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Dellorto Carbs and California Smog Check II

Hello again from San Jose. Thanks for the article on Dellorto carburetors in the September edition of JHPS: yet another boost of inspiration from Greg Fletcher. Maybe I can pull my JH out of hibernation after all?

Here's the deal: The last time I smogged my '74 JH, 1997, it took a full week and plenty of blood, sweat & tears. I had to rebuild the Strombergs (including new jets), change the intake valve timing, change the oil, spark plugs & points, and then add an alcohol-based fuel additive. Only after all the above did the car pass (at the Referee station) - good thing they allowed me to tweak the needle settings, timing & dwell right there. When the 1999 smog cert was required, I decided to leave it in the garage until it becomes exempt in 2003. Alas, it is rather sad to let the car age unused.

In reading through your article, you mention that the Dellorto carbs offer some ability to smooth the JH's idle performance. This is where I had the most trouble passing smog: idle emissions. Do you think the Dellortos might offer some improvement in idle emission performance compared to aged Strombergs? Since I was planning to switch to Dellortos eventually, could there be merit in doing it sooner rather than later? If so, any recommendations?

Taking it a step further, I no longer have the original air intake/ filter box, instead using the K&N air filters. In switching to Dellortos, would I need to reinstate the original air box, or are there alternatives like the K&N?

Finally, any gut feel about the performance differences between a JH with Strombergs and an electronic ignition system versus Dellortos and an electronic ignition system?

Thanks as always,
John Busch
San Jose, California


This smog inspection thing is really becoming a bane to California Jensen owners. I do think the Dellortos would offer some improvement in idle emission performance compared to aged Strombergs. Sadly, aged Strombergs (as far as emissions go) should be replaced with new units for optimal performance (as recommended by the manufacturer). This probably goes for the vacuum retard capsule and the distributor as well. Old, but rebuilt Dellortos on the other hand will be much easier to tune for an emissions test with an old distributor. The only problem is that the Dellortos, which came standard on UK cars are not considered original equipment on Federal cars by the Department of Motor Vehicles. I was able to get my '73 (now, for the time being exempt from Smog Test) to pass three previous smog tests with Dellortos, so it's possible but that's definitely no guarantee you would be successful today.

I also used the stock Dellorto air box which is very similar in appearance to the Federal one. Using aftermarket air filters would almost certainly get you a "fail" based on the crank case ventilation and charcoal canister not being correctly connected.
If a California "Test Only Station" (the DMV considers cars over five years old as "older" and designate many get a test only inspection- something I just needed to do with my '95 Land Rover) pulls out the big book, which is standard procedure- they will know that Strombergs are not present and you'll be busted for aftermarket equipment, they won't care if purified tap water is coming out the exhaust.

If a regular Smog Test is required, my feeling is that you still have an opportunity to get through with Dellortos and that having them as your carburetors would be more helpful, assuming your engine is in reasonable internal condition. Keep in mind Lotus had Dellortos on all their U.S. bound cars during the mid to late 70's but since they came in as "original equipment" it's not an issue. Too bad Jensen didn't do the same thing, as some stupid DMV technicality is what's screwing owners over now in California.
So I'd say it comes down to how the smog inspection would need to be handled, in any event I think you would need the correct factory air box or similar(the Euro box looks almost the same, but differs in cutouts and mounting inside) and charcoal canister (or similar style) equipment to make it appear legitimate.

From a performance and serviceability standpoint, Dellortos are king- you can jet them for economy or performance or a combination of both, port on port carburetion has no equal and it's why so many owners spend so much money to convert their cars.

On a positive note- JHPS member and JH owner Steve Pike of Pike Automotive in Glendale, CA puts a cataylic converter on (when necessary) and gets those JH's though the Smog Test, he has yet to have one fail.




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