[DeTomaso] Holley 4010 Good or Bad?

[Daniel C Jones]

> I was given a Holley 4010 carb by a coworker. He claims it worked good on a
> built up 350 Vega. It is a square bore and specks out to be 650 cfm's. I've
> searched the web and the archives with mixed reviews. Anybody have any
> experience with these carbs?

I've not used one myself but they are basically an updated version of the
Autolite 4100 carb, supposedly designed by the guy who originally designed
the 4100.  The 4010 (squarebore) and 4011 (spreadbore) series of Holley carbs
were introduced primarily to combat the popularity of the Carter and Edelbrock
AFB's.  The 4150/4160 modular construction has several gaskets that are below
fuel level and are prone to leak.  AFB's, on the other hand, have a single
piece aluminum main body casting with a top plate.  Since there are no gaskets
below fuel level, they don't have the tendency to leak that 4150's and 4160's
have.  In response to this criticism, Holley introduced the 4010 and 4011
series of carbs which use a less likely to leak 2 piece main body.  In most
respects, 4010's and 4011's are more like Autolite 4100's than AFB's and
employ the standard Holley metering scheme (fixed jets with power valve
enrichment, non-air valve secondaries) but have annular boosters like the
4100.  I believe all the 4010 and 4011 Holley came from the factory with
power valve blow-out protection.  Holley dropped the design but 4010's were
available in 600 and 750 CFM ratings, while 4011's came in 650 and 800 CFM
ratings.  Both versions use standard 4150/4160 tuning parts (jets, diaphragm
springs, accelerator pump cams, and power valves).  There is some anecdotal
evidence that 4010/4011 series are prone to vacuum leaks at the carb base
when mounted on some aftermarket manifolds which have thinner than stock
mounting flanges.  I've also heard of problems with sinking floats though
Holley has nitrophyl replacement floats for that. Mike Ulrich has a book out
on Holley 2010, 4010 and 4011 carbs.

Dan Jones