Mike's "Write Stuff"
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Write Stuff

This page is just a quick list of stuff I need to add to the Shop section of my website. I get lots of good ideas for pages, and jot down notes here so I don't forget about them. Then, when I have time - and if needed when I get around to doing the work so I can take photos - I take the basic notes here and make a new page out of it.

 

TV Cable Geometry Explained

It took me forever to understand how the TV cable hookup at the carb (or throttle body for EFI) needs to work and why it is so important. Most documentation on the subject is very poor, and at best written by and for someone with about a 4th grade education. Most folks have no clue why this is so important or how to figure it all out, but it's really not that hard once you get a few diagrams together to take some measurements off of and explain it all from there. It all, um,  revolves around converting angular motion (the throttle linkage on the carb rotating open and closed) to linear motion (the TV cable moving in and out) - basically doing the reverse of what the piston, rod, and crankshaft do inside the engine - and how the distances all relate to each other. A simple animated GIF or two should make it really clear, and I can explain in simple terms why the distances are so important to get right. Way too many folks just don't get this and burn up their transmissions because of that lack of understanding.

Low Washer Fluid Sensor

This is something every new car has and it makes life a bit easier on the driver by giving them a bit of warning before the washer fluid runs out. Nothing stinks more than have no washer fluid when you really need it. Most of the systems are pretty simple - power runs form the fuse block, to an indicator light in the dash somewhere, then out to a simple "closed when fluid it low" switch in the washer fluid reservoir, then to ground. The type of sensor varies a good bit, but they all work basically the same way - the switch contacts close when the fluid level gets too low and the light goes on.

GM had a slightly different setup where the light is mounted on the washer reservoir and always on, and the sensor is blocks the light from shining on a fiber optic cable until the level is low enough. The fiber optic cable runs inside the car to the dash area and lights up an indicator of some sort when the sensor is low enough. This is RPO (Regular Production Option) CD2, and from what I can tell, it was available from 1970 up until the 80's on many different GM vehicles. I have a one I scored in a junkyard, but the sensor is trashed. I'm going to try and take it apart and figure out how to make a custom depth sensor for use in other washer systems. The really cool part is that this uses molded connectors that plug into the existing wiper connectors, so it's a total plug in setup. That's pretty cool, and now that I know what to look for at the junkyards, I can keep an eye out for this and grab 'em when I see 'em.

Low Fuel Sensor

Most of the systems I've seen use a self-grounding sensor that goes inside the tank. Once a suitable sensor is found, you need to mount it on the float support mechanism so it comes on some reasonable distance from the bottom of the tank. I have to go check out a few systems to see what works best. I do know that the early 1980 Toyota Corolla series of cars could access and remove the fuel level sensor and low fuel light assembly without dropping the gas tank - there is a small cover in the middle of the trunk or hatchback floor that you unscrew, then you remove the assembly from the top of the gas tank. Pretty slick - I might just do that to some of my other cars. It would certainly make "tuning" the low fuel sensor much easier.

Impulse/Latching Relay and "Chime Once" for Indicator Lights

A subtle but nice trick. Most sensors act like pushbutton switches - low fluid sensors in particular are prone to fluid sloshing around, so the light goes on and off when the fluid level is right at the sensor location. It's much nicer to have the indicator light come on (and issue a one-time chime of some sort) and then leave the indicator light on until the ignition is shut off. To do this, you have it wired through a latching relay so that once it comes on, it stays on, and then you hook up a chime to sound once when the connection is made.

Warning Lights Without Separate Senders

Autometer make a box to do this for 3 gauges, but I'm the sort of guy who wants to figure out how to do it for myself so I can do it cheaper and for any number of gauges. Most gauges are very simple - the sensor is a variable resistor that responds to something - pressure, temperature, fluid level, etc. - and the gauge simply shows the amount of resistance that is present against a (supposedly) calibrated dial. By creating a "magic box" of electronics, you can create a separate grounding contact that is only connected when a preset resistance is reached. You can also be really trick and put a "calibrate" mode on the "magic box" you're building so that when it is in calibrate mode, as you turn the adjustment dial, the gauge moves and you can see what the warning light "set point" will be. I know enough about electronics to know that this is possible, but not enough to know exactly how to do it. I hate knowing just enough to be dangerous. :-)

Carb Tuning

All those levers and screws look pretty intimidating at first, but the basics are pretty easy. I need to write a page about how to do a basic tune-up on any carb - how to set the idle and mixture screws for properly with a vacuum gauge and a tach.

Holley Carb 'Must Have" Accessories and Parts

Getting your carb "just right" is possible with the usual "out of the box" pieces, but after you do it a few times, you'll really appreciate a few extra pieces to make your life a lot simpler. Below is the list of stuff I bought from Jegs to tune my Holley 1850-2, in addition to the basic Holley rebuild kit I bought at my local parts store.

  • 555-15216 JEG'S Nylon Fuel Bowl Washers - Replacement Fuel Bowl Washers 10/pkg
  • 720-1511G Mr. Gasket Power Valve Protector - Power Valve Protector
  • 555-15220 JEG'S Steel Carburetor Linkage Bushing - Steel Carb Linkage Bushing
  • 132-120062 Barry Grant Fuel Bowl Screws - 2-1/2'' Fuel Bowl Screws, Set of 4
  • 510-26-113 Fuel Bowl Level Clear Sight Plugs - Clear-View Sight Plugs for Holley Carburetor Fuel Bowls Made by Holley
  • 510-20-48-1 Holley Throttle Shaft Service Parts - Throttle Shaft with Ford Automatic Transmission Kickdown Lever; Use with R1850 Carburetor
  • 510-20-59 Holley Vacuum Secondary Quick-Change Spring Kit - Quick Change Kit for 1 x 4 bbl. without Balance Tube
  • 510-34-6 Holley Metering Blocks - Side Hung Fuel Bowls; Standard Finish

This is not a complete list - I had a bunch of parts still laying around from previous tuning efforts (jet kits and spring assortments). Also, some of this is specific to the crusty old carb I bought used as a starting point (the bowl screws, Ford throttle linkage). Other "must have" items like reusable bowl and metering block gaskets ("Buna-N" is a typical trade name) were included in the basic rebuild kit. The metering block is to convert to a secondary metering block from the original secondary metering plate - this gives me the ability to swap jets for tuning. Basically, I wrote this down as a starting point for a future web page about this before I forgot about it.

Electrical System Troubleshooting to Find Bad Connections

You can use a hand-held voltmeter to tell the voltage difference between any two arbitrary points in the electrical system. Most folks use this to measure from the positive side to the negative side to indicate the full power in the system, but you can also check between two points on the positive or negative side to see the voltage drop along that wire. For example, with the engine running, if you check between the positive battery terminal and the alternator output terminal, you should ideally see 0V difference, though a typical real-world system will be up to .5V or so, and anything over that indicates power is being lost along the way and not doing you any good. Another good test is between the alternator output terminal and the power lead to a high-drain accessory such as the headlights or the wiper motor. Or from the positive battery terminal to the starter positive connection. The same applies on the ground side - checking the starter mounting bolts to the negative battery terminal can be enlightening if you have done a starter replacement and you left a lot of grime on the starter mounting pad area or on the mounting bolts. Finding and fixing that extra 1V drop in various places can mean a lot for things operating right - faster wipers, brighter headlights, faster engine cranking speeds, etc. Use the "divide and conquer" method to isolate bad connections in a wire run - compare measurements from the middle of the run to one end to find which area of the wire run the problem is in.

Orderly Fire

This comes up too often to not get a page - the different firing orders, cylinder numbering, and location of cylinder #1 are enough to drive you nuts if you work on more than one make or engine style. I have several I've had to work on, and each time I have to get used to a new engine, I find the official documentation lacking. I'm going to make a simple graphic for each engine family I can find showing the engine cylinder numbering, with a close-up of the distributor showing where each number goes plus showing the distributor rotation. I also need to include a note here about how it's not critical where #1 is on the cap, so long as the order is right and the rotor position is matched to both the actual wiring and the internals of the engine. When doing certain kinds of swaps or oddball wiring, you can sometimes get a much cleaner ignition wiring setup if you simply move the location of the #1 wire on the cap so that you have fewer wires crossing each other in weird ways.

Two important things are cylinder #1 location and distributor rotation. Not everyone put cylinder #1 in the same place! GM starts at the front drivers side cylinder for #1 and alternates side-to-side on the block so that #2 is the front cylinder on the passengers side, #3 is the next one back from the front on the drivers side, and so on. Ford starts at the front passengers side cylinder and numbers the passengers side #1-#4 from front to back, then the drivers side is #5-#8 also from front to back. For distributor rotation, some GM's (Chevy and Buick are the ones I have personal experience with) and Ford distributors rotate in different directions. Chevy and Buick rotate clockwise, Ford rotates counter-clockwise, and I think Pontiac and Oldsmobile use counterclockwise distributor rotation. And that's just for the V8 stuff - inline 6 engines, V6 engines, and inline 4-cylinder engines are often different.


Comments? Kudos? Got some parts you'd like to buy/sell/barter/swap? Nasty comments about my web page so far? You can email Mike or Debbie.

Pretty much everything on this website is copyrighted, if you want to use something, ask first.

Page last updated 01/02/2009 01:51:39 PM