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Unread 08-03-2012, 04:04 PM   #16
Dadamsnv
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Quote:
Originally Posted by 1SASjeepster View Post
Dadamany,

I read where you cleaned your spark plugs with brake cleaner. I know it would probably never happen in a spark plug situation at least not enough to get you BUT I will tell you this anyhow. Brake cleaner and high heat create PHOSGENE GAS. It is a very deadly chemical weapon that only one whiff of it is enough to destroy your lungs for life. One whiff, not one full breath, just one whiff. A welder used brake cleaner on some parts because he ran out of degreaser and didn't want to go to the parts store. He was in a greatly ventilated garage. He began and was out. He got to the hospital and he has been going weekly for breathing treatments because his little whiff destroyed most of his lungs. It is something to think about.

I understand the spark plug is in the cylinder and exhaust gases flow out through the exhaust pipes BUT there are instances in a mechanics life when the gas mixture backs up and goes out through the carburetor. Be careful.

Take care,
YIKES!! I wish I knew that BEFORE I did it!! goodness!

If I ever write a book on tips for how to not kill yourself, that will most definitely be included.

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Unread 08-03-2012, 04:28 PM   #17
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Having said all of that jazz about main jets, I was running pretty quiet, sluggish, but smooth, so I pulled my old #80 main jets and swapped them with #79s (one step leaner). I didn't bother to test drive it (this was a few nights ago, I'm about 4 days behind), because I was so cocky about having the "feel" for mixture tuning. So, upon starting the jeep, two big splotches of black, wet, fuel coughed out of each exhaust pipe (running duels), and I knew something bad was happening, but I drove it anyway. I was blowing clouds of black smoke on the way to work, and had no power at all, but idle was just fine and dandy. I had a massive stumble off the line as well. It would start to go, stumble, go fine, then cough its brains out. At work, I did a little thinking, and realized I didn't reassemble my accel pump arm when I put the bowl on after changing the jets. Duh! over my lunch break, I headed down to the jeep, popped the hood. drained the bowl into a solo cup, pulled the bowl off, and fixed the arm, no problem. I went to grab the cup, and it had turned to a pile of gooey melted plastic. A lesson to everyone: red solo cups may do well with alcohol, but not gasoline!

I knew this would only fix the stumble off the line, and I was pretty sure that I messed up the main jets somehow. I figured either they were mislabeled, or one fell out, or some goofiness. I drove to lunch to test it out again, and the poor thing coughed and sputtered so bad, and the plugs loaded up so thick, that I was getting slower and slower. I knew I wasn't going to make it home later. I remembered it ran better with a base timing of 13* as set by the vac gauge, and I just so happen to have my vac gauge and a 9/16" ratchet, so I pulled over in the McDonald's parking lot, popped the hood, plugged the vac advance, and timed the base with the vac gauge like I did before. I then proceeded to enjoy a medium #13 (the thought of bad luck didn't even cross my mind until now) and drive home. I made it the 10 miles home... BARELY. I had my flashers on and I was doing 20 max in a low RPM to keep the mixture a little towards the idle/leaner side. She died 20 yards from the garage. I begged her to start, and I used my granny 1st to put her away.

I called work, told them what happened, and came back in with the truck to finish the day.

Later that night, I pulled the jets and compared them to my 80s. Sure enough the 79s were way way bigger... like a fuel firehose. I took another good hard look at the old jets, and I figured out that they were 60s I put them back in, retimed the base to 8* and put new NGKs in her. It was back in business after burning all the crap out of the pipes.

The next day I bought 59s and 58s at summit.
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Unread 08-03-2012, 05:27 PM   #18
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Okay, trying to play catch-up here. I put the 59 mains in last night, and also put the timing tape on and took a centrifugal advance curve.

I popped in the 59s first. Changing jets on the Holleys is very easy...

1: pull either bottom bolt to drain the bowl. Use some towels and a little fuel catch undet the bowl.
2: undo the other three bolts and pull off the bowl. The metering block (has idle screws in it) may come off as well. no big deal.
3: jets are visible at this point in the bowl side of the metering block. Take them out.
4: put new jets in. DONT PUT THEM IN SUPER TIGHT! Jets only need to be snug. They seem to tighten themselves down over time.
5: reassemble bowl making SURE TO PUT THE ACCEL PUMP ARM UNDER THE SPRING LOADED PUSHER BOLT this time.
6: fill bowl with fuel.
7: done.

After a short time, the fabric seals on the bowl bolts tend to tear up, use this part to fix that.

http://www.summitracing.com/parts/HLY-108-98-10/

or

http://www.summitracing.com/parts/MOR-65225/

Then I put the timing tape on. I used an electrical wire to gauge the circumference of the harmonic balancer, and then did some math to figure out the diameter of the harmonic balancer so I could figure out which tape to use. I then did some extra math to figure out how much influence the wire thickness had on the circumference measurement to double check I chose the right timing tape.

I'm curious how accurate the timing marks on the timing cover are on these motors. I'm sure I did the tape measurement right, and I'm sure I got the right tape on there, and I got the 0* on the tape and the balancer lined up, but, according to the tape, I was sitting at about 12* advance when I thought I was at 8* :/ Not sure what thats all about. At least with this tape, if it is slightly wrong in the end, I will still get a good idea what changing centrifugal timing elements does for the overall curve.

Charting the timing curve was nice and easy as well. All i did was set the GF in the cab while I adjusted the idle adjust screw to reach 200 RPM steps from 800 to 2600, which she verified from in the cab (the sunpro has 100 RPM gradients so that was easy), and the I wrote down the timing, for each step. I had the vac advance plugged off for this test so I could isolate exactly what the centrifugal was doing.

Then we went to sonic burger and enjoyed the added power and exhaust noise from the leaner jets
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Unread 08-03-2012, 06:28 PM   #19
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I forgot to mention, when I had the main jet mishap, I was getting 2-3 miles per gallon
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Unread 08-04-2012, 01:00 AM   #20
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Since I have a decent base tune, I decided to take a PTC (partial throttle cruise) vac reading to determine what my power valve should be. Cruising on a flat road at 55, my vac reading was 12 in Hg. Since I will be wheeling this rig, I decided to go with an 8.5 in Hg power valve. Jeephammers advice is to use a power valve 3 in Hg less than PTC for wheeling, but I went with 3.5. This helps those hills and starts a bunch! Especially considering the one in the Holley rebuild kit was a 4 in Hg!!!

I didn't get pics but the power valves come with gaskets, and they screw into the Venturi side of the metering block. Super simple.
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Unread 08-05-2012, 12:08 AM   #21
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So this is how today went: wakeup, ponder what to change with my tuning, get a call from my buddy that his bike broke down, hop in the truck, throw the bike in the truck, go to shop, deal with shop papers, go to breakfast, drop friend off, get a call about mom's surprise BBQ, pick little brother up for BBQ, drive keep for 1 hour with bro, hip in car, go to BBQ, day over.

Needless to say, today got totally waylaid. I had fun with the bro, and at the BBQ, but I was hoping to get pretty far today.
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Unread 08-05-2012, 01:00 AM   #22
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However, I was able to play with the centrifugal timing quite a bit yesterday, and now that I'm done preaching about base tuning, and jet tuning, here comes the fun stuff.

I bought an MSD HEI weight and spring kit [pic 1] and installed it

I had to remove the distributor cap. Under the cap is the rotor [pic 2]. Two little screws take the rotor off. Under the rotor is the spring and weigh setup [pic 3]. Next the springs come off. I used needle nose pliers for this BE GENTLE [pic 4]. With the springs removed, the weights slip off. Next snap the "E" clips off of the center plate (don't lose them!), and pull it off. All the parts should now be loose. [pic 5].

Reinstall the new parts in the opposite order. This is where I ran into problems. The MSD kit is supplied with three bushing sizes to fit the weights on the distributor. None of them fit my setup. I had to drill out the bushings to make them fit. I figured it was a loss at this point, but I went with it anyway. The kit came with three sizes of springs also, and I used the ones that most closely resembled the ones I had in before. There is a very significant quality difference in the MSD setup over the stock unit (most likely a summit brand unit) [pic 6]. [pic 7] shows the new kit installed. After finishing the install, I ran a new curve [pic 8]. This curve kicked in way late and had low maximum. Also, the RPMs shot up from 1800 to 2100 at the slightest change of the idle adjust screw. So I ditched that setup, pulled it all apart , and popped in one lighter spring an left one previous spring in and reran the timing curve [pic 9]. This curve came in earlier than the last, but still behind stock, but the max advance was still way too low. So I ditched the MSD setup all together

I went back to stock, and used one stock spring and one of the lighter MSD springs. Upon changing the center plate back to stock, I shot one of the tiny "E" clips across the face of the earth. That's why I call them Jesus pins. It's the only word I can muster when they shoot into the next dimension, or wherever they go. I was able to find one that was left over from my carb rebuild kit though [pic 10].

My final timing curve of the day was pretty good, the adv started nice and early, and went up to a pretty high amount [pic 10]. I hopped on the rig, and did some really hard takeoffs and 0-60s (with no timer) and had no detonation. I gained a TON of responsiveness and power from this new timing curve, and the jeep totally rocks now. I'm not sure I will drop to both light springs, I think this will start the curve climbing at around 800 RPM, and that may be too much. I will also plop in the #58 mains tomorrow or the next day.

I left my computer at work, so I apologize for no excel graphs, but the numbers should do for now.

Tomorrow, I will be scuba diving all day.
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Unread 08-05-2012, 01:01 AM   #23
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Quote:
Originally Posted by em2mccue
This is what I will be doing this weekend. So I guess I hope you have to get everything done on Saturday during the day. That way I can read it Saturday night and do it Sunday. Cause I need as much help as I can get. Good Luck.
I hope what I did so far helps you out! I didn't get as far as I wanted, but right now my motor runs freaking good compared to last week!
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Unread 08-05-2012, 05:34 AM   #24
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Those recurve kits usually reduce total advance to 15 degrees instead of the factory 20. For big cams that need 18at idle to keep them happy. That way they still get their 34 to 36 total without too much timing on top or too little down low.
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Unread 08-05-2012, 07:32 AM   #25
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Great thread idea


Shawn
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Unread 08-05-2012, 08:04 AM   #26
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You mentioned in an earlier post that you wanted or was going to research what a vacuum gauge can tell you. Here is what I use...

Take care,


When using the gauge, hook into a good port directly off of the intake manifold. Any competent engine should be running between 18-22 inches of mercury.

(1) The vacuum gauge can be used to check for a leak in the valve train, intake manifold or head gasket. With the engine at normal idle and at operating temperature, hook up the gauge. Normal operation would have the needle/ pointer holding steady and not fluctuating. If the needle holds steady, than drops an inch or more, and then returns again to normal, and repeats… this signals one or more engine valves are closing but not seating properly, thus creating a leak. Each time the valve doesn't seat properly, the pointer fluctuates. The fluctuation isn't much, maybe 1-3 inches of mercury.

(2) If the pointer drops sharply 5-10 inches from normal, and then returns… this signals a cylinder head gasket. This behavior will repeat itself. If the leak is between two adjacent cylinders, the leak will be more pronounced.

(3) If the pointer/ needle fluctuates constantly at a reading of 3-8 inches of mercury BELOW normal, It indicates intake system leakage.

(4) If you think you may have a "back pressure" issue, get the vehicle at normal operating temperature and slowly bring engine to 2,000 rpms. Close throttle quickly. If no back pressure is present, the pointer will jump past your normal reading and smoothly return to normal, just as fast. If it is slow or uneven return, there is an issue of back pressure. You can also test it another way… hold the engine at 2,000 rpms and watch needle. If it begins to decrease gradually instead of holding steady, there is an exhaust restriction somewhere.

(5) Continuous pointer movement an inch of so above or below normal indicates the need for further checking of the ignition system with electrical test equipment. You may have a weak ignition coil, high tension cable leaks, bad distributor cap, bad spark plug or incorrect spark plug gapping.

From "Petersen's Basic Tune up and Test Equipment."
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Unread 08-05-2012, 10:36 AM   #27
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Quote:
Originally Posted by 86cj74.2L
Those recurve kits usually reduce total advance to 15 degrees instead of the factory 20. For big cams that need 18at idle to keep them happy. That way they still get their 34 to 36 total without too much timing on top or too little down low.
That makes a ton more sense now, thanks

Too bad summit didn't know enough to inform me of that. But at least the springs were useful.
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Unread 08-05-2012, 10:37 AM   #28
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Quote:
Originally Posted by swatson454
Great thread idea

Shawn
Thanks man
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Unread 08-05-2012, 10:38 AM   #29
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Quote:
Originally Posted by 1SASjeepster
You mentioned in an earlier post that you wanted or was going to research what a vacuum gauge can tell you. Here is what I use...

Take care,

When using the gauge, hook into a good port directly off of the intake manifold. Any competent engine should be running between 18-22 inches of mercury.

(1) The vacuum gauge can be used to check for a leak in the valve train, intake manifold or head gasket. With the engine at normal idle and at operating temperature, hook up the gauge. Normal operation would have the needle/ pointer holding steady and not fluctuating. If the needle holds steady, than drops an inch or more, and then returns again to normal, and repeats… this signals one or more engine valves are closing but not seating properly, thus creating a leak. Each time the valve doesn't seat properly, the pointer fluctuates. The fluctuation isn't much, maybe 1-3 inches of mercury.

(2) If the pointer drops sharply 5-10 inches from normal, and then returns… this signals a cylinder head gasket. This behavior will repeat itself. If the leak is between two adjacent cylinders, the leak will be more pronounced.

(3) If the pointer/ needle fluctuates constantly at a reading of 3-8 inches of mercury BELOW normal, It indicates intake system leakage.

(4) If you think you may have a "back pressure" issue, get the vehicle at normal operating temperature and slowly bring engine to 2,000 rpms. Close throttle quickly. If no back pressure is present, the pointer will jump past your normal reading and smoothly return to normal, just as fast. If it is slow or uneven return, there is an issue of back pressure. You can also test it another way… hold the engine at 2,000 rpms and watch needle. If it begins to decrease gradually instead of holding steady, there is an exhaust restriction somewhere.

(5) Continuous pointer movement an inch of so above or below normal indicates the need for further checking of the ignition system with electrical test equipment. You may have a weak ignition coil, high tension cable leaks, bad distributor cap, bad spark plug or incorrect spark plug gapping.

From "Petersen's Basic Tune up and Test Equipment."
This info is perfect for this thread. Thanks a bunch
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Unread 08-06-2012, 10:51 AM   #30
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I don't know if I mentioned this earlier, but even though my new tuning rocks (not done with it yet!), I have a huge blip at 800 RPM that makes my takeoffs pretty lame. Its not a power valve thing, because when I'm wheeling and I put the RPM at 800 steady, it chugs and bumbles even on a flat surface, but as soon as I push the pedal, the accel pump and, depending on how hard I push, the power valve take it right out of the chug. I feel like it is my base timing advance.

Having said that, I did some research on timing at altitude (I live at 5000 ft) and found that you can advance the base timing quite a bit at this altitude. The rule I found, but I'm not sure I can really trust it yet, is you can increase timing 1* per 1000 ft. This would put my new base timing at 13*. And, what do you know, that is almost exactly where my vacuum gauge base tuning was set.

So, I RETRACT MY PREVIOUS STATEMENT ABOUT VACUUM TUNING THE BASE ADVANCE. I will reset my base timing using my vacuum gauge, then report what that value is. I will hopefully do this tonight.

I also ran across the subject of octane rating in tuning the vehicle's timing. I'm using 91 octane all the time, and that allows me to even further advance my timing, but I think I will tune the timing for 87 octane to keep the jeep safe. I don't need racecar tuning, I just need a really good/golden DD tune.
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