hello, i'm having a lack of power past about 3500 rpm and also a popping noise coming from the carb, i have played with the timing a bit and it seems to have helped a little, because before when i would rev it it would pop a lot more. i have the mixture about right i think. and the 2nd cat will glow red, could this mean its cloged? i have just changed the fuel filter also. i will be getting an rb header soon but i need to be able to drive the rx-7 as my dd because she is my only transportation right now. thanks! 85 gs w/ rb holly 465

 

Have you checked for spark on the leading plugs? If those are good, it could be clogged cats. Do you still have a working air pump hooked up to the main cat? If yes, then undo the exhaust just before the main cat and see if that makes any difference.

 

the leading plugs have good spark and i have removed the air pump when i instaled the pb holly carb. so most likely its the cats? thanks

 

Yep, might as well gut them until you can redo the exhaust. Fwiw, exhaust is the first mod, carb and intake the second. Headers should wake up the Holley quite nicely.

 

alright i'll remember that, thanks.

 

Definitely cats. Had same problem with my 82 when I first got it. Gutted cats=more HP!!!

 

ok thanks, also anyone komw what the popping from the carb could be? it still pops under a load. maybe pinging? not really sure what detanation sounds like.

 

Get your exhaust fixed, check your timing.

 

ok thanks guys, i've got a long day at work ahead of me so i think its time to say goodnight. tjanks

 

alright, tommorow i'm going to try to un-bolt the 2nd cat, hopefully the bolts dont snap off, this way i can punch them out and put them back on until i can get an rb system.

 

The popping and loss of power could be cats, but could also be an ignition issue. A worn cap/rotor or bad plug wires could do this. Inadequate grounding of the engine can also cause issues. Installing a new cap/rotor only takes a few minutes, so unless yours in fairly new, I would suggest trying that before dropping the exhaust system. Good luck.

 

yes i have new cap, rotor, wires, plugs, and coils, i will try to get everything grounded better. this morning i cut the cat out and the core of it was in chunks, so i assume that is what restricts the flow. and i started her up with an open pipe, man she is LOUD, now i need to get a piece of pipe to go where the cat was so i can get the muffler hoocked back up until i can get an rb system. thanks

 

A cat full of chunks will do it, I'm suprised you didn't hear some rattling.

 

ok, so today i got the muffler hooked back up, and i drove her and it was still popping and boging down, now this is the odd part; the timng was just set to factory not long ago, so i thought hmm maybe i'll put it back the way it was when i bought it, and and that was it- now she pulls hard, i dont know why. correct me if im wrong- when set to factory spec the rotor should point to the firewall? so to put it back where it was when i bought it i pulled the dizzy and turned the rotor clockwise; it is now pointing at the clip that holds the dizzy cap on. what do you guys think?

 

also i'm running the stock fuel pump right now ( i will upgrade soon ) and my fuel pressure gauge says its only puting out 3 psi, is this normal?

 

I'm gonna guess that either your front pulley is misaligned, or you lack a true understanding of how to set the timing. But hey, as long as it runs, right?

 

well, i set it as per the haynes repair manuals instructions, is it even possable to put the pully on wrong? i have never had it off. and what do you think about where the rotor is pointing? thanks

 

As long as everything is aligned correctly, and yes the pulley can be put on in four different ways, then the position of the rotor has no part in setting the ignition timing. Clip the lead on the front lower plug wire, and shine the light on the pulley, then rotate the dizzy as needed to align the marks. One thing to note; if your idle speed is over 1000 then remove and plug the vacuum advance lines on the dizzy to ensure that vacuum advance is not influencing your adjustments.

 

that's how i set it. maybe one of the previous owners set it 90 degrees off?

 

bump

 

lack of displacement

 

 

Oh Yeah rotarty motors dont have displacement mazda must a misplaced it

 

Well, this thread has suddenly gone to hell in a handbasket...

Yes, your pulley may be off 90 degrees, or 180 even. There is a procedure in the Archives that will walk you through the process of getting everything lined up properly. Not hard to do, just involves looking at the flywheel through the little inspection hatch on the top rear of the motor (by the rat's nest).

 

ok thanks, i'll search for it.