| Carb and Tank Support |
The first thing I do to any stocker is MIG weld a 1/8" x 3/4" x 3 3/4" long HRS strip to the tank. Place it immediately in line with the "tank to block" bolt. Then I MIG four large spot welds around the whole "tank bolt support" bracket (the R3's are especially weak because this bracket is only "plug crimped" to the tank's sheet metal). Now, I know there are lots of tank supports available, some good, some not-so-good......but none are as good as this for the price ($10ea....$7ea three or more).
When attaching the carb to the engine, first tighten the carb to block bolts snug (with a gasket) and check the gap between the block and the tank. If there is a gap, use an appropriate washer (this is critical if you're running a restrictor plate and two gaskets!)....if not, just make sure that the holes in the tank and block are aligned and tighten all three bolts evenly.
The best carb brace I've found is the piece (#DK-929) that attaches to two of the head "sheet metal" bolts and has a long arm reaching to the 10-32 hole at the back of the carb just under the filter adapter ($10). Note: always attach to the head first and bend the arm up-or-down and in-or-out to ensure that you're not introducing undue stress to the carb.
This is my formula to help prevent carb breakage and I've all but eliminated the problem except for rare occasions.
Craig-
Summerlin Racing Engines |
| Throttle Linkage |
Move the cylinder head bolt #555082 (with the stud above the hex) to the #8 head bolt position.....(it's the one in the middle closest to the flywheel.....I get the number based on B&S's recommended torque sequence.....hmm, you are using their recommended sequence aren't you?)
Now, stand behind the engine and notice that the angle of the carb to the block puts the bellcrank arm 90* to this (#8 position) head bolt. Attaching your throttle linkage on this bolt reduces undue stress on the carb boss (where the shoulder bolt that the bellcrank pivots on is attached) because you're pulling "square" to the pivot and not at an angle.
Drill the hole in your throttle linkage mounting bracket to 5/16", slip it over the stud portion of the head bolt, and tighten with a standard nut. Note: Don't over-tighten, it ain't comin' off,.....be sure when removing your engine that you don't loosen this head bolt as you attempt to remove the nut!) Adjust your cable clevis so that your pedal and throttle shaft arm both bottom out at the same time (once again to avoid any undue stress).
Craig-
Summerlin Racing Engines |
| Animal Dyno Test |
When I first received my Animal, I did nothing more than take it apart and wait for WKA rules. Well, I grew tired of waiting and began to test the engine within (what I perceived would be) "box stock" rules. Turns out that I was close because I didn't have to replace any modified parts when the rules were released. :-)
I decided to take a fresh approach, start without any predetermined ideas, make one change at a time, and document each one. I have attempted to outline my findings here for your viewing pleasure...
I disassembled the engine partly for curiosity but mainly to check clearances and to make sure that nothing was missing or loose. I decided that the clearances were acceptable and (with the chrome plated rings) I left the rough finish on the cylinder bore. I reassembled the engine exactly the way I found it with one exception.....I stone cut the valves and seats (I was glad that I did because they both needed it).
This brings us to the first dyno pull.....gasoline, stock spark plug, stock timing (~23*), and stock carb with BGB rod, 95 main, and 32 pilot.
NOTE: All of these dyno tests were done with a Robertson super snake pipe (unmuffled and without wrap).....I also raced an RLV with success.....I may do a pipe comparison if you guys want to see one. NOTE2: This engine was shipped and tested with the "removeable plastic fin" aluminum flywheel. NOTE3: All of these dyno tests were done with the stock Champion spark plug as shipped from B&S. I tested another engine with an NGK #BPR8ES with success. I've been told that a Bosch #F6DSR is a good choice (hhmmm, may need to do a plug comparison as well). NOTE4: I didn't record any cylinder head or exhaust gas temperatures with these tests....that'll come later as we begin to fine tune.
Then, I made another pull to establish a baseline. Below is a graph comparing the two (dashed is second pull and solid is first pull).
I was very impressed with the torque and horsepower of this short stroke, short rod, aluminum flywheeled engine.....so I compared it to a very good WKA muffled R3 stocker. Below is a graph comparing the two (dashed is WKA Raptor and solid is gas Animal).
Next, I took the Walbro carb apart and used the parts found in the 555537 methanol conversion kit. Not knowing where to start, I picked middle of the road.....the BHA metering rod set in the second groove from the top, the #135 main jet, and the #38 pilot jet. I re-assembled the carb and dynoed it again. Below is the comparison graph (dashed is the gas Animal and solid is the meth Animal).
The power picked-up a bunch! However, the engine was begging for timing advance....at full power there was a substantial amount of fuel spewing out of the carb. Guessing, I added a #5 offset key and the engine responded by making more power and it sounded much happier! Below is a comparison graph (dashed is stock timing and solid is advanced timing).
It was about this time when WKA released their Animal rules and this is the only time that I made more than one change. This brought me in spec with WKA and didn't nullify any of my previous tests.
1) I added a B91XL muffler to the pipe.
2) I installed a Dyno #AN001 cam with .009"/.009" lash cold. The intake centerline was 105.75* and the exhaust centerline was 115.5* (the profile was within tech).
3) I installed a WKA approved flywheel at 33* (same as the other flywheel) without a key.
Below is a comparison graph (dashed is before these three changes and solid is after)
Now we're making some serious "box stock" Animal power! However, the overall personality of the carb at these settings didn't appear as if it would race well and I wanted to try and find more power with carb tuning. So, I made seven more pulls making one carb tuning change at a time. I'll post these results at a later date....gotta get to work. :-)
Craig
Summerlin Racing Engines
Speed Costs Money, How Fast Ya Wanna Go? |
All times are GMT -5. The time now is 07:16 AM.
|
