ASEmaster

I recently reinstalled my stock carb after a thorough cleaning and in the process I scratched up that thick plastic gasket that goes between the carb and the intake manifold. Now I'm showing symptoms of a major vacuum leak and I've got a good idea of where it's coming from. I bought that replacement paper gasket (mazda Part #0823-13-221C) from Racing Beat which they said could take the place of the big plastic thing (if I read correctly), but my question is...

will it hurt anything having the carb sit so much lower w/out the big plastic thing? Also, what do I do with all those vacuum lines plugged into the old gasket? I'm not worried about emissions, as there isn't any testing here in Indiana.

85RX7GS

iTrader: (1)

Should be okay. However, some of those vacuum lines under the hood need to be hooked up for the car to run. Make sure that all necessary hoses are attached. On the other hand, you could always try it to find out.

ASEmaster

Don't suppose anyone can tell me exactly which ones are essential for the car to run?

yayarx7

none that I know of. I just have the vaccuum advance for the distributor hooked up to my 83. And I am told these are not really needed. all the other nipples are capped.

BTW go to a junkyard and get another base plate. thats what I would do.

SilverRocket

ASE,

Sorry I didn't answer your PM, I have gutted all my emmissions but not by replacing that gasket like you're talking about. I just capped everything off on the carb, except for the air vent as I can recall... if you get rid of the vacuum advance, don't cap the vacuum pots on the dizzy - leave them open. You should also run a little air breather on your oil filler tube to prevent condensation. I recommend you do a search of the old threads, there has been a number of discussion about removing emmissions gear...

I did forward your question to another forum member who knows much better than me, so hopefully he'll get back to you soon!

NanaimoRx-7

Hey Silver---You helped me out when I junked my emission crap, the only thing I couldn't find was that breather type filer you keep mentioning. Where did you get yours? I've got some condensation, but no rust yet...I'd like to keep it that way.

**Long Live the Thread of 1414**

SilverRocket

Believe it or not, I picked it up at Canadian Tire

It just looks like a little mini K&N filter, it fits right on the stock nipple on the filler tube.

Some folks also suggest running a line to the air cleaner, but for some reason this didn't work as well for me

*Long live the 1414*

Felix Wankel

I believe you will need the spacer, or the carb won't clear the shutter valve. I'm not 100% sure offhand.

And you don't need any vacuum lines for the car to run. Remove the solenoids, plug off the vacuum advance diaphragms, and run a vent off the oil filler tube downwards (or put a small breather on it), and cap all the other fittings off.

You can also remove the ACV valve and air pump if you remove the cats.

SilverRocket

Felix, I'm pretty sure you leave the vacuum advance pots uncapped don't you?

Felix Wankel

I dont think it should matter. I just have a bunch of caps laying around, figure I might as well make use of them.

SilverRocket

I remember someone giving me a reason why they're supposed to be left open, but what that is I can't remember

REVHED

The plastic part isn't a gastket. It's a phenolic spacer which stops heat transfer between the intake manifold and carb. You're actually supposed to use a gasket on either side of the spacer. If you look at it closely you'll see that the gaskets are still on there but they've been fused on over the years. And trust me, they're a bitch to get off. Let me know if that didn't make sense. I'm drunk... burp.

Sterling

The diaphragms on the distributer are hooked directly to the advancing mechanism with little arms. If they are capped off, the diapraghms can't move as far as they should, and your timing won't advance all the way.

ASEmaster

Wow, it sounds like there's quite a bit of knowledge and experience at this forum! Thanks for all your input. The more I look at my situation, however the more I think I'll just save for the Holley conversion and do away with all of my Nikki vacuum troubles. I'm pretty sick of messing w/ that stock carb.

Most reviews I've found on the Holley conversion from Racing Beat speak pretty highly of it... is that the consensus here? Are there any downsides to the Holley I should be aware of? It will require my purchasing a new fuel pump and regulator too, right? Any thought on the matter would be greatly appreciated. (If I don't get my RX running before I get married in May, I fear it will never run again!)

SilverRocket

The Holley is supposed to offer the best mix of driveability and power for street driven cars. The only downside I've heard about it is that it bogs down if you're in the gas during a hard corner. RB sells a center-pivot float bowl conversion kit for 200 bucks that supposedly helps the problem.

peejay

Assuming the butterflies will be able to open fully, and nothing will foul on the manifold, you'd have to put about 1/2" worth of spacers on the oil metering pump rod because the carb will be that much closer to it.

I don't see why not to use the phenolic spacer, unless yours is broken. It not only helps keep intake manifold heat from getting to the carb, but it also shields from exhaust heat. If you're de-smogging the engine, you can just put vacuum caps on the nipples, or use short lengths of hose to go from one to another.

ASEmaster

Here's my plan:

Going to try the stock carb w/ the original phenolic base one more time. I'm going to run a very small bead of silicon around the top and bottom of the phenolic base prior to assembly. I'm also going to replace all the vacuum lines running to that base, and the carb, and the airbox because they're pretty old and might not be sealing like they should since they've been removed and reinstalled so many times here lately. If this doesn't work I'll start saving my lunch money for that Holley I guess.

Any suggestions on something else I might want to try while I've got everything apart?

SilverRocket

If I had my carb/intake manifold apart, I'd probably lose my shutter valve. Just an idea for you.

BTW I really do recommend losing the smog crap if you won't get in trouble for it, it simplifies things a lot and cleans up the engine bay which makes doing work a lot nicer. No more troubleshooting mysterious vacuum leaks lol. You'll have to do it anyways if you're lookin to do an aftermarket carb conversion.

hanman

I would not recommend using a silicone based sealant if you have an o2 sensor. The silicone is detrimental to them.
You really shouldn't need any sealant, just the gaskets.
hanman

ASEmaster

I don't think there is an O2 sensor on an '83, is there? I think perhaps the problem may not be the base gasket after all. I've got a wheezing noise that seems to be coming from around what my diagram shows as the "choke diaphram". It has 4 lines on it, one big one and one small one on each side. It seems to be only drawing a vacuum from the air box when the engine in accelerated. When I hold it at a constant RPM, it doesn't suck anything. Is that how it normally should operate or could the diaphram be dried out and cracked inside? Right now I've got the belt pulled off the air pump. Also at constant RPM it will cough and sputter slightly even at high engine speed, but it's flawless when the engine is accelerated. This is driving me nuts!

ASEmaster

Just in case anyone is curious, the problem has been solved and after many months of frustration, my blue beauty is roadworthy once again! That choke diaphram I mentioned earlier was the stem of the problem. The kicker is, the fix was to plug it w/ my finger while the engine ran for a minute, and then it fixed itself! I guess it just needed a strong vacuum on it for some reason. At any rate, the stock Nikki is working as well as it ever has... now to work on all the other issues! Thanks for all the suggestions everybody!