I don't have a Q-Jet on hand and I really need to know (in general) how tall the damn things are. Need a measurement from the top of the air-horn to the bottom of the baseplate.

I'd be in your debt.

Take care,
Chuck Riddeck

 

Just a smidge more than 1/4" shorter than your average Holley 600-850 CFM 4150 carb. I actually measured this a few months ago when I was fitting a QJet on top of a blower under a really tight hood. I was scraping for every tiny fraction of hood clearance I could.

A Holley with a choke tower will require a much taller air cleaner than a Qjet simply beacuase the choke tower on a Holley is.... tall. If you try to fir the air cleaner lid down too tight on top of a Holley w/choke tower weird fuel metering in the primaries results- the kinda stuff you simply can't tune around. This is almost as important whne dealing with a Holley as the overall height of the carb, in my expereince

Also, note that the MASSIVE secondary throttle plates on a QJet stick down out of the BOTTOM of the carb quite a ways and well off to the sides. So you have to make sure they don't touch anthing down underneath or you could have to space the carb UP with thicker gaskets to gain clearance- negating the QJet's height advantage.

When installing a QJet with a low-profile air cleaner.... the lowest setup I have been able to run successfully is a 14x2.5" filter element in a housing with a common 1.5" drop base. When running something this tight you MUST install the simple external sheet metal "baffle" on the QJet that sticks up like an air dam just behind the QJet's choke tower between the primary and seconday side of the carb. Failure to do so will result in a bog in the primaries that simply can't be tuned out (bad ariflow quality through the primaries). Surprisingly, if you open up the area above the carb just 1/2" (to a 3" element in a 1.5" drop base) there will be no bog and the "baffle" will not be necessary. In other words, that's about as low as you can go.

Shaving off a QJet choke tower..... well, you got me there. Never tried it. I can think of a number of reasons why it SHOULDN'T work like the fact that one of the bowl vents is built into the back of the choke tower airhorn. But I haven't actually tired it, so I can't say for sure.

 

I *THINK* it's around 3.5", maybe a bit more...
The q-jet is taller than an edelbrock/carter carb.
Remember, for most manifolds you'll have to allow space for an adapter. Also, take some time with a grinder and blend that adapter into the manifold some - back around the secondaries where the adapter necks down a bunch...

 

Thanks guys!

That takes care of what I needed to know. Now... I've got to do some fabrication.

Take care,
Chuck Riddeck
Progressive Race Engine Development