OEM Carb Spacer "Gaskets": how soft should they be?
11-08-08, 08:32 PM
#1
OEM Carb Spacer "Gaskets": how soft should they be?
As we all know, the OEM carb "gasket" on the SA's actually consists of the phenolic carb spacer/heat shield, and the permanently-bonded gaskets on either side.
My question is; should those "gaskets" be soft (like silicone) hard (like a rock) or should they have SOME give to them as it looks like they originally did, based on the impressions the carb and manifold left in them over the years?
I ask this, because for as long as I can remember, mine have been hard like a rock. But this is the only one I've owned, so I don't know if that's normal, or a sign that mine is expired.
Being concerned about vacuum leaks, last time I built the carb I put a VERY thin layer of silicone on either side. This seemed to work OK (if it's thin enough it doensn't block the vacuum ports) but it's a royal pain to strip whenever the carb needs to come off.
So, what has been the group's experience?
My question is; should those "gaskets" be soft (like silicone) hard (like a rock) or should they have SOME give to them as it looks like they originally did, based on the impressions the carb and manifold left in them over the years?
I ask this, because for as long as I can remember, mine have been hard like a rock. But this is the only one I've owned, so I don't know if that's normal, or a sign that mine is expired.
Being concerned about vacuum leaks, last time I built the carb I put a VERY thin layer of silicone on either side. This seemed to work OK (if it's thin enough it doensn't block the vacuum ports) but it's a royal pain to strip whenever the carb needs to come off.
So, what has been the group's experience?
11-10-08, 04:49 AM
#5
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Mine were hard as a rock, came out in pieces. Used gaskets supplied by carb kit w/o knowing that is bad. Damn I'm sucking wind. I cut out new gaskets from 1/64" carb gasket paper, and am praying I start so I can go to work shortly! I'm really supposed to just use the spacer dry? The surfaces seem to rough to me to seal, but I've never done this before on my rex. Could be begging for advice later, but hope not!
11-10-08, 06:01 AM
#6
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When I replaced my stock Nikki with the Sterling there were no gaskets of any kind in between the spacer and carb or manifold. I didn't use any with the Sterling and have had no problems. The material the spacer is made of is soft enough that once you tighten down the carb it should seal just fine.
11-10-08, 06:10 AM
#7
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I hear you man, thanks. Just seems so bizarre based on all previous experience, but since everything else about our cars is different...
I'll let you know if it's working tonight.
WooooHoooo, I finally made my 10th post.
I'll let you know if it's working tonight.
WooooHoooo, I finally made my 10th post.
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11-10-08, 04:51 PM
#9
Thats weird that all you guys say that you have had problems replacing those gaskets. I replaced mine and have had ZERO problems because of it. Took out old nasty hard as a rock pieces (multiple pieces) and replaced with the ones in the rebuild kit and all has been good since. I did not use any RTV or other type of "hold it in place" glues.
11-10-08, 05:41 PM
#10
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factory supplies a pretty hard gasket with a new one. you're not really supposed to change em, but if you do you can buy the rx2/3 carb gaskets.
mazdatrix lists em.
mazdatrix lists em.
11-10-08, 07:17 PM
#11
Come to mention it, what's the torque spec for the carb nuts? Not listed specifically in the FSM that I can find.
That's what I was hoping to learn, having only ever seen one of them.
11-10-08, 07:19 PM
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OK folks, I'm pretty sure the 1/64 carb paper did the trick for the spacer, but not positive yet. I found a bad leak at the acv block-off plate, and on of the bolt holes is fairly stripped. Picked up some replacement bolts, as the originals seem to be self-tapping. If this fails, any reason why I can't just JB the vacuum ports closed and use a little red RVT to seal the plate where the exhaust port is? Already JB'd the shutter valve holes, so it's not like I'm returning to stock emissions anymore anyway. Also picked up some new crush washers for the brake vacuum banjo bolt, their leaking too and so was the hose. Got some heavy vacuum line on it now, but assume the fuel line was used to protect it from heat.
Can't believe with all the projects I've done, this would be the PITA!
Can't believe with all the projects I've done, this would be the PITA!
11-10-08, 10:31 PM
#13
The original hose for the brake booster isn't actually fuel line, though it kind of loks like it; it's a formed hose, and fairly rigid. And a famous source of vacuum leaks when it dries out from heat and cracks on the bottom/inside.
Here's my carb spacer, FWIW.
Here's my carb spacer, FWIW.
11-10-08, 10:46 PM
#14
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G_d Bless! New bolts did the trick. Cut another gasket for the ACV block-off plate, spread a coat of Hylomar HPF on it, and snugged the baby up. Proof of the spacer plate seal will be in the morning, too late to be pissing off the neighbors yet again tonight.
If I may be so bold as to suggest to the moderator powers that be, could you please addendum all carb rebuild threads to start off:
"Don't f*** with the original gaskets on the carb spacer, NO MATTER WHAT! But if you do, don't use the damn useless gaskets in the rebuild kit."
Would have saved me a hell of a lot of aggravation. I've done at least a dozen rebuilds over the years, on a variety of cars, and never experienced anything but success with the supplied gaskets.
DivinDriver, oh ya, show off your still intact gasket on your spacer, trying to **** me off!?! I see your using the same kind of hose on your spacer I installed on the brake line. Since you said the original isn't fuel line, what exactly do you use on it? I grabbed the blue cause it was the thickest, heat resistent stuff I had lying around. Many thanks to you, trochoid et all. Hoping to burn off another 1,000 miles worth of tire in the morning.
If I may be so bold as to suggest to the moderator powers that be, could you please addendum all carb rebuild threads to start off:
"Don't f*** with the original gaskets on the carb spacer, NO MATTER WHAT! But if you do, don't use the damn useless gaskets in the rebuild kit."
Would have saved me a hell of a lot of aggravation. I've done at least a dozen rebuilds over the years, on a variety of cars, and never experienced anything but success with the supplied gaskets.
DivinDriver, oh ya, show off your still intact gasket on your spacer, trying to **** me off!?! I see your using the same kind of hose on your spacer I installed on the brake line. Since you said the original isn't fuel line, what exactly do you use on it? I grabbed the blue cause it was the thickest, heat resistent stuff I had lying around. Many thanks to you, trochoid et all. Hoping to burn off another 1,000 miles worth of tire in the morning.
11-11-08, 09:21 AM
#15
The original hose that goes from the intake manifold banjo block to the brake booster hardline is a factory-formed hose. On my 80, it's Mazda part number 8871-43-836. Also known as the "mystery hose."
Regular vacuum hose might work OK, but that area is exposed to a lot of heat, so the hose cooks over time.
And if the hose collapses from high vacuum (a problem that gets worse as diameter increases & bend angle increases) you could lose brake boost.
I don't know if they are still available or not; I've been able to stay supplied from junkyard picks thus far.
Regular vacuum hose might work OK, but that area is exposed to a lot of heat, so the hose cooks over time.
And if the hose collapses from high vacuum (a problem that gets worse as diameter increases & bend angle increases) you could lose brake boost.
I don't know if they are still available or not; I've been able to stay supplied from junkyard picks thus far.
11-11-08, 09:34 AM
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Thanks man, I'm thinking of using 3/8" copper tubing with fuel line to connect, so there's nothing to collapse. Still sucking air, going to hylomar my paper gaskets tonight. I'm tired of f'ing around!
11-15-08, 05:21 AM
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Just damn, roughness of the raw spacer was too much for even hylomar to overcome. I'm going to check the boneyards today for a "new" spacer, and if I can't find one then it's off to Toyota for some f.i.p.g. Hate to make the carb semi-permanently attached to the spacer and intake, but I can't tell you how tired I am of f'ing with it!
Figure I can always use some piano wire to remove it later, and beg one of you to sell me one of your spacers.
Mystery tube fix 1.0 works, but too getto to live with. 1.1 will be a proper bent brake line with flare fittings like Mazda should have had it to begin with.
Careful, first they take your sig, then your woman and your job!
Figure I can always use some piano wire to remove it later, and beg one of you to sell me one of your spacers.Mystery tube fix 1.0 works, but too getto to live with. 1.1 will be a proper bent brake line with flare fittings like Mazda should have had it to begin with.
Careful, first they take your sig, then your woman and your job!
11-15-08, 12:02 PM
#21
I'm pretty sure they intentionally did not use a hard line in order to deal with engine motion on the mounts.
You need enough flex to accomodate torque reaction, or you'll shear the pipe through metal fatigue before too long.
Oh, and make sure you note that 4-digit number on your spacer - - different engine builds had different vacuum porting on the spacers. You need to match original unless you're strippping your carb.
You need enough flex to accomodate torque reaction, or you'll shear the pipe through metal fatigue before too long.
Oh, and make sure you note that 4-digit number on your spacer - - different engine builds had different vacuum porting on the spacers. You need to match original unless you're strippping your carb.
Last edited by DivinDriver; 11-15-08 at 12:06 PM.
11-15-08, 12:17 PM
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Your right, I should have realized that! Now I'm gonna worry till I get home. Could have had the hose from Mazda today, if I didn't think myself such an evil genius. Picked up 3bond 1194 for the spacer. After exhaustive research it appears to be the best solution.
Thanks for saving my life(OMG, no brakes!).
Thanks for saving my life(OMG, no brakes!).
11-17-08, 07:21 AM
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Well the 1194 took care of the vacuum leak, then the return line clogged. Pulled the tank and cleared that, finishing at 3am. Started the car this morning, and now I'm burning oil like a banshee, and my rusty racing beat header's blown through. The only thing that's gone easy in the last few weeks is the carb rebuild itself!!!
11-17-08, 12:33 PM
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I'll want to get one, but least of my problems right now. I've got to get a nother header, and check my oil pump. Hoping its just stucj wide open. Never burnt oil before, now its a fog machine. Got a racing beat header for a 12A lying around?