BBR's 83GT - 552 BBF version 3.0 (at least)

[milner351]

some don't have small enough ends on them to fit into spark plug holes, others do, and I'm sure the quality varies with price like anything else - certainly on my "someday" list.

[DanStokes]

I need to take a nut the same size as the glow plug holes on the M-B so I can see if it would work for the Diesel. That would make it worthwhile. The one at Costco has a video output jack which would be excellent if I can figure out how to stream it to the camera or maybe ME's smart phone. I'll check that out.

Dan

[Scott Liggett]

Reading your saturday adventures, I would take a step back here. Your air cleaner got crushed on the first run with the scoop. I seriously doubt that the engine suction could that, but 100 mph wind pressure from above certainly could. It was hitting the platter like upside down lid. I would make a run with an actual air filter like a K&N, or tape close your scoop. See what happens before going crazy with engine tearrdowns. The air.pressure hitting the top of the engine could be leaning things out. A whole bunch of fresh, cool air in a ram air effect will want more fuel than than stagnant, hot, under hood air. Thats the whole point of the hood scoop, silly.

[BBR]

The real issue I'm trying to double check is the fact the afr's changed radically after the "event that sucked". On the way out to the track, the cruise was a very rich 12.5:1 (and I was kind of expecting it to be). First pass, sucked the filter but afr's were ballpark. Second run (no filter or base, +2 on secondary jets), motor noses over like it was getting no air in the carb (caused by scoop I suspect). Third pass (filter base only), car shows to be surprisingly lean at wot. Fourth run with regular air filter assembly on, shows to be lean again, but better than previous pass. On the way home, cruise was an surprising 14.5:1. So, something along the way changed. Not exactly sure what, but I want to cover all my bases rather than miss something and hurt a motor.

[CDMBill]

Did you use some compressed air to blow out all the carb passages as well as those in the metering bodies and fuel inlet needle and seats? I also assume did a running check of float levels and lastly do you have fuel pressure gauge you can monitor by eye or Go-pro down track?

The likely hood of some little bit of metal ending up in the wrong place during sugery or after seems likely never mind when the filter collapsed. When I had a dominator carb on mine using a filter made power on the dyno and at the track as measured by trap speed. I used a 3.5x16" K&N or Wix, still do on the EFI deal just squeezed into an oval to cover the two throttle bodies.

In car camera that can see the AFR and fuel pressure makes for good replacement data logger.

[BBR]

Did you use some compressed air to blow out all the carb passages as well as those in the metering bodies and fuel inlet needle and seats? I also assume did a running check of float levels and lastly do you have fuel pressure gauge you can monitor by eye or Go-pro down track?

The likely hood of some little bit of metal ending up in the wrong place during sugery or after seems likely never mind when the filter collapsed. When I had a dominator carb on mine using a filter made power on the dyno and at the track as measured by trap speed. I used a 3.5x16" K&N or Wix, still do on the EFI deal just squeezed into an oval to cover the two throttle bodies.

In car camera that can see the AFR and fuel pressure makes for good replacement data logger.

I did do float and fuel checks at the track. Everything seemed normal. I also blew everything out good this time! I thought I did last time, but must have been day dreaming and missed something. I have a fuel pressure gauge, but it is underhood. I will be dang sure and take the GoPro with me next time out.

I'll button it back up this weekend and see how it runs.

[milner351]

another option to consider once you have things sorted out is a pan that seals the carb to the underside of the hood, it would be interesting to see what if any affect that would have.

[BBR]

Yes, I think some sort of a pan would help. It would have to be huge because the hole in the hood is so large.

I made the jet extensions last night for a whopping $2.79. I found out it's easier to cut one end with the tubing cutter (block side) and then use the Dremel for the outside. Then clean it up with a small file. Reason being, even with a small bevel around the lip, the jet will not fit in and I did not have a good way to flare the lip back out. Maybe a conical grinding stone would work, but I did not have one handy.

Pics:

[CDMBill]

So those are the externally adjustable metering blocks? An air pan of whatever size really helps inlet air temps, 1% power for every 10*.

My isolator is worth 40* down track in warm to hot weather.

We're your 1000 ft. Intervals down proportionately? If so its likely the carb, if not the scoop, inlet setup.

[BBR]

No these are just regular old quick fuel blocks.

I don't think I really had enough passes the other day to concretely nail down just exactly what is going on.

I did put the carb back together and then took it for a test drive. Afr's were consistent with what I had on Saturday on the way home from the track and the car seems to run fine. It's tough to do any wot blasts on the street though because it won't hook and it goes way too fast way too quickly. I did richen up the secondary jets a couple of sizes. I'd rather be on the too rich side and work it lean, than the other way around.

[CDMBill]

Stupid question, how are the jets retained in the tubes? I had little brass hex shaped extensions that screwed into the metering block which were threaded for the jets on the end.

[BBR]

The jets thread in normally. The tubes are just a very tight fit on the jet.

The carb guys I have been consulting on motorsports village and now racingfuelsystems.myfunforum.org, have found that the screw-in style do not work as well as they should and can become a restriction with bigger jets sizes. I was running a set of them and decided to go ahead and eliminate that as a potential problem. The ones I made are identical to ones you can purchase commercially, except mine cost $3 to make.

[BBR]

While I was unable to get out to the track this weekend, I did have time to correct a nagging problem with the driveshaft loop. Sometimes on the street and every time I launched, I could hear a clunk, that for all the world sounded like it was coming from the pass rear suspension. Wyatt, one of the guys with us on DW said he saw sparks come out from under the car in Memphis when I launched, but we had no idea where they could have come from. I looked and looked for what it could possibly be. Finally I looked farther up and figured out the front u-joint was banging the bottom of the driveshaft loop. It fits pretty close but man, it sure sounded like it was coming from the back.

So I begin by pulling the passenger seat out. Surprise surprise!! There is my tire gauge I thought I lost in LA during Drag Week! Yeeeeeessssss!!!!


Then, I pull out the driver's seat and, surprise, surprise there is the pocket knife I lost on DW too. Double Yeeeeessssssss!!!!!!!


Finally I get the lower bar of the loop out and just as I suspected, there are witness marks from the yoke touching it.


I had another old driveshaft loop, so I cut the "loop" part off of it with a chop saw, welded it to this bar, then cut out the offending section and welded up the inside.


Shot some paint on it and bolted it back in.

[CDMBill]

Are you running stock style motor mounts or rubber trans mount? While the driveshaft may well angle further dawn at launch if the rear end separates, I wouldn't expect the yoke to be moving in relation to the loop unless the engine and trans are moving in relation to the loop. Are the witness marks from the weld on yoke of the shaft? You have fixed the interference point but looking at your launch pcture in your signature I wonder if other stuff is moving around?

Just FYI I still run stock mounts with a home made torque link off the driver cylinder head and a poly trans mount. Its a street car ya know and I want that smooth quiet ride.

[BBR]

It has rubber mounts for the engine and the trans. I'm sure everything moves around a bit at the hit and is probably exacerbated by any wheel hop the car may encounter. The marks are from the yoke ujoint ears and the driveshaft unjoint ears. It is a 1350 joint 4" driveshaft. At rest there was about 3/8" of clearance, so it was pretty close just sitting still. Plenty of clearance now, but a limiter might not be a bad idea.