Author Topic: Blocking Off Exhaust Crossover  (Read 7420 times)

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440sixpack

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Blocking Off Exhaust Crossover
« on: December 14, 2018, 12:43:16 AM »
On Mopars you can get a block off intake pan.  is there any reason on an FE I can't make metal block off plates for the crossover ?


My main concern would be will the heat destroy the fiber gasket around it ?   if so is there another way.

Drew Pojedinec

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Re: Blocking Off Exhaust Crossover
« Reply #1 on: December 14, 2018, 02:09:13 AM »
I cut a piece of sheet metal, tap it in, and smear some epoxy over it to hold it in place.

Lotta different ways to skin this cat

cjshaker

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Re: Blocking Off Exhaust Crossover
« Reply #2 on: December 14, 2018, 08:14:22 AM »
Lots of guys just use a butter knife, cut and trimmed to fit the area. I've done this also. Works good because they're about the perfect size, and stainless.
Doug Smith


'69 R-code Mach 1, 427 MR, 2x4, Jerico, 4.30 Locker
'70 F-350 390
'55 Ford Customline 2dr
'37 Ford Coupe

440sixpack

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Re: Blocking Off Exhaust Crossover
« Reply #3 on: December 14, 2018, 10:00:55 AM »
I was thinking more of a metal piece that fits the hole in the intake gasket.  if you just plug the hole in the head wouldn't there be a chance of it coming lose and falling down behind a valve ?

jayb

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Re: Blocking Off Exhaust Crossover
« Reply #4 on: December 14, 2018, 10:02:46 AM »
I've done exactly what you suggest countless times, usually 18 gauge or thicker sheet metal.  Just size it to fit the gasket opening, and use some silicone to hold it in place when you install the intake.  Works great.
Jay Brown
- 1969 Mach 1, Drag Week 2005 Winner NA/BB, 511" FE (10.60s @ 129); Drag Week 2007 Runner-Up PA/BB, 490" Supercharged FE (9.35 @ 151)
- 1964 Ford Galaxie, Drag Week 2009 Winner Modified NA (9.50s @ 143), 585" SOHC
- 1969 Shelby Clone, Drag Week 2015 Winner Modified NA (Average 8.98 @ 149), 585" SOHC

   

Barry_R

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Re: Blocking Off Exhaust Crossover
« Reply #5 on: December 14, 2018, 10:53:42 AM »
Yep x3
silicone and a chunk of butter knife, dulled off razor blade, or a piece of hobby shop brass

BigBlueIron

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Re: Blocking Off Exhaust Crossover
« Reply #6 on: December 14, 2018, 11:30:17 AM »
Recently on a Streetmaster I cut a chunk of scrap aluminum to kind of fit/fill the hole then welded it in. Dressed with a grinder. looks like it was made that way.

The reason I choose to do this is it just makes more sense to me, I didn't want to fiddle with a little piece of metal just the right size and have one more thing that might slip or move on manifold installation. I actually started to fit a piece and thought why don't I just weld the damn thing closed! I know that will be fool proof. Which is important because I'm the fool.

Falcon67

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Re: Blocking Off Exhaust Crossover
« Reply #7 on: December 14, 2018, 11:32:27 AM »
I use pieces of .015 stainless shim stock.  Allways block crossover down here on any "hot rod" motor, even with a cast iron intake. 

440sixpack

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Re: Blocking Off Exhaust Crossover
« Reply #8 on: December 14, 2018, 11:53:49 AM »
 Thanks I fab something up.  I just didn't want one of those " what were you thinking " moments to come back on me.

chris401

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Re: Blocking Off Exhaust Crossover
« Reply #9 on: December 14, 2018, 12:01:07 PM »
Has anyone here ever compared temperature before and after a plate of metal? Although exhaust is not swishing directly through the cross over heat does transfer through the metal plate. I have been threatening my self with testing for years but haven't yet.

cjshaker

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Re: Blocking Off Exhaust Crossover
« Reply #10 on: December 14, 2018, 12:48:52 PM »
Never did a temperature test, but if you look at factory cast iron manifolds, the paint is always burned off at the exhaust crossover. Then there's the reason for the valley pan in the first place, to keep oil from coking and baking onto the bottom side of the intake due to the crossover. You don't get any of that when the crossover is blocked. There's no doubt that it helps.
Doug Smith


'69 R-code Mach 1, 427 MR, 2x4, Jerico, 4.30 Locker
'70 F-350 390
'55 Ford Customline 2dr
'37 Ford Coupe

440sixpack

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Re: Blocking Off Exhaust Crossover
« Reply #11 on: December 14, 2018, 01:07:54 PM »
If you block the crossover do you still use the vally pan then ?   I guess it wouldn't hurt anything.

cjshaker

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Re: Blocking Off Exhaust Crossover
« Reply #12 on: December 14, 2018, 02:06:55 PM »
Guys differ in opinions, but I always try to use the pan. It does help keep oil from being thrown on the bottom side of the intake, which has to help keep the temp down, at least somewhat. Some intakes just don't work well with the pan though, so it depends on that also.
Doug Smith


'69 R-code Mach 1, 427 MR, 2x4, Jerico, 4.30 Locker
'70 F-350 390
'55 Ford Customline 2dr
'37 Ford Coupe

thatdarncat

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Re: Blocking Off Exhaust Crossover
« Reply #13 on: December 14, 2018, 02:11:34 PM »
Has anyone here ever compared temperature before and after a plate of metal? Although exhaust is not swishing directly through the cross over heat does transfer through the metal plate. I have been threatening my self with testing for years but haven't yet.

I haven't done a temp test either, but along with the keeping the heat from running through the manifold, exhaust gases are very corrosive, that's why so many of the factory aluminum manifolds rotted out through the exhaust crossover. Blocking the cross over will help keep your new or collectable aluminum intake from deteriorating.
Kevin Rolph

1967 Cougar Drag Car ( under constuction )
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1966 Country Squire 390
1966 Cyclone GT 390
1968 Torino GT 390
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440sixpack

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Re: Blocking Off Exhaust Crossover
« Reply #14 on: December 15, 2018, 12:24:34 AM »
I just have a cast S code intake but with an electric choke I see no advantage to heat in the intake.