Belly Tank Build Diary

[Mike Brown]

Mike, will that pull shaft stay cool enough to use Loctite?  Some types of it lose grip strength at elevated temps.

I installed the original alternator pulley with red Loctite (271) a shrink fit and two 1/8" spring dowel pins.  After drilling out the dowel pins and using a heat gun I was unable to remove the original alternator pulley.  I did not want to heat it up with a torch and risk damaging the shaft or bearings so I machined the pulley off in the lathe.  I have an infrared temperature meter so I can check the temperature at the end of a run.  So far at the end of a run I have been able to touch all of the parts on the top of the engine so I estimate that they are 160 degrees or less.  Loctite lists the maximum temperature of 271 at 450 degrees F.  This could be why it is called "red death". 

[Mike Brown]

Mike,
Are you planning to cross pin the pulley to the shaft or "Dutch" pin it? For something like this I really prefer the Dutch pin method as it is like putting in a precision key. When you have dis similar metals like you have you really need to do it with a small milling cutter, carbide if possible. This is a favorite way to key things together of the "Kansas Bad Man" Max Lambky.

Nice job on the soft jaws!!

Rex

Thanks for the comment on the soft jaws.  I am planning to cross pin the shaft with two short 1/8" spring pins.  I have used "Dutch" pins but prefer keys and keyways where possible.  I own broaches for cutting keyways and Woodruff cutters for keyseats.  The blower pulley is a press fit onto the blower shaft.  I am hesitant to remove material from the blower pulley with machining for a keyway or a Dutch pin for fear of loosening the press fit of the blower pulley to the blower shaft.  With the combination of Loctite and a shrink fit I had to machine the original alternator pulley off of the blower pulley to remove it so I have confidence that it will stay put. 

[Mike Brown]

"The fire suit was manufactured by Stroud Safety.  The arm restraints are integral to the fire suit.  I was advised that Bob Stroud submitted for and received compliance."

It (like mine) was probably in compliance when it was manufactured.  So we're following what I believe to be the "letter of the law" and we have a new strap located on the wrist with the proper hardware.  We were told to make that modification and used it all last year.  I'd hate to get to a meet and have a problem . . .

I sent the same photo of the arm restraints with buckles to the tech directors of the SCTA, ECTA and LTA.  They all replied that these arm restraints were acceptable. 

[Mike Brown]

This was my original tensioner for the supercharger drive belt.  There was no spring just a jack bolt to tighten the belt.  The idler pulley was too close to the crankshaft pulley. 

[Mike Brown]

I fabricated a new idler pulley tensioner arm that moved the pulley closer to the supercharger pulley.  With a smaller blower pulley and the same length belt there is substantially more wrap on the supercharger pulley.  The new arm utilizes double shear for the idler pulley mount.  The doubler plates are made from 1/4" aluminum. 

[Mike Brown]

I found a photo of the original blower idler.  It was a compact system that fit well but was definitely too close to the crankshaft pulley. 

[Mike Brown]

YES    ..  on smallest part of arm , generally the wrist area ..   STEVE

There is a thread on Landracing.com with extensive information regarding the rule change for arm restraints.  It appears that the "smallest part of the arm" refers to "non sewn in restraints".  So if you have a fire suit with integral sewn in arm restraints and change to the 3-bar style adjusters you meet the new requirements. 

4. Section 3.D.3 Arm/Leg Restraints: Page: 42 Add what is in bold after the first sentence in the first paragraph; SFI specification 3.3 arm restrains with a manufacture date of 2006 or later are required in all vehicles. IN ADDITION: ALL ARM RESTRAINT HARDWARE MUST BE OF A SINGLE PIECE MANUFACTURE. I.E. NO TWO PIECE OR WELDED “D” RING STYLE ADJUSTERS. ADJUSTABLE TETHERS SHOULD USE A 3-BAR SYSTEM SIMILAR TO THAT USED IN LAP BELT ADJUSTERS. NON-SEWN IN RESTRAINTS SHALL HAVE A TIGHT FIT AROUND THE NARROWEST PART OF THE ARM. ALL ARM RESTRAINTS MUST BE DEMONSTRATED TO BE EFFECTIVE.

[Mike Brown]

Part of the tuneup changes for this year is to eliminate the ECUs control over the supercharger boost.  The supercharger has the previously mentioned bypass valve that "unloads" the supercharger.  The concept is that the blower is unloaded during high vacuum in the intake manifold.  This reduces intake air temperatures when no boost is required.  In addition via a solenoid valve controlled by the ECU the boost can be turned off or modulated to a lower level.  This is necessary in modern high horsepower cars to make them driveable.  Typically the body computer tells the ECU that traction has been lost or dynamic stability is at risk to reduce the boost.  I don't have a body computer and want my boost on all the time only to be controlled by my throttle.  Most tuning professionals don't recommend eliminating the boost control valve but it can be replumbed without the solenoid so under high vacuum conditions the valve is opened to the bypass position.  When the throttle is opened and vacuum drops the spring in the dashpot closes the valve allowing boost to build.  I removed the solenoid on my engine and plumbed the dashpot directly to a port in the intake that sees both vacuum and boost.  Aftermarket superchargers like those manufactured by Magnuson have a bypass valve that operates in this fashion.  It will be interesting to see if this helps with the performance. 

[Mike Brown]

The new supercharger tensioning system is ready to install.  I machined a socket with ball recess for the jack bolt that will hold the idler pulley in place.  The jack bolt has a brass tip with a ball end machined on it.  Note that the post is welded to the mounting plate for those with a sharp eye.  The 8-32 flathead screw held the post to the plate while I was aligning everything before welding. 

[Mike Brown]

The tensioner installed.  The alternator has been removed for easier access.  The post that has the jack bolt bolts to holes in the end of the cylinder head.  The alternator mount is slotted for adjustment so I could not weld the post to that plate.  I think with the experience of building a belly tank lakester I should build ships in a bottle when I retire. 

[Mike Brown]

Today I replaced my AutoMeter tachometer and shift light with an obsolete Stewart Warner B-757 shift light.  A land racing friend uses one on his flat head powered roadster with great success.  I found the shift light on Ebay for $68 including shipping.  It is a very basic shift light that uses LEDs.  There is a small numeric display that shows RPM and nine really bright yellow LEDs that illuminate at a preset rpm.  The rpm setting on my original tachometer was an analog knob.  I kept accidentally bumping the knob and changing the shift point.  The shift point was usually higher which led to running up against the rev limiter in the ECU.  I did not like any options that I came up with lock the knob down.  This shift light is digitally programmable for shift point and pulses per revolution.  These settings are retained when power is removed.  I put a matching connector on the shift light so that it can be easily swapped with the tachometer if needed.  I fired the LSA up to test the shift light.  The over driven supercharger pulley is now installed along with the removal of the boost control solenoid.  The engine now builds boost very quickly.  We will see if this is an advantage on the next test and tune session. 

[Mike Brown]

After much research I have decided to stay with the MAF tune up on the LSA engine.  The engine will still need a tune up on a dyno to expand the VE tables to match the increased boost from the smaller blower pulley.  The factor engine controller has short and long term trim tables that are used to store fuel and ignition changes that the controller learns while running.  With a battery disconnect switch which kills all battery power this information is lost and the controller starts from scratch each time the engine is started.  I decided to wire a circuit that has constant battery power to the controller so that these trims can be stored and viewed.  The long term goal is to make these changes permanent.  As the engine gets more runs the fueling and timing tables should get more accurate making it easier when I do switch to a speed density tune up.  The controller is a GM E37.  I could not find the pin for this power anywhere.  Luckily the fuse box (which came with the GM controller and wiring harness that I bought) had a fuse labeled "ECM KEEP ALIVE" (fuse #10).  So the plan was to disconnect the wire from this fuse and run a circuit directly to the battery.   

[Mike Brown]

There is not much room in a belly tank lakester but I was able to disassemble the fuse box and verified the ECM Keep Alive wire (the small red) one. 

[Mike Brown]

I added an inline fuse holder to protect this circuit that was connected to the battery.  I like to keep things labeled even if it is very basic.  The current draw is in microamps.  I could not even read the current on a digital multimeter that reads in milliamps.  I used a 5A fuse. 

[Mike Brown]

I added a switch accessible outside the body to turn the ECM keep alive power off if needed.