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  #1  
Old 01-22-2003, 10:12 AM
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Default 4.0 Flexplate orientation for install

Hey there, hope someone can help here... I can't locate this info in my Haynes nor anywhere on teh web or this site, searching avails nothing. I've rebuilt my motor and thought I installed the flexplate as I removed it, but it appears to be out of sync with the timing. Can someone shed some light as to the correct assy procedure based on #1 at TDC, where should the three long slots be? Should one be at 60 degrees so it lines up with the CPS or should one be at 0 degrees so that it is straight up in relation to the top of the engine... Please help if you can as I'm pulling my hair out, and there just isn't enough there as it is......

Thanks
Steve
sclay@excite.com
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Old 01-22-2003, 04:09 PM
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Default Re: 4.0 Flexplate orientation for install

If the flexplate bolted on. You did it right. It will only bolt on one way. And I don't think it will work backwards. Your problem may lie elsewhere.
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Old 01-23-2003, 11:28 AM
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Default Re: 4.0 Flexplate orientation for install

Did you put the timing chain sprocket on in the right position, and how about the chain, have you got 15 pins between the timing marks as shown in the Haynes manual? Recheck the dist. to see if its in the proper position. It's easy to over look the little things, Good luck.
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Old 01-23-2003, 12:50 PM
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Default Re: 4.0 Flexplate orientation for install

I just rebuilt my engine also. The flexplate can only line up with the bolt holes one way. What is the exact nature of your problem? If its a timing issue be aware that the haynes and chilton manual depict the distributor to be seated at the 4 o'clock postion when its seated. This is not correct. The distributor when fully seated should appear to look more like 5:30.
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Old 01-23-2003, 06:47 PM
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Default Re: 4.0 Flexplate orientation for install

Well, to be honest the one thing I didn't pay close attention to was the timing gears. I've rebuilt many Ford 302's and such but never had I come across in the manual as to checking the 15 tooth gap. I saw it the other night after reading things thoroughly in my Haynes manual... Checked and doubled checked timing, compared its positioning with my 88 cherokee, same same... Timing light shows it to be firing around 10 deg BTDC...

Problem is it idles ok, but any increase in RPM yields sputtering and backfiring. I am beginning to believe that I don't know as much as I thought and that I have in fact missed the cam timing by a tooth or two. Especially after those who posted that the flexplate only bolts up in one position due to mounting stud offsets..

I am actually glad to know I don't need to pull motor or tranny to fix... WILl be pulling timing cover this Sat. and checking that. I am feeling confident that I screwed up when I put on the new timing set. Will let all know as soon as I find out for sure.

Steve
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Old 01-27-2003, 08:39 AM
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Default Re: 4.0 Flexplate orientation for install

Here's the latest.... pulled timing cover this weekend, verified cam to crank timing is nuts on... 15 pins between.
Distributer checked and is nuts on, even compared it to my 88 cherokee, the one in question is an 89..

Only thing I can think of is the flexplate orientation. In rebuilding this motor I had to change the crank as it had thrown a rod bearing. Could the machined hole in the end of the crank be in a different position to the original, I used this as a reference when installing the flexplate.

Does ANYONE have a procedure to install the plate as it appears that it could possibly be installed in one of two directions from what I have read elsewhere but can't find proper procedure documentation... since the timing holes are 120 degrees apart and the bolts holes are 60 it would be easy to be off 60 degrees.... Surely there must be a reference as in one timing slot should line up with the cps when at #1 TDC or something...

BTW, motor runs but will not run smooth above idle, spits and sputters as if timing is off. I know timing is done with both the CPS and the cam sensor in the distributer.

HELP!!! [img]images/graemlins/cussing.gif[/img]
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Old 01-29-2003, 08:02 PM
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Default Re: 4.0 Flexplate orientation for install

Ok, here is the ending of the saga for any who care....

Had a problem after rebuilding my 4.0, would start but not run above idle, spit and sputter. Went thru everything..

Timing chain checked, marks are exact and 15 pins apart when checked by the book.

Distributer timing was exact, and btw it the book does a pretty good job, just make sure that the crank is at 0 TDC and that when you stab the dist into the cam that the oil gear in the bottom is lined up just right so that it will drop in with no effort, once in the rotor should be just past the #1 contact in the cap, as in trailing edge of the rotor just passing the cap contact.

FYI - as stated earlier (and I didn't have to pull anything to check this) and found in other publications, the flywheel or flexplate will only mount in one position due to staggered bolts holes (thanks JEEP).

Now the solution to my problem.....

Finally checked out all sensors and found none bad. Decided, after much frustration, to check the Crankshaft Position Sensor and see if moving it made any difference.... BANG! Problem found. Seems there is slight movement of the sensor for adjustment, moving it closer to the flexplate made the new motor run like a top. Seems that the distance was causing the missing at higher RPM. Such a simple cure for a perplexing problem. I figure during the install of the motor the CPS must have been hit or changed. An easy oversite that caused me a week of frustration.

Moral is, for most timing, missing, dieing problems... CHECK THE CPS!!!!!!

Thanks to those who helped with replies.

Now for the lift, new paint, and move some thing from the old 2wd 88 Cherokee to the 89 4wd....

Steve [img]images/graemlins/givemebeer.gif[/img]
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Old 01-29-2003, 08:16 PM
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Default Re: 4.0 Flexplate orientation for install

Congrats on getting it running right. When I rebuilt my 4.0L I had a timming problem too but with mine the dist was 180deg off, and a one of the 3 ground wires on the back pass side of the head had broken off. It took me almost a good 2-3 weeks and lots of beer to finger out mine, but 2+yrs later all is good but the slight piston slap it has b/c I didnt have the cash at the time to bore/sleve all cylenders...Good luck...andy
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  #9  
Old 01-29-2003, 08:38 PM
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Default Re: 4.0 Flexplate orientation for install

My timing was off 180 initially, I assumed after timing the new timing chain and gears that it was at #1, as it normally is with other motors I've rebuilt... WRONG!!! If the cam gear and the crank gear marks are point in towards each other it is at #6 TDC... If you stab dist as I did for #1, your 180 out....

Obviously I'm not alone....

I saw in another post your heading to Sturgis this August.... I was there this past year 2002... what fun was had.... I don't have answers for 4.10 with 31's. I run 31's on my stock gearing and had no problems on the highway. I'd assume with 4.10 you'd actually be better off as teh gearing would be closer to stock gears with 235 tires..... Hope you enjoy your trip....

Steve [img]images/graemlins/givemebeer.gif[/img]
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