure to drive.
Country flag
Frankenhealey said:
....but the look SOOOOOOOOOO good and give you much more paddock credibility :cheers:
Teaser pic (not for <span style="text-decoration: underline">YOU</span>, but the OP :wink: ):




For educational purposes...









Darth Vader
Country flag
The Webers are nice and all if you like that sort of thing, :wink: , but I'm taken with the swell job of lacing in the safety cage tube.


Luke Skywalker
Country flag
Ok, Ok......enough of this Weber love. SU's can be just as sexy! Plus, I've always thought you should leave with the girl you brought to the dance. Just old fashion I guess, like my car.......
Country flag
Oh just admit it Dougie, you went with SUs so you'd have more time for driving/racing, instead of all that fun time getting the Webers tuned...

... can't fool me... :wink:


Jedi Warrior
I had three Solexes on my Bristol 400, which is basically a pre war 328 BMW engine. It was a b---y nightmare to jet them correctly and took me about six months of utter misery. Getting the engine out was bad enough and the rebuild had cost me $20,000, so I was anxious not to hole a piston or whatever and have to do it again.

SUs are simple and work extremely well, only at peak revs to the Webers have any advantage, so apart from pose value, they probably don't make a lot of sense on a Healey engine.
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