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Posts posted by WayneC

  1. Here's a whitewall in 205/75-15 that looks nice, but not highly-rated:

    http://tinyurl.com/leuyd5z and http://tinyurl.com/qyse9h7

    If you can stand blackwalls...


    And, 215/70-15 is also a possibility (I use them on my 1971 Avanti)

    http://tinyurl.com/mejr956 (whitewall, low price and highly-rated)

    http://tinyurl.com/l3lafww (whitewall, but not highly rated)

    http://tinyurl.com/2esycue (blackwall)




    On the links above that go to TireRack, click on the "Surveys" and "Reviews" tabs near the bottom of the page to see how users rate them in various ride categories.

  2. Anyone know of a source for the "proportioning valve" below the brake booster (or specific info on what other vehicles used that same "valve")?

    Actually, I do not think it is a proportioning valve, but rather a junction block with a switch that activates a dashboard light if pressure is lost in either the front or rear brake lines.

    I found some Chrysler and Corvette junction blocks on eBay that are quite similar to the one on my '71 Avanti, but they are not exact matches.

    Update 2/2/2015: it appears to me that the junction block is most likely a match to the '68-'69 Camaro block (Camaros got front disk brakes with the Z28 option in late 1967).

    I haven't ordered one to check it to see if pipe threads are a match, but it looks very much like my '71 junction block.

  3. Here is some info I've collected in the past (I don't really know much about the industry standard numbering system, and it's possible even the standard numbers have changed over the years, but a good brake supplier/distributor can probably make sense of them, even ones that changed):

    rear brake shoes: Industry standard #173 through 1971 Avanti serial 1661, Industry standard #228 after serial 1661 (but I also have conflicting info saying all '63-'83 Avanti's have a Spicer 44 axle and use EIS #ES449R shoes)

    rear wheel cylinders: 78-86 Ford Fairmont wagon, or 62-63 Mustang & 73 Fairmont sedan, or Wagner F37782

    rear springs & other hardware are 66-73 Jeep CJ with 11" drums: EIS# H7137

    rear brake flex hose: NAPA #11146 or EIS SP948

    I expect the Avanti parts suppliers may be the safest source.

  4. Not an expert here, but the serial numbers may denote differences in adjustments made at the factory, jet sizes, and differences in the throttle linkage and/or an extra vacuum port to accommodate a method of downshifting the automatic transmission when you stomp on the gas pedal (like a throttle valve cable).

    Also, when a car maker produces many thousands (or millions) of cars, minor differences between carbs can save them money by eliminating things not needed on some models, like extraneous vacuum ports, while providing those things on other models.... so for example, a carb intended for an automatic may come from the supplier (ie, Rochester or Holley) with a cable clamp on the accelerator linkage that is not present on the otherwise identical manual trans carb, which has an empty hole where that clamp would go (may be a bad example, the clamp might come on the transmission cable assy instead, or the hole may be absent on the carb intended for a manual tranny).

    I suspect a carb meant for a car with an automatic transmission can probably be used on the same model car with a manual transmission, but the opposite could be problematic. It should be possible (don't ask me how, though) to find the specs for jets/accelerator pump, float levels, choke, etc and purchase correct parts for the carb variation you choose, thereby transforming that carb to match the specs of the carb that was originally used on the car you have.

    Each new model car is tested exhaustively and tweaked/altered by carb experts to get best balance of driveability and economy under many driving conditions before the car goes into production. If the tuning items are anywhere close to correct, most of us would never know the difference (we'd just ignore the stumble that only occurs when we goose the throttle while going about 45mph up a hill). A Rochester carb for a Silverado probably needs very different calibration than one for a Chevy Nova, even though the same basic 4-barrel carb model is used for both, and both vehicles may have a 350ci engine. If you buy a carb with different serial numbers than the one used on your car, you ARE the carb test engineer, since the carb was not tuned/configured specifically for your vehicle.

    Carburetor overhaul companies, like recarbco ( http://www.recarbco.com/) can probably find the correct carb and/or rebuild yours to factory specs based on the serial number. I had them rebuild my '71 Avanti carb some years back and was pleased with the work.

  5. You said: "So today i moved the accelerator pump linkage from the middle spot to the top. It made the car bog a little, and if I blipped the throttle it would almost die before regaining idle. So i went to the bottom hole and it got better off the line. But still not perfect."

    ...I thought I understood that when I read it, but on re-reading I am not certain I did... is the "bottom hole" on the lever closest to the carburetor pivot point or furthest away? I expect the hole closest to the carb pivot point gives the earliest & longest squirt.

    If the bottom hole was best (furthest from the carb pivot point), that would give the softest squirt, but that still apparently wasn't soft enough. Am I understanding correctly that you had the best result with the rod in the furthest hole from the carb?

    Did you adjust the idle mixture in accordance with the Edelbrock pub? (see "Idle Mixture" on page 6 of the Edelbrock manual linked in my prior post).

    Out of curiosity, have you tried simply removing the linkage rod (to the accelerator pump lever) for a test?

    In perusing the manual I linked in my prior post, it appeared to me that it is possible to change the jet size for the accelerator pump, although that manual does not list other available sizes (there is a chart showing the accel pump jet size that comes standard in each Edelbrock carb type, and the 1405 uses the smallest/leanest size). Can you see a strong fuel stream from the accelerator jets when you blip the carb linkage off idle in the garage?

    A vacuum leak can give similar "stumble" symptoms at low rpm, so you might check for gasket leaks or loose vacuum hoses.... Vacuum leaks usually result in an uneven/rough idle, too, but not always, because you may have masked that while adjusting the idle. You can use a propane torch (valve opened a bit without lighting it, and pointed away from the carb, air cleaner removed) as a method of finding leaks, by directing the propane flow closely and slowly around the seams at the base gasket of the carb, around the outer edges of the intake manifold, along vacuum hoses, etc, listening for the engine idle rpm to increase noticeably when the propane stream passes a leak. Do it outdoors so the propane gas doesn't collect in your garage

  6. I don't have much sweet knowledge to lay on you, I've never played with an Edelbrock carb.

    But, it seems to me you are on the right track with the accelerator pump, considering the car seems to only have an issue off a dead stop. I would not fool with those metering rod springs until you get the stumble fixed.

    You might check to make sure the choke is properly adjusted.

    4 degrees advance timing at idle (with vacuum canister vacuum hose disconnected and plugged) should be fine.

    Is your idle set at 600 to 700rpm in drive, engine warmed up, tranny in Drive, with the brake on?

    There are a number of Edelbrock carb tuning videos on youtube, have you perused those?

    And, do you have this:


  7. I can't tell you much about the differences, except to say that all quadrajets are not the same, even for the same make and model car. There are many variations, even among Corvettes, because the carbs were tuned/tweaked by engineers from Rochester for the specific vehicle configuration during extensive driving at the GM test track prior to production. Variations include transmission type, jetting and adjustments, mixture rods, type of choke, fuel entry point, vacuum take-offs, etc, and I recall that some early smog-era carbs (1973 and later) even had plastic caps over the mixture screws that had to be broken to change the mixture (so smog station inspectors could spot carb-tuning violators). The stamped number reflects all the specifics of that particular variety. I never associated better gas mileage with post-smog carbs; my recollection is that mileage degraded rather than improved, as did driveability, but much of that may have been attributable to added smog equipment rather than the carb itself.

    I will try attaching some photos of my carb, as it looked when returned by the rebuilder:


  8. My 1971 Avanti (T400 trans) carb reads 7028208 DB.

    The "28" says it is a 1968 ("41" would be 1971); this carb would have been correct for a 1968 Corvette (Avanti Motors used base Corvette engines).

    I believe it to be the original carb, but I'm the 2nd owner of the car (purchased about 1979). I did send the carb away for rebuilding in 2006, and I was unable to find any old records to determine whether I'd recorded the number I found on it before I shipped it to the rebuilder... I seem to recall that I sent it out because it had a leaking/stripped fuel filter inlet (I normally rebuild my own carbs), and I did find an email from the rebuilder referring to having tested my carb on a test engine and that the filter housing helicoil didn't leak during the test, which bolsters my belief that the carb returned to me is the same one I sent him.

    This link has a code breakdown that might be helpful:


    Corvette carbs (base engine with automatic trans) for:

    1968... 7028208

    1969... 7029202

    1970... 7040202 (and later in the model year: 7040212)

    1971... 7041212

    Probably any of the above would work fine.

  9. I've not done the repair, but there is some good info on Bob Johnstone's website:


    Also, I copied info posted by "Billy" some years back about repairing the separation of an '87 Sky Top moon roof,

    and made a Word document from that. I cannot find anything on this forum now on that subject.

    I'm a bit uncomfortable about posting something here that was written by another forum member.

    Click the Avanti photo to the left of this post and send me a personal message via this forum with your email address and I'll send you that 284kb file.

  10. Not necessarily.... when Stude went out of business they still had a large parts stock, probably ordered in large lots for expected mass production. Altman bought the factory and the parts along with the rights to produce the car; there may well have been enough parts to last for many years.

    The Avanti power window switches of the 60's and 70's (maybe even early 80's) were also Ford parts, used on T-Birds.

  11. For backspace, if 4 1/2" backspace fits, worst case you'd need 1/4" spacers on the wheel studs, which isn't optimum, but might

    work. Stock wheels were 3 3/4" with 6" rim, Magnum 500 wheels were 4 1/8" and later wire wheels were 4", I think.

    But, it seems to me the wheel width is an even more serious issue, as it may very well rub the wheel opening lip in the front, not to mention the frame, during turns, especially if you hit a bump at the same time.

    Just for the heck of it, I went to the Coy website and didn't find a 19" wheel in that C67 style.

    Here is a writeup done about wheel fitting, but it doesn't directly answer your question...


  12. To get #7 (closest to firewall on driver side) I jack up the left front and with my upper body positioned below-left of the belhousing, I use a spark plug socket with a hex end (at the rachet end), placing the socket on the plug by hand and using a box wrench to turn the socket (ratchet box wrench would probably work even better than a regular box wrench, can't remember if I tried one). Remove the socket as soon as the plug loosens and turn it out by hand.

    IIRC, I get #5 and the others from the wheel well by using a long extension on the ratchet.

  13. Have a look at this Corvette forum thread:


    In addition to recommendations on chemical strippers, there is a link to a video showing razor blade stripping,

    which has lately become a common method.

    A Google search returned these paint references:



  14. You sound as though you know a bit about carbs... have you tried looking down the primary throat while jazzing the throttle linkage? You should get immediate strong double streams of gasoline squirting into the throat when you pull the throttle linkage.

    If not, the accelerator pump is bad. That's a pretty simple fix. You can purchase an accelerator pump separate from an entire rebuild kit, but it does require removing the top of the carb, and it's easy to drop bits & pieces into the intake manifold, so best to remove the carb and make the fix off the car; it's also possible to break/ruin gaskets when disassembling a carb that's been installed for some time.

    Have a look at this link: http://www.camaros.net/forums/archive/index.php/t-67610.html

    If you are mechanically inclined, it's fairly easy to do a complete rebuild on a quadrajet with instructions that come with the kit, and there are websites that have instructions, even videos on youtube; for example...


    I rebuilt the quadrajet on my '80 last year, using a kit from this vendor:


    Unfortunately, the website I referred to for rebuild instructions is no longer available, but generally the instructions that come with a rebuild kit are sufficient. Take a lot of digital pics as you disassemble the carb, in case you need to refer to them later.

    Be especially careful removing/installing the fuel inlet tube fitting, because the large, fine-thread fitting is easy to cross-thread and if you chew up the threads on the carb body, there's no easy home repair to fix that.

    Here are some quotes from a Corvette expert ("Lars") in 2002 regarding problems he's seen with Q-jets stumbling off idle:

    Jammed accelerator pump check ball
    Results in: Off-idle stumble or hesitation, hard cold-start.
    Comments: This is a common problem in carbs that have been allowed to “dry out” for a while. Sediment in the bottom of the fuel bowl will lock up the check ball as if it were set in concrete. This will prevent any accelerator pump discharge.

    Accelerator Pump Rod Installed in Wrong Hole in Pump Arm
    Results in: Off-idle stumble or hesitation.
    Comments: There are two holes in the accelerator pump lever arm for the lever arm rod to engage into: Inner and Outer. The outer hole produces a leaner pump shot, and can cause a lean stumble on engines requiring a robust pump shot. Corvettes and performance cars always used the rich, inner pump arm hole.

    Jammed accelerator pump
    Results in: Off-idle stumble or hesitation, hard cold-start.
    Comments: This is becoming a common problem. The alcohol additives in modern fuels are not compatible with the materials used in many accelerator pumps (even some of the pumps in brand new carb kits). This causes the pump plungers to swell up and to seize in the pump bore. The spring on the pump shaft still allows the shaft to move up and down, making it look as if the pump is functioning. But the pump itself can be seized up solid in the bore with the shaft working just fine. To fix this, you must install a pump that is specifically compatible with alcohol.

    Worn accelerator pump
    Results in: Off-idle stumble or hesitation, hard cold-start.
    Comments: Common on older carbs and on carbs that have been allowed to dry out (vehicles stored without being started through the entire winter season). The rubber plunger material will dry out and shrivel up, making the accelerator pump completely ineffective. The pump must be replaced.

  15. I've not done this type of repair, but I also own a Corvette and I frequently peruse Corvette forums.

    Recommendations depend on what areas are separating... around the edges, or the center cross-bracing.

    Corvette hoods are produced as 2 panels (inner support structure and outer skin panel);

    in this case those 2 panels are bonded at the factory with a bonding adhesive at the hood perimeter, and with scattered "gumdrop" spots of bonding adhesive between the center cross-bracing and the underside of the hood skin.

    I know this one is generally recommended for full-surface bonding of panels on early corvettes (outer perimeter of hood):


    Others can be used:

    Ecklers bonding adhesive: http://www.ecklerscorvette.com/catalogsearch/result/?q=bonding+adhesive&x=0&y=0

    West System epoxy & hardener: http://tinyurl.com/2vfxxul

    On the center cross-bracing, the failing gumdrops are removed and surface remnants sanded off completely; these are recommendations for gumdrop replacement adhesives:

    3m 5200 marine adhesive

    a variety of Liquid Nails adhesive in a caulking gun tube that says it is for use with fiberglass)

    ask local automotive paint supplier for a quality "hood gumdrop adhesive"

    3M black urethane windshield bedding compound

    Thorough cleaning/sanding of mating surfaces is particularly important underhood, because oils and fuels may have contacted the surfaces.

  16. It might be worth pulling the brake shoes on one side and installing the drum to see if it will rotate without the shoes. I know you said the drums slide over the shoes with just slight friction, but this is a fairly easy test to confirm the cause is definitely not the shoes. (it just doesn't seem likely that both drums would suddenly start rubbing on the backing plates just because they were R&R'd; more likely a shoe or a shoe adjustment piece/linkage has slipped out of its proper position/attachment)

    Another test might be to shim the studs with very thin washers before installing the drum, to see if that frees the drum...

    If so, eighth-inch shims for wheels are fairly common, perhaps the local FLAPS would have them for your bolt pattern (4 1/2"?), and thinner individual washer-shaped shims might be available as well, since they are common for disk brake caliper adjustment. But, hub shims might only be compensating for something that's out of position.

    Might be possible to insert a long narrow strip of paper (maybe cut from a magazine cover) at the outer edge of the drum while installing the drum, then try to slide the paper around the perimeter after the wheel nuts are installed (no wheel) to see where/if interference occurs with the backing plate. But, I would think if you snug a drum down just enough that it barely drags, and rotate the drum a few turns, you might be able to discern rub marks on the backing plate when you remove the drums.

    Here are a few hits I found with a Google search, but nothing really new in them...




  17. I don't think I'd be beating on the backing plates, certainly not yet.

    This is a dohh! guess: did you check to make sure the parking brake is not engaged?

    More thoughts...

    Is it possible there's some sort of indexing locator on the drum & hub to indicate the drum needs to be in a particular orientation with the hub (perhaps a raised bump on the hub that mates with a hole in the drum, or vice versa)? ...a mis-matched locator bump might cock the drum slightly and cause the drum to distort a bit when the wheel nuts are tightened. The Stude parts manual hub illustration on page 101 shows something on the stud circle that appears as though it could be a locator.

    Have you tried installing one drum at a time and found it locks up with either drum (only one) installed?

    You might read through the shop manual's rear brake section for clues and note things like making sure the shoes are engaged in the slots at the wheel cylinder.

    If you didn't change the brake shoe adjustment, maybe try turning the brake shoe adjuster (top rear behind the backing plate) to loosen the fit (shoes further from the drum surface), install the drum and if the axle doesn't lock up, then adjust the brake shoes to be snug.

    Maybe take the drums to a brake shop and have them checked for true and machined if needed (doesn't explain why it worked before removal, but is it possible drums were dropped on the garage floor after removal?)

  18. ...post #66 "Get it all buttoned-up and back on the wheels and on the ground about 8:30 last night."

    conflicts with your statement that the car "was and still is on jack stands"

    More food for your own thought...

    Does it lock up if you snug the wheel nuts without a wheel & tire in place, or only with the wheels in place?

    (eg, is the problem related to the drum/axle or the wheel/tire?)

    Does it lock up when either side wheel is installed, but the opposite wheel is not installed?

    (eg, is the problem on one side or both sides?)

    What suspension bushings did you replace and what is their proximity to the wheels & tires?

    Is it possible that there is some latitude in how/where the rear spring is attached to the axle (or difference in the width of any new bushings used) that could cause the spring or bushing to contact a tire sidewall?

    Is it possible you reversed a bolt on re-installing something, and now the nut end is where the bolt head used to be, so the bolt end is sticking out too far and contacting something?

    Did you replace any old U-bolts with new U-bolts that might be longer than the old ones?

    Since this car is new to you...

    Are these the same wheels & tires you originally removed (from the same axle)? eg, is it possible the former owner installed wheels with different offsets, front wheels vs rear wheels (or rim widths or even wheel size) and you've reversed them by installing a wheel on the rear that formerly was on the front, and now the wheel or tire sidewall is contacting something (like the backing plate or the rear spring)?

  19. More thoughts...

    Normally, front shoes are the shorter of the 2 shoes (less brake lining area), and/or sometimes narrower... is it possible you reversed the shoes when you re-installed them? There usually are raised "bumps" in the backing plate that properly position/align the shoes, so if you reversed wide and narrow shoes, you could cause interference between the drum and the wider shoe.

    "Started the car, put it in reverse, no movement. Locked up tight."

    ...were the rear wheels back on the ground, or were you doing this while the car was still jacked off the ground? Posi rear ends give power to the wheel with the most traction, I'm not sure what they do when neither wheel has traction (equal power to both, or no power to either?). Yet, you do state that the wheel turns until the lug nuts are finger-tight, so it would seem that tightening the lug nuts is causing the stoppage (have you tried just pressing against the outside face of the drum without the nuts in place, while turning the drum, to see if that pressure prevents the drum from turning and perhaps learn by sound or feel where the rubbing or interference occurs

    "Tried every combination of brake drums, wheel spacers, and wheels on both sides of the rear."

    ...Did that include placing the spacers inside of the drum rather than outside? (i.e. is it possible those spacers were inside the drum rather than outside... there may be marks or corrosion patterns that tell you where they were).

    Seems like there ought to be a way to gently/incrementally snug the lug nuts, turning the drum each time, until it rubs something (just before it locks up), and then figure out by sound or feel what it's contacting (like perhaps the edge of the brake shoes) that keeps it from turning when the lug nuts are tightened further.

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