QIK59

I am selling a very nice 1969 L36 390 HP 427 intake manifold.

This is an original aluminum low-rise Quadrajet carb intake off a 1969 390 hp 427 Corvette.

All the threads are in good shape with no heli-coils apparent.

Includes an NOS choke thermostat as shown in the photo's.

Selling for $500 firm plus shipping.

larrya764

I'm guessing after 2 years and 3 months you've found a home for this manifold, but I just wanted to check. I have a vacuum leak on mine at the EGR crossover. Thanks!

GOSFAST

You can do quite a bit of "fixin" on an aluminum intake before you get up to $500.00?? We fix these all the time!

Be a different story if you didn't have one!!

Thanks, Gary in N.Y.

P.S. Repairs on cast iron would also be a different story!

larrya764

I e-mailed a guy in Maryland that works on aluminum. He told me I should just buy a used one when I mentioned wanting to get it built up and milled down to spec. I would prefer to keep my original manifold, but he seemed to allude to it being VERY expensive (More than $600). Do you have a shop, or a website I can check out? I would DEFINITELY be more interested in having it repaired, rather than swapping it out FOR SURE! Thanks!

restoman1

Larry, the 3947801 doesn't have an "EGR crossover". Are you instead referring to the "hot-slot" channel at the front of the carburetor pad? (see lower left picture below).

On cars with the "hot-slot" channel, the holes at the ends of the channel are cast/drilled into the crossover passage that goes below the manifold plenum floor. The original idea was to get hot exhaust gases to the carburetor base plate right away to prevent carburetor icing, which is why these cars also use a stainless steel baffle between the carburetor base plate and the carburetor gasket. To protect the aluminum carburetor base plate from direct exposure to the hot gases. This design resulted in a number of damaged carburetors and carburetor fires (and a huge safety recall), and was abandoned after 1969.

Plugging the holes at the ends of the "hot-slot" prevents overheating and damaging the carburetor, but it leaves the crossover passage functional. This is important for proper function of the remote choke thermostat coil mounted in the well in the intake manifold on the passenger side. If that well doesn't get hot from the gases going through the crossover passage, the choke won't fully open.

In most cases, the best compromise is to plug the "hot-slot" holes (to protect the carburetor), and either remove the flapper valve in the heat riser or just wire it in the fully open position. That will still allow some exhaust gases to heat the choke well so the remote choke thermostat works.

In my case, since I live in Southern California and it RARELY gets cold, I tapped and plugged the two holes in the hot slot (middle picture below). You can also just plug them with small freeze plugs (right picture below). I kept the heat riser to make it appear original, but I removed the metal "flapper" plate inside. HERE'S how to do that (see my reply in post #5).

If you live in a warm area of the country, the extra few minutes it takes the engine to warm up isn't a big deal. If you live in a COLD area of the country, you'll see a 10 to 15 minute difference in how long it takes for the engine to warm up. In my opinion, it's still WELL worth it to plug the holes.

Ed

GOSFAST

If you don't need the heat-crossover (or the passageway in front of the carb) just use a set of "LPG" intake gaskets, closes it all off.

I have worked with and repaired a couple of these in the past!

Thanks, Gary in N.Y.

P.S. Hi Larry, not sure how anyone (myself included) can give you a "fixed" price without having the part in front of you on the bench! If you want me to take a look at it just get back to me and we'll arrange for you to ship it here! Worst case scenario will be a little frgt charge back and forth, will cost nothing to just check it out!

QIK59

You're just complicating the dung out of the "problem"

Tap the the exhaust holes and install 1/4" pipe plugs and then fill or build up the crossover slot with a good epoxy and file it level.

Don't know your skills level but this is something an old skool CAR GUY would be capable of ; my observation is that most (95%) Corvette owners aren't (old skool) car guys

If they're unable they send it out to someone and pay up the "ying yang" LOL.

larrya764

Thanks guys!

I'll install the plugs. I don't ever take the car out on days where the carb could potentially ice anyway. Although with as hot at the 427 runs, those might be the best days to do so.

I do need the crossover open, because that choke really DOES warm things up faster. I want to make sure it's open when it's done.

Thank you again for all your help!

larrya764

Old skool car guys? 27563481

Wait.... strike that.... reverse it!

QIK59

This is good

Make sure you get the recessed hex or square socket pipe plugs - that might take some doing !

Then tap carefully - don't go to deep / too far with the tap and keep trying each plug to see how much (more) to keep tapping.

Also find some thicker and softer carb gaskets - maybe Mr Gasket 56C or 4256G to help seal any eroded or problem area's

I don't believe you will EVER run into an icing problem unless you go for a long steady state highway drive in the middle of winter.

I don't run a choke at all on my car and have the bottom of the intake coated with zirconium oxide (the mat'l that the space shuttle tiles were made of) for intake mixture heat insulation purposes.

My heat crossover is blocked and no heat riser valve

When I start the car I reach under the air cleaner and set the throttle on "low - fast idle" and let it warm up for 10 -15 minutes to warm up the oil and for the pistons to expand (reduce piston slap) - no stumble , no icing