Words and Photos By: Jeff Smith
If you want to learn some useful tips that will make the challenge of working on cars a little less stressful, you need to search out the people who attack this task on a daily basis. That’s what we did. For the last few years, every time we go to someone’s shop, we look, we listen, and we ask questions. The people out there doing the work are the ones turning the wrenches and rebuilding the engines and transmissions, and they are the ones who come up with these little gems — not us. We’re just smart enough to write the ideas down and pass them along. So, take a few minutes to read these short tips, and apply them the next time you open the drawer on your tool box, pull out that 9/16-inch or 15mm wrench, and go to town.
Level reasoning
Home brew
Talking torque
The reason for this multiple effort is to burnish the surface of the new nuts to the washer, or to the face of the part like a connecting rod cap. This burnishing process drastically changes the friction applied between the nut and washer. This is also true for connecting rod cap screws and head bolts. As the under-head area is burnished, the friction required to turn the nut or bolt under load is greatly reduced. Less friction means more torque is applied to stretching the bolt instead of overcoming friction.
In the case of ARP rod bolts for example, ARP specifies a torque based on using ARP’s Ultra-Torque lubricant. This lube is very stable over several tightening applications. Did you know that regular engine oil loses its lubricity over successive torque applications?
We’ve actually performed a similar test to ARP’s testing that reinforced, for us, ARP’s findings that the stretch load changes significantly even after the second application of torque. This means that if you were to torque a rod nut three times using engine oil, the actual bolt stretch would decline after the second and third applications because the friction is increasing.
The reason ARP’s Ultra-Torque is so good is that its lubricity does not change. We’ve also found outside data suggesting that as much as 70 percent of applied torque is used to overcome friction and most of that friction occurs underneath either the bolt head or the nut — not in the threads. Think about that.
Header fabrication
Crank gear calls
Flare leak fix
Khoul Tools makes a nice tool (PN P45 for 3/16- and ¼-inch tubing flares, $59.97 Summit Racing) that essentially performs this same task. The tool uses a diamond dust-covered arbor that helps seat the fittings. But on the other hand, valve lapping compound is far less expensive. Permatex sells a small tube (PN 80037) for $5.00 — and it might just do the job. A long-time engine builder named Vinny gave us that little tip.
As a bonus tip, if you’re looking at a Phillips screw that is tight and the screwdriver is slipping, dip the end of the screwdriver in lapping compound. The abrasive will drastically improve the grip strength of the tip.
Homemade tool
How to ID a 12-bolt differential
Here’s the scenario, you’re at the swap meet and a seller is offering what he claims is a 3-series 12-bolt posi, but you’re not sure. It might be a 4-series. With GM 10- and 12-bolts, the position of the ring gear carrier flange changes between 2-series gears (2.56:1 or 2.78:1), 3-series (3.08 through 3.73:1), and 4-series (4.10:1 through 4.88:1). The chart below is the distance from the ring gear face flat flange to the inboard vertical machined wall of the carrier bearing flange. The 4-series will have the thickest flange, while the 2-series will offer the thinnest. This photo is measuring a 4-series posi. Of course, if the carrier only sports 10 flange bolts, you’ll know it’s only a 10-bolt!
Carrier Flange Distance
2-Series 0.590-inch
3-Series 1.020-inches
4-Series 1.325-inches
No jumping bungie
Torque converter pattern
To determine the distance of your torque converter bolt pattern, measure from the crank centerline to the centerline of one attaching bolt hole, then multiply by two. So, if the measurement is 5.75 inches, multiplied by 2, the distance equals 11.5 inches. There are two different early GM converter bolt patterns (10.75- and 11.5-inch) for the PG, TH350, and TH400 transmissions. There is also a metric pattern for the 4L60E trans with 298mm converters that is 11.1 inches. A 10.75-inch flexplate can be modified to work with the metric converter pattern by slightly elongating the holes outward with a rat-tail file or a die grinder. Be aware that the external balance weights for 383 and/or 400c.i. small-block Chevys on some aftermarket flexplates may not clear the metric converter bolts for a metric converter. We do know that the TCI flexplate for this application (PN 399373) does clear the metric bolts.
4L60E full-face bellhousing issues
One of the very popular swaps right now is upgrading an old three-speed automatic like a TH-350 or TH-400 to a late model electronically-controlled four-speed automatic overdrive transmission. The late model electronic GM 4L60E is a great swap, but you will face a few hiccups. One is that these later transmissions use a full-face bellhousing, so the torque converter bolts can only be accessed through the starter motor. But in early Chevelles and perhaps other cars, there is insufficient room to squeeze an old-style starter motor because of the full-face bellhousing. This will require a more compact starter motor like the late model permanent magnet style starters.
Trans cooler fitting warning
All GM automatics are not created equal when it comes to the cooler line fittings. Early Powerglide and TH350 transmissions used a tapered pipe thread fitting in the case. The later TH400, TH200C, 700-R4, 4L60E, and early 4L80E transmissions including all the one-piece cases and some 4L60Es with the separate bellhousing use 1/4-pipe NPSM (National Pipe Straight Mechanical ) threads. The number of threads per inch is exactly the same, so the fittings will interchange. But NPSM threads are not tapered.
Why is this important? Most enthusiasts think NPT stands for National Pipe Taper — it does not. NPT is the acronym for National Pipe Thread. Most pipe threads are tapered. Straight mechanical threads means the female threads in the trans for the cooler lines are not tapered. Because the thread pitch is the same, it’s very easy to install a tapered 1/2-inch NPT pipe fitting into these female threads in the case. Pipe fittings will work, but tighten the tapered fitting very carefully, because over-tightening can easily crack the case, which will ruin your whole week!
In the photo, the far left fitting is a tapered pipe thread TH-350, the middle one is a NPTSM fitting from a metric 4L80E, and on the right is a typical tapered thread pipe fitting. If you are having trouble seeing the difference, then this is why this is an important thing to know. The straight thread fittings from these transmissions do not use a washer to help seal, but do thread all the way into the case, while tapered pipe threads generally leave a small portion of exposed thread.
Fragola, for example, offers an aluminum fitting that uses the correct 1/4-inch NPSM fitting with a -6 male adapter on the opposite end (PN 925137, $6.97, Summit Racing). Other companies carry similar fittings, including Summit and TCI, among others.
Another point with the later 4L80E transmissions – where one cooler line fitting is relocated to the rear of the transmission – is if you change the fitting to use AN line, make sure the rear fitting uses an internal extension. TCI sells this pair of fittings, including the extension (PN 831011, $30.97 for pr., Summit). You can expect major damage to the 4L80E if this extension is not used, because the lube is not directed properly. We’re here to help!
Torque angle
Many late model engines like the GM LS series and Ford’s Mod motors require a torque angle spec for many of the critical fasteners such as main cap bolts. In order to perform this process, you will need a specific torque-angle tool (PN OTC-4554, $15.97 Summit Racing). This is the only way to do it. The process is simple as is the tool. Let’s use the torque spec for the inboard bolt on a 4-bolt main LS engine as an example. The first step is to torque the bolt to 15 ft-lbs. With that accomplished, the torque angle gauge fits between the socket and a standard breaker bar. The small right-angle stop pin is placed against something solid to prevent the gauge face from moving. Next, zero the indicator on the gauge and then tighten the main cap bolt until the gauge reads 80 degrees. That’s it — the fastener is torqued. This does take more time than merely torqueing the bolt, but the process is more accurate. An equally important note is that torque-angle is a method of tightening a fastener, so it is not limited to torque-to-yield bolts like an LS head bolt. Torque-angle can be applied to any fastener given the proper specs, as the bolt stretch is not nearly as affected by bolt friction.
Cranking call
Carefully set the timing at 15 degrees BTDC, and take the time to pre-fill the carburetor with fuel. You can do this by using a small funnel to pour fuel through the primary vent tube. Pump the carburetor linkage until you have delivered two or three shots of fuel from the accelerator pump, then let the engine sit for about 10 seconds so the fuel can vaporize in the intake. Assuming you installed the distributor properly – it should start on the first crank.
This is ideal for breaking in flat tappet cams, and avoids excessive cranking of the starter motor while waiting on the fuel to make it to a dry carburetor. Pre-filling will also reveal any carburetor leaks that you can repair before attempting to start the engine.
Clutch release question
If you suspect the clutch is not completely releasing when you put the clutch pedal to the floor, try this quick test. With the car at rest, start the engine and push the clutch pedal to the floor. Wait around five to seven seconds and shift directly into Reverse. Do not select a forward gear first. If the Reverse gear crunches, this is a clear indicator the clutch is not fully releasing and is still spinning the input shaft. (Of course, this won’t work on newer transmissions like the T-56 with synchros in Reverse!) There are probably a dozen variables that can cause this — you’ll just have to run them down. Here’s a hint: Try the easy fixes first. For example, is the clutch linkage properly adjusted with sufficient travel to release the clutch? We’re working on a story that will run through a complete blueprint procedure for proper clutch release performance. You wouldn’t believe how many variables there are to make sure the clutch fully releases to allow the trans the shift properly. We’ve already counted at least 20.