Running my almost stock 455 powered '67 with T400 and 3.08 rear back in the day I changed from well-worn but "grabbed pretty good" regular street tires around 26" tall running into the 13's a small amount. I picked up some pie-cut 28.5" slicks and immediately lost 2 tenths. No such thing as 60' on the handwritten time slip but probably affecting you the same way. Better 60' but slower everywhere else. I would suggest on the switch-pitch front doing a little rewire and just activate the SP manually all the time. Off the ign. switch +12V to switch on dash and then to the SP terminal at transmission. Turn on at the line and then off once you get 100-200' down track. Might be worth something. The 13" SP is barely 2000 rpm on high so it is not that great compared to the 12" around 2800 behind a BBB. The converter change would probably get all of your ET back. I want to add that just because you have a SP transmission doesn't necessarily mean the SP is working. The manual switch will allow you to confirm it works. Light power braking in gear and turning it off and on should make a difference in engine rpm. I've had bad solenoids and even converters that refuse to switch the pitch.
Sounds like the exact same change I made. I picked up about a tenth in the 60ft (2.17 to 2.06) after swapping to the slicks. I was actually able to just barely beat my previous personal best by about a tenth in the quarter (I posted my 2019 timeslip with my runs from Saturday to show the differences). Really haven't made any changes to the car other than the slicks. I might try foot braking harder the next time I run. I just worry about pushing through the beams. I was really banking on swapping a 12" converter in thinking that would get me the few tenths I need, but that will have to wait now. I am going to fine tune my ignition timing curve and rebuild the carb and hope that makes the difference. I found my mechanical advance limit bushing sitting on top of my timing cover. It's probably been sitting there for a long time, I was fighting some part throttle ping last year when I bought the car back and ended up pulling some timing out and putting heavier springs on the weights. With the bushing in, I should be able to add a bit of initial timing and still run 33* or so of total timing at the track. I may also drop down to a slightly lighter spring (running a blue and silver from the crane kit currently, might go back to two silvers). The extra timing at lower rpm might help off the line with the stock 13" converter. I have really want to run one of Bruce's controllers or wire something up myself, but I shockingly have a stock setup that functions so I have been reluctant to change it. That being said, I believe the way it is setup from stock I won't be able to footbrake it to high stall, but it should be in high stall once I floor it and get off the brake. It definitely works. I can feel the stall change cruising in third under part throttle and it is noticeable when the microswitch sticks at idle since the car wants to creep a lot more. That is really my only issue, the microswitch is not always being depressed when I come to a stop. I usually just tap the throttle and then it will switch from low to high. The carb appears to be a service replacement likely from some time in the 80s. The numbers come back to a 67 Camaro, but it has the correct Buick linkage and runs awesome. The accelerator pump is a little weak and the body gaskets are seeping, so a basic rebuild will probably help out. I don't have enough time left before the Nats to get into a stock+ rebuild and calibration. For something that has likely been sitting in the trunk for decades, it is pretty awesome how well it works as is.
IIRC correctly the high stall is on at idle but comes off some point above idle at light throttle but then comes back on around 3/4 throttle like a semi-downshift and then the downshift. The problem is the high stall is giving something away through slippage once you start moving down track and that is why you want to turn it on at the line and completely off once moving. It probably will only make a small difference with the 13" converter but everything helps. I did the manual thing for a long time. The controllers are only worth it if you are going to be spending a lot of time at the track. I built my own timer when I got serious but another option would be to use a manual switch to turn it on at the line but use a pressure switch to turn it off once it hits second. Nice on the timing. That would make a big difference getting more initial in there and a quicker rate.
If you disconnect the kick down/switch pitch switch from the carb you can move the plunger to the high stall position and it will stay there. ( at least it will on mine).
What I will likely do for the variable pitch is wire in a 3 position switch. Position "I" would allow the system to function like stock, the "0" position (centered) would keep the converter in low stall (no 12v) and the "II" position would put 12v to the stator solenoid to command high stall. Like you said, probably a very small change at the track, but I only need .018 seconds to hit my goal so every little bit helps. Later on I may do something using the brake switch and see if I can eliminate the microswitch on the throttle linkage. It just doesn't actuate reliably enough at stoplights to be useful. But I do like how the system is supposed to work in stock form for everyday driving. The part throttle high stall is a lot of fun and using a toggle switch to get that would take some of the magic away for me. I wanted to play with the timing more last week but just had too many other items on the to-do list. I'm sure having the timing all in a few hundred rpm sooner will help. If it messes with my in gear idle too much I'll switch it back for the drive home. Doesn't that plunger also control the WOT 3-2 downshift? Not really needed at the track but helpful for street driving. I'll play with things this week if my other projects go smoothly. Modifying the switch pitch is a bonus item at this point. My other plan is figuring out how to make the most out of my Starwars aircleaner handicap. It must be installed for BSA but I may try to run a slightly taller filter since, for normal air cleaners, flipped lids and 1/2" taller elements are allowed per class rules. I may ask if I can run without any filter at all.
As if I don't have enough to do in less than a week, I ordered a new limited slip carrier and rebuild kit for the stock 8.2. It comes with 3.55 gears but not sure I want to put those in without a GV. I already dislike driving this car at 70mph with the stock 2.93 gears. It is highly likely I won't even get the parts in time, but if I do, I'll reuse the 2.93 gears for now. There was a lot of metal in the gear oil when I pulled the cover. Most of it is likely from the wear in the auburn carrier but I am sure the bearings are in need of replacement as well.
That new carrier needs at least a 3.36 ratio gearset, 2.93's won't work. 'Maybe' there's a ring gear spacer out there that will allow the use of 2.93's, it's not an off-the shelf item. EDIT: Scratch that, I had that backwards, 2.93 are thicker than 3.55's. ^^^ That mod made a big difference on my 425 '66 GS back in the day. It had noticeable more power off the line , it got me into the 13's.
You are right! I knew that too and that is why I hadn't ordered a carrier yet. I guess I was tired last night haha. I think my problem would be that the 2.93s are too thick for the 3 series carrier. If it shows up on Monday or early Tuesday I might make an attempt to throw it in and deal with the 3.55s for a bit. I had no plans of taking the interstate to BG anyway. I've only built 1 or 2 rears before though so not sure if that is something I want to rush to do before a several hundred mile road trip. I'll see how my other projects go. The driveshaft is done, I should have all the parts I need for the transmission leaks soon, I pulled the carb off today hoping I can start rebuilding that at work if we have a slow night. I tried putting a smaller water pump pulley (1375146) on but it hits the water pump in spots when tightened down. It doesn't seem horribly bent. Ordered some shims for it and I hope that will be enough to make it work. I definitely enjoy playing with the timing curve in cars. One of the first tweaks I ever did to a car was adjust the timing after reading Larry's thread. It does make a huge difference. I have gotten a few cars to run faster than they should just by dialing that in. I'm excited to see just how much I can get done before Thursday night. Michael (Trunkmoney) said he might be able to bring a 12" VP converter to BG. I think I'm going to bring trans fluid and a jack adapter and try and swap it out there if he does.
I don't know if this helps, but I live here in BG and have jacks and stands. If the weather is nice, I have a lift at my house but I don't have a tall transmission jack.
The worst thing you can do is rush a gear change and then have noisy gears. At that point you'd have to spend more time trying to fix it. If 2.93's don't suit you at 70 MPH then imaging higher rpm PLUS rear end noise at 70 mph. Also once gears get noisy they rarely get much quieter after putting mile on them even after readjusting them. Put fresh fluid in the rear and close it up for now.
Greg, that is a very generous offer, I appreciate that! A lift would be very helpful for getting all the other stuff out of the way like the exhaust and some of the harder to reach bellhousing bolts. I'll see how the rest of my projects go, how the car does on the trip down to BG and figure it out once I get there. I plan on bringing a set of jack stands and a trans jack adapter for my floor jack. You are right. I know I have the right tools to do the job and I am pretty meticulous but my worst case scenario would be digging into the rear, finding an issue I don't have time or parts for and then trying to bandaid it to make the trip to BG. Waiting sounds like a good idea. I can do the gear swap and a gear vendors at some point over the summer when my Corvette is back together.
Unless that rear end is special, my thought would be to look for another one to build so you have very little down time. Probably find a housing, maybe gears and a posi in BG. After waiting 2 years for machine work on my 350 engine, I'm definitely not taking anything apart I don't have spares readily available to replace.
I put it in the back seat! Will be there Wednesday afternoon. Not sure if we'll head to the track, so PM me when you will be in BG. We're staying at exit 22 on I-65.
That is a smart way to go. Two years for machine work is maddening. When I built a 350 in 2015 I was upset when it took 3 months (they also butchered it but that is all contained in another thread) I have spares of most major driveline components except for the rear. I saw GSFred had a 3.55 limited BOP 8.2 for sale but I'd have no way to get it home and I think he mentioned it needed a new pinion seal and backing plates. These rears certainly make things a struggle sometimes. Unique axle bearing size and it is wider than other years of A-body so you need a specific offset wheel to keep centered in the wheel well. That is much appreciated! I am going to try to be in BG late Thursday morning/early afternoon. I wish I could have taken Wednesday off too but I am already pushing my luck at work for taking Thursday through Saturday off haha Carb is all done. It is certainly no show piece and anyone who rebuilds these for a living would probably cringe at some of the steps I skipped but I just wanted it clean with fresh gaskets and a new accelerator pump. I didn't pull the idle air bleeds, throttle blades or air flaps off. It ran perfect before, just looked like a fire hazard. Someone has definitely been in here before, but it looks like they did a good job. Float level was good, secondary air flaps were adjusted correctly, the carb came apart very easy.
By the way, for anyone who does want to try their hand at rebuilding their own quadrajet, Ken's (Everyday Performance LLC) book is awesome. Super helpful and covered every step. The only things I had to fill in the blanks on were some differences with my early 67 4MV compared to the later carb in the book, but I have never taken a Qjet apart before and was able to dig right in to it.
Too late now, but I like to soak carbs in Evaporust as part of the cleaning step. It removes the rust from the various linkages! I also recently got a $120 10 liter ultrasonic cleaner. It doesn't perform miracles but is handy for cleaning carbs and everything else.
I strongly considered buying something to let the carb soak in but I just felt I was running out of time. I will absolutely be back into this carb again someday soon. For now, it fits with the rest of the "patina" in the engine bay haha. I'm honestly shocked at how enjoyable it was to rebuild this carb.
Took the car out for a test drive today and everything seems great. Managed to make the 67-70 AC water pump pulley work and it seems to keep things right at 180 now. I also added a bit more initial timing (from 8 to 14 without vac advance) now that I have a mechanical advance limit bushing in place. Total is at 34 degrees and I'm not getting any pinging. It is pretty fun blowing the tires away from a 20 roll. I think the accelerator pump in the carb prior to the rebuild was definitely worn because the car feels much snappier now. I never really had a stumble or bog but it would sometimes feel lazy off idle. One issue I am having is I'm unable to get the car to idle below 750-800rpm. I'm betting it is the extra ignition timing at idle. 20" of vacuum and I have the idle mixture screws at about 2 3/4 turns out each. I can get the engine to stumble and start to die when covering the primaries, so I don't think there is any sort of vacuum leak. 750-800rpm is decent though, I'd just prefer 50-100rpm lower. Later tonight I plan on swapping that fuel sending unit and maybe polishing the glass on the car. I'll start packing it up tomorrow night.
