Would I get a little better performance if I take the vacuum line off the EGR valve and plug it? I don't live in a smog county so it doesn't matter...I was just wondering if it will make performance better or if it would hurt anything.

Thanks

 

touchy subject around these parts, but would probably have to adjust your carb mixture.

 

that question came up with my truck, but the question was weither or not the EGR valve was working.

I had dead cylinders on the back of the engine on both sides, and I was told by the head shop to check the EGR valve to make sure it was working.

acording to the head shop, if the EGR valve isn't working, or is pluged, it could raise the temp on the back of the engine by as much as 200 degrees which could lead to burnt valves.

Now, how much truth that statment holds, I don't know, I'm just passing along what I was told.

I did find how ever that the valves wern't burnt, the problem looks as though it was in the block, (so far) (I'm still rebuilding the engine)

Stu

 

Here's my guess:

If I plug it, then the hot exhuast gas will be stuck in that little chamber in the intake manifold, rather than going through the intake and being burned.

I would assume the EGR needs to be running to keep the engine from overheating, but thats just my 2 cents. Wanted to see if I was wrong.

 

I know when I put my engine back together, I'm going to put a new EGR valve on.
I sent the EGR valve plate in with the heads to have it hot tanked to make sure it gets cleaned, I don't want to take any chances, this rebuild is becomming an expensive adventure for me on a truck I'm not sure was worth the money, but I'm already commited now to the project, so I might as well follow through with it.

The guy at the head shop was guessing on the problem being caused by the EGR valve, but it turned out that the problem wasn't burnt valves anyway.

Mine was a combonation of problems from a leaky brake booster to bad distrubitor, to bad rings, on an engine that only had 65,000

I have a Toyota with 225,000 + and it's still going strong, I still don't get this 65 to 70,000 miles and it's wore out idea. (maybe a bad thing to say in a Ford group)

Stuart

 

Those darn spacer plates are a mess. When they first came out they burnt out because they were made of aluminum. And even if your engine has a cast iron replacement, it's probably full of carbon. Mine's gettin kinda rusty. Dont you hate emissions equipment

I'm guessin this engine of yours had seen a hard 70k miles? Or sat forever?

 

"Mine was a combonation of problems from a leaky brake booster to bad distrubitor, to bad rings, on an engine that only had 65,000"

And there's your answer. Brake fluid inhaled into the intake manifold will ruin ANY engine, and probably an aluminum one like the Toyota a lot quicker than it did the Ford.

 

Usually, the vacuum source for the brake booster is the main vacuum port on the rear of the intake manifold. That port gets vacuum from the runners for the two rear cylinders (#4 and #8). Any vacuum leak on that port (such as one caused by a ruptured brake booster diaphragm, or automatic transmission vacuum modulator diaphragm) will lean out the A/F mixture for the two rear cylinders.

Lean A/F mixtures produce more heat during combustion, which can cause various heat-related problems in the engine.

To reduce CO and HC emissions, early (pre-EFI) emissions controls relied on carburetors that were calibrated to deliver an over-lean A/F mixture (too much air, not enough fuel). Unfortunately, another side-effect of the excessive combustion heat produced by over-lean A/F mixtures is increased NOx emissions. When the combustion temperature gets high enough (about 2000F), the combustion starts using the surplus oxygen that was not used to burn fuel to burn the nitrogen in the air.

The purpose of EGR is to prevent excessive NOx emissions caused by running over-lean A/F mixtures. EGR works by diluting the intake charge with an effectively inert gas, which reduces the heat produced by combustion to reduce the formation of NOx.

A side-effect of EGR is that it also mitigates some the other problems caused by over-lean A/F mixtures (such as pinging, reduced performance from excessively retarded ignition timing to compensate for the over-lean A/F mixture, overheating, etc.).

Disabling or removing EGR, without making any other changes, will cause you to have heat-related problems associated with over-lean A/F mixtures (as well as produce high NOx emissions). At a minimum, you need to re-calibrate the carburetor to deliver the proper A/F mixture for an engine without EGR. You may also have to adjust the ignition timing (both base and advance curve) to prevent pinging.

As for longevity, I've seen plenty of M-block (351M/400) engines go over 200K miles without any major problems. My stockish 351M now has almost 190K miles, and I flog it mercilessly, but keep it reasonably well maintained.

An engine that goes bad after only 60-70K miles has either manufacturing defects or poor maintenance/abuse. From what you've said about your F250 with a leaky brake booster and bad distributor, I would suspect the latter.