three strikes and theyre out! ive had absolutely no luck with the cast iron crossover plugs that came with my 455 edelbrock manifold.we did a nice tight file fit and used a couple hi temp sealing methods around the port with felpro gaskets .after a long awaited spring cruise i can hear it starting to blow by again.at some point in the near future ill remove them and forget about it .there are more permanent fixes for this ,but for me its not worth the aggravation .plugging this crossover might make a difference in hundreths of a second at the track ,but for a street driven weekend warrior (imo)its just not necessary.

 

I almost plugged mine when I did my BBO. Bit so many threads like yours made me decide against it. I was going to use the file fit as well.

 

Sounds like to much back pressure, mufflers to QUIET, pipes not big enough??
Just trying to help.
Johnny

 

W/z manifolds 2.5 exhaust with pypes mufflers .

 

x2

I've actually been lucky with the way I blocked the exhaust crossover though. I used soda cans wrapped around the gasket at the exhaust port. No leaks yet.

 

If there is a metal supply house near you (or a sheet metal fabrication house) try to get a piece of 321 stainless sheet that is 18 or 19 gauge thick. Cut out some rectangular pieces large enough to cover the openings and slip them between the gasket and the head. The heat generated by the exhaust isn't hot enough to melt the stainless and they should last a long time.

 

My machine shop made a set of block off plates from 1/8" thick steel.

Shaped them to a press fit into the cross over ports.

Been in there for 8 years with no issues.

There are thick enough not to burn thru.

 

finally got around to pulling the intake and removing those plugs.embarrassing driving around with that awful clacking. worse part about the job is cleaning off all the old gaskets.i also need a better way to drain the radiator ,you turn your back on that petcock and its either dribbling all over the floor or shooting past the catch pan lol

 

Slip a piece of rubber hose on the end of the petcock. How long ? As long as you need it to drain to your choice of locations.

 

Mondello sells stamped sheet metal that fits into the oval opening on the early head crossover when using fiber intake gaskets. HR-351 is the part number. I would not endorse Mondello for anything, but I bought these and they seem to work pretty well.

 

I shaped a couple blocks of aluminum and had them welded into the intake manifold crossover ports.

 

Thanks for the suggestions I will try a more permanent solution on the 455 I’m building now . Hopefully I won’t have to open this motor up again anytime soon.for a street car I’m plenty happy with it as is

 

for whats its worth i talked to B mondello about these plugs and was told they should be ground down just enough that the plug would be sticking up above the head 1/4 to3/16 of an inch and then pound them flush with a good sized hammer then seal with hi temp silicone. when i did mine all i had to do was lightly tap them flush which is why they ultimately failed .lesson learned