Motor back together, first start, goofy idle timing advance

[one finger john]

To pressurize the system see if your local Auto Zone or car parts place has a hand pump pressure checker with gauge.

You probably can borrow it for free (and free is always good).

John

 

[Lee_in_KC]

Engine was pulled yesterday morning, so the opportunity to test it in the car is missed. I'm going to try to the bicycle tube trick. Waiting for the brown truck to deliver new gasket set for the water pump.

 

[fletcherson]

Engine was pulled yesterday morning, so the opportunity to test it in the car is missed. I'm going to try to the bicycle tube trick. Waiting for the brown truck to deliver new gasket set for the water pump.

At least it's a bucket and not a truck with AC, etc...still no fun having to pull a fresh motor, I've been there too. I made a pressure tester. I had a Mack, but the pump failed, so I took a radiator cap and took the relief spring out of it, installed a fitting and connected a hose from it to a fitting with a regulator and shutoff valve and air hose fitting, gauges, etc. it works better than the other one, I just set the regulator to however much pressure I want, and watch for leaks. I can shut the valve and let it set for a period of time to test for slow leaks, sort of like a compression leak down test...before I made it, I tested them by installing a modified cap that didn't block the overflow spout and put air pressure into it via the overflow port, spout, whatever.

 

[Gerry]

I used a tyre valve (tubeless) ground down where the bulge is and a short bit of hose jubilee clipped to it and then to my fuel tank to see if the tank was leak free. Just connect to your tyre inflater and squeeze till the pressure is right. Then use the deflate button to let the pressure go. Simple

 

[Lee_in_KC]

Got the leaking water pump re-gasketed and back on the block. Pressure test was completely successful!! No leaks anywhere. Had the plugs out for the test. Rotated the crank and checked the tops of all pistons for water. Checked the oil pan for water (shined a light through the drain hole and looked down the dipstick hole. Also rotated the motor in the stand so that oil drain hole was the lowest point on the motor... no drips (other than a little clean residual oil.

Here is my test set-up. Turned out my lower radiator hose was just the right length!! Had to turn the water neck around, though.

 

[2old2fast]

Lee/ motor -1 gremlins -0
dave

 

[Screaming Metal]

Metal,
How much of a load does a 671 put on a small block at idle when it is producing very little boost ?
Is that why so much advance is needed initially. When would boost retard come into play?

John


A 6-71 takes about 50 horses to turn it at the crankshaft, when a blower is idling on top of a motor, it isn't producing any boost, the intake charge flow is or should be sync'ed to the flow of the blower (no pressure). While the motor is idling, it need spark advance just like a normal motor.
As your motor revs slowly like going down the highway, the motor need a normal spark curve setup for the motors components, either a stock heavy-duty motor or a street/strip setup.
Believe it or not, driving down the highway under normal cruise conditions, no boost should be present, as the motor is taking in the little wind the blower is putting out.
Now, step into it a little, you should see the boost gauge just flutter a little, maybe hit 1 psi....romp into it heftily, you should see all your boost, ie, 5 to 7 psi at the boost gauge.
5 to 7 psi is normal on a fairly stock sbc, 8-10 psi, you want your motor built pretty tough, 10+ psi, you'd better have a good bottom end because a stock motor will break a crank and/or rods.
That blower, all it is is a air pump, plain and simple, it just makes the motor 'think' its 4 or 5 times bigger than what it is! Thats why it makes its power, its cramming all that mixture into the cylinders under pressure.
A street car usually only needs 5-7 psi to turn your car into a tire frying wheelie demon, at the track, we run up to 20+ psi....
Anything over about 10 to 12 psi on a blower, your raising your compression ratio in the cylinders enough to need o-rings on the head gasket surfaces....

 

[Screaming Metal]

Got the leaking water pump re-gasketed and back on the block. Pressure test was completely successful!! No leaks anywhere. Had the plugs out for the test. Rotated Hthe crank and checked the tops of all pistons for water. Checked the oil pan for water (shined a light through the drain hole and looked down the dipstick hole. Also rotated the motor in the stand so that oil drain hole was the lowest point on the motor... no drips (other than a little clean residual oil.

Here is my test set-up. Turned out my lower radiator hose was just the right length!! Had to turn the water neck around, though.

Hey Lee, when you pressurized your motor, did you spray soapy water all over? What I normally do is a setup like what you have there, but with a pressure gauge and shutoff valve. I pressurize it, then shut the valve, and watch to gauge to make sure it holds pressure....if it holds for 30 minutes with no drops, your good.

 

[one finger john]

Metal, thanks for the answer. How are the blower vanes synced and would this be of advantage to Lee?

John

 

[Screaming Metal]

What John was asking above, ALOT OF FOLKS ASK THAT VERY QUESTION! Just think about it for a second. Running time on your blower, what percentage of the time is your car producing boost? Very damn little. So, you need a timing system for a motor your building. If you go to cruise night, and your romping down on that blower, yes, your motor will live, but think about the punishment your putting on the motor. A good rebuilt strong motor will last a long time, but for someone with a lead foot, bearings/seals and rings will have to be replaced sooner.
That blower would tear a well built motor apart in short order, if it produced boost all the time. Bearings/pistons/rings would be trashed almost immediately. Thats why the drag cars are rebuilt between rounds, running max boost at max rpms all the way down the track.... I've seen then bearing shells seperate from the liners in the bottom end, with all 8 rods bent.
At the track, we run 2 magnetos with 2 sets of plugs because we're pumping in so much boost, we're close to blowing out the spark, along with the nitromethane thats loaded with oxygen.

With the blower, your motor thinks its 4 to 5 times bigger than what it is, when you apply power to it with that 6-71 supercharger. That means that you would need to replace your motor innards 4 X's as often....
Just a thought....

 

[Lee_in_KC]

SM, I did not spray it with soapy water. Also, I don't have a gauge or valve. That's why I used the quick-connect fitting I had on hand to retain the pressure. I set 20# on the regulator on my compressor and plugged in the hose. I let it sit like that for 15 minutes, then disconnected the hose and let it sit for another half-hour. I then plugged a bare nipple fitting into the quick-connect to release the pressure. It squirted water out for about 5-6 seconds, then air for another 5-6 seconds.

 

[one finger john]

But Metal, ummmmmmm, when we "time" something we synchronize two operations so they can work together or build upon each-other.
A rootes blower does not deliver compressed air like a centrifugal supercharger in that the rootes unit will essentially supply "gulps" of air from the vanes. Where as the centrifugal blower will supply compressed air in a smoother more controlled manner. Fewer, larger "gulps" from a rootes vs more, smaller "slices" from a centrifugal unit.
The rootes unit will have air pulsation (minor at idle) that intensifies as rpms build.
I suppose that can either be a boon or a bust depending on the phasing of those "gulps" of air.
So I am asking, how should the vanes be timed or phased to effect low, mid range, or top end performance and can this vane phasing actually be felt or be noticed thru, say, improved gas mileage or such.
Can supercharger timing be used to tailor engine performance and how could this enhance Lee's particular street blower set up?

John

 

[Screaming Metal]

Hey John! By sync'ing, I meant matching your blower to your app. your using. Matching your drive pulleys to your rpm, because blowers setup with close tolerances produce more boost down low, for like low rpm motors. The higher you spin the motor, the less blower speed you want. Matching your blower 'tightness' or internal clearance to fit your app. also. Kits avoid this. Its kinda like purchasing a blower kit with matching carbs, everything is made to run together. Lee's kit has run perfectly before on a motor, so everything is good-to-go....
Example, start producing boost too early (too much over-drive), your motor is starting to rev, just as the blower boost is coming on....this is a very dangerous situation, because the motor can backfire, while the intake is being pressurized....'BOOM'.... That is enough to engage your pop-off valve or burst-plate, possibly spit out your intake and blower gaskets. Kits purchased from B/M, BDS, and others are matched to avoid this. BUT, if your assembling your blower piece by piece, this can happen.
I'm just throwing out this info for someone not purchasing a whole kit from someone, or is adapting a kit to their particular setup.

The pulses of the rotors can affect certain things, and can help here, there. But, its not applied to street apps....this is mostly efi and computer stuff related....usually sensor related stuff.

There are many diff. blowers, 2,3,4,6,8,10,12-71's, diff. blowers made by gmc to blowing insulation and compressing diff. things in the industrial world. Then there are the paxtons, the whipple, hi-pressure tapered vane units, etc. Theres enough of diff. types and makes to take up several paragraphs.
I've even done up a few units from old smog-air pumps to be used on motorcycles/snowmobiles for racing because they are circular and small, making for fitting into tight places easier....
Some of the early german units used on their WWII planes looked like a std. turbocharger, with a gear drive one the front, which worked great with the nitrous....kinda similar to the paxtons

 

[fletcherson]

Hey John! By sync'ing, I meant matching your blower to your app. your using. Matching your drive pulleys to your rpm, because blowers setup with close tolerances produce more boost down low, for like low rpm motors. The higher you spin the motor, the less blower speed you want. Matching your blower 'tightness' or internal clearance to fit your app. also. Kits avoid this. Its kinda like purchasing a blower kit with matching carbs, everything is made to run together. Lee's kit has run perfectly before on a motor, so everything is good-to-go....
Example, start producing boost too early (too much over-drive), your motor is starting to rev, just as the blower boost is coming on....this is a very dangerous situation, because the motor can backfire, while the intake is being pressurized....'BOOM'.... That is enough to engage your pop-off valve or burst-plate, possibly spit out your intake and blower gaskets. Kits purchased from B/M, BDS, and others are matched to avoid this. BUT, if your assembling your blower piece by piece, this can happen.
I'm just throwing out this info for someone not purchasing a whole kit from someone, or is adapting a kit to their particular setup.

The pulses of the rotors can affect certain things, and can help here, there. But, its not applied to street apps....this is mostly efi and computer stuff related....usually sensor related stuff.

There are many diff. blowers, 2,3,4,6,8,10,12-71's, diff. blowers made by gmc to blowing insulation and compressing diff. things in the industrial world. Then there are the paxtons, the whipple, hi-pressure tapered vane units, etc. Theres enough of diff. types and makes to take up several paragraphs.
I've even done up a few units from old smog-air pumps to be used on motorcycles/snowmobiles for racing because they are circular and small, making for fitting into tight places easier....
Some of the early german units used on their WWII planes looked like a std. turbocharger, with a gear drive one the front, which worked great with the nitrous....kinda similar to the paxtons

I would love to see a smog pump blower setup. Cool idea!

 

[T-Test]

I would love to see a smog pump blower setup. Cool idea!

See John's books at TBucket plans. He put one on a lawn mower.

 

[fletcherson]

See John's books at TBucket plans. He put one on a lawn mower.

That's what I need to keep up with the weeds, lol!

 

[Lee_in_KC]

Well guys, so as not to leave you hanging, here's the end of this particular saga. Motor is all back together and back in the car. Original headers and mufflers are back on. Started right up with 30* initial advance. No leaks anywhere!! I fiddled with the idle mixtures a little more then drove it around the neighborhood at 2000 RPM for about 20 minutes, watching the water temp. It got up to 180 and stabilized, which is exactly what it used to do. I have a 180-200 stat. When I got back I was able to adjust the idle down to 800-900 (lumpy cam). I was then able to back the timing off to right at 20* and the motor idled like it used to. I'm good with that! I'll be watching temps, listening to the motor closely and checking plugs as I work back up to my usual driving style.

Thanks for all the advice and guidance, guys. It was really helpful.

"On the road again... I just can't wait to get on the road again..."

 

[2old2fast]

GREAT news , glad to hear you got it handled , now go dump the oil , change the filter , look for shiney stuff , fill it up & take it easy for the next 500 ..
dave

 

[RPM]

So glad to hear you got it al straightened out.

 

[PotvinGuy]

I would love to see a smog pump blower setup. Cool idea!

I bought this auto twin screw supercharger at the swap meet. The old sales guy said it would fit on top of my Small Block Chevy. He said it was so good that you could do anything with it, like make slushes. I know a deal when I see it.