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Over the last several years I've had a recurring "vapor lock" problem. After driving, even short distances, and parking the car, It would fail to restart after sitting for more than 20 minutes or so. If it did start it would conk out within a minute or so and not restart.

After replacing virtually the entire fuel system, including a carburetor rebuild and changing the rubber tipped needle and seat for a steel one, I finally isolated the problem to heat buildup in the intake manifold after shutdown.

The manifold and carburetor were getting so hot after the engine was shut off, the fuel was boiling before it could make it to the cylinders. It would even vaporize out of the fuel bowl.

Anyway, I removed the intake manifold with the intention of blocking the exhaust crossover passages that heat up the carburetor to aid in cold starts and cold weather. I live in Atlanta so I'm not worried about that.

The intake manifold gasket is a one piece valley pan type. Unfortunately, no one makes those with the crossover ports blocked. Two piece gaskets are available without the valley pan but I like how neat and clean the valley pan keeps the underside of the intake as you can see in the photos. As you can see, the inside of my engine looks really nice. No coke or crud anywhere. That black goop is melted RTV sealant and its only in the center where the exhaust crossover is.

Mondello makes an aluminum intake manifold without the crossover passage but it costs about $900. $1500 if you want it polished and ported. They also make crossover blocking plates but they can only be used with their proprietary gaskets which, of course, do not have a valley pan. You have to buy a valley pan from them separately.

I decided to take a different approach.

I purchased a tub of refractory cement. It's used for patching cast iron furnaces and sealing firebrick in chimneys, etc. It withstands temperatures of 3000 F and is guaranteed not to stretch, crack, shrink, pull away, etc. Bonds to any surface.

I stuffed the passageway with stainless steel wool to act as "rebar" for the cement. I packed the passageway as much as I could using plastic knives and whatever I could push the cement in with. I think a grout bag would be a good way to do this but I didn't think of it in time.

I let the stuff harden and dry for a couple weeks before assembling the car.

So far it's working perfectly. The car has never failed to start. The carb base is much cooler than it was prior to blocking the passages.

I wire wheeled the mating surfaces.

Why did I paint the manifold black?

A previous owner had already painted the entire engine 1970-1976 Olds metallic blue. The correct slate blue costs about $38 per can from Bill Hirsch. Since there's not enough room to paint the entire engine while its in the car, I didn't see any point buying it. I sure as heck wasn't going to spend that same amount of money on the wrong color blue to match, ether.

The intake manifold can barely ebven be seen anyway with the air cleaner on it so I opted to use an $8 can of Duplicolor gloss black that I already had on hand.

Removing the manifold without removing the distributor was pretty easy but reinstalling it with the dizzy in place would take at least two people. One person would have to carefully lower the manifold while the other maneuvered it under the dizzy overhang without messing up the gaskets.

I was on my own so I pulled the dizzy after witness marking the rotor position and base to block position.

I also removed the oil filler tube to make even more room. A few whacks with a rubber mallet loosens it up pretty good.

Instead of using RTV sealant, I used Permatex spray copper. I coated each side of the gasket and the mating surfaces of the heads. I did use RTV in the corners of the deck where the front and rear rubber seals meat the edge of the heads. This is the recommendation in the shop manual and in the gasket set instructions.

I figured after 50 years, engine sealing technology has probably advanced quite a bit so I felt comfortable using the copper spray instead of messy RTV.

So far, so good.

Almost forgot. Here's the stuff I used to block the exhaust crossover.

Otto,
O'Reilly Auto Parts carries a spray paint line called "VHT" that has the correct engine color for '66 Toronados. It is expensive a $10 per can. I asked about having the engine color mixed using Omni urethane and they quoted $60 per quart or $40 per pint.

Several years back when I built an engine for my 1973 442, I used both the bathtub gasket and the Edelbrock/Mondello intake gasket 7284 in conjunction with Mondello's heat riser blockoff plate without issues. My car was a little cold on startup, but not bad.
Marty, St. Louis

The Mondello guy told me their blockoff plate wouldn't work with any gasket but the one they sell.

I checked O'Reilly along with Advance and Auto Zone but noine had the right color and basically told me if it wasn't on the shelf they didn't have it. Oh well. Black came out fine.

Otto,
The VHT part number is SP403-Titanium Silver Blue
Marty

Thanks. I'll write that in the manual for future reference.

I am no fan of spending a lot of money on paint, feels like a terrible ripoff. I like
Ford Blue for engines, nothing on transmissions. Bruce Roe

1. Now that you've blocked the crossover passage in the intake manifold, you need to assure that the heat-riser valve on the exhaust manifold can never close. If the heat riser valve closes, you'll have an extremely restricted exhaust on one bank, with attendant poor performance.

2. Shoulda painted the top side of the manifold "silver", and then you could tell folks it was aluminum.
I'm not fond of paint on the inside of an engine, paint you don't apply doesn't flake off and fall into the oil.

3. When it was me, I used the bottom part of the "turkey tray" with the port openings cut off; and paper gaskets between manifold and cylinder head. The tray can be cut in such a way that there's little tabs that hook under the head to keep it in place.

4. You did well by NOT using RTV along the port openings, RTV is best when applied to the seam between two gaskets, or between a gasket and a rubber seal--as you did. RTV shouldn't be used ON a gasket, it should be used INSTEAD of a gasket...if you accept that sort of thing.

5. "Mondello Performance" in Paso Robles hasn't been run by a Mondello for years. Lynn is not well-liked on other Olds forums. Joe Mondello's son Bernard sells Olds parts from a different business--Bernard Mondello Racing Enterprises. I don't recommend buying ANYTHING from "Mondello Performance"; it's like buying from Eastwood--many products sourced from other companies, with added markup and poor after-sale service.