Timing trouble after removing AIR system?

[3Csparky]

Once again here's another discussion about an ongoing project. It has to do with the AIR removal and associated trouble with timing. Although I've read many posts on this subject I'll be interested in any more tips and suggestions on getting the most out of this monster of an engine. I'm not the most mechanically inclined but want to give it a shot.  Hm? Thank you for all and any advice and happy trails.

[cook elandan]

     I had just started to remove the AIR system on my 89 also.  Had some hydroboost issue along with a leaking power steering pump, so having to remove half of the front of the engine, AIR is not going back on. 
     Like you said there is a lot of information in the threads that let you know what you need or should do when you remove it. I know that Jim Elliot had been mentioned in one of the threads, he was on another site and was the go to guy to get the most out of the engine.  He as since past so one is not able to get the one on one with him.  So you have to find his posts or talk here on this site and get the wealth of know how from these guys and gals.
     Make a file to hold you information you need, copy paste, information in to the file and start to get it in line, everybody has different and same opinions, there is a lot of information on it.



     But most of what I think that is needed for it from what I have read and most have given part number that they have used also.  Try not to go with the cheap parts, payment is in the end.
re-curve distributor
(possible)adjustable advance
corrected timing
rebuilt/replaced carb
correct thermostat
correct spark plugs and gap
good air flow through radiator
good air flow around engine (all deflector shields in place, mainly passenger side to keep from burning plug wires)
cold air intake for carb
good flowing exhaust
good gauges-vacuum, temp, oil, ect....
GREAT FOOT TO GAS PEDAL CONTROL
and for the best results would be a rebuild of the engine with cam, heads, intake ect... that are matched.
but that is JMO.

[tmsnyder]

I haven't heard of any trouble with timing after removing the AIR system. What troubles?  They would just continue to run lousy due to the wonky timing that GM put in them in order to appease the federal air pollution police. And since the point of the smog timing is to send unburned fuel into the exhaust manifold where it is burned outside of the engine with the addition of air, with the air pumps gone there would be unburned fuel flowing out the tailpipe.   I'm not sure which is better, burning it in exhaust manifold and cracking those with all that wasted heat, or dumping the unburned fuel out into the environment.   I guess I'd go with the latter since it will just be stripped out by the rain and consumed by bacteria in the soil and water anyway.


The best reason for removing them, if your part of the world allows it legally, is to eliminate parts of the belt and pulley system that could fail and leave you stranded on the side of the road.  The next best reason would be get the engine running more efficiently.  It should improve fuel mileage and pollute less in the end (if that's something that concerns you), I personally don't load the family into the RV and burn 100s of gallon of gas in order to pollute less, if that were the case we'd just stay home and not have any fun.


If you remove those air pumps, the belts needed to run the engine change.  I did this recently and posted the belt numbers on the sticky page with that topic.  It's here: "This is on a 1989 chevy 454 with originally two smog air pumps. I ripped those off, so now there are three belts. Closest to the block is a V belt running just the power steering pump off the crank. It's a 41 inch belt, p/n 15410. The next one away from the block runs the power steering pump and A/C and water pump/fan off the crank. It's 59.5 inches long, p/n 15595. I would have liked it to be a little longer, had to loosen and pull in the p/s pump to get it on. And the third is a serpentine flat micro-v belt running only the waterpump/fan and alternator from the crank. It's a 52 inch belt 060520, it used to be a bit longer to run the smog pump but that's gone now. So that 52 inch belt would be a good one to carry as a backup in case your smog pump locks up on the road and you just want to slip this on to run the alternator and fan which are critical to get down the road."


The next improvement is to get the flow restrictors out of the exhaust manifolds.   These are the AIR injection ports, they look like fingers poking into the center of each exhaust port, they extend into the actual cylinder head and block up part of the flow path.  The exhaust gas has to flow around these fingers to get out of the engine.   If you remove the external plumbing and leave these in place they continue to block the flow.  People do remove these then plug the hole with a pipe plug but that's not the right thread.  Not that it won't work, if you jamb a tapered pipe plug into that hole it will get tight and plug it.  That's the typical 'solution' .  I couldn't find the right plug for it but luckily your engine comes with 8 of them, they just have a 3/4" hole through them.  What you do is cut off the little fingers and makl them about 3/4 inch long.  Then into the factory tubing nuts which thread into the manifold and seal against the flare on the air injection fingers, press in a little chunk of 3/4" round steel and weld it on the hex-nut end.   Then the stubby fingers go back into the manifold where they came from, only now they don't make it into the exhaust flow, followed by the tubing nuts which are now plugs, having the right thread and gas seal against the flare on the stubby finger. 


To recurve the distributor this is the vacuum can I installed, Accel 31035.

http://static.summitracing.com/global/images/instructions/ACC-34000V.pdf

As delivered, it starts adding advance at 6.5 inHg and maxes out at 6.75 degrees distibutor timing, 13.5 degrees engine timing, at vacuum more than 12 inHg.  Running directly to manifold vacuum although if you wanted to keep the vacuum plumbing intact as from factory it would be ok as long as all the thermo valve are working and there's no leaks, and it's connected to manifold vacuum (not ported, must be manifold vacuum for this canister and mechanical advance set). 

This is the mechanical kit I used, Moroso 72300:

http://www.moroso.com/sites/default/files/instructions/72300_inst.pdf

I put on the medium springs, so it should add zero advance until 1000-1500 rpm, then maxes out at 23 degrees at between 2500-3000 rpm

At crank:  12 degrees BTDC
At idle, 12 +13.5 = 25.5
WOT at or above 2500 rpm:  12 + 23 = 35


None of this is rocket surgery, this is just standard timing for a pre-smog era engine across all the engine manufacturers.   It's $40 for the two parts and you'll have the timing back to the way was before the federal govt got involved.


Mine already has cold air intake from Holiday Rambler, and I got the flapper valve in the air filter housing working again so that it draws a bit of warm air from around the right exhaust manifold during cold weather, to prevent icing up the carb. 


Also make sure the heat riser / flapper valve in the drivers side exhaust pipe is actually opening once the engine warms up.  These can seize up and be stuck closed, restricting flow from the exhaust.  I disabled mine and wired it full open with bailing wire but if your vacuum lines and switches are working just leave it and let it do its thing, as long as it's working. 


Good luck, take good notes.

[Rickf1985]

That was where I set mine up and I had detonation at 60 MPH cruise so I am going to need to back down the advance  a little. Are you running regular gas and is your EGR still hooked up?

[3Csparky]

Yes regular gas 91 oct. egr? What's the degree on tdc? i??  Can't decide which one is correct. I think 4 btdc

[cook elandan]

I think rick was asking tm, for here in Ohio 91 oct is premium where 87 is regular. When you remove the AIR system, you can remove the EGR valve, located on the front left side of the intake.

[tmsnyder]

Yes regular 87 octane fuel and the EGR is disconnected.  It's still in place, just no vacuum line connected.  I ran it about 2000 miles last year after timing it by ear.  This spring I checked the timing with a light and it was at 13*.  I put it at 12*for this summer.


Rick, did you swap out the vacuum canister and the mechanical advance to something known? If it's OEM canister and weights/springs, these smog systems are set up for very little initial timing, then they get a bunch from the mechanical advance so that at WOT they end at around 35 btdc to try to get some performance back.  So the mechanical advance must be adding like 31 degrees of timing.  If you set initial timing at 12 you'll end up with 46 at WOT which is way more than 35-36.  35-36* btdc for over 100 years is the optimal timing for a gas engine doing work, that's my understanding anyway.  The more the better, until it pings and then back it off but if it's running 46* total then I imagine it's going to ping.

That was where I set mine up and I had detonation at 60 MPH cruise so I am going to need to back down the advance  a little. Are you running regular gas and is your EGR still hooked up?

[Rickf1985]

I am running the same can and weights as you.

[tmsnyder]

Well that's odd.  Are your mechanical advance weights are all swinging freely?  I remember those being a little tight on mine initially, can't remember what I did but seems like there's another set of plastic bushings in the kit that were looser on the two posts.

Is your timing set using the #5 cylinder by laying on your back underneath the motor and shooting it from underneath like mine?

I am running the same can and weights as you.

[Rickf1985]

Yup and yup, there were a couple sets of bushings plus I lubed them up so everything is moving as it should. I am just going to reset the vacuum advance back a couple degrees. Just curious, where are you located? I know that out in the midwest they use upwards of 15% alcohol in the gas and that might be why you are not pinging and I am at 5% alcohol.

[tmsnyder]

I'm in Buffalo, NY, the 87 octane regular gas here is 10% ethanol.

[Rickf1985]

Should be about the same then. They say 5% here but that can range from 5-12% by law.

[Oz]

Not a mechanical guru here.  Does the timing need to be adjusted after removing the AIR system?

[Rickf1985]

It does not have to but a lot of people like to change the timing advance to a manifold vacuum controlled system that was used before the emissions controls needed the ported controls to operate correctly. With manifold advance you get better initial acceleration and better gas mileage with lower engine operating temperatures. The mileage difference is not enough that it is worth going through all that is involved just to try to get that one or maybe two MPG gain. And as can be seen in the thread it is not just a matter of changing the timing only, parts have to be changed in the distributor.

[tmsnyder]

Most of my 8000 mile trip this summer was with 85 octane and I never heard any pinging.  It was set at 13 or 14 last year, I set it to 12 before the trip and glad I did b/c most of what I ran into out there was 85 octane.  My timing light is a basic non-dial back one.  I never did check to verify that the timing mark was correct.

Rick I had to drill out the plastic bushings that the weight set came with, otherwise they would hang up on the pivot.  If yours were as tight as mine were originally that might be the cause.


My EGR is not connected to vacuum, that might make a difference.  What's the rest of your setup?

[Rickf1985]

Mine is set up the same as yours, I don't remember where exactly my initial timing is right now but I believe it is at 12. My EGR is still hooked up since removing that can cause detonation but as soon as I can make a block off plate I will be removing it and revisiting the timing. The bushings are free and lubed. Advance was checked and moving free and smoothly. I really wish I had never sold my Sun distributor tester!

[tmsnyder]

Can too lean a carb setup cause detonation? 


Try cooler spark plugs?


Not to promote sending people off this website, but chevytalk has a lot of knowledge on chevy engines.  This might be something to take over there to that forum.

[MotorPro]

Yes lean can cause detonation. So can carbon build up on top of Pistons. Top end cleaner might help. Is it dieseling when you shut it off? Colder plug can help with detonation but will foul easier so not the best solution.

[Rickf1985]

Guys, This is turning into a fix it post for my engine. I am good, I just have not had time to work on it. I have been building engines for 40 years so I have this under control. I appreciate all the suggestions. I try to shy away from any mention of my past engine building experience since for some reason it always seems to get me in hot water.

[M & J]

I used to be a moderator at Cheytalk.org. Same as tmsnyder, not promoting another site but everyone can use alternatives.

[Rickf1985]

I will check them out.