Through the Smoke and Bull
Tom’s tech tips

This issue I want to write about a few things I have discovered recently working on the old bullnose Saabs.  They fall into the category of "did you know that..."

Last fall I decided to help the car I drive all over the country keep its cool in the summer.   (This would be my 1961 96 affectionless nicknamed by its former owner, the late Larry Williams, the Get-Away Car. (Hey it has a bullet hole in the trunk!)  I had already fitted the 940cc engine with a four-core radiator but it still seemed to heat up if you pushed the car hard on long pulls.  It had never really overheated but had put the needle just into the red on the temperature gauge a few times.  The most memorable time was in 2001 while driving on vacation in Old Mexico coming out of an ocean town called Port of Penasco.  We were pulling a long, long steep grade on a hot day and the Saab 96 loaded with my family of five and all our luggage!  (Try that Chevy Chase!)  Another time was while I was "stroking" west on I-70 out of Denver heading to the Eisenhower Tunnel for the SOC 2009 at Copper Mountain.  To me the reason the engine ran warm was that it seemed the coolant did not circulate fast enough to make good use of the radiator’s extra row of cores.  So on these pulls I had to do what I always do when you engine temperature climbs too much, lower engine temperature by left off the gas more.  I drive with a triple set of Exhaust Gas Temperature gauges (EGT) on all my cars.  Lower your EGT, and your coolant temperature will quickly follow.  After seeing two other bullnoses that summer with cooling flow issues, (I discovered one had too long a hose on it and it caused a "bend" or “kink” that restricted water flow.  And the other one had all kinds of small road stones and junk, like old coagulated anti-freeze, restricting the hose/inlet.  Since these types of restrictions can hide under the engine with the “mystery” hose down there, I decided my Get-a-way car might be suffering a similar condition.  

The bullnose engine uses a water inlet that is not the same as the later long nose cars use.  The bullnose engine's water inlet (next to the exhaust manifold) has to run under the engine to reach the outlet on the generator/water pump.  This design makes for a tight fit for both the inlet and the hose that run to the water pump outlet. 

That said I was looking at the horned shaped inlet I had just removed from my get-a-way car and decided the passage way was too small, only about 7/16" diameter.  There was plenty of aluminum there on the sidewalls so I decided to bore it out to approximately 9/16" to increase the flow of water into the block from the water pump. (I actually used a 17/32” drill bit cause it was sharper!) I also looked carefully at my partially collapsed hose and it was clear to me that it was just a little bit too long.  Drilling out the water inlet was easy and I decided I should drill/mill out some more inlets so I would have them in stock the next time I needed one.  In doing so I discovered that not all water inlets are made the same.  Even though the casting numbers 707713 are the same on all inlets, the bore size is different.  Some were like my narrow 7/16" one and the others had been cast with a larger bore of approximately 9/16".  I assumed this was a running change (like all manufactures do).  Change the part but leave the part number alone.  Annoying at times to try to figure out what you actually have.  We run into this all the time with the Big Three (little three now) in my transmission business with parts. I figured it was may be a 93/96 issue that Saab had figured out with the larger engine needed more circulation.  I asked a few people who had bullnoses if they knew of why the difference and no one knew there even was a difference!  About then you get thinking you are real smart...found something on your own did you…you smile…and then read about it elsewhere!  I recently did discover 93’s used the smaller inlet and 96’s were the larger ones.  Nicklas Enander, with XP Power in Sweden, wrote about it in his fine two stroke publications, “XP EXTREME POWER, Two Stroke Engineering Solutions”, that I had bought many years ago.  Funny how smart you get when you read someone who is smart!  Anyway, I drill/mill them all out now to increase the coolant flow dramatically.
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Now time to work on that hose that runs under the engine that gets soaked with oil and collapses!  I discovered that all the collapsed hoses I found were too long.  Take the bend out of them and they were all 11 3/4" or longer.  I decided 11" the good fit (maybe 11 1/4" on a few) any extra length and the hose would bend or kink.  My guess is that if you are luckily enough to still have NOS hoses, they too would be 11" long.  But I have to rely on plain old 3/4" heater hose for my jobs.  The natural bend of the hose from being in a roll makes the bend angle perfect for this application.  Just cut to 11" and install.  I would advise bolting it all in place (leaving you clamps loose) and getting the fan belt on the generator/water pump, to see the exact fit needed.  You can them "peak" under the engine and see if your hose is fitting properly.  Also, if it is too short it will cause the hose to stretch, thereby collapsing it too.

I also learned from re-reading (yes I had made notes in Niklas’s writings years ago but failed to retain any info in the gray thingy inside my head!) Nicklas's information states that the water pump outlet can be smaller too.  Some have a "lip" by the outlet next to the impeller that can cause the pump to drop efficiency.  There again, drill or mill them out to 17/32” to 9/16”.  Check the water pump inlet too.  Most seem ok but now’s the time to make sure all passages are large enough.  By the way, Niklas has a great website for old Saab parts www.classicsaabracing.com.  In my view, Niklas is one of the leading Saab two stroke experts in the world and his writing and parts are great. 

Also, if you need to rebuild your water pump/generator, Erik Randa in Sweden sells a good little conversion kit to repair your old impeller and replace the no longer available parts in the pump. Go to www.randa.se to check out this and the other parts he makes and sells.  Good bullnose stuff there. If you just need an o-ring to fix yours, drop me a self-address envelope and I will mail you a couple for free (I had to buy five hundred to get one!) 

Do all this and you should have a free flowing water pump and cooling system.  I still have to test mine this summer on some big ass hills but my late fall results looks like a rather "chilling" success.

A couple other quick points, be sure to use only distilled water if you can.  Try to avoid tap water (Which I did use for years from a non water softener source).  I had a pump I rebuilt last fall that I put some tap water in over night to test for leaks. (I forgot about our shop having soft water).  Next morning I had no leaks but I looked inside the outlet with a flashlight only to discover the impeller had already rusted badly!  It was soft water…I guess that salt really does work fast!  

Lastly if you need the upper radiator hose for a bullnose stroker, get a NAPA #7446 and cut off about 2 ½” to 3” from the end of the hose that is a little crooked.  Take that cut off piece and you now also have the small couple for between the thermostat and the radiator in one hose purchase!

Good luck keeping your bullnose cool and as always, Safe Saab'in
Tom Donney, 3553 5th Ave South, Fort Dodge, Iowa 50501 or email tomsaab@gmail.com or 515-368-7222
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