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Re engine timing

C

captain_peter

Contributing Member
"Hello every one out there.
n

"Hello every one out there.
now that we made it through another winter and we out of hibernation, I got some questions regarding timing 2 GMC 4.3 ltr V6's 1989. 205 hp.4bbl Rochester carbs. On my manual shows on 89 octane to set to 6 btdc and 86 octane 1 btdc the problem is the fuel I buy is 87 octane so I am wondering what is the in between set up ?"
 
"My manual actually says 1 BT

"My manual actually says 1 BTDC w186-88 AKI octane; 6 BTDC w189 AKI octane, so if running 87 I would set it at 1 deg BTDC and see how it runs."
 
"Thanks Bob for answering so p

"Thanks Bob for answering so promptly,
The set UP on my engines were at 6 BTDC and I set them to 1 BTDC and then to 3 BTDC.and never noticed any difference. Probably if I use some gadgets it may show, but not by other means.
Also in the Manual says to set the idle speed to the in gear rpm and then shift to neutral is this correct since I been told to leave it in gear when I am checking with the timing light?
Any suggestions will be appreciated."
 
I'm not sure what the book

I'm not sure what the book says but...I've always set my idle speed (in gear tied to the dock) and then pop it into neutral to check the timing. Maybe next time I'll check it both ways and see if there's much difference?
 
"Hi Bob,
Since we are on this

"Hi Bob,
Since we are on this subject of timing, in the manual also says if you use your timing light on the fourth cyl.in firing order the timing light should be in the same position as cyl. #1"
 
"You've got me scratchin m

"You've got me scratchin my head on that one???? I've always only used cyl # 1, on your engines should the front cyl on the port side of the engine."
 
"OK...I understand what you ar

"OK...I understand what you are saying, I guess this is a way to determine if you have a sloppy dist, never tried that but will file it upstairs under "good to know stuff" thanks"
 
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Hello ones again
I am trying

Hello ones again
I am trying to adjust the distributor on 1989 GMC (OMC) 4.3 LITRE ENGINES BUT I AM FINDING IT VERY DIFFICULT TO UNDO THE BOLT THATS HOLDING IT. I AM WONDERING IF THERE IS SOME SPECIAL TOOL FOR THIS PARTICULAR TASK. NOTTIG SEEM TO FIT THAT GIVES YOU ENOUGH ROOM TO MANUEVER.
ANY SUGGESTIONS ?
THANKS
 
They do make dist. wrenches th

They do make dist. wrenches that are offset. Might find one at a local parts house. I use a 9/16 ratchet wrench on my 1990 4.3L. Works nicely.
 
"Hello Chuck,
Thanks for your

"Hello Chuck,
Thanks for your feed back. The problem I am having is that around the dist. there is so much stuff that I am having problem fitting any thing and be able to maneuver more than an 1/8 of an inch, which means the wrench is not able to catch on the next groove.
Thanks."
 
"Whatever is in the way move i

"Whatever is in the way move it.I have been known to bend flat wrench's for projects, and label it in my tool box, to use on a item that i know will be used again and again.

Just a suggestion."
 
"Thanks Chiefalen for the sugg

"Thanks Chiefalen for the suggestion, I was at the tool shop this morning and bought a set of open end wrenches with a square hole on the other end to use a vertical extension to attach to a ratchet wrench hopefully this will do the job.
Thanks."
 
"I may not have been clear. Wh

"I may not have been clear. When I said "ratchet wrench" I meant a "gear wrench", not a ratchet and socket. I reach in from the transom side and have plenty of room."
 
"Hi Chuck,
Thanks for the ext

"Hi Chuck,
Thanks for the extra effort you taken to clarify the subject. After I wrote realized what you meant, but didn't give it much thought. Reaching from the transom side for me its not an option.The transom of my boat extends over to the back of the carburetor and also quite low.
Thanks."
 
"I am wondering if you guys ca

"I am wondering if you guys came across a similar problem like I am having with one of the engines in my boat. Runs smooth on low and high rpm but at about 2200 it runs rough like if you taken a plug wire out. omc 4.3 litre i/o 1989 4 bbl rochester,
Thanks"
 
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