Distributor Timing\Vac Stuff

[ClarkGriswald]

Ok here is my question of the moment. I have recently rebuilt my 2150 carb, and in the process of trying to tune it correctly have bypassed ALL of the vacumm garbage that is the CTO's and the EGR and the Oxy pump garbage. (Oviously no emmisions testing here in MI.) I am determined to elimiate all these systems and need a little help\info on making it run right. I took the vac diagram that is in the tech section and blanked out all the lines and redrew my own diagram and hooked it up accordingly. Now, here is my problem. The engine runs really good now and very very smoothly even though I still dont quite have it dialed in like I want it, but I experience some bad pinging when its warm and in hot ambient temps. My first thought was "now that I good vac hookup to my distributor I probly have to backoff the timing to compensate" does this sound right to you folks? Many times in the past ive just retarded in small steps until it no longer pings like that under hot\load. I also read a thread somewhere that talked about how if you eliminated your egr you have to recurve the dist?? hmm.. So anyone that is running there 360 with very simple basic setup like this (ie. older ones) what do you run your timing at?? Im sure ill get yelled at for this one by the OEM guys. heheh (no offense I respect people that deal with all that extra equip and actually make it work and pass those inspections).I just refuse to belive that an engine HAS to have an egr to run right, but I do suspect that other parts of the system are no doubt setup to run in conjunction with the egr.. I want to go back in time and have a very simple setup that is reliable.. ok enough of my ramblings.. Thanks a million for any help here...

Here is my current setup
http://www.btc-bci.com/~jaserb/images/Guess.jpg
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88 Grand Wagoneer
D44's front\rear
AMC 360
TF 727
NP 229 (Funky)
Bone Stock (for now)
NO RUNNING BOARDS!

[This message has been edited by ClarkGriswald (edited August 17, 2000).]

[This message has been edited by ClarkGriswald (edited October 02, 2000).]

[BobBarry]

<BLOCKQUOTE>quote:</font><HR>Originally posted by ClarkGriswald:
runs really good now and very very smoothly even though I still dont quite have it dialed in like I want it, but I experience some bad pinging when its warm and in hot ambient temps. My first thought was "now that I good vac hookup to my distributor I probly have to backoff the timing to compensate" does this sound right to you folks? Many times in the past ive just retarded in small steps until it no longer pings like that under hot\load. I also read a thread somewhere that talked about how if you eliminated your egr you have to recurve the dist?? hmm.. So anyone that is running there 360 with very simple basic setup like this (ie. older ones) what do you run your timing at?? Im sure ill get yelled at for this one by the OEM guys. heheh (no offense I respect people that deal with all that extra equip and actually make it work and pass those inspections).I just refuse to belive that an engine HAS to have an egr to run right, but I do suspect that other parts of the system are no doubt setup to run in conjunction with the egr..<HR></BLOCKQUOTE>

You're right on that last point. The carb is jetted very lean, compared to pre-EGR carbs, so when you take the EGR valve out of the loop, the inert gas it partially filled the cylinders with is being replaced by regular air with all that combustible O2; since the carburetor isn't providing more gasoline, you've got a very lean mixture prone to pinging.

If you want to cut the EGR out, you'll have to recalibrate the carburetor (not something I'd relish doing on a 2150), or back off the timing so it doesn't ping. That last solution is just a bandaid, and would result in poorer performance than when the EGR is working (the EGR cuts out under full-throttle load anyway, so it doesn't ultimately hurt performance in those circumstances).

You've got to think of how each change you make affects the fuel-delivery system, and compensate by making other adjustments. The factory engineers put all those hoses and valves there for specific purposes; I'm not saying you have to retain all those parts, but you do have to re-think the fuel-delivery when you start removing those parts.

I'm still of the opinion that most of what we consider "smog-junk", while unsightly, does not have any negative impact on performance on a stock or near-stock rig when functioning properly. It is when they're not functioning properly that performance degrades.

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Bob Barry<UL TYPE=SQUARE>* '78 Cherokee 4-door
* '88 Grand Wagoneer[/list]http://studentweb.providence.edu/~rbarry/wheels/

[ClarkGriswald]

So the pre egr's 360's had different carbs on them then? or just jetted richer?? are these the jets in the bottom of the float bowl or are those only a maximum flow thing?. I wouldnt be against getting a new 2 barrel manifold with no egr circuit and a larger\more adjustable 2 barrel carb, although I was kinda liking the idea of altitude compensation. What other carbs have this altitude thing??

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88 Grand Wagoneer
D44's front\rear
AMC 360
TF 727
NP 229 (Funky)
Bone Stock (for now)
NO RUNNING BOARDS!

[ClarkGriswald]

Well today I retarded the advance (by ear) just slightly, so I would be safe from ping and went and bought a timing light.. when I got home and put it on there I was at right about 12 degree's. And that is just what my emmisions sticker says to set it at.. so Im thinking from watching the marks as i advanced it that it was previously set at around 15 so my belief is that whoever worked on it last. advance it like that to make up for poor port vacuum to the dist. cause there was a big ole crack goin right thru the port on the carb. once I put in a good carb and eliminated all those vac lines, I had good vac.. then it was advanceing to far and causing ping when warm.

I see what you are saying B.Barry about what the EGR does. How hard is it to rejet if its only a matter of boring those jets in the bottom of the float bowl or just replacing them with larger numbers then thats no biggy for me. I used to tear down my carbs on my banshee every week or so (or more) when tuning it. (I ended up being everyones carb guy cause I could do em so fast.)
So anyhow it ran quite well the whole trip today (around 40 miles round trip) it had just a tad less takeoff but real smooth) still plenty of power on the low end.

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88 Grand Wagoneer
D44's front\rear
AMC 360
TF 727
NP 229 (Funky)
Bone Stock (for now)
NO RUNNING BOARDS!

[TPIGUY]

Hey Clark, TPIGUY here.

Before you go and spend a couple hundred on a new carb or worry about retarding your timing to get rid of the ping, I have all the parts I need now to build a throttle body fuel injection system for your Jeep. I am now in the process of getting an EPROM burner so that I can reprogram the calibration chips for any vehicle. So if you want me to furnish you a system for cost only, E-mail me off list at WEG1192@aol.com. I have some shareware that allows me to look at and modify the tuning values of a GM ERPOM. I just don't have a burner yet that will allow me to actually save the program to my EPROM. Should have one by next week though.

[reddog]

Clark, The EGR impact performance little if any and speeds up warmup, so it may be of some use where you are. Also I noticed on your diagram you have the dist hooked up to the canister purge. You may want to hook it up directly to the manifold vacuum for a more constant vac source. For accuracy its best to change jets as opposed to drilling them.

Kerry

[scotty]

i have for some reason had alot of bad luck with egr. almost every car i own has had the egr valve removed and blocked off. when the valve goes bad,it basically creates a very large vaccum leak,resulting in a super duper lean mixture that will not idle for crap. i agree that most smog systems have little afect on performance when function properly. however,i do tend to think they dont really help enough for it to be worth the hassle of repairing/replacig them when they malfunction. id be willing to bet the the convertor does at least 90% of the emissions reductuons. id rather replace my cat every 5 years than bother with egr valves or air pumps. if every one junked every bit of emisions equimentmother than the cat,but always had a good cat on their vehicle,the overall emisions releaed by automobiles would have to be alot less.

you never see an air pump on a brand new fuel injected car. ironically,engine compartments are becoming quite simple-use a computer to make the engine always run at the ideal fuel mixture,and a catalytic convertor .nice and simple.

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scott
85 grand wagoneer
258 with motorcraft 2bbl/904/twin stick dana 300/dana 44/welded amc 20
38x15.5 gumbo mudders
snorkel/dual batteries/onboard air/"custom" convertable
3 inch body lift/mostly stock suspension/"modified" fender openings
custom front/rear bumpers and brushgaurd

possible small block chevy "test" swap in near future

[irbob]

Check out this post On a question I had about the EGR and CTO it may be of some help.
http://www.cs.colostate.edu/~zeimet/ubb/Forum2/HTML/000579.html

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Me (http://www.bigfoot.com/~irbob) IFSJA Window Sticker (http://www.angelfire.com/az/irbob/sticker.html)
83 Brougham, 360, 999 Auto, NP229, F/Dana 44F, R/AMC 8 7/8", 31X10.5 Pathfinder's, Rancho 9000's, 2" lift blocks. "Have you been off road lately?"

[BobBarry]

<BLOCKQUOTE>quote:</font><HR>Originally posted by ClarkGriswald:
I see what you are saying B.Barry about what the EGR does. How hard is it to rejet if its only a matter of boring those jets in the bottom of the float bowl or just replacing them with larger numbers then thats no biggy for me. I used to tear down my carbs on my banshee every week or so (or more) when tuning it. (I ended up being everyones carb guy cause I could do em so fast.)
So anyhow it ran quite well the whole trip today (around 40 miles round trip) it had just a tad less takeoff but real smooth) still plenty of power on the low end.
<HR></BLOCKQUOTE>

The procedure for rejetting a carb depends on the model. You can swap the main jets on your 2150 easily enough (they take standard Holley jets, AFAICT); the main issue, however, is part-throttle mixture control. You can fine-tune this on Qjets with different size and taper metering rods, but I'm not sure how it's done on a 2150. The trouble with doing it by jets alone is that a jet size rich enough for a midrange without the EGR may be too rich at full-throttle. Since EGR only activates at part-throttle, you're looking at richening up that part of the fuel-curve alone. The 2150 was never a pre-emissions carb, but I believe its cousin the 2100 was. Maybe the jetting from one of those would be a good baseline for you.

Again, though, a lot of work to omit something that doesn't have much negative effect on performance. I have removed EGR's from smog-motors before, but have always had to compensate; the easiest way was just to replace the stock carb with a Holley 3310... http://www.cs.colostate.edu/~zeimet/ubb/smile.gif

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Bob Barry<UL TYPE=SQUARE>* '78 Cherokee 4-door
* '88 Grand Wagoneer[/list]http://studentweb.providence.edu/~rbarry/wheels/

[ClarkGriswald]

Well today I went all over looking for the jets for the 2150, they are not standard holley jets cause nobody including any race shops recognized them and i held them up next to holley main jets and they are way larger . although i did notice this... i have two sets of these since the carb i rebuilt and am using was a reman. both have the same sized jets in them but my old ones are way worn and quite larger of a hole in them.. I used a #52 wire sized bit that almost could be stuck through that hole already but wouldnt go thru the stock jet. just hit it quick to round out the already enlarged hole. and tried em out.. no more pinging and i am at my orig timing now.. runs quite good..

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88 Grand Wagoneer
D44's front\rear
Warn 20990 Lockouts
AMC 360
TF 727
NP 229 (Funky)
Custom Hacking Via S.P.A. (Standard Polish Archetecture)

[christopher]

<BLOCKQUOTE>quote:</font><HR>Originally posted by ClarkGriswald:
Well today I went all over looking for the jets for the 2150, they are not standard holley jets cause nobody including any race shops recognized them and i held them up next to holley main jets and they are way larger . although i did notice this... i have two sets of these since the carb i rebuilt and am using was a reman. both have the same sized jets in them but my old ones are way worn and quite larger of a hole in them.. I used a #52 wire sized bit that almost could be stuck through that hole already but wouldnt go thru the stock jet. just hit it quick to round out the already enlarged hole. and tried em out.. no more pinging and i am at my orig timing now.. runs quite good..

<HR></BLOCKQUOTE>I have a 2150 that hesitates on excel and has a slightly rough idle. after trying everything I wasnt able to fix it. A retired mech told me to rejet to the next larger size. I never have done this, will it work and since you couldnt find replacments will I. I have my egr valve in . any info would help.

[ClarkGriswald]

<BLOCKQUOTE>quote:</font><HR>Originally posted by christopher:

[/b]<HR></BLOCKQUOTE>I have a 2150 that hesitates on excel and has a slightly rough idle. after trying everything I wasnt able to fix it. A retired mech told me to rejet to the next larger size. I never have done this, will it work and since you couldnt find replacments will I. I have my egr valve in . any info would help.

[/B][/QUOTE]

Concerning your rough idle.. I found that once I got a vacuum gauge and actually set the idle mixture properly that I had to go a lot richer than I had thought it should be. like 2 or 2.5 turns out instead of 1 or 1.5 like I had thought. My idle is smooth as silk now. I took a test drive tonight with the higher jetting and I have better power when I floor it, and smoother more positive accel from a stop. Allthough my midrange\part-throttle is still slightly pingy under the right conditions like a big hill when its bogging just before it downshift's. My top end is not boggy or weird like its to rich.. mabye I can go not another wire size but a few more passes with the bit I used. to bore it out just a tad more.. (these are extra jets by the way I still have a fresh pair of stock's)


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88 Grand Wagoneer
D44's front\rear
Warn 20990 Lockouts
AMC 360
TF 727
NP 229 (Funky)
Custom Hacking Via S.P.A. (Standard Polish Archetecture)

[Brown Bear]

You guys have made my day. The Minnow is getting this surgery this weekend or the next. I can't wait. Maybe I can run my idle screws at 1.5 instead of the 3-3.25 they're at now. Woo-hoo. I can't wait. Maybe I can improve on my 8 mpg too when I finally get the timing set. I'll probably need some oven off or something. I can't see a hint at timing marks anymore.

Nathaniel

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1984 Grand Wagoneer
bone stock
P235/75 R15 Daytona Stag XT