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Old 09-03-2007, 04:09 PM
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Carb selection help

Hi Guys,

My son never takes the easy road, he seems to prefer challenges!
Current case in point . . . he bought an 86 Chevy C-10. It
originally had a six cylinder in it and someone pulled it out and put
a V8 in it. It was supposed to be a 350 but according to the numbers
it's an 1978 305 with a 2bbl carb. (I was working a lot of overtime
when this occurred so I didn't have the opportunity to see/talk him
out of buying this "gem" before he bought it!)

It's always been a booger to start - especially when it's hot.
Poking around on it the other day we found the base of the carb is
evidently warped - if you spray carb cleaner at the base of the carb
the engine revs right up. The carb only has TWO bolts that hold it
down! And there's only two holes for bolts in the carb! Now, in
what automotive engineer's world was this ever OK??? (I'm a little
grumpy at automotive engineers right now . . . just changed the
battery in my Mom's Grand Prix -> who in their right mind thought
molding the windshield washer reservoir around the battery was a good
idea??? GRRR!). We took the carb off and cleaned everything up and
put a new gasket in but it's still got a good leak around the base of
the carb which I imagine is from it only being bolted down in two
places for the last 30 years - the carb base is probably warped.
It's also got this "hot air" choke thing that I haven't investigated
yet, but just looks like a bad idea! (I'm figuring that exhaust cross
over in the manifold is plugged up too)

Digging around I found a factory Chevy aluminum intake that should
work fine on this '78 engine - it's casting #14057053. (I figured if
we're going to muck about with repairing the carb we might as well go
to a Q-jet).

I was over at my mother's house the other day and while poking around
the garage looking for a set of refrigeration gauges I ran across two
quadrajets in the garage. I dunno the story on them, though I suspect one of them is mine from many years ago (my father has passed away so I can't ask him).

One of them is 7043526 which figures out to a 1973 Oldsmobile 350
carb. It has a hot air choke and the fuel inlet comes straight in
rather than coming in from the side. I have no idea on this one as I
can't every recall an Oldsmobile even on the place.

The other is a 7029202 which figures out to a 1969 Chevy 350 - I
suspect it came out of my 'vette as I remember replacing the QJ in it
with a Holley (it was a long time ago!). It's fuel inlet comes in from the side and it uses a divorced choke.

My first question is whether either of these 350 jetted carbs work OK
on the 305? Or should we change the jetting? If so, to what?

My first choice would be to rebuild and use the second carb but I doubt
my son keeps this gem of a truck for long and I really don't want to
let that carb go.

The first carb will require a fuel line to be fabricated but that's
easy enough to do. The aluminum intake we have does not support the
hot air choke but there's a retro-fit kit available to convert it over
to electric choke.

Also, both will obviously need rebuilt. It's been a while, but I've
rebuilt a couple in the past. Looking around I see that Autzone,
Oreilly, and NAPA all have kits that are pretty reasonable - around $15
to $20. Years ago I always got my kits from NAPA and was happy with
them . . . does anyone have any recent experience with carb kits and
which ones are better than others?



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Old 09-03-2007, 04:26 PM
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Have the factory aluminum intake checked for warpness before you install it, these had quote a rep for being warped due to the high heat of the EGR. Do not use standard fel pro gaskets with a aluminum intake, they do not crush and will not seal, they are made for cast iron intakes and the weight crushes them. If the intake is okay ask for intake gaskets for a 1986 monte carlo with a 305, they came stock with these intakes so the gaskets will be the correct ones. Either Q-jet will work fine. Have it boiled out good to be assured all the passages are clean. The 2 barrell intake came with only 2 studs for many many years and it worked because the base wasn`t very large. You can also inspect the carb gasket for cracks. Your cheapest and easiest route would be to remove the base plate off the 2 barrel carb, take it to a machine shop and have it planed to assure flatness, then buy a new carb base gasket and your set to go.
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Old 09-03-2007, 05:44 PM
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Hi Doublevision, thanks for the reply!

I'll check the intake out soon - thanks for the tip! If it's not usable I'm sure a cast iron can be had from the junk yard pretty easily. (the aluminum one is just one I ran across a while back and in one of Dave Vizard's books he said they were available pretty reasonably and were a good performance buy so I picked it up)

I'd forgot about the gasket issue - I ran across that when I put an Edelbrock performer on my '74 C-10 but that's been a couple years ago so it's nice to be reminded.

I did kick around having the original carb base milled but the carb looks like a ball of mud and there's lots of "stuff" that looks like it's been discombooberated so if we're going to spend some time on this I figured we might as well make a full project of it!

Besides, this truck isn't his main transportation - it's for hunting, fishing, etc. so it doesn't matter if it's down for a while so I figured it would be a good learning experience for him . . . pulling a distributor and getting it back in right, getting a manifold off, cleaned up, and back on, getting a carb rebuilt and setup correctly, etc. are all good experiences and a Chevy small block, no matter how geasy and worn out it is, is a good place to start!

Unfortunately I'm not such a good teacher these days . . . years ago when I was younger I was kind of a gear head but for the last 20+ years I've just been busy with other things so I've been away from wrenching on things. I bought an old Chevy C-10 just for a beater truck a few years ago and the boys and I have had some fun working on it - we've replaced the heads, cam (went to an Edelbrock Performer), intake (Edelbrock Performer), distributor (went to a Mallory HEI), exhaust, and radiator. Those things were mostly just to get it up and running though! I'm looking forward to doing a more proper "project" though I dunno what I want yet . . . I've kick around fixing up the C-10, or finding a '70's Camaro, or even a t-bucket . . . decisions, decisions, decisions!

Thanks again for the help, take care,

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