Why So Much timing?.... Need Help.

84Black&Silver

Daily Driver
Dec 14, 2010
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Oakland CA.
Hey guys im finish up My 84 el camino and have been driving it lately trying to figure and work out all the bugs. I put a 5.7L long block motor out of a 95 tahoe in it bone stock. I also swapped over everything from my original motor , HEI distributor with electronic Vacumme advance , carb , a/c smog equipment , I mean everything. When it came time to do the timing on the motor it dose not like anything under 12* , it wll run really shakey and spit out of the carburator and turn off when I stab the throttle. At 12* it runs ok , still Shakey in park and in Gear and I think under powered. However it will not spit out the carb and turn off when I stab it. What can be the problem? Its really bugging me that its under powered and not running smooth. Any ideas? I will greatly appreciate and Help and Advice you guys can help me with. Thanks in Advance.
 

tiedyemike8

Frequent Racer
Oct 28, 2009
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Naperville, IL
Which balancer and timing tab are you using? The newer engines had the timing tab at 12:00, the older ones were at 2:00 or so. If you are using the newer balancer with an older timing tab, when you set the timing at 12 deg adv, the engine is running several degrees retarded.
 

tiedyemike8

Frequent Racer
Oct 28, 2009
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Naperville, IL
Then I would be looking for a vacuum leak, carburetor adjustment, and double check the firing order. You might have a crossed wire. A compression test might help, and I would put a vacuum gauge on the engine to see whats going on.
 

84Black&Silver

Daily Driver
Dec 14, 2010
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Oakland CA.
I will double check my firing order today and also check for vacuume leaks. hopefully I have time to do a compression test this weekend. I,ve always heard of timing a car with a vacuume guage but never really seen anyone do it or looked into how its done , can you give me a quick run down? Thanks For The Suggestions I really appreciate it! Its driving me crazy how the car is always running rough and is under powered , I need to figure this out!
 

bowtie81

Moderator
Mar 28, 2008
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sarnia, ontario canada
Is it still the old cam or a new one? Make sure you dont have a chewed up lifter or cam lobe. That happened to me once.
 

art

Amateur Racer
Aug 8, 2008
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Mastic, New York 11950
84Black&Silver said:
I will double check my firing order today and also check for vacuume leaks. hopefully I have time to do a compression test this weekend. I,ve always heard of timing a car with a vacuume guage but never really seen anyone do it or looked into how its done , can you give me a quick run down? Thanks For The Suggestions I really appreciate it! Its driving me crazy how the car is always running rough and is under powered , I need to figure this out!
Timing with a vacuum gauge is a matter of more is better. You will find the "happy spot" by trial and error. Also if you have the vacuum advance can that worked on another engine, it may be too much (or not enough!) for what you have now. The "timing sticky" in this forum may be a good read about now. It will explain more about vacuum advance and why you need it. With a dial back timing light and a tach, you can map out your entire curve too.
 

84Black&Silver

Daily Driver
Dec 14, 2010
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Oakland CA.
Barry 85 SS: The 95 Tahoe the motor came out of was TBI injected I swapped my inake and carb on to the Motor

Bowtie81 : it has the stock cam and lifters the motor came with. I didn't change anything internally.

Art : my car has the electronic vacuume advance set up. Where the computer advances and retards the timing as needed? It dosent have the vacuume addvance can , just an electrick plug that goes to the harness. And thanks I will take a look at the timing thread!
Thanks Guys for the Help , appreciate all the info and Suggestions.
 

madmaxx57

Amateur Racer
Oct 5, 2010
237
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DURAND IL
ok, i just thought of this. maybe worth checking into it.. on a tpi harness there is a conector that you must disconnect if you are setting base timing. i know you arent running a tpi, but you might want to look or check to see if this is the case on you electronic setup?..just a shot in the dark...maybe start advancing it until it starts hard against the starter or pings then retard it 2 deg. or replace the electronic dist. with a plain old hei?..just some ideas..good luck
 

84Black&Silver

Daily Driver
Dec 14, 2010
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Oakland CA.
Madmaxx57: I've heard about that wire your talking about but I have no clue where its located or where to look. The only wires coming from the distributor is the main plug that plugs to the harness and if I unplug that it just wants to die. I can keep it running with the throttle but it just runs like garbage and wants to die.. Anyone have any idea where that wire is located? And I don't think the computer will let it ping. I did think about replacing the distributor with a regular vacuume advance one but, I think that will throw off the computer and set the CEL on.?
 

art

Amateur Racer
Aug 8, 2008
248
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Mastic, New York 11950
Um the computer has no way of knowing if it is pinging IIRC. 1984 onboard stuff wasn't that good. If when you unplug the big 4 or five pin deal in the front and it has trouble running, your base timing is wrong. All the 'puter does is add or subtract timing in response to the "map" signal. (just like a vacuum advance can) So I would try setting the base timing the way the sticker on the shroud suggests and see how things are. If all else fails, a trip to a diagnostic facility is not a bad idea.
 

84Black&Silver

Daily Driver
Dec 14, 2010
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Oakland CA.
art: I thought it did? I had read that the computer wouldn't let it ping because it would gather info from the knock sensor , map sensor and a few other sensors and it would advance or retard the timing on its own.. Maybe im wrong on that?... how do I set base timing without the computer advancing it while im trying to set it?

SSedan64: I did put all the sonsors back on the motor , knock , MAP , Carb , everything. I put it all back stock all sensor and emission equipment.
 

madmaxx57

Amateur Racer
Oct 5, 2010
237
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DURAND IL
on tpi;s the timing wire is right above the distr...just one wire..little plastic conector..maybe look at a wiring diagram to get the color..i would also say your base timing is way off...honestly i would start advancing it just to see what it would do?..can it run anyworse?..and yes the knock sensor will send a signal for the ecm to retard timing when it senses a rattle..i was thinking if you just put in a regular distr ,it would eliminate that set of electronics..i dont think it will set off the light..i have this setup on my 57 chevy with tpi. no light..but at this point the light is the least of your worries...just throwing some options out there..
 
Feb 17, 2010
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Get your compression test done before you start beating your head too much. I had a similar problem, turns out the heads were junk.
 

tiedyemike8

Frequent Racer
Oct 28, 2009
658
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Naperville, IL
What size motor did the carb come off of? It could be running way too lean, also. Can you adjust the mixture screws to get a lean roll? What happens to the rpm when you pull a vacuum line off of the manifold?