Dyno result...found my bog. (long story)

[slocrow]

July 6th results from long-winded Frank.
 Hi folks; I got the coupe dynoed yesterday and things went pretty good.
As some of you know I've had a bog, stumble condition with my coupe for a couple of years. Oh I tried various adjustments, bought the Edelbrock calibration kit and spoke to them directly and at shows. They seemed to always want to blame something other then their carb. Ultimately they may have been correct. I knew I was running on the rich side and wanted to blame my bog problem on a sporadic over rich situation. I was at a cruise in Akron, OH the other night and when leaving I was embarrassed once again. I had it and called to make an appointment to dyno the car and hopefully resolve the problem. Yesterday was that appointment.

 I got there around 8:30 AM and reintroduced myself to Ron Hutter, the owner of Hutters Performance Center. He owns, as the name implies, a performance engine building business set up in a town just East of Cleveland, Ohio called Chardon, a really nice country location. Small town USA.
He was part of our old gasser gang and also happened to be in my long ago Army reserve unit. I probably hadn't seen him since circa 69. Since then he had kind of made a name for himself in the Busch truck series  with the GM Buick V6 and now is heavy into the SB2 V8's, with engines currently running in the Winston cup and Busch truck races.

 The business is mostly housed in two major buildings, each approx. 50' deep by 100/150' wide. The first building has 4 bay areas. A cement block wall segregates one bay as it houses the chassis dyno. Two others are large double wide sized and the 4th plus bay area is rented to one of Ron's two sons, Mark, who run's "Route 6 Choppers" out of that remaining area. Clean and orderly (I hesitate to use the word spotless) is the appearance of the entire work area.
The second building, set at 90 degrees to the first, appears similar in size with several abutted structures off the back wall. This building is for engine dyno(s) and various specialty rooms for engine machining work, assembly and office needs. I counted six additional employees other then family. This is all laid out on about 5 acres of neatly manicured property with a huge parking area and driveway, offering a good wide, straight 1/8 mile section for practice launches. This is all set back a 1/4 mile from the main highway, behind his home (an old style colonial/Victorian) located up front near the road. A sweet set up for a guy with a quite unassuming personality.

 Upon my arrival we chatted a while and renewed an old friendship, prior to him introducing me to his second and youngest son Trevor, who would be doing the grunt work on my coupe with Ron looking on. Trevor returned home to join the family business after graduating from Ohio State and bouncing around the corporate jungle for a couple of years. He is the company's computer whiz kid and LS1 guru.

 Trevor hooked up the coupe to the dyno and proceeded to flog it for a base line. He and Ron reviewed the data but with the exception of a brief couple of over rich conditions, exhibited by the black exhaust discharge, couldn't get it to stumble like it does for me while driving. They attacked the carb, an Edelbrock 750 manual choke, by first pulling the top and then taking the balance off the intake. Seeing lots of trash in the fuel bowls and a desire to clean out the passages necessitated a trip to the carb cleaner booth. The float levels were checked and the primaries were down sized a couple of steps with the secondarys coming down one size, in an attempt to remove a "fat" condition. Getting back on the dyno again revealed a top end horsepower drop but a much better air/fuel ratio throughout the range. With a little more tweaking and some more flogging they pronounced it running smoother but couldn't get it to stumble or puff black smoke, at all. It did indeed sound and respond crisper. He unhooked it from the dyno and suggested I take it out in the drive and highway to see if it ran better. I cruised out the drive, made a left onto the highway and jumped on it from a rolling stop. The revs came up, the front end came up and with tires smoking it fell right on it's face. I tried it several more times and pretty much got the same bad result. I drove back and into the shop driveway, bogging at will. With them watching, I reproduced the sad event in the drive twice more. I asked Ron if he wanted to take the wheel and he agreed it would be worth a try. Same result except his experience drew more from each incident. It was agreed that unlike the dyno pulls, it was the cars launch or movement that produced the correct circumstances for the bog. The problem had to be laid at the feet of the carb or possibly an ignition power source, which would short out with the weight transfer, causing the ill effect.
Once more back into the breech as the carb top was removed and the interior reviewed for suspected culprits, first. Lot's of fuel pressure from the stock pump, as the line was removed. Surprised me and to Edelbrocks credit they had suggested too much pressure could be a problem. With the top off both Trevor and I were surprised at the low level of fuel remaining in the bowls. When Ron looked he thought it might be passable but upped the levels with a float adjustment just to be sure. With this one correction made, it was time for another asphalt attack. Presto, no more stumble. I could hardly believe it was gone. Fuel starvation. Who would a thunk it with those always wet plugs and that occasional black smoke.

 Apparently, even with my 200#s, there wasn't enough weight to keep the front-end suspension travel down enough to overcome the then short float level settings. That, combined with the fact that I went from a 4 degree up engine setting too a 3 degree down only exacerbated the primary bowls low fuel condition, there by bringing this situation on even more frequently.
 I did get it to flutter slightly on the way home but only for an instant and only that once in all my launches. I'm pleased to have isolated the problem and fixed it for the most part.

 With the original "fat" base line the engine was making, with hood off and no air cleaner, around 247HP at the rear wheels, peak. With the carb adjusted leaner two different curves were recorded. One pull was with the hood off and a second with the hood on. The air cleaner was in place both pulls. With the hood off it made 233.8 HP @ 5228.82 RPM & 267.38 ft/lbs @ 3870, at the rear wheels. That's a negitive13 HP difference for the air cleaner and leaner settings.
 With the hood on and using the under hood heated charge we drop even more. Those numbers are 218.67 @ 5210.9 with 258.21 ft/lbs @ 3834.01. Also interesting to note was that both runs were leaning out at the top. Not out of range but getting leaner. Ron pointed to a poorly bent (slightly kinked) 3/8 fuel line from the tank. I'll have to get that on the list.

 All in all it was a good day with money well spent and I'm pleased to know more about the engine. The old gas mileage should also improve and who knows, I may richen her back up, find a less restrictive air cleaner and run without the side panels in the future.
 
 Oh yea, that pesky exhaust leak I had was coming from a 3/16 hole in the carb heat block off plate on the intake. That was also nice to find.

 So now you know the whole story and hopefully found it interesting and informative. Watch for me being removed from the grounds of upcoming events for smoking the baloney's. See you in Columbus!

[nomobux]

Great report. Might I ask what this venture set you back. Had a friend take his to a dyno shop in Yakima Wa. wednesday, but have yet to get a report. His new GM crate is becoming to be the motor from hell.     nomobux

[slocrow]

Great report. Might I ask what this venture set you back. Had a friend take his to a dyno shop in Yakima Wa. wednesday, but have yet to get a report. His new GM crate is becoming to be the motor from #####.     nomobux

Glad you liked it. I was there from 8:30 to 1 PMish. Dyno time is $85 to set it up and $125 an hour. They only charged me $278 out the door for everything. When making the appointment I had asked for a ballpark figure and Ron suggested around $250 so that was pretty close and it was over 4 hours of tinkering. I mentioned that I could buy a new carb for that $250 price and his responce was, "we'll get your card sorted out". Glad I went that way as any new carb's floats would have also been set incorrectly for the car, most likely and I would have had the same problem.

[nomobux]

Sounds like a fair price. They have alot invested and the expertise. Hell, that's only one nite in a down scale yuppy no-tell motel. Glad things worked for ya

[Ohio Blue Tip]

Glad you got your problems sorted out, good story.  Hope to see you on the 17th in Ohio or at Louisville.

[Dave]

So will you take me for a ride and stand on it so i can spill my beer on  your seats
Glad its fixed id hate to beat ya with my little 350...
Dave

[1FATGMC]

Frank glad you got things worked out.

I might add that an air/fuel ratio meter could have really helped you out.  I've been running one for about 8 years now and it has helped me to figure out what is wrong more than once.

It works good setting the idle, lets you know if you are running rich/lean at different throttle settings and at cruise.

Coming back from New Mexico yesterday and a little before that sometimes when I pulled out to pass or on long/steep hills pulling the teardrop and in the secondaries it would bog big time.  Looking at the meter (about 12 LED'S) I could instantly tell it was going way lean.  Under heavy acceleration I'm running high 12:1 ratio and it would go from that to off scale (over 17:1) at the same time as the bog.  I'll be checking the float level, installing a new fuel filter and since the pump has over 100,000 miles on it I'm going to replace it also.

A good one of these meters with lots of LED's is about $140, but money well spent.

The next one I get will be a Wide Band that is even more accurate.  With it I will be able to see what is going on and also control the megasquirt fuel injection I want to go to and be able to addjust the A/F ratio for different throttle settings not just the 14.7:1 that is normal with factory fuel injection.  The down side is that the wide band O2 sensor along with the controller it needs are around $350.

Thanks for the interesting post ,

Sum