I'm in the process of putting a pair of rebuilt heads, an Edelbrock Performer 400 intake and Edlebrock 600 carb on my 78 Bronco. The Fel-Pro intake gaskets I got from Summit do not have a hole cut out for the exhaust crossover. Will I have any problem with the passage blocked off? Is there a benefit blocking off the passage? Will exhaust heat eventually melt through the gasket over time? Thanks for any advice.

 

It depends on the intake manifold you have. If there is a provision for egr you should probably trim the gasket, if not you can cover the port in the head with a small piece of thin stainless.

 

Cut that hole open or you are going to come back to this forum posting; rough running, hesitation, plug fouling, and throttle sticking(carb icing).

 

[font size="1" color="#FF0000"]LAST EDITED ON 02-Sep-01 AT 09:05 AM (EST)[/font][p]OK - which of the last two posts is true? The engine had no EGR, but the intake apparently has provision for it at least to the point where it passes it through. I thought that the idea with an intake is 'cooler is better'. Why would they block this off on the gasket if it is a bad idea? I really don't savor the idea of pulling that intake off, cleaning it up again (2-4 hours), ordering a new gasket set, etc if I don't have to. My engine is a 1972 351 CJ (4V), the gasket a Felpro 1228 and the intake an Edelbrock Performer (2665) BTW. Thanks...

Tom

 

[font size="1" color="#FF0000"]LAST EDITED ON 02-Sep-01 AT 02:35 PM (EST)[/font][p]If you live in a warm climate, or only drive in the summertime, you could get by probably with blocking it off, but you will probably still have to wait a while longer for the engine to warm up. Every combination is different. If you use your engine in cooler weather or wintertime, blocking off the passage is a bad idea. It just won't run right. The engine can't burn liquid fuel. The fuel has to be atomized, sort of like a spray gun. The fuel mist comes down from the carb and will hit the "hot spot" created by the exhaust passage. This will keep the fuel atomized. If the hot spot doesn't exist, part of the fuel can hit the cooler metal on the manifold and turn back into a liquid. It will then roll around in the manifold and go into one of the cylinders causing it to run rich. Since it fell out of the air fuel mixture, some of the other cylinders will run lean. This whole process is aggravated by the cooling effect of the atomization process. Have you ever sprayed an aresol can for a long period of time and noticed the can got cold? This also happens in the carb and is how it can get so cold, frost can build up on the carb butterflies, causing them to stick. Another rule of thumb is, always question why the factory put something on an engine before you do away with it.

This is also why fuel injected cars run so much smoother. They only have air in their intake manifolds, no fuel to drop out. And the injectors spray an atomized fuel spray right behind the intake valves, creating a good combustable mixture.

 

HI
i just put a edelbrock performer400 on my 351m and a holley4bbl
where is this hole were talking about???What is carb icing???
I'm wondering i i should pull my intake??My 78 is a non catylyst
motor...But has a pcv....

 

It's the smaller holes on each side, in the center of the intake manifold with corresponding holes in the heads that are connected to the exhaust ports. The smaller sized bolts in the center of the intake are on either side of this hole.

 

Well - I got lucky. I pulled off the intake without ruining the gasket - cut the hole and then reassembled. I have not fired it up yet but since I am in a colder climate, I'm glad I did it. Thanks!


Tom

 

[ENDQUOTE]

If you used the factory type all metal gasket with the integral valley pan - then you are OK. It has the cutout. If on the other hand, you used the Felpro composite gasket then it probably did not have the cutout.

Tom

 

I have a 400 with a vacuum leak at the back of the intake manifold. Which gasket brand is the best to use to reseal it? Maybe this question is too subjective but for all the work I'd like to use the best. Also I've read about RTV in the head/block corners...any other tricks to make sure it seals this time and lasts a while?

Thanks in advance,

Chad

 

I have had the best luck by not using the end seals at all. Clean up the surfaces and put a 1/4 or so thick bead of silicon sealer all the way across the block.

 

The end seals wont give you a vacuum leak, only an oil leak if not done properly. My repair manual suggests some silicone at each corner, which i did. If you have a look at the gaps, you can see that using the cork end gaskets there is going to be gaps and this will cause oil leaks. Also, if your heads have been milled, the cork gaskets could hold the intake too high and THAT could cause vacuum leaks.

The intake I use (Australian brand, single plane, 351C) doesnt have the exhaust crossover and I must say that I have never seen my carb get cold; it is usually quite hot to touch, actually. If you completely block off the exhaust crossover runner in the heads, and smooth that exhaust port, would it help performance?

 

My brother lives in Australia, and he says you have a rainy season(winter) where it might get to 40 degrees, and a dry season(summer) where it gets fairly hot. You probably wouldn't have too much trouble with carb icing in those conditions. Can you pretty much start it up and take off, or do you have to let it warm up a little? He has since moved up the coast a little where it is warm all year round.

 

I blocked off that heat cross over path on my new engine and I've come to regret it. This winter when it got pretty cold I had troubles warming up. It's fine when the outside temp is 32 or better.

Ber Tracks

 

Well, to tell the truth, I do need to warm my car up for like 10 minutes before it will run smoothly, but as it's only a weekend cruiseit doesn't really cause a problem. I could understand if someone needed to use their truck to get to work every day and didnt want to have to wait around for 10 minutes or more.

I originally had no thermostat in the car, and during winter it wouldnt go over the blue (ie 'cold') bit of the temp guage unless stuck in traffic. Fittted a new thermostat and now it sits at halfway all the time (goes up a little in traffic but not much)