exhaust crossover

[ironman_gq]

whats the best way to block the exhaust crossover on a stock manifold. they dont seem to sell a stock style gasket with the blockoff built in like they do for chevy's

[jeepsr4ever]

I use a racing intake gasket (these block the EC) and then cut the valleypan to fit. Otherwise you would need to fabricate something or weld your manifold.

[ironman_gq]

will i lose any driveability by blocking the ec

[Goose]

Well It will show up on very cold days.. Mine has some Carb icing problems on very cold days.

[1980_Cj7]

What is the benefit to blocking it, keeping the fuel cooler???

[Goose]

Pretty much, if you block the crossover the manifold will stay cooler under the carb.. this will help with vapor lock and or keep the intake chafrge cooler.. on a race rig this will net a denser air fuel chqarge

[AMX69PHATTY]

Can also cut piece to fit over the passage out of thin gauge sheetmetal.
I used a piece of galvanized dryer duct :shock:
Siliconed it in place on top of the valley pan gasket.
Size cut fit inbetween the 2 seal beads on the valley pan.
A "fancy" way is to have a shop pour melted aluminum into the crossover passages.
Then on both ends of the passage grind flush.
This equalizes all the exhaust port volumes.
I had this done to my '70 304 Heads when they were ported.
It was done by Bischoff Engine Service in Indiana.
BES won the PHR Engine Dyno Competetion last year with a Ford.
=D>
http://www.besracing.com/

[tomcat]

Will it has also some effect if you use a EFI manifold?

Also in cold weather?

[Goose]

Well not if its port injected.. as there shouldn't be any liquid to freeze. (Of course this is just a surmise on my part.. I dont have one) :sa:

[tomcat]

Ok, was thinking the same cause of the dry runners.

[Goose]

Of course the optimum arrangement (For other than Daily drivers) would be to pull intake air from outside (hood scoop or ducting) and block the crossover.