View single post by Esprit2
 Posted: 03-12-2023 06:47 am
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Esprit2

 

Joined: 05-01-2005
Location: Minneapolis, Minnesota USA
Posts: 575
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JH12947 wrote:
No. I pulled the tags had a closer look.
> They are quite definitely R5325 and R5326. No A or P.
> Perhaps "R"econditioned?

R means "re-configured". Dellorto had previously built the carbs to a similar but different spec, and put them into inventory. Later, a need for a very similar, but different carb came along; so rather than build from scratch, they pulled the carbs out of inventory and re-configured them to the new, required spec.

A = Anterior = Front
P = Posterior = Rear
That has to do with how the throttle linkage and couplers are installed on the carb bodies & throttle shafts, as well as other accessory parts. A two-carb set always has one 'A' carb, and one 'P' carb. This is the first Dellorto tag on which I've not seen either an A or a P. An R, when added, is normally in addition to the pre-existing A or P.

> In any case, they are spec'd exactly like the
> Talbot 2.2 so it's a good assumption.

Is your engine a basically stock 907... ie, 2.0 Litres? The 911 is a 2.2 Litre, and carbs jetted properly for a 911 will probably be too rich for a smaller, 2.0 Litre 907.

> Jets seem ok except the pump and idle circuit.

The Idle Circuit feeds the engine up to 3200 rpm, then it transitions to the Main circuit. So, if the Idle Circuit isn't right, then much (almost half) of the power band isn't right.

> Engine will idle fine with the mixture screws
> completely seated and backing them out has little impact.

That's not good. The Idle Mixture Screws should end up about 3 1/2 to 3 3/4 turns out. Less than that (and fully seated IS LESS than that) indicates the Idle Circuit is too rich, and you're trying to compensate by adjusting the Idle Mixture Screws too lean.

Regards,
Tim Engel

Last edited on 03-12-2023 08:02 am by Esprit2