[rico717]

I put 72 sus on my 73 and stripped off all the smog since its exempt. Can I get rid of the air pump? Is there a replacement adjusting pulley?also the anti backfire value keeps sucking air cause its not hooked to anything, can it go by the wayside?

Rico

 

[john cross]

Well, I am not a mechanic, but I have exactly the same setup. I have a 73 with SU carbs off of a 72. I took a look at a Factory Service Manual and took a look at what all of the emissions systems do. Basically, I could see no harm (power loss) in any of them left over after the conversion. The EGR system definitely causes a power loss. However, the vacuum line that drives this system is fed from a nipple that was a part of the old Hitachi rear carb. When you remove the carb, unless you drive it from somewhere else, this system becomes non-functional. The air pump definitely robs power as well, so you could remove the pulley and plug up the hoses. However, I looked at everything else, and the systems really do not matter. The A/B valve simply helpd smooth things out after you take your foot off the gas by pumping air into the intake, thus slowing the deceleration. No effect on performance. There are a couple of other systems there that justy keep it running better. In my case I have l;eft everything on except the EGR, which is still disconnected. I would suggest that you hook our A/B valve upto something. I think there is supposed to be a tee in the vacuum curcuit that goes to the throttle control valve (another emissions device), but I can't remember. Good luck.

 

[FlameZZZ]

Hey you should try this,its just a theory so no laughing,take the smog pump hose
that creates pressure and rout it to the air cleaner so that it pushes more air into the carbs. thus creating a mini supercharger.After all thats basicly what turbos do and blowers aswell. I'd try it but I dont have the pump or brackets,good idea though
right? Let me know if its ever been done,I have an idea. There will be a test soon and I will post results via G-tech.

 

[VA240Z]

If you have stripped off all your smog parts you need to remove the AB valve as well and plug the balance tube where it was connected. That sucking is from the intake drawing air in which will cause your carbs to run lean. To actually get the full effect of removing the smog parts and smog pump you also need to remove the exhaust jet nozzles that are inside the exhaust manifold and plug the exhaust manifold where the air gallery attaches. If during your swap to SUs you are still using your 73 intake and balance tube, then you need to make sure you plug up all the openings that are not being used. No expert on 73 balance tube, but I know if you have a leak in the balance tube its **** to get your carbs set right and performance will suffer. May want to look for a 70-72 balance tube. Cleaner in appeance with less holes to plug then your 73. You can still use your N33 intakes.

FlameZZZ, hate to rain on your parade, but smog pump as a "minisupercharger", not going to work. Someone brought this up before. Search the archives if you want the specifics. Keep thinking outside the box.

Later,

Mike

 

[johnh240]

Remove the nozzles like VA240Z said, they extend into the exhaust manifold and cause a restriction. You can remove the pump too, it has it's own belt so you shouldn't need to worry about a tensioner. The alt and water pump run from the other belt and is tensioned by the alternator. As far a the throttle closer and anti-backfire valve are concerned, I would leave them both on the car. They both help reduce excessive richness under decel and backfire under same condition. Just route the input of the anti-backfire valve to the big connector on the back of the air filter or put a small K&N filter on the input. The anti-backfire valve only should operate when you have high manifold vac conditions, like decel with the throttle closed (leave the small vac line attached to it, that is the signal for it to open). If it is leaking and sucking air ALL the time then it would be better to just remove it and plug the manifold hole/tube. Neither of these items cause any loss of hp/performance.