hey, I just signed up... All the group support in here looks awesome.

to business: i just recently dropped an 83 12a into an 84 gsl, that was also 12a before I blew the motor. when i bought the donor car i knew the motor wasn't idling, but i checked the compression myself and it was good, I was having huge problems getting it to idle in the donor car, but got sick of the car wasting space so I proceded with the swap. it went well, had the motor running in 3 days... the idle is better and the car is running (after having the battery break out of the hold down strap and destroying the fan).

Now i've been playing with the timing and have the motor down to a reasonable idle (steady at 900rpm) but now the motor makes a very loud whooshing noise when i turn it off. its coming from the carb(I think) but can't seam to figure out whats causing it. has anyone else had this problem and managed to fix it? also any clues to getting it down to the 750 i'm sure they're supposed to run at... any help is greatly appreciated, thx guys!

oh by the way it has a racing beat exhaust on it and no air pump(obviously)

 

check if you have an vacuum leak

 

http://www.mazdatrix.com/faq/shutter.htm

 

will definately check that. I have one that I know is good because thats what I thought was wrong with my other motor when it started running bad... week later an apex seal and an oil seal went, and i havent gotten around to rebuilding it. never even thought of it...

 

This doesn't happen to sound like a quiet backfire does it? Sometimes mine will do that when I shut her down, more of a whoosh than a bang...

 

well thats what i'm not sure of... it sounds like the carb is sucking in air after i shut her off. I thought maybe it was a backfire too, my exhaust is leaking at the header at the moment because I used the old gasket(which is in rough shape) and I;m waiting for mazda to send me a new one. i have yet to check the shutter valve though. can someone explain this valve to me?? i know where it is what it looks like and how its supposed to opperate, but what does it do/prevent?? haynes manuals don't explain its actuall function... oh also other than the choke being a little sticky the carb is in good shape and i believe it was rebuilt and serviced in 04, so i don't believe its vacuum related, but i wont rule it out cuz the car did sit long enough to allow anything to go wrong.

 

Id check your vac hoses. When I was working on my carb i left a hose off and it did that. my Fb makes quite backfires sometimes when i shut her down too. Never when im in public tho, or in a parking garage it just decides to give me a damn heart attack

 

lol I know! its like it only wants to cry to me!!! I have replaced several vac hoses, including some that i'm positive are bypassed(air conditioning), but every once in awhile I notice another one that has slipped or is cracked. will triple ckeck though...

also where the hell do I find those damn base wrenches?

 

k so i just checked the shutter valve and it is indeed shot. but i'm having a problem finding the wrenches i need to get the base nuts off. i checked the snap on website and didn't even find them there... does anyone know where i can get them? when i took the carb off the other car I removed it in sections so i didn't need them... but I don't want to have to rebuild the carb so those wrenches are necessary... or would a crow foot do the trick?

 

well I replaced the shutter valve last night. didn't have the right wrenches but got the carb off by removing the emissions system... whooshing noise is gone... thx guys!!!

 

You're welcome.