BJ8-BT7 Tri-carb Conversion?

[62BT7]

Forum Members: Howdy, I'm a new member, an owner of a recently acquired '62 AH 3000 Mk. II. I have a project in mind and have looked online for the answer; also inquired of the local AH club to no avail. Here's the issue: The owner(s?) past at some point installed a later version BJ8 engine (29KR, etc.) into my car. The car runs great on the stock BJ8 carbs, but I'd like to take a run at installing the original tri-carb set up. Yes, I've heard it's a relatively tricky assembly, harder to tune, etc. Call me crazy...but I'd like to give it a go. I have the complete set-up in boxes in the garage (E-bay purchase) and have pored over diagrams and photos of the assembly, linkage, etc. I'm comfortable I can do it mechanically, but the missing link for me is the tri-carb>BJ8 rejetting. I've seen a web post on rejetting a triple BJ7 set up (HD6?) to a BJ8 cam but nothing on a triple HS4 carb set up to a BJ8 block & cam. To throw a bit more on the bonfire: I live in Denver at 5000' altitude. Does anyone have ANY info on the rejetting issue? Any other tips would be greatly appreciated. Many thanks in advance.

 

[Johnny]

Sounds like your already to go here. Why not just install them and worry about the tuning afterwards? If your asking has anyone else done this before I'm sorry I can't help you there.
Good Luck.

 

[bighly]

You might consider sending them off to Joe Cortino or another reputable carb rebuilder. I had good luck rebuilding my twins a few years back. Not hard, just need a clean area, good light and patience. Once on the car tuning them is not that difficult and once set, don't change them. Remember 90% of SU problems are electrical (timing).

If you need assurance about your kit being complete call Bill Bolton. He should have any missing bits. Alternatively get a hold or Roger Moment there in Colorado, he is a very very saavy cat on these cars. Rumor is Roger accepts bribes.

 

[nevets]

I agree with the others. Do the install and mess with the fiddly stuff afterwards, that’s assuming they are in good working order. Just food for thought…there is a reason why BMC switched back to a dual carb setup, but reason probably doesn't figure into the equation. Whatever your plans you will find a wealth of knowledge on this forum and many helpful people. Best of luck with your Healey.

 

[healeynut]

Actually the reason was entirely logical - Healey got feedback that the tri-carb set up was to difficult to maintain....

 

[jstmorris]

Hello; You may wish to check out the following article "Austin Healey 3000 Tri-Carb Setup & Camshafts" in the Technical Menu of the AHC of UK web site: https://www.austinhealeyclub.co.uk/ under the heading "Triple HD6"
--Scott Morris

 

[62BT7]

Scott: Thanks very much. I've seen this article before a few months ago, it's part of my growing conversion library. Although I suspect there's probably a near perfect jet for the conversion I plan, there's obviously little chance anyone would have the exact same set of variables as my situation (altitude, slightly modified distributor curve, a future aluminum head install, etc) Still, it was worth asking if anyone had jetting info on the basic tricarb>BJ8 conversion. The article you've attached just reinforces that the stock MK II jet/spring set-up probably will be OK (e.g. in the article it was the best with a BJ8 cam and 3 HD6's) and it'll probably fire up with the 3 HS4's I'll use. Finding that elusive best jet combo will no doubt be like finding a needle in a haystack...ha! Couldn't resist! Thanks again.

 

[GregW]

I haven’t paid for the full version of this program, but WinSU seems pretty cool. It doesn’t cover my Mikuni carbs but it may help with what you want. You can download a trial version to see how it works before you take the plunge.