how do i set the timing on a 1988 gmc seaira 350?
the truck wants to die when you step on the gas for some power. it all so studers when ideling in revers and all drive gears idels awsome in neutral and park it will rev up awsome as well in neutral and park
- Anonymous1 decade agoFavorite Answer
there's only one way to time any motor and i don't know of any performance shop timing any other way then total timing, warm up the motor first and you want 36degs of timing @ 3000RPM after you have set the timing @ 36degs @ 3000RPM then check it again at an idle ( if you have vacuum advance you need to pull and plug it to check timing at an idle) timing should be between 6 degs and 10 degs at an idle.
but i don't think this is whats going on, one check your fuel pressure as that has TBI, fuel pressure should be at 40 to 45lbs at an idle.
also look at the base of the throttle body and along your intake for vacuum leaks, you can check this by spraying some carb cleaner at the base of the throttle body and along your in take right next to the valve covers, also look for warn or broken vacuum hosesSource(s): over 30 years of building hotrods & classic cars & harleys. owner of Toads Timeless Restorations (est 2000)
- DeanoLv 71 decade ago
Locate the timing connector that is usually underneath the plastic cover under the hood. It is a tan wire with a black stripe. This connector has only one connection and its sole purpose it to set timing. Start motor and get it close to operating temp. and then disconnect the timing connector. The SES light on the dash will come on, don't worry about that as that's what's supposed to happen. Then with the timing light connected to #1 cylinder, aim and look directly down behind the water pump to see what the motor's timing is. These were set at zero degrees, but I alwasy tried to get a little more so I used to set at 2 BTDC. To adjust, loosen distributor bolt a little and rotate to where you want and tighten bolt and recheck. Then reconnect timing connector. You can clear the code now.Source(s): I was a GM mech for years.
- jasonbatlaLv 41 decade ago
Theres a plug up on the firewall on the passenger side that needs to be un pluged after you start the engine,look for a brown wire with a white strip,set the timing,turn the engine off then connect the plug back in,start it up so the computer can make the adjustment,might want to check the EGR valve too
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- gearnofearLv 61 decade ago
With it being a 88, I would first check out the vacuum advance diaphragm and make sure it is working correctly. from what you described it sounds like the advancement is not operating correctly. you can test this with a hand operated vacuum pump. when vacuum is applied your RPM's should increase, if they do not then you have a problem with the vacuum advancement. If they RPM's do increase, then you need to locate the timing marks on the harmonic balancer. once they have been located check to see what your current timing is. You sticker under the hood should tell you where you should be (often times this is around 0 to 10 degrees) if your on your mark then your problem lies else where.
- 1 decade ago
I ALSO HAD AN 88 GMC 3/4 TON P/U WITH THE SAME PROB. IT WOULD SEEM TO IDLE OKAY AFTER SOME ISSUES TO GET IT TO START. I SET THE TIMING 4 TIMES AND CHANGED THE PLUGS, WIRES ,CAP AND ROTOR,AND TIMING GEARS W/CHAIN AND FOUND OUT IT WAS THE SPEED SENSOR ON THE TRANSMISSION. THE PROB IS THAT WAS THE FIRST YEAR THEY WENT COMPUTERIZED BUT IT WAS HALF WITTED. THE SPEED SENSOR CONTROLS THE ENGINE SO WHEN YOU GET ON IT IN NEUTRAL IT SEEMS SOMEWHAT OKAY BUT WHEN YOU PUT IT IN DRIVE IT FALLS ON ITS FACE. OR YOU CAN GO FOR A LITTLE AND WHEN YOU GET ON IT A LITTLE IT HICCUPS, AND WHEN YOU REALLY GET ON IT IT BACKFIRES. THIS IS REALLY COMMON WITH THE 700R4 TRANS. PLEASE GET BACK AHOLD OF ME IF THIS IS THE SAME THING YOU ARE EXPERIENCING SO I CAN LET MY BOWTIE BUDDIES KNOW OF ANOTHER ONE.
- G MLv 41 decade ago
Instruction for setting the timing are on the emission decal on the fan shroud/core support.Source(s): Retired A S E and Oldsmobile Master technician
- tronaryLv 71 decade ago
You need a timing light to see if it's out of time and also to set / adjust timing. If it runs it is nothing major wrong. You will need to learn about a timing light.
- Anonymous4 years ago
Thank you all for your answers and opinions.
- SherieLv 44 years ago
Can you give more details?