Exhaust Restrictors in Intake Gaskets

[Its Just Me]

Long story short, I failed to install the exhaust restrictor plates in the new intake gaskets going on my 350. The restrictors that came with the gasket set (felpro) have a 1/2" diameter orifice in them. I'm running an aluminum dual plane intake (Weiand 8004) that has the exhaust crossover passage but does not have the choke heat coil provision. I will be using an electric choke.

I'm not sure what the purpose of the restrictors is as they do not block the exhaust flow, they just slow it down.

Should I be removing the intake for new gaskets and the restrictors or is there no issue to be concerned with?

I'd would much rather do that now vs after the engine is back in the car.

Any advice appreciated.

Thanks

Scott

[lastss]

No reason to be concerned, there are some 60s gm intakes that had a pathway that directed the heat under the float bowl area that were horrible. The newer intakes don't have that issue and leave them open for better street ability. In a rare chance its a problem you could add a insulator between carb and intake rather than re do the intake.

[FASTSS454]

They limit the amount of hot exhaust flow, more flow more heat more hp loss and greater possibility of vapor locking in the hot summer months, I would buy gaskets that completely block off the flow on a nice weather driven car myself.

[stangeba]

I don't recall the size of the gasket hole for the heat crossover on my 71 all stock 4 BBL 350. I did remove the right (passenger side) exhaust restricter that attached to the manifold above the donut, back in the 70's. My 71 used this restricter but older vehicles used a spring / weight "heat riser" valve. These were famous for rusting and sticking. Good times!

Why do I mention the above? If there is no restricter or riser to force exhaust through the intake to keep it warm, this path does not see much flow.

The process of the air/fuel  mixture passing through the intake runners acts like a refrigeration unit, causing the A/F mixture to cool and condense causing it to run rich, even when the engine is up to temp. The oil splashing under the intake (not all engines, like in-line 6 or 4 cyl) helps keep the intake warm also.

My brother in-law has an old video (I will look for) of a in-line 6 cyl with a GLASS intake manifold, turning to frost inside while the engine is running. Very cool. (no pun intended) Here is the info we share with our customers at Stovebolt.

http://www.langdonsstovebolt.com/tech/why-you-need-to-heat-your-intake-manifold/

 

 

(rev to add heat riser picture)

Bruce

[Its Just Me]

Thanks guys.

I'm normally a horsepower guy and that alone would push me to change the gaskets as Big Daddy suggested. But this is a very mild 350 (kind of a putz as I've been calling it) that won't see any track time.

I have headers and 2-1/2" full dual exhaust so I don't think there will be much exhaust flow pushing though the intake, even w/o any restrictors in place. I will let the oil and the minor exhaust flow do its job of heating the intake that Bruce indicates is necessary.  If I feel it gets too warm, I can always get a carb insulator suggested by Bob.

There, I think I credited everyone!

My winter engine project has been fixing some minor internal issues, a lot of oil leaks and throwing a nice coat of paint on. Nearly finished.

Project "Putz" is still on track!

Scott