Removing emissions on 80s sbc?

[JoeliusZ28]

Posting a new thread in hopes i get more visibility here than my project thread.

Basically I've got an 80s 305 im trying to get tuned properly. Its always idled like crap (shaky, exhaust sound is "huffy puffy"), and this past weekend the EGR valve failed. As an emergency fix, I blocked it off but it seems this wasnt a good solution since it is spark knocking under load now. Looks like my options are to replace the EGR valve or keep it blocked off and re-configure the vacuum advance in the distributor. Engine seems to run very smooth at RPM / under load, good vacuum etc. Im assuming there is a vacuum leak hidden somewhere thats affecting the idle, or *possibly* a dead cylinder.

I guess what I'm looking for is opinions on this. Is deleting EGR a beneficial move or not and worth recalibrating the carb/distributor? I'm reading it does a lot of good things but my highest priority is to make this thing run (idle) *correctly*. The idle isnt bad, but every other 350 ive owned idled smooth as a top, and so does a buddies 305 K5 that is all stock also. The idle could very well be nothing to do with emissions controls, but I'm trying to eliminate variables. I'm picking up a new EGR valve this afternoon to try that as a solution for now.

I'm also looking at putting headers on it, but there is some kind of heat riser built into the passenger exhaust manifold that i believe dictates the engagement of the electric choke. Am I going to lose the functionality of the choke if i remove that? Or am I not understanding this system correctly?

Any advice appreciated

[MP81]

Doesn't the heat riser just heat the air coming into the engine some, which in turns open the choke quicker? If I'm thinking correctly, it should be a thermal spring choke (or whatever the correct name is), based on the engine heat/air temp. It expands and uncoils, turning the choke off.

[JoeliusZ28]

Ok so if i remove the manifold it will just stay in choke longer?

[Atrus]

be a man, just throw a manual choke on it

[MP81]

Ok so if i remove the manifold it will just stay in choke longer?

Yes, slightly. The heat riser is more for winter, I'd think.

[JoeliusZ28]

Ive only seen the choke stay on longer than a second a handful of times, so i believe that.

[Darren]

What are you trying to accomplish?

Absolutely remove all emissions crap. But if you have a vacuum leak find that soon. You'll never be able to get it to idle correctly without it. Did you rule out a intake leak, I know you were looking into that. Less is MORE with these engines. Remove anything and everything you do not need. Why are you worried about electric choke?

[JoeliusZ28]

I want the engine in good tune with crisp response and no weird noises. Yes there could be a vacuum leak at the intake gasket but i have no way of knowing for sure. Could be a lot of work to go through replacing those and wind up with nothing changing so im trying to start simple first. Think i might work on replacing vacuum lines this week even though they look fine.

I also ordered a distributor recurve kit today. This will allow me to reconfigure the distributor for non-egr. I found some pretty detailed instructions here:

http://outintheshop.com/faq/hei.htm

Debating if i want to snag that new egr valve and try it since thats a "right now" fix and i wont get this kit until next week much less have time to deal with installing and fine-tuning it since my class starts nexts week again.

[Darren]

Grab some carb cleaner and start spraying around. Find the leak.


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[JoeliusZ28]

Well im getting closer. Decided to buy the new EGR valve and at least see what it would do. Bolted it on, spark knock problems went away entirely. So i spent some time reseting the base timing (turns out I'd already had it set perfect) and test driving it. Idle was still extremely shaky, and engine was making a mild knocking sound. I hooked up a vacuum gauge to see what that was doing and it was steady at 17 inches. In doing so... i discovered a vacuum line that had come loose under the filter base where i couldn't see it. Reconnected that, and the idle is now considerably smoother, but still not smooth enough. Hoping i can clean up the rest by just replacing the rest of these lines and eliminating any potential leaks and doing the carb cleaner trick as necessary.

[JoeliusZ28]

So dumb question here... Im looking into what will be necessary to run headers on this thing, and i dont see a provision for the egr system in the exhaust. There are air lines all over the place but where is the egr getting its exhaust gas from?

[MP81]

I believe it comes through the head and the intake manifold, doesn't it?

[JoeliusZ28]

I was wondering if thats how it did it, all of my other vehicles have has something connected to the exhaust manifold. So headers wont affect it.

[MP81]

I was wondering if thats how it did it, all of my other vehicles have has something connected to the exhaust manifold. So headers wont affect it.

Nope. Aluminum intake (if you went that way, if you have to pull yours off) should have provisions as well.