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  #91 (permalink)  
Old 03-07-2012, 10:27 AM
lt1silverhawk's Avatar
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Hey cobalt,

Quote:
Originally Posted by cobalt327
The red cam-shaped plastic piece is the eccentric that lifts the secondary hangar/secondary metering rods in relation to the air valve opening. It has to be replaced, Ruggles has the kit, $12 to your door.
I had to go back to the rebuild thread as well as all the pictures I took last year to see if I had removed and reinstalled it, but nothing came up. So I am going to assume it has been inside the open space where the key goes all along. Ruggles does cover the procedure for removal and installation in his book (chapter 5, "Rebuilding the Carb", section "Air Horn", page 84), so I should be able to go through that.




Quote:
Originally Posted by cobalt327
I noticed in one of the earlier photos the little anti rattle spring on the power piston that keeps the primary metering rods from vibrating (thus wearing) inside the jets was out of position. Later photos show it back in correctly, so that should be OK. That spring can be omitted if there's any question as to the condition of it, it's there to insure 100K mile service life under all conditions and many guys leave it- and the small clip I'll talk about next- off the carb altogether. I use them FWIW.
Yes, that looks out of place because it came off when I removed the airhorn gasket. But it was fine before and I did reposition it before closing everything up.




Quote:
Originally Posted by cobalt327
On thing that you have got to fix is the small hook that clips to the needle part of the needle and seat assembly. The hook does not go through the hole in the float arm. This is a common mistake, but it can cause the needle to hang up and the float level can be all over the map. So, hook it over the cross piece closest to the power piston.
I am confused on this one. Would the cross piece be the pivot arm for the float?




Quote:
Originally Posted by cobalt327
I'd remove the epoxy. It's not doing any good and even though it can't fall into the float bowl, no reason to have it going through the engine. I'm guessing it was there for prevention's sake. If the well plugs ARE leaking get back to the forum and we can get into it further.
Yes, I had used the epoxy as precautionary measure (there was some discussion about them on pages 3 and 4 of the rebuild thread). I'll go ahead and completely remove it on the next dis-assembly. I don't believe the wells do leak, but if they do, I can attempt to install new plugs.




Quote:
Originally Posted by cobalt327
EDIT- The air bleed that's damaged needs to be opened back up to the same diameter as the undamaged one. You can use a small pick or smooth nail if small enough to resize the opening to match the other one. Dress the air bleed tip so there's no ragged edges, just don't shorten it excessively (excessive would be more than say 0.015").
Ok, sounds like an easy enough procedure.



Thanks!

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  #92 (permalink)  
Old 03-07-2012, 08:46 PM
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Quote:
Originally Posted by lt1silverhawk
I am confused on this one. Would the cross piece be the pivot arm for the float?


The well plugs that you have don't leak in the vast majority of cases. The older cup plugs were the culprits that gave the bad reputation about leaking well plugs to the Q-jet- and spawned a generation of guys who needlessly apply epoxy to them.

I personally have never seen an epoxy that wouldn't delaminate after being exposed to heat (and possibly fuel) Although Ruggles has recommended Marine Tex for this, he also sells threaded plugs, IIRC. The only sure-fire method is mechanically plugging the holes w/threaded plugs after the old plugs are removed. There are some fosdick o-ringed plugs that were (are still?) sold for this that are also to be avoided, IMO. The o-rings are not going to stand up to the conditions any better than epoxy, IMO.
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  #93 (permalink)  
Old 03-07-2012, 09:06 PM
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carb trouble

You can use an oxy-acetylene welding tip cleaner to clean up the air bleeds. Just don't get too vigorous with it, since the tip cleaners are actually little round files and will take off metal.
I hope you sprayed the venturies to get them clean. they looked pretty nasty.
You must adjust your idle speed screw (there is only one and it is on the throttle linkage side of the carb) to get an idle speed of around 500-800 rpm, THEN adjust the idle mixture screws (2, one on each side of the primary float bowl) for "lean best idle". You do this by running them both all the way in, but don't make them tight as you will damage the seat.
Next, with the engine off, turn them both out 3 turns (for a Quadrajet, 1 and 1/2 turns for a Carter).
Start the engine and check the idle speed. Turn the 2 idle mixture screws in or out as needed to make the engine run faster. Turn each one only 1/4 turn at a time, and make sure that they both are the same number of turns out.
Once you have the fastest idle with these two screws, go back to the idle speed screw and reduce the idle back to 500-800 rpm.
Generally speaking, once the idle mixture screw have been set in this manner, they might need only 1/2 turn in either direction to prevent a lean spot just off idle (assuming that the accelerator pump is working correctly).
Again, make sure that you only turn the mixture screws 1/4 turn at a time, turning first one and then the other so that they are both the same number of turns out. If they come out different, then you have a vacuum leak.
If your idle is set over approximately 1,000-1,200 rpm, then your engine will diesel (run on after shutting the ignition off). This is VERY bad for the bearings!
Set the timing now.
After setting the timing, you may have to increase or reduce the idle SPEED screw, but don't touch the 2 mixture screws again unless the engine has a lean bog or miss just off idle.
Good luck.
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  #94 (permalink)  
Old 03-08-2012, 10:53 AM
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Hey cobalt and barry,


@ cobalt: Thank you for the picture. I thought I understood what you meant but not having the carburetor open made it difficult. I also saw the image you uploaded to your album (currently your last uploaded image). This helps!

As to the plugs, I remember you did mention during the last rebuild that they weren't very likely to leak. I dabbed epoxy over them as a precautionary measure at the suggestion of the video series I was following on Youtube for rebuilding Q-jets. But I have seen no leaking and will remove the remaining epoxy upon dis-assembly when I reposition the needle hook.




Quote:
Originally Posted by barry425
You can use an oxy-acetylene welding tip cleaner to clean up the air bleeds. Just don't get too vigorous with it, since the tip cleaners are actually little round files and will take off metal.
Got it.


Quote:
Originally Posted by barry425
I hope you sprayed the venturies to get them clean. they looked pretty nasty.
I did spray everything I could with the carb and brake cleaners, and then wiped it all down. I didn't pay any attention to the venturis buit I can give them more a more rigorous cleaning during dis-assembly.


Quote:
Originally Posted by barry425
You must adjust your idle speed screw (there is only one and it is on the throttle linkage side of the carb) to get an idle speed of around 500-800 rpm, THEN adjust the idle mixture screws (2, one on each side of the primary float bowl) for "lean best idle". You do this by running them both all the way in, but don't make them tight as you will damage the seat.
Next, with the engine off, turn them both out 3 turns (for a Quadrajet, 1 and 1/2 turns for a Carter).
Start the engine and check the idle speed. Turn the 2 idle mixture screws in or out as needed to make the engine run faster. Turn each one only 1/4 turn at a time, and make sure that they both are the same number of turns out.
Once you have the fastest idle with these two screws, go back to the idle speed screw and reduce the idle back to 500-800 rpm.
Generally speaking, once the idle mixture screw have been set in this manner, they might need only 1/2 turn in either direction to prevent a lean spot just off idle (assuming that the accelerator pump is working correctly).
Again, make sure that you only turn the mixture screws 1/4 turn at a time, turning first one and then the other so that they are both the same number of turns out. If they come out different, then you have a vacuum leak.
Thank you, this helps me a lot. As to the vacuum leak, based on the responses of a couple of members, I am suspecting that I didn't do a good job of sealing the intake manifold gasket on the passenger rise (the plugs came out more fouled on that side than the driver side). There also been some smoke coming out that side at times as well.


Quote:
Originally Posted by barry425
If your idle is set over approximately 1,000-1,200 rpm, then your engine will diesel (run on after shutting the ignition off). This is VERY bad for the bearings!
That's good to know! Unfortunately the tach in the truck doesn't seem to be very accurate so I'll be using the RPM readings provided by the timing light (timing light shows about 200 rpm higher than what the tach registers).I did adjust the idle speed screw a few days back and it seems to be hovering around 750 rpm once at operating temperature.


Quote:
Originally Posted by barry425
Set the timing now.
That is the next step. I did being work on a timing tape. Just need to find time to sit down carefully make the markings. I'm thinking that it doesn't need to be big enough to go all the way around (full 360 degrees). Maybe up to 60 degrees before and after TDC (180 degrees) should be sufficient. Any thoughts?


Quote:
Originally Posted by barry425
After setting the timing, you may have to increase or reduce the idle SPEED screw, but don't touch the 2 mixture screws again unless the engine has a lean bog or miss just off idle.
Good luck.
Got it. I have the screws at four full turns out right now and will leave them be for the moment.




Hopefully by this Friday evening, I will disassemble the carb, clean up the venturis some more and reposition the needle hook into the correct position. Saturday morning I start working on the timing. I will report back as regularly as I can.


Thanks for the continued help!
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  #95 (permalink)  
Old 03-08-2012, 12:51 PM
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Timing

There should be marks on your dampner and on the drivers side timing chain cover, so you shouldn't need timing tape. Start at 5 degrees before TDC (Top Dead Center) and go from there. If you can find a Motors Manual for the year of your engine/car, it will list the timing information in there. In my opinion, Chilton is a poor second to Motors, and Haynes sucks because the info is hard to find and is sometimes even missing. You can also go to a Chevy dealer and get the specs from them.
The more you advance the timing, the faster the engine will run until you reach a point where it is too much timing and it will begin to stumble and slow down. Moving the distributor CCW (Counter ClockWise) will advance the timing. Check timing with the vacuum hose removed from the distributor and plugged.
Total timing at 3,000 rpm should be no more than 34 degrees with todays lousy gas, if your timing light will work at that rpm.
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  #96 (permalink)  
Old 03-08-2012, 01:36 PM
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Quote:
Originally Posted by lt1silverhawk
I did being work on a timing tape. Just need to find time to sit down carefully make the markings. I'm thinking that it doesn't need to be big enough to go all the way around (full 360 degrees). Maybe up to 60 degrees before and after TDC (180 degrees) should be sufficient. Any thoughts?
Sorry, that should say 120 degrees, not 180 degrees.



Hey barry,
Quote:
Originally Posted by barry425
There should be marks on your dampner and on the drivers side timing chain cover, so you shouldn't need timing tape.
There is a tab with marks (image below) on top of the damper. But I am making the tape more as an added assist and peace of mind to make sure everything is right on the money.







Quote:
Originally Posted by barry425
Start at 5 degrees before TDC (Top Dead Center) and go from there. If you can find a Motors Manual for the year of your engine/car, it will list the timing information in there. In my opinion, Chilton is a poor second to Motors, and Haynes sucks because the info is hard to find and is sometimes even missing. You can also go to a Chevy dealer and get the specs from them.
I've been using the Autzone website as a reference and it calls for 8 degrees BTDC. I can stop by the local Chevy dealership and ask.




Quote:
Originally Posted by barry425
The more you advance the timing, the faster the engine will run until you reach a point where it is too much timing and it will begin to stumble and slow down. Moving the distributor CCW (Counter ClockWise) will advance the timing. Check timing with the vacuum hose removed from the distributor and plugged.
This is where I recently hit a trouble spot. The last time I installed the distributor, I did in such a way that it now hits the intake manifold when being turned CCW. So I need to take it out and reinstall it while making sure it doesn't hit the firewall either.




Quote:
Originally Posted by barry425
Total timing at 3,000 rpm should be no more than 34 degrees with todays lousy gas, if your timing light will work at that rpm.
After the last timing light turned out to be a dud, I waited and bought a fancy one (Equus 5568 Pro-Timing Light) and its features include "tachometer ranges from 249 to 9,990 RPM", so I am sure it will do fine at 3,000 rpm.
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  #97 (permalink)  
Old 03-08-2012, 02:12 PM
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That's a good light. I have the same one. You can advance it as you pull up the rpm's.

With that light you don't need timing tape. I've never seen a balancer spin. I'm sure it happens sometimes, but i've never seen it.

8* is correct for your truck. My 76 is the same.
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  #98 (permalink)  
Old 03-08-2012, 06:09 PM
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Outer ring movement.

Just put a sharpie line across the outer damper ring to the inner hub and use that as a visual reference to see if the damper outer ring is moving over time.

If you put the sharpie line near to the damper TDC line you will be able to see it w/the timing light with the engine running.
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  #99 (permalink)  
Old 03-08-2012, 06:49 PM
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Hey Pugys and cobalt,

Quote:
Originally Posted by 123pugsy
That's a good light. I have the same one. You can advance it as you pull up the rpm's.
After reading all the reviews of the various timing lights for sale on Amazon, I think its a good one too, and fairly priced. May be a bit advance for a rookie like me. Does the advance feature only works on the new DIS ignitions, or old ones too?




Quote:
Originally Posted by 123pugsy
With that light you don't need timing tape. I've never seen a balancer spin. I'm sure it happens sometimes, but i've never seen it.
Quote:
Originally Posted by cobalt327
Just put a sharpie line across the outer damper ring to the inner hub and use that as a visual reference to see if the damper outer ring is moving over time.

If you put the sharpie line near to the damper TDC line you will be able to see it w/the timing light with the engine running.
Ok, the sharpie method is much easier. Personally, I don't think the damper is spinning but playing it safe never hurts.




Quote:
Originally Posted by 123pugsy
8* is correct for your truck. My 76 is the same.
Got it, that's the one I will stick with.


Btw, how much timing does the vacuum advance add?
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  #100 (permalink)  
Old 03-08-2012, 07:31 PM
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timing

Generally speaking,
Initial timing=8 degrees
Mechanical advance in distributor=26 degrees (at the crank)
Subtotal=34 degrees
Vacuum=14-16 degrees
Total= 8+26+14=48
This may be a little high for todays gas. I would limit total around 45 degrees.
Here is a method for finding the optimum timing settings. It is best if done on a hot day.

INITIAL:
Disconnect the vacuum advance hose and plug it.
Set the initial timing at 8 degrees.
Take off from a dead stop and see if the engine pings right off idle. If it does, then back off the initial timing until it stops.

MECHANICAL:
Make sure that the mechanical advance is correct with the timing light. Then take the warmed up engine out on the road and floor it.
If it is an automatic and it pings just after it shifts into a higher gear, back off the mechanical timing (you may have to buy a spring and weight kit).
If it is a stick, put it in a high gear (like 3rd) and floor it. If it pings, reduce the mechanical advance in the distributor (again, you may need a kit).

VACUUM:
If it doesn't ping, then put the vacuum line back on and drive it up a long hill. If it pings, get an adjustable vacuum pot and back off the total available vacuum timing by the screw/cam adjustment on the inside of the distributor (NOT the screw inside the vacuum nipple).

Continue the above steps until you get it to never ping and you're set.
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  #101 (permalink)  
Old 03-08-2012, 07:40 PM
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dampner slippage

I have seen several dampners slip. The guy with the sharpie idea has it right. make sure that the mark goes from the timing mark down the front of the dampner all the way onto the hub of the dampner so you can see if the rubber layer is allowing the outer ring to slip. IF IT IS, GET A NEW DAMPNER! THIS THING WILL BE A GRENADE AT FREEWAYS SPEEDS!!!
I always run a FluidDampner on all my stuff. I hate buying radiators, water pumps, belts, air conditioner compressors, fenders, batteries, etc. just because I wanted to save a buck and use a worn out dampner.
The rubber on your dampner looks bad to me. It should be even all the way around, but yours seems to be pushing out in at least one spot.
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  #102 (permalink)  
Old 03-08-2012, 08:05 PM
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Hey barry,


Quote:
Originally Posted by barry425
Generally speaking,
Initial timing=8 degrees
Mechanical advance in distributor=26 degrees (at the crank)
Subtotal=34 degrees
Vacuum=14-16 degrees
Total= 8+26+14=48
This may be a little high for todays gas. I would limit total around 45 degrees.
Thanks! I appreciate the break down.


Quote:
Originally Posted by barry425
Here is a method for finding the optimum timing settings. It is best if done on a hot day.
And it would start to cool off this weekend.


Quote:
Originally Posted by barry425
INITIAL:
Disconnect the vacuum advance hose and plug it.
Set the initial timing at 8 degrees.
Take off from a dead stop and see if the engine pings right off idle. If it does, then back off the initial timing until it stops.
Ok, simple enough.


Quote:
Originally Posted by barry425
MECHANICAL:
Make sure that the mechanical advance is correct with the timing light. Then take the warmed up engine out on the road and floor it.
If it is an automatic and it pings just after it shifts into a higher gear, back off the mechanical timing (you may have to buy a spring and weight kit).
If it is a stick, put it in a high gear (like 3rd) and floor it. If it pings, reduce the mechanical advance in the distributor (again, you may need a kit).
I looked up the instructions (here) on how to do this on my timing light. I think I've got it down.


Quote:
Originally Posted by barry425
VACUUM:
If it doesn't ping, then put the vacuum line back on and drive it up a long hill. If it pings, get an adjustable vacuum pot and back off the total available vacuum timing by the screw/cam adjustment on the inside of the distributor (NOT the screw inside the vacuum nipple).

Continue the above steps until you get it to never ping and you're set.
No long hills around here, just a couple of freeway overpasses. Ok, will give this a shot in this sequence. Hopefully it won't get too complicated.




Quote:
Originally Posted by barry425
I have seen several dampners slip. The guy with the sharpie idea has it right. make sure that the mark goes from the timing mark down the front of the dampner all the way onto the hub of the dampner so you can see if the rubber layer is allowing the outer ring to slip. IF IT IS, GET A NEW DAMPNER! THIS THING WILL BE A GRENADE AT FREEWAYS SPEEDS!!!
Ok, two votes for the Sharpie method. I definitely appreciate the warning on this.


Quote:
Originally Posted by barry425
I always run a FluidDampner on all my stuff. I hate buying radiators, water pumps, belts, air conditioner compressors, fenders, batteries, etc. just because I wanted to save a buck and use a worn out dampner.
The rubber on your dampner looks bad to me. It should be even all the way around, but yours seems to be pushing out in at least one spot.
Interesting. I will look it over completely and see if there are any places where its pushing out. I will also put up close up shots so you guys can get a better view. I honestly wouldn't know what to look for in terms of bad rubber.




Thanks for the continued help Barry!

Last edited by lt1silverhawk; 03-08-2012 at 08:15 PM.
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Old 03-08-2012, 09:02 PM
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dampner slippage

If the dampner is over 20 years old, trash it. It can come apart at any time... right in your face if you happen to be revving the engine from under the hood.
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  #104 (permalink)  
Old 06-25-2012, 10:28 AM
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Hey All,


Doing a follow up to the truck's driving issues. The truck has been running fine after being timed by ear last time. I was supposed to have base-timed it and report back three months ago, but a few things came up that kept me from working on it. Right now, its parked and being readied for a smog check.




----------




The truck still seems to be leaking and/or consuming large amounts of oil. I thought it was the valve cover gaskets again, but they seem to be ok. While I have not verified it, I believe the rear main seal is to blame.




----------




Two weekends ago, I did a base timing on the truck by disconnecting the vacuum advance, plugging all ports and using a timing light. The reason why the timing mark was never falling onto the marker tab was because the the distributor was turned too far advanced. I brought it down to 9*, took it for a very quick spin, and it drove just fine. That's not where I am going to leave it, but it is in a very good spot. Wasn't able to figure out how to do total timing on the timing light itself (Pugsy, if you're reading this, I can use some help since you said you have the same light as mine)




----------




I also went and head and addressed all the issues that were brought up regarding the carburetor. All results have been posted here: Post #145



Quote:
Originally Posted by cobalt327
The red cam-shaped plastic piece is the eccentric that lifts the secondary hangar/secondary metering rods in relation to the air valve opening. It has to be replaced, Ruggles has the kit, $12 to your door.
I ordered the kit from Ruggles and replaced the cam, the "tension spring" for the shaft, as well as the screws for the air flaps.




Quote:
Originally Posted by cobalt327
On thing that you have got to fix is the small hook that clips to the needle part of the needle and seat assembly. The hook does not go through the hole in the float arm. This is a common mistake, but it can cause the needle to hang up and the float level can be all over the map. So, hook it over the cross piece closest to the power piston.
Got that fixed.




Quote:
Originally Posted by cobalt327
I'd remove the epoxy. It's not doing any good and even though it can't fall into the float bowl, no reason to have it going through the engine. I'm guessing it was there for prevention's sake. If the well plugs ARE leaking get back to the forum and we can get into it further.
I completely removed it all.





Quote:
Originally Posted by cobalt327
EDIT- The air bleed that's damaged needs to be opened back up to the same diameter as the undamaged one. You can use a small pick or smooth nail if small enough to resize the opening to match the other one. Dress the air bleed tip so there's no ragged edges, just don't shorten it excessively (excessive would be more than say 0.015").
Quote:
Originally Posted by barry425
You can use an oxy-acetylene welding tip cleaner to clean up the air bleeds. Just don't get too vigorous with it, since the tip cleaners are actually little round files and will take off metal.
I used the oxy-acetylene cleaner and filed 'em clean by starting with a small size and kept increasing until I maxed out without removing any material from the tubes themselves.




Quote:
Originally Posted by barry425
I hope you sprayed the venturies to get them clean. they looked pretty nasty.
I sprayed them with carb cleaner and wiped them down with the shop towel. They seem a little better now..




----------




Quote:
Originally Posted by sbchevfreak
Is it just me, or do the "even" plugs look to be badly oil fouled? If so, I would be looking at intake gasket sealing on that side....
Quote:
Originally Posted by SSedan64
They do look oil fouled and the Spark Gap looks "HUGE" What are you gapping your Plugs at?
I removed the plugs again yesterday to see how fouled they are now and to determine if the intake manifolds need to be replaced. The truck has been driven less than 100 miles since the last time the plugs were checked (see image in post #9 here for comparison). Upon removal, the spark plugs appeared to be covered in even more oil than last time. Cylinder #1 was thickly caked in oil. But oil spots on the shop towel from the wipe down don't seem to be any worse. Any ideas? Does intake manifold gasket still seem like a concern?







----------




Quote:
Originally Posted by cobalt327
Was a compression test done on this beast? Results?
While I had the plugs out, I went ahead and did a compression test yesterday. I was doing it by myself so my procedure was to let it crank for five seconds, and record the result. I did each cylinder three times. Below are the results.

Cylinder . . . . . Test #1 . . . . . Test #2 . . . . . Test #3 . . . . . Average

1 . . . . . . . . . . . . . 165 . . . . . . . 165 . . . . . . . 165 . . . . . . . . . 165


3 . . . . . . . . . . . . . 170 . . . . . . . 170 . . . . . . . 170 . . . . . . . . . 170


5 . . . . . . . . . . . . . 165 . . . . . . . 165 . . . . . . . 165 . . . . . . . . . 165


7 . . . . . . . . . . . . . 160 . . . . . . . 160 . . . . . . . 160 . . . . . . . . . 160


2 . . . . . . . . . . . . . 160 . . . . . . . 160 . . . . . . . 160 . . . . . . . . . 160


4 . . . . . . . . . . . . . 160 . . . . . . . 160 . . . . . . . 160 . . . . . . . . . 160


6 . . . . . . . . . . . . . 160 . . . . . . . 165 . . . . . . . 162 . . . . . . . . . 162.33


1 . . . . . . . . . . . . . 165 . . . . . . . 165 . . . . . . . 165 . . . . . . . . . 165


Percent difference between highest average (170) and lowest average (160): 6.25%
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  #105 (permalink)  
Old 06-25-2012, 02:02 PM
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Compression test is excellent. You propped the carb open?

If the threads of the plugs are what's wet, that's usually from external oil getting down into the wells where the plugs live (often it comes from the v-cover gaskets). It's the color and condition of the electrodes and porcelain (wet [oil], dry/tannish [normal], fluffy/black [rich] or shiny/white [hot]) that's the main concern. If they are wet w/oil, you have a problem of some sort. Being as how the compression tested so good, I'd be looking at the PCV valve and the tranny vacuum modulator first.

If the intake gaskets are leaking from the underside (lifter valley), it's almost impossible to tell unless you had a before and after vacuum reading to compare. Lacking that about all you can do is check everything you can that might be a cause for oil reaching the combustion chambers. Work from the easiest to the hardest by the process of elimination. I'd hate to think it was still the intake gasket(s).

What if anything were done w/the valve stem seals? Do the plugs show more oily deposits on one side than the other? If so, next time before removing the plugs (or now if they're still in order and you can put a few from each side back into the heads where they came from) you can mark the top of the plug w/a sharpie to see what the position of the plug's electrode is to the exhaust valve to see if the chambers are pulling oil past the seals. This is similar to "indexing" plugs if my explanation is unclear (which wouldn't surprise me! lol).
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