[DML] Re: Carbureted PRV

["content22207" <brobertson@xxxxxxxxxxxx>]

You've got Volvo's nomenclature a bit off:
B27 - 2.664 liter displacement PRV, available in A E & F series. Used
1972-1979.
B28 - 2.885 liter displacement PRV, available in A E & F series. Used
1980-1987.
B280 - 2.885 liter displacement *VERY DIFFERENT* PRV. Used 1988-?.
Also imported by Chrysler as the "3 liter" (rounded up for marketing
purposes) engine in its Eagle Premier (not to be confused with AMC's
Eagles, which used an inline 6 cylinder engine).
A series - single barrel Weber carburetor.
E series - high compression fuel injected (Bosch K Jetronic).
F series - low compression fuel injected (Bosch K Jetronic).

I just purchased a new in the crate A series engine. Will upload pics
as soon as I get them developed (35mm -- am a tad old fashioned). Is
*MUCH* easier to work on than E or F series. Note that after 1975, A
series was basically relegated to industrial applications. Renault
continued to carburete its PRV's, but Volvo switched to fuel injection
in production automobiles.

B27 and B28 are essentially the same engine. Only difference is
displacement, and correspondingly larger cylinder heads. The imfamous
"oil passage problem" to camshafts applies to both engines. Plus Volvo
used a weaker oil pump in its PRVs than Renault, exacerbating the problem.

There are slight differences in fuel injection between B27 and B28 --
fuel/air mixture unit is identical, but the lower body is a one piece
casting with integral throttle plates (vs isolated throttle plates
adopted for B28) and the throttle plates have no deceleration valves.
This is identical to Renault Z7 series BTW. I have a spare B27F. Will
photograph it and upload as well (now I know what to shoot the rest of
the roll of film on!).

One major difference between B27 and B28 CIS (Constant Idle Speed) is
the use of an auxiliary air valve vs an idle speed motor. Aux air
valve takes off from the same location under the fuel distributor, but
uses a nipple pressed into the lower mixture body rather than a loose
tube sealed with an O ring -- MUCH less prone to vacuum leaks.

Getting back to your carburetor question: Renault had great success
carbureting the PRV in its Apline sports car (another rear engine
application). Two versions: a dual carburetor setup (a single barrel
linked to a two barrel at full throttle), and a triple carburetor
setup of 2 barrels. Note however that both used high compression
blocks. Would probably be too much carburetion for an F series block.

I know a fellow with a brand new single venturi A series intake
manifold who may sell it if you're interested. Contact me off list:
brobertson(at)carolina.net. Will bolt right up to a DeLo block. You'll
need to plug the old K Jetronic injector ports too.

Bill Robertson
#5939



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