Gary Lewis Posted August 10, 2020 Share Posted August 10, 2020 That does help for sure. I think I have all those identified. I still just can’t figure out what creates the vacuum. Gasoline engines operate differently from diesels in that the gas engines have a throttle. And because there's a throttle there's a vacuum in the intake manifold. The more throttled the engine is the more vacuum there is. IOW, at idle there's max vacuum and at WOT there's min. Link to comment Share on other sites More sharing options...
Rusty_S85 Posted August 10, 2020 Share Posted August 10, 2020 On MY 300 the AIR goes in just before the CAT that is after the 02 sensor so cant see the issue in running the air pump. I also find it strange that sniper said to remove all the smog stuff as it is not what the law wants you to do and you can be fined and / or go to jail. Just strange is all and yes all my smog is gone This high idle you talk of even if the smog stuff is on or off the motor the idle should be able to be adjusted so look for a vacuum leak somewhere. On the 2 belts for the ALT. What you have now you cant do that. Look at all the belts: belts run from motor out on crank. 1 belt for ALT/water pump/crank 1 belt for PS/water pump/crank 1 belt for AC/water pump/crank 1 belt for ALT/air pump Only non AC motors had 2 belts for the ALT and the air pump ran off the crank IIRC. I just went thru all this when I installed the AC compressor on my motor. Oh my motor never had the air pump on it and I blocked off the EGR but the valve is in place and can hook a vacuum hose to it but it will never work. Yes you do have vacuum hoses to the HVAC control and with out it you could not change air flow from the defrost to floor or vents. Only vacuum you need: carb to dist. and Intake to power brakes & HVAC panel. That is all I have on my truck and it runs great working on getting the MPG up a little bit. Dave ---- If the air injection is at the converter or after the O2 sensor then it wont have a negative effect on the operation of the EFI, but Holley still strongly recommends against using their EFI with emission systems. It probably has to do with the fact that out of the box the default setting for the sniper is on the rich side and could pose a risk to converters. If one were to have their unit tuned via laptop by a tuner then you would be a bit better off if you do plan on keeping emission systems like the AIR pump and converters. Me I am getting rid of it cause on V8`s the air injection ports are in the heads and I have aftermarket heads without exhaust cross over and without thermactor ports so I could never hook up those emission systems if I even wanted to. Of course by law you cant remove the systems but it doesnt stop people and people dont go to jail over it for old vehicles such as ours. Link to comment Share on other sites More sharing options...
Rusty_S85 Posted August 10, 2020 Share Posted August 10, 2020 Great info Dave! Thanks! If I’m losing the carb and going EFI, what would hook up to the Distrubuter? Jim Sniper both their base and their Stealth 4150 has what is called a timed port or ported vacuum for vacuum advance. There is also manifold vacuum if you want to run manifold vacuum for vacuum advance as well. Link to comment Share on other sites More sharing options...
FrazerJames Posted August 20, 2020 Author Share Posted August 20, 2020 Sniper both their base and their Stealth 4150 has what is called a timed port or ported vacuum for vacuum advance. There is also manifold vacuum if you want to run manifold vacuum for vacuum advance as well. This question is tied to the vacuum discussion above. I’ve got vacuum lines attached to the air cleaner. I believe one is to open up a door to introduce warm air in the winter. However, the vent going to that seems to have been broken off a long time ago. Is that vent necessary? Or is that vacuum line to the “door” even necessary? Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted August 20, 2020 Share Posted August 20, 2020 This question is tied to the vacuum discussion above. I’ve got vacuum lines attached to the air cleaner. I believe one is to open up a door to introduce warm air in the winter. However, the vent going to that seems to have been broken off a long time ago. Is that vent necessary? Or is that vacuum line to the “door” even necessary? If you can retain the stock air cleaner, then that vacuum 'door' is important. It modulates the incoming air temperature, to provide quicker warmup in winter and prevent icing in the venturi and intake manifold. Rusty seems to be our resident Sniper expert, but if the EFI is compatible with the air cleaner it will surely have an easier time with constant air temperature and warm air at startup in winter. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted August 20, 2020 Share Posted August 20, 2020 This question is tied to the vacuum discussion above. I’ve got vacuum lines attached to the air cleaner. I believe one is to open up a door to introduce warm air in the winter. However, the vent going to that seems to have been broken off a long time ago. Is that vent necessary? Or is that vacuum line to the “door” even necessary? The foil flex hose that goes to the exhaust shroud is a couple of bucks at any parts store, and we'll worth it imo. Link to comment Share on other sites More sharing options...
FrazerJames Posted August 21, 2020 Author Share Posted August 21, 2020 The foil flex hose that goes to the exhaust shroud is a couple of bucks at any parts store, and we'll worth it imo. Interesting! How does it gauge temperature? Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted August 21, 2020 Share Posted August 21, 2020 Interesting! How does it gauge temperature? One of the two poker chips has a bimetal disc that will turn off and on the vacuum traveling to the motor attached to the flap. Actually, there should be a vacuum restriction/ check valve to act as a damper between the two, so the flap isn't flapping in response to instantaneous temperature differences. The flap is modulated, so it isn't just off or on, but will move between the two extremes. Link to comment Share on other sites More sharing options...
Rusty_S85 Posted August 21, 2020 Share Posted August 21, 2020 If you can retain the stock air cleaner, then that vacuum 'door' is important. It modulates the incoming air temperature, to provide quicker warmup in winter and prevent icing in the venturi and intake manifold. Rusty seems to be our resident Sniper expert, but if the EFI is compatible with the air cleaner it will surely have an easier time with constant air temperature and warm air at startup in winter. Thats why I wanted to keep my warm air functional. It is true that the point is to help maintain even air temperature for the carburetor. But in cold weather pulling in warm air will also help to warm up the engine as well over pulling in cold air. That is partly why I would really like to keep it functional. But as of now I do not know. I am still on the fence myself on the air cleaner on if I want to go dual snorkel or just go single snorkel. The more I think about it I just dont see how the OE single snorkel would be restrictive to the point it would result in 40 to 60 hp reduction over a open element aircleaner. But the snipers both the regular sniper and the sniper stealth they are setup to take OE aircleaners by having the same locating tabs as a carburetor to locate the aircleaner. Link to comment Share on other sites More sharing options...
FrazerJames Posted August 21, 2020 Author Share Posted August 21, 2020 Interesting! How does it gauge temperature? And actually, now that I think about it, will I even have an exhaust shroud if I’m upgrading to the EFI exhaust manifold? Just found the air cleaner section in the documentation. Going through it now! Link to comment Share on other sites More sharing options...
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