Hot Rods Does a 305 Engine HAVE TO HAVE an EGR ?

I posted previously about my engine ping with my intake manifold that

does not have ​

EGR Valve.

1) Does a 305 require/need one ?

2) If it does require an EGR , will not having one cause engine ping

 

My 305 pinged with or without egr if I lightly tipped the throttle to keep speed up inclines. This is on a stock 1986 305 with a factory leaned out q-jet. I had 14* initial timing to make it peppier. It pinged on 87 or 93 octane with up to 15% ethanol. Switching to 89 octane ethanol free fixed my ping.

Have you tried a combustion chamber cleaning yet? Richen up the afr a little?

 

But no it does not require it unless you are smog tested

 

I remember pulling those damn things off during the early 70’s when they were new. Along with the pumps.

 

EGR inop can cause ping city, the timing is way too advanced at times otherwise is my understanding. I'm sure it can be made to run OK but have to know what you're doing.

 

One way to clean combustion Chambers is to spray H20 (water) down the carb @???? 2500 rpm by using a spray bottle.... It works!
You could see the tan colored gunk coming out of the exhaust...

 

We pulled the EGR and built block off plates on all of the round track 305's we built. No issues.

 

Exactly. After a little timing tweek they ran just fine.

 

From somewhere before 1900 until the mid/late sixties, early seventies all gas engines ran and often ran well without an Exhaust Gas Recirculating system. Now the people who like to breath air without chewing it first will tell you that you must have it. But, if the vehicle is old enough to not be smog controlled the choice is yours.
-Dave

 

It obviously needs a different motor...305s are not hot rod material.



pm sent

 

A 305 Chevy stock comes with one and no the EGR valve is not necessary for the function of the engine and not having one will not make it ping. Not using the proper fuel for the vehicle and notbeing properly tuned will make it ping though.

Here is the rub, anyone can swap a motor, almost anyone can screw an engine together (although some men take it to a whole nuther level), but, you knew that the but was coming right? But tuning is an art, some men are blessed with being able to tune naturally and others learn it, but it is an art all to itself.

 

I never liked the idea of running exhaust back into the intake. What a EGR amounts to is a vacuum leak. But instead of relatively clean air. Its exhaust that is being vacuumed into the air fuel mix. Ive disabled every EGR on anything I ever had that was equipped with one.

 

Blocking off or having an innoperative EGR valve can and will cause pinging.... here is why explained to me at one of the many training classes at Ford.

EGR is misunderstood my most people, they think they are reburning the exhaust to clean it. WRONG. The fuel is already burned so there is nothing left to burn. What they are using the burned exhaust gas for is to take up a little space in the cylinder. If you have a 1 liter cylinder using 14:1 A/F mixture it would require X amount of fuel for proper combustion. A 3/4 liter cylinder would require less fuel but make less power. Go back to the 1 liter cylinder. If you add an inert gas (the exhaust) into the cylinder... say 25%, it would make it use the same amount of fuel as that 3/4 liter cylinder..... but this is only done at a steady state light cruise.... so you get better mileage. Since the timing and carb is calibrated to do this, once you make the EGR inoperable.... at a stead cruise or light acceleration it is lean... hence the ping you created by defeting it. In the long run it increased mileage and reduced emissions because you are burning less fuel with EGR.

Now, on the OP's 305.... you do not have an EGR calibrated carb so it won't have the lean condition at cruise if the carb is calibrated properly, if it still has the distributor that came in it and all of the vacuum valves and such still connected and working, retard the timing a tad bit until the pinging goes away.

 

so you get better mileage? I thought it was so the combustion temp would be lower, and not form so much NOx.

but it's been a long time since I gave a shit about how modern cars work.

 

supposedly. But how does putting hot exhaust in lower temps? And if it doesn't hurt performance, why doesn't NASCAR guys use it on their cars?

 

Actually both. Primary purpose is to reduce NOX, it lowers peak combustion temperatures. Supposed to also increase efficiency, some. Nascar and racing engines don't use it because it isn't necessary and/or another component that might fail.

 

This is true. Years ago a popular hot rodding trick was to add water injection to cure the detonation blues. The military used to use it on piston engine aircraft in WWII in order to extra maximum hp out of the engines without them disintegrating due to detonation. It works by lowering the temperature of the combustion process, which rejects detonation. (similar to what EGR does) One result that was noticed on engines that were torn down later was how clean the combustion chambers were, the water turns to steam and literally steam cleans the carbon deposits away. You can do this, as you said by spraying water into the carb, or use a very light trickle of water from a hose. The danger is that too much water can cause hydraulic lock up of the engine, and that tends to bend connecting rods and do other real bad damage, so the rate has to be very slow. Also, excess moisture can end up in the crankcase and cause problems with the oil. So you have to be careful, but slow application of water can clean up light deposits in the combustion chambers. Hopefully none of those deposits are so large as to get caught between the exhaust valve & seat and cause it to hang open.

 

sure, I can copy and paste from wikipedia. or you could look it up.

"exhaust gas recirculation (EGR) is a nitrogen oxide (NOx) emissions reduction technique used in petrol/gasoline and diesel engines. EGR works by recirculating a portion of an engine's exhaust gas back to the engine cylinders. This dilutes the O2 in the incoming air stream and provides gases inert to combustion to act as absorbents of combustion heat to reduce peak in-cylinder temperatures."

 

Maybe the 305 self-identifies as a 283

 

The "water trick" works but it's best done at a fast idle after a good long summertime highway run. Using a spray bottle helps limit the amount to prevent hydrolock.

 

This is not really accurate. The purpose of EGR is not to improve gas mileage by reducing the amount of fuel consumed, it is to lower the combustion temps in order to reduce the production of nitrogen oxides (NOx). Nitrogen has a high reaction temperature. At elevated combustion temperatures nitrogen in the atmosphere that is consumed by the engine reacts with oxygen to create nitrogen oxide compounds that are then emitted into the atmosphere creating smog. EGR is used to reduce NOx emissions. It might take up space in the combustion chamber, but the purpose is to lower the combustion temps, and thus the amount of NOx produced.

25% would really be an extreme amount of EGR, more common is around 5 - 15%

 

Ooops, Jim beat me to it.

 

Some engines pinged before a EGR was ever thought of. And some never pinged. And every engine that I disabled the EGR on never pinged after I was done with it. Its easy to do if you Know How.

 

Yes, NOX is reduced, I was simply trying to explain why it will ping when blocked without changing the carb or ignition. The class was a 5 day course being taught by one of the engineers that helped develope Ford's system, so I have a feeling he had better insight than most.

 

What's amazing is the engineering contortions they went through in the early 70s to reduce NOX emissions, at the expense of performance and especially, fuel range. Right in the middle of double digit monetary inflation and crude oil embargoes. They lowered compression, buggered with the cam profiles, retarded ignition advance etc etc. And EGR, and a big ass catalyst to burn off all the wasted fuel spewing out the tailpipe. Can't help but think they could have found better ways.

 

And the reason is ...... EGR reduces combustion temps. When you remove it you remove the temperature reducing effect, leading to detonation (ping or knock). As well as a combustion chamber more fully packed with air & fuel, which will produce higher peak pressures. Reducing timing reduces peak pressures & temperatures, reducing the tendency toward detonation. This isn't rocket science, it's long established engine tuning techniques.

 

They did find better ways.... EFI !!

Carburetors just could not meter the fuel as precise as injection. The advent af EFI and computer controlled timing has lead to cleaner more efficient engines. EGR is pretty much a thing of the past on most engines now although variable cam timing is used to cause reversion to introduce exhaust gas instead of a valve. All of that and some of the newer motors make killer HP!! And get 30 mpg....

 

As a parts man that spent several years working at a Ford store I believe you should never underestimate the ability of a Ford engineer to get creative. Regardless of any other side benefit, it's been my understanding since I learning this in the 70's, EGR is mainly used to reduce oxides of nitrogen. Enjoy....,
-Dave

 

The start of this was looking for something on a now obsolete engine to help a guy out...ended up a lesson which was great. He stated he had a lean EGR carb with no EGR. probably the real culperate. Today in 2018 we have high compression engines with great fuel mileage that live because of electronics and we don't want to care about on this site. I'll live with my dual quad Y-Block that gets 10 mpg because I want too. Thanks for the learning experience...

 

In his other thread he said he has an Eddy carb.