Ive seen it mentioned where its something to block off when doing an intake manifold gasket, IIRC, as it helps to prevent excess heat to the manifold and reduce chances of percolating fuel in the carb. What are the steps to block this off, and where exactly is it located? Im getting ready to do my intake gasket over and if it applies to me, I'd like to block this thing off while im doing this.

roe

Get a gasket with the crossover blocked, Felpro 1215 for BB. Need elec choke if it's cold.

the function of the cross over is to heat the floor of intake for better atomazation/vaporizing of the airfuel mixture to increase cold weather drivabilty.

yes,it will help with fuel perking in the carb, but it can also make it run ruff/rich while cold untill it gets up to operating temps.

it also does what the old H-pipes in the exhaust did. even out the exhast pulse between the cys and helps with scavaging of the exhaust ports. (this is why the sound of the exhast system will change when you block them giving a deeper more divided sound of the cyls at duel pipe ends.) check that out when you block them, listen close before and after.

IIRC i used the metal shell of a radio

I cut 2 oval shaped pieces and trimed to cover the hole in the head with out covering the 1/2 moon shaped hole you see when intake is inplace.

you do not want them too thick,the intake bolts will keep working loose around the center of intake. but not so thin it will burn thru over time.

i just used copper rtv to glue them to the head and placed the fel-pro 1213 gaskets with the cross over blocked on top of the blockoffs.

the gasket alone will burn thru in short order every time.

MP used to sell a kit with SS plates,I still have them,to me they seem a little thick, bolts kept coming loose,I would have to re-torque the 4 center bolts around the heat cross over every 3-6 months.

IIRC,the radio shell was just the right thickness and ez to trim with metal/tin snips.

when you pull the intake you will see the oval hole and the 1/2 moon shaped hole. just trim them to cover the oval hole.

another trick I did one day R&R the intake was to trim both VC along the edge of intake runners so I could pull the intake without pulling the VC. clearance them just enuff the intake clears the VC lip.

sometimes you have to trim cast alum VC in the same place so they will seal the gasket by not hanging up on the intake runners. same idea for fast R&R of intake.

now is a good time to check/replace the o-ring on dist and check the oil line/ferrel/fitting for the gauge.

Very nice info. I had already picked up a set of Felpro gaskets part# MS90109, which I believe doesnt have the heat crossover blocked. Right at the center point of the gasket, there is an oval and a half moon shaped openings. The oval opening right there with the half moon shaped opening is the one I need to block if Im traking correctly. Right?

Also, one side of the gasket has a ridge built into it. Does this ridge need to face the head surface or the intake surface when I replace the gasket?

roe

I blocked mine off cutting a piece from an aluminum pop can.

If you do this, make sure its mountain dew.

Fish

You might look into a shield to block oil coming up and splashing on the bottom of the intake. That would cut some heat down for you much like this project will.

Mountain Dew cans are made of a special alloy that is patented.

Thanks for the tips. In about a month I will have some free time and will be installing headers, recurved dizzy, blocking the heat crossover, and tuning the carb. I think I'll be very happy with the results.

roe