Messages

61

Restoration / Re: Correct Bi-metal choke kit

« on: May 08, 2014, 07:17:02 PM »

I'm no mechanical engineer, but I do know that ALL bi-metal springs contract with cold and expand with heat. As a matter of fact, everything in the universe contracts with cold and expands with heat. That's just physics.

I believe the differences between the two types of springs (Rochester -vs- Holley) is the way their made (?)

Bi-metal coils consist of two strips of different metals, which expand (or contract) at different rates as they are heated (or cooled), welded together back to back. (That part I'm positive on!)

(Here's the part I'm not so sure of) The metal that expands faster is on one side of the strip for one type of coil and on the other side of the strip for the other type of coil (?) This would make one coil move down when heated and the other move up when heated and vice versa, but again, I'm not sure if this is actually correct.

I'll see if John or any of the other guys can add anything to this.

Ed

Ed, I guess I phrased my question wrong.  I was wondering why a manufacturer would make a spring that would contract with heat rather than expand, not why that would occur.  I understand that everything expands with heat but when you bend a piece of bi-metal into a coil it depends on the direction it is bent (with or against the metal that expands more with heat) that determines how the coil behaves when heat is applied.  With respect to the end of the coil (which is all we care about here in moving the choke linkage) the up or down direction with heat can be controlled by just flipping the spring over as in either of your Q-Jet vs Holley drawings.  If either of those springs is wound the other direction they will behave the wrong way unless flipped over again.  As I posted above, I have 2 springs that act differently when heat is applied. Both could be made to work for either a Q-Jet or Holley simply by removing them from the bracket and re-installing in the opposite orientation as Mike S. and I did.  The only reason, I'm belaboring this is because, like the original poster, I was scratching my head when I bought and installed the new spring because I assumed they all expanded when heated.

62

Restoration / Re: Correct Bi-metal choke kit

« on: May 08, 2014, 05:48:38 PM »

That's because I just used Photoshop to copy and edit the two drawings. It's not "true to life", just a representation showing the movement of the coils.

Ed

OK.  I'm sure I overanalyzed them because of my mysterious reversing coil.  Any idea why some contract and some expand with heat or is there a manufacturer out there selling reverse contracting springs?  I guess I could speculate that some manufacturers solve the Holley vs Q'Jet difference with the spring orientation and some with the spring movement direction when heat is applied.  I checked and I did buy a Q'Jet spring and it was clearly on backwards.  It now matches the first drawing on the left side.

63

Restoration / Re: Correct Bi-metal choke kit

« on: May 08, 2014, 05:20:36 PM »

On my one 67 BB, I had a replacement choke coil and it was opposite in operation.
You can slide the coiled ribbon spring off its shaft and reverse it on the and get it to work opposite.
It's a snug fit but it does slide off.

I recently replaced mine and after installing it correctly it was moving the wrong way as it heated up.  I compared it to the one I replaced and warmed each with a lighter and one contracted with heat and one expanded even though they were oriented the same way.  I corrected the new one I had by doing exactly what you did but I did have to bend open the frame a bit to get it out.  BTW, I've studied those drawings in Ed's post above and something's not right because both the Q'Jet and Holley springs are reversed in the hot position compared to the cold exactly as if they had been removed and flipped over like we did.  (look at the curl on the end of the spring in the drawing to see what I mean.) I didn't know about the Holley vs. Q'Jet difference so thanks Ed for explaining my mysterious reverse spring. But clearly there's two issues here.  One is the Holley vs Q'Jet difference which is solved by the spring orientation but the other is that the bi-metallic spring, depending on how it's made can either expand or contract with heat. So you have to know both to get the spring moving in the right way for the application.

64

Originality / Re: Early '67 a/c compressor decal?

« on: March 20, 2014, 11:23:20 AM »

Maybe not a perfect solution, but why not splice an orange bottom onto the correct dated green one you have now?  The bracket almost makes them look like 2 different stickers anyway (which, I'll confess, I thought they were).

65

Originality / Re: Early '67 a/c compressor decal?

« on: March 20, 2014, 12:04:38 AM »

Steve,

Not quite as early as you want but my '67 02B car has the orange lettered Caution with Model No. 6550133 and code no. 011771

Mike

66

Restoration / Re: Mult-Leaf Springs or Single for 1967 L30M20? - That is the question.

« on: February 12, 2014, 01:02:56 PM »

Thanks Kurt and Gary for the explanations.  It's not as simple as "more is better".

67

Restoration / Re: Mult-Leaf Springs or Single for 1967 L30M20? - That is the question.

« on: February 10, 2014, 04:30:18 PM »

Monoleafs are inherently superior to a multileaf.
But there were some design issues in the rear suspension that forced them to switch to multis for higher hp engines.

Kurt, Can you elaborate on monoleafs superiority? For a car not subjected to wheel hop what are the advantages to not going to multi leaf?
Thanks, Mike

68

Decoding/Numbers / Re: I need information on my 68 camaro please

« on: January 27, 2014, 09:19:27 PM »

Did RS cars get 3.08 also for '67?

Yep. For 67 and 68, the LF7 and L30 (with Powerglide) received the 2.73 10 bolt axle unless the car also had the RS option. If it did, then it received the 3.08 10 bolt axle.

Ed

Thanks Ed.

69

Decoding/Numbers / Re: I need information on my 68 camaro please

« on: January 27, 2014, 07:22:19 PM »

You can rule out the Rally Sport. For the base LF7 (327/210) and the optional L30 (327/275), the BP axle (2.73) came on non-RS cars. (RS cars got a 3.08.)

Did RS cars get 3.08 also for '67?  The BP axle code on the chart here shows 3.08 in '67 but changing to 2.73 in '68.

70

Decoding/Numbers / Re: Console/Gauges VIN Decode

« on: January 14, 2014, 10:21:22 PM »

In 67, the tag only tells if equipped with a console.
U17 was available on any V8.

Gotta look at the wiring to tell if it had gauges originally.

An old post I know, but this is the exact mystery I'm trying to solve.  My firewall has no hole for the oil line gauge but the trim tag indicates console and I have a low fuel light at the speedometer.  What exactly about the wiring should I look for to determine if gauges were original?  Yellow low fuel sending wire or something else?  Also is there any precedence for an early February '67 car (327 automatic with AC) to have the oil pressure line routed through the grommet in the corner of the firewall behind the power brake booster? Could this be an anomaly chalked up to human error or corner cutting?  Again, there is no hole in the firewall where it should be, just a dimple.  There's a 1/8" hole low on the firewall behind the distributor.  I've read what I could find here and at TC about the grommet vs. brass fitting and when that was changed over and this car is squarely in the midst of that time period but nothing I read clears this up.