bjhines

That's another one I might try to find cheap to test with.

So... The pump pulls excessive current at +4"hg vacuum. I should limit it's operation to below 3" vac or so. 1. A 3" vac switch hooked into the crankcase or recovery canister should do the trick. The pump would cut off when crankcase vac approaches 3" and we are good. PCV valve should do the trick at idle and part throttle. 2. A 10" vac switch in the intake would cut the pump off whenever the intake vac is greater than 10". This would indirectly control the pump when PCV valve is capable of providing flow. The pump would only turn on when the throttle is mid to WOT. 3. A micro switch on the throttle would cut the pump on at mid to WOT. This would ensure that the pump only works when the PCV cannot. This is another indirect approach but it would work. 4. A relief valve that would open to atmosphere to allow free airflow for the pump under high crankcase vac conditions. The LS1 A.I.R. system came with a large 5/8" port tee that opens when 10" vac is applied to the diaphragm port. I could indirectly plumb this to intake vacuum to open up the port on the tee when PCV can do the work. This would allow me to run the pump all the time and simply relieve the load on the pump. 5. I could combine several switches into a logic controller that could do many things under different conditions. I would like any help finding a vacuum switch for this purpose. Does anyone know what to look up when searching for an automotive Hobbs switch that is not $100 or more?

see there.... Look at you... Got this thingy going all ready and I am just beginning to figure it out. It appears that mine already had the foam removed. I would mount the pump assy with the motor UP. You have it DOWN and oil will collect in the rubber bulb that encloses the motor. We may even need a drain in the plastic cover with a one way nipple to drain liquids when the pump is off. I am looking for vacuum switches. I can't seem to find many automotive versions. I have found some industrial and refrigeration related parts, but they are very expensive(>$100). So... The pump pulls excessive current at +4"hg vacuum. I should limit it's operation to below 3" vac or so. 1. A 3" vac switch hooked into the crankcase or recovery canister should do the trick. The pump would cut off when crankcase vac approaches 3" and we are good. PCV valve should do the trick at idle and part throttle. 2. A 10" vac switch in the intake would cut the pump off whenever the intake vac is greater than 10". This would indirectly control the pump when PCV valve is capable of providing flow. The pump would only turn on when the throttle is mid to WOT. 3. A micro switch on the throttle would cut the pump on at mid to WOT. This would ensure that the pump only works when the PCV cannot. This is another indirect approach but it would work. 4. A relief valve that would open to atmosphere to allow free airflow for the pump under high crankcase vac conditions. The LS1 A.I.R. system came with a large 5/8" port tee that opens when 10" vac is applied to the diaphragm port. I could plumb this to intake vacuum to open up the port on the tee when PCV can do the work. This would allow me to run the pump all the time and simply relieve the load on the pump. 5. I could combine several switches into a logic controller that could do many things under different conditions. hmmmmmm.....

I got my hands on a 12v electric pump from an LS1 GM smog system. The pump weighs 2.25 pounds and draws 11A free flow, and up to 20A restricted flow. It achieves highest vacuum(4"hg) at 17A with a small amount of airflow. The pump runs cool with air flowing through it. The impeller housing gets hot very quickly when the airflow is stopped or severely restricted. I think the heat is from the impeller, not the motor, although it does draw nearly twice the current when stopped up. The turbo-Buick guys are using these pumps only under boost. That means pump-duty is intermittent and likely has a lot of airflow. I would be concerned about overheating the pump under continuous, high vacuum/low airflow conditions. For this reason, I would use a micro switch on the throttle or a vacuum switch to shut off the pump under high vac conditions. ...

I found an LS1 GM smog pump to play with. The pump alone weighs 2.25 lbs. These things are a lot like 12v shop-vacs. They have an extremely high RPM rotor that moves a whole lot of air. The motor will run free flow for 10 minutes before it even gets warm. The housing gets hot very quickly when airflow is blocked and the motor draws nearly twice the current. I think most of the heat is coming from the impeller not the motor. The free flow current draw is ~11A. Restricted flow current draw goes up to almost 20A. Pressure side restriction at 2 psi. The pump pulls the highest vacuum with some small amount of flow at 17A. Vacuum is 4"hg at 17A. It looks like the Turbo guys are using these intermittently; only when boosting above a certain level. The original duty for these things was only for a short time after startup. I would set it up to work only under full throttle for a track car. A microswitch or a vacuum switch would do fine to operate a relay to switch this thing on only when needed. PCV could do the rest at idle and part throttle.

I like the catch can. I assume it has a "road draft" tube that dumps the vapors near the ground like cars of the 1950s. How about moisture buildup around town? My oil fill cap would always have a slimy milky coating on it from moisture buildup. My MLS head gaskets seep oil. I have them on the SBC V8 as well as one on the L24. The sides of the engine would get oily until I got a proper vac pulled on the crankcase. The vent system eliminated the moisture/vapor problems entirely.

I tried vents, I even tied both vents to a catch can with vent on top. It always made a misty oily mess. My valve cover collected a lot of moisture around town. I wanted to positively ventillate the crankcase using whatever method worked best for weight and money spent. Obviously dry sump and racing vac pumps are tried and true but out of my budget. There are a lot of advantages to PCV systems, including longer oil life, cleaner engine, fewer external leaks, better ring seal, even pulling fumes out of the fuel tank if you use the tank vent line. I saw a lot of folks on track dumping oil, smoking in turns and braking zones, etc. I figured this was a common problem, but I was surprised at how little was ever done to solve the problems.

The Subaru pumps do not have an easy to use inlet connection. They appear to have a filter housing around the motor which would need to be modified. In addition the motor on these units appears to be very small. The GM LT1, LT4, and LS1 secondary air pumps have large electric motors and easy to use hose connections.

In my search for info on this I have come across several other potential ways to deal with this problem. Many cars come with a secondary AIR/smog pump. During the 1970s and 1980s these were usually mechanical pumps driven by the accessory belts. It appears that GM and Ford used similar designs that even incorporate the same pulley hubs. I found that the mid 1980s Ford truck smog pumps are $50 rebuilt. These pumps require some oil vapors to operate properly so they are usually plumbed first in the system and then on to a catch can and vent. The CFM depends on pulley speed, and they can pull 16" of vacuum. GZ motorsports offers upgraded pumps for use as crankcase evacuation pumps There are a variety of electric pumps available as well. German makes offer the best quality pumps, but there are many GM/Delphi AIR pumps that will work as well. Racetronix offers a neat little wiring set up for these pumps.

The tee in the line runs up to a custom made catch can. In the beginning, I had 3 problems, low pressure when hot, over heating the oil(water is fine), and starvation in right hand turns after hard braking zones. The 3qt accusump did it's job well even with low system oil pressure. ...

Ummm.. No.. The thermostat is not capable of responding to the flow of cool water until it has cycled through the engine and reached the thermostat. With over-cooling of the water sitting in the radiator the engine will cool off too much before thermostat closes. This is temporary, not constant. The engine will again come up to operating temp and then more over-cooled water will again be introduced causing a pulsating temperature condition. It is not a constant condition, The engine will reach operating temp repeatedly, over and over again.

I turns out that the flow control valve and blowby was enough to relieve high vac conditions. The pulse tubes could never generate more than -8"hg vac. They were the high flow rate vac source, beyond 6-8" vac the PCV was the only source capable of drawing higher vac. The PCV is a limited flow high vac source that is easily overcome by blowby before it can draw much more than 10-12"vac on a sealed crankcase. I suppose that without a properly functioning PCV valve, an open manifold source could quickly oil-can the fuel tank. On my SBC, Holley 4150, highest manifold vac is off idle @ 2500RPM = 22"hg vac. I don't think the L24 ever made that much vac. This SBC system is on a well sealed crankcase and breather system. It takes ~60 seconds for the crankcase to equalize to atmosphere from 11" of vac on shutdown. On startup, The vacuum will build slowly(~30 secs) to ~11"hg at idle. Blipping the throttle will build vac to ~8"hg very quickly but it climbs slowly to 11" after that. Driving on the highway gives good vac on all but long full throttle runs, even then, it is better than 2"hg vac.

LOL! This was my first post here! and it comes up again. Here is the original system on the L24 with DCOEs. you can see the top vent tube going down to where the exhaust check valve is located. The copper piping provides manifold vac to the brake booster and allows for venting the block through PCV. I have done the same thing for my V8 powered Zcar. This time using 2 pulse tubes, and better check valves that can take the heat. I do not have the vacuum relief valve in place on this build and the V8 does not have a block breather like the original L24 engine. PCV inline adapter recovery canister Exhaust pulse tube and check valve ...

TONY!!! You think it through and you will understand! The baffles only keep the temp steady. They are not used to keep the engine hot, The thermostat does a fine job of keeping the engine hot. regardless of external conditions. Radiator airflow is usually regulated by the cooling fan, but the air-baffles help to improve the operational range of the cooling fan control. Poor radiator airflow control will lead to temperature pulsing within the engine which is not optimal.

The baffles were set to keep engine temp steady. In cold weather the over cooled charge of water would shock the engine. The engine temp would fluctuate, Not that it stayed cold, It just pulsed, this is not optimal. The baffles were set so that the engine temps did not pulse. It never mattered at idle sitting still, the cooling fan controlled the airflow through the radiator when parked.

The whole idea of placing cardboard over the radiator is to keep the water from overcooling in the radiator and shocking the engine when the thermostat opens to exchange the water. I drove a big rig for years and had to deal with service problems related to the cooling system(Canada to Florida/winter to summer). The radiator baffles were to keep the exit temps from the radiator closer to engine operating temps. The Datsun engines have no mystery cooling problems. There is no problem with warming up a Datsun engine in 0f-100f weather. If you fail to turn on your cooling fans it will overheat quickly in 0f weather sitting still.

I have installed these pulse/evac tubes on several vehicles. I have used these exclusively on vehicles with full, performance exhaust and free-flowing/loud mufflers. The main problem has been the poor quality of the check valves that come in the kit. I am using 1984 Ford 5.0 truck A.I.R. check valves that were designed to screw into the exhaust manifold AIR distribution tubes. They can handle the heat and they work very well. There is no real trick to installing the tubes. Pay attention to the instructions and place them where the exhaust pulses are at their maximum amplitude. This is right after/at the collector. The further downstream you place them the less amplitude the tubes have to work with. You want about a half inch of the tube sticking into the exhaust pipe. This minimizes odd flow effects on the wall of the exhaust pipe. There is no Bernoulli effect or other fancy **** going on. I have seen a lot of folks who insist on turning the tubes 180 so that the slash cut end is perpendicular, facing downstream. I dunno how that works for them but it really gets in the way of exhaust flow. You can expect 3"-6"hg of vacuum from these with much more flow than the PCV can deliver. The pulse tubes work pretty well at idle up to full throttle, mid-RPM. There is too much positive pressure in a full exhaust at WOT high-rpm for these to work well. I still prefer the excess crankcase gases flowing into my exhaust instead of my air cleaner. ...

I had starvation with the early corvette pan. I had a lot of other problems as well. The pcv valves have a variable flow rate that is tailored to a specific application. I pulled a bunch of pcv valves out of their boxes and blew thru them to find the one with the most flow and suitable connections. Most any V8 engine pcv is a good start.

No more starvation problems at all. The windage tray, pan baffles, extra capacity, and trap doors keep everything under control. I run the oil level so it just barely shows on the stick. It has plenty of capacity to deal with the accusump discharge. I added the crankcase evacuation system and got some initial testing results. The system uses PCV and exhaust pulse generators. I have PCV drawing 15" vacuum with a low flow rate at idle. It takes about 30 seconds to draw 12" of vac in the crankcase at idle. PCV will not maintain crankcase vac under load. I have exhaust pulses drawing 6" of vacuum at part throttle with a high flow rate. Exhaust vac fluctuates with throttle blips but seems to maintain at least 5" under all but full throttle high rpms. The two sources together maintain good vac under all but sustained full throttle operation. The crankcase vac is never worse than 2" vac as far as i can keep my foot in it on the highway.

If only.... everything could be soooooo incredibly rare and complex as Tony makes it out to be. I have tackled some bitchin problems with my newest track toy, But this over complexificatation of freshman, newbie, neophytical problems is maddening. Tony wastes more neurons and electrons than anyone else allowed to post on this forum.

I don't know the LS1 ODBII system that well, but... I know that ODBII systems usually check the condition of the EVAP canister and that the tank is air tight. On startup, the computer will open and close a series of valves to draw a vacuum on the entire tank and evap system and hold it for a set time. Then the computer opens the evap purge line and then checks the O2 sensor readings for enrichment from the Evap canister's contents. If this system fails any of the tests twice in a row; a variety of codes are logged and a check-engine-light will activate.

Thanks FastZcars, After test fitting several parts. It takes a thick front seal to properly fit the Edlebrock 2-piece front cover. Indeed, a thick seal fits like a glove and seals well. The oil pans are not the important factor, It is FIRST the Dipstick location(left<=79<right), and secondly the front cover design(thin<75=<thick). But really folks... Even the INSTRUCTIONS for the Edelbrock cover don't seem to mention the exact year or the thickness of the front seal. They supply a front pan-seal in the timing-cover kit, but don't mention it's thickness, only it's part number(#54-0607) which NOBODY sells. I got the collar sealed with some black RTV... Underneath, injected in the split, and on top between the collar and hold-down clamp. It may or may not stay in place, but I did get a good seal that I tested with a smoke generator to a few PSI. The engine is the only part of this car I did not build myself. It has been the most dangerous and challenging source of problems in this entire build. I will NEVER!!!! EVER!!!! again buy a complete engine from another home builder. There is no continuity or documentation. Note to self... BUILD THE DAMN THING TO A SPECIFIC YEAR!!!!!! Use all the aftermarket parts you want but build it to suit a detailed set of replacement parts from a specific year. I cannot stress enough how important this is if you EVER try to get gaskets at a track event, or on a budget. ------------------------------------------------------------------------------------------------------------------- Now, about the buildup of pressure inside the engine... I am adding the Crankcase Evacuation Kit offered by MrGasket. I am routing from the top of both valve covers to a catch-can. PCV to the intake works for part throttle operation and exhaust pulses work at moderate to full throttle. In my experience the evac tubes use exhaust pulses and a check valve to generate significant flow but low actual vacuum. Obviously they work better on open headers, but they will still pull considerable flow with a good exhaust and mufflers.