[65sport]

I just obtained a nice RAIV intake manifold but it does not have the cast iron cross-over.

I considered slapping some metal over the holes and bolting them down. But I've driven a V8 with no heat cross-over, and it was very cold natured even in Arizona.

My Q-jet has an electric choke so that's not a problem.

It appears I can obtain an electric EFE grid for the Q-jet for $99. I was wondering if they cut down on performance.

Re-pro iron cross-overs are $139, and they sell "cross-over shields" and they are $99. Are the shields needed ?

I can get a 12 V oil pan heating pad surprisingly cheap. Has anyone done that?

I have RA exhaust manifolds, I see they have hot air stoves available.

Thoughts?

[Joe's Garage]

You don't really need to run the heat shields, but they WILL make a difference in how hot the intake gets during the summer. Without them, you could experience some fuel percolation.

We usually run the crossover without shields and then run a heat shield under the carburetor. That way the intake itself warms up quickly but the heat isn't too much for the fuel in the carburetor.

Good luck!

[Cliff R]

You can run without the exhaust crossover just be aware that with a cold intake it will not be fully up to par until the intake fully heat soaks. Since you have an electric choke it will make things a LOT better as far as cold starts and warm-up with the fast idle feature.

Heat is both your friend and your enemy with these things. Heating the intake improves efficiency but at the same time heat soaking the carb in some scenarios can lead to boiling the fuel inside the bowl and the negatives that come with it. Personally I prefer to leave them open for most applications, especially if the car is in a Northern climate and/or will be driven in cool/cold weather.

Lots of opinions on this topic and I get butt-loads of calls to the shop from folks having issues if/when the well meaning engine builder blocked them off thinking there is a performance gain of some sort running a cold intake on a wet flow system. The only time that could/would be true is if you are drag racing, running a cold intake, and flooding the engine with fuel on a hard run. The problem with that deal is that it can work pretty well in early rounds when you have a LOT of time to cool things down. If you make it to later rounds and they start "hot-lapping" you back to staging and trying to finish up for the night it becomes difficult, if not near impossible to duplicate the cooler engine situation from your last pass.

I run my engine fully warmed up and well heat soaked at the track, and even sit there at idle to keep things warm waiting for my opponent to put away the dry ice and bug sprayers plus all his friends to push the car in the staging lanes to get him ready to make the call. I may give up a couple of hundreds of a second on the next run but for sure it's a lot easier to be consistent in the last few runs when they are only minutes apart........FWIW.......Cliff

[Formulajones]

I run the repo cross over. Works fine. I don't have the heat shields on it because at the time I ordered the shields were on back order with no ETA so I just skipped it. Never did get back to putting them on and that was maybe 4 years ago.

I daily drive the car and race it. The setup works really nice in the AZ heat, and the cold up here at 5,000 feet for that matter. It's doing exactly what I hoped/wanted to accomplish, and that's keeping the divorce choke functional while at the same time keeping some or as much heat as possible out of the intake itself since they are 2 separate pieces.

[jerry455]

I had a 1986 Grand Prix with a home version of a ZZ3 350 crate engine. They used the aluminum late 80's Corvette heads that had no heat cross over. I used an engine block heater that goes into a water core plug. They used to be a GM option for cold climates. It warmed the coolant and then the block to around 120*. It worked great for me in the Metro Detroit area. I daily drove that car from 2000 until 2009 and plugged it in when I could at home over night. They are easy to install and have been around for a long time. I was a GM accessory part but a lot of places sold them. They were very popular in the northern states.

[NeighborsComplaint]

with an electric choke, the heat crossover is not needed. You should be taking it easy until your waiter and oil temps are in the normal operating range anyway.

[FrankieT/A]

Blocking off the heat cross over changes the sound of your exhaust.

What I could never understand was the '72 crossover fits 65-72 but the '71 doesn't really fit the '72 well. If they would have cast the '72 version it fit everything.

[Formulabruce]

Originally Posted by jerry455

I had a 1986 Grand Prix with a home version of a ZZ3 350 crate engine. They used the aluminum late 80's Corvette heads that had no heat cross over. I used an engine block heater that goes into a water core plug. They used to be a GM option for cold climates. It warmed the coolant and then the block to around 120*. It worked great for me in the Metro Detroit area. I daily drove that car from 2000 until 2009 and plugged it in when I could at home over night. They are easy to install and have been around for a long time. I was a GM accessory part but a lot of places sold them. They were very popular in the northern states.

RPO K05. Buddy has a '74 Firebird that came with one as ordered. My 2500 HD has one factory.
RPO K05 isn't over with!! Great post.