1quik6

Was in the process of changing out the intake on a 327/365. When I removed the intake, the ports on #7 & #8 head were plugged solid (soft) with antifreeze that had coagulated. Is this normal or was the old intake gasket leaking by? Why is it that the (underside) intake water jacket by the distributer is plugged but the one at the thermostat is not?

67L36Driver

There is no water jacket cross-over in the intake manifold at the rear of the engine. Each side of the engine block flows coolant independently of the other. Water pump has one inlet (bottom radiator hose) and two outlets on front of block. Passage at front of intake manifold serves to collect coolant from each side of the block to send it back to the radiator.

ctjackster

365 (L76) owner - the correct intake for your engine is the 3844461 aluminum intake, a dual plane intake with a Holley 2818 on top in oem configuration.

you may not have had the correct intake on there (the one you pulled off); suggest you post up the casting number.

1quik6

I had an original 327/365 intake #3844461. That is the same casting # intake I put back on. The old al. intake corroded from the inside right by the temp. sensor (that made #2 intake with the same problem 2 years later). How about the ports on the head?

JohnZ

All heads have coolant passages at both the front and rear (since the same head is used on both sides - no LH/RH difference), but there's no crossover passage at the rear on the intake manifolds - the only coolant crossover is at the front, where the coolant exits through the thermostat housing.

ctjackster

here, swiped this pic from an ebay listing:




(couldn't find a bottom pic handy) You see that the intake runners are easy to see, they run from side to side (actually top to bottom in the pic) along each side of the carb mounting area, and each runner breaks and services two intake ports on each leg (two ports x 2 legs x2 main runners = 8 cylinders). You can also see the thermostat mounting hole on the front of the manifold, on the right in the above pic. That also has its own "runner" associated with it, and it terminates into a water jacket port in the front of both heads (the temp sending unit hole is near the bottom port in the picture). No other place in the intake manifold for collant flow, so not sure what ports were plugged.

I am betting it is the exhaust crossover that was plugged by accumulated crap, THAT runner is dead center and it bisects the manifold top to bottom.

1quik6

ctjackster, The head itself had the plug of coagulated antifreeze. It was the last squared port on the head (both sides) nearest the distributer that were plugged.

MikeM

It's not a problem.

ctjackster

using Brian's (AllCoupedUp's) web site as a resource, you mean the coolant passage shown on the furhtest left side of this picture - the rear of the engine, ringed by orange RTV (this one dead ends into the intake):




I just had my intake off, while those rear dead end coolant passages were not blocked off by "coolant crud" I don't think what you saw would be an issue, aside from telling you the state of things in your cooling system - might want to flush the block, open the block coolant drains below.

1quik6

Thanks for posting the pics. Yes, the one's that had the "coolant crud" were to the furthest left on the pic. Now I'm ready to fire her up & check for leaks. Thanks for the responses to my questions.

ctjackster

having just "been there done that" with that manifold, I urge you to use a strong bead of RTV on the front and rear surfaces as seals (rather than the pieces of gasket that come with the intake manifold kit) - I had a rear seal leak and you don't need that aggravation - and otherwise seal the coolant passages as is shown in Brian's picture. Borrowing yet another pic from Brian, here is what I am talking about, note also that you should run the ends of these beads just to the inside of the valley (this is not shown in the picture, but it was a good suggestion by another member), so it forms a slightly larger plug on the inside once the mani is installed which will help keep the bead from blowing out