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This ties in with my post over on the General discussion board on my engine rebuild. I am having my carb rebuilt on my 1980, 12A engine and we have removed the carb from the intake manifold. Between the carb and intake manifold is the carb spacer, which I've also see it called carb insulator, that's the black 'plastic' piece with 5 vacuum line connectors from the control valve rats nest. There appears to be gaskets on both sided of the spacer which seems as though they are bonded to the spacer. The faces of the spacer, which I assume now were the original gaskets, are hard as a rock and can not be peeled back or separated easily from the plastic. Should these gaskets be removed or were they in fact bonded to the plastic? Because they are so hard I'm concerned about re-using them.
The "gaskets" on the spacers are not meant to be removed. Removing them will actually ruin the spacer. The spacer is meant to be reused. The gasket part will seem hard.
Last edited by KansasCityREPU; 03-26-22 at 06:08 PM.
Just like KC said, those gaskets are bonded and not intended to be removed. Even though they're practically hard as rock, they'll seal fine unless notably damaged.
Also don't use the two gaskets that come in most carb rebuild kits that look like the two on the baseplate. Using them in addition to the original bonded baseplate gaskets will only cause more issues.
Thanks for the replies. So I called the person rebuilding the carb and told him not to remove the gaskets, his reply was "its too late". He said he had removed them from one side and started on the other, took him about 3 hours. He said he did'nt scrape or damage the plate surface and is planning to use the gaskets in the rebuild kit. Based on your comments should we anticipate any problems? He said he could send pictures on Monday.
Well if they're off they're off. You'll want to look for a new phenolic spacer (carb spacer) to replace it, but in the short term the included gaskets will probably work enough to drive. Might leak might horrendously, might not. Only one way to find out. For the long term though, definitely look for a new spacer.
Last edited by Benjamin4456; 03-27-22 at 08:47 PM.
I was able to buy this isolator part new from Mazda last week. It did cure my vacuum leak and the gaskets that are preinstalled were aged, delaminating, and rock hard. It came in the mail pretty quickly. Not sure if it's compatible with an 80 model though and I'd verify the part number first before ordering.
Not sure how it cross references with the SA manual one P/N 8871-13-220B.
Both will physically fit either carbs/manifolds and can work with them, however if stock emissions equipment is still installed and in use the "C" code can not be exchanged with the "B" code (aka, 79-80 is different that 81-85). Emissions routing within the spacer changed between years as well a couple other small tweaks. I couldn't find a photo of the "B" code spacer (and I'm unfortunately not at home to look at mine) but I believe it also has a different shaped heatshield to accommodate the other type of ACV setup on the SA versus the added shutter valve on the FB.
Re-using the gaskets on the isolator for these cars is institutional or tribal knowledge from regular reading of the forums here. Another is not replacing the original needles and seats with ones from the rebuild kit. You might want to contact whoever is rebuilding the carb and let them know about that too.
Re-using the gaskets on the isolator for these cars is institutional or tribal knowledge from regular reading of the forums here. Another is not replacing the original needles and seats with ones from the rebuild kit. You might want to contact whoever is rebuilding the carb and let them know about that too.
Thanks everyone for the continuing support. I guess I didn't get the memo about the gaskets on the isolator but I'll make sure he knows about the needles and seats. Out of curiosity what happens when you use the needles and seats from the rebuild kit?
And attached are pictures of the isolator as it is currently. The top has the gasket removed and he has just started on the the bottom. The plan will be to use this part with the gaskets from the rebuild kit and see what happens. But meanwhile I'll try to locate a replacement with the bonded gaskets in tact. I need the original configuration pat no 8871-13-220B. Anyone have one laying around? Unfortunately the C configuration doesn't work with my 1908 SA.
Your spacer has all the extra heat shielding removed.
Yes, when it was new it looked like this ('81-85 shown). The plastic wings keep all the exhaust heat from soaking into the carb. And the rubbery gaskets are factory bonded onto it and meant to be permanent. They feel like hard rubber and can be used over and over again (that's why it took him 3 hours to remove one).
Out of curiosity what happens when you use the needles and seats from the rebuild kit?
They stick and/or don't seal and cause flooding. The seats are the primary offender and often the new needles can be installed if they are burnished before doing so. Still, I'd only suggest using the new needles if the old ones are damaged (which is fairly uncommon, but will depend on how the car was stored/for how long and with what fuel).
For whatever reason most of the replacement seats are either not machined properly or are machined poorly and just don't seal. Seeing as how a seat can't really go bad (it'd be like a jet going bad; it essentially never happens) there is rarely a reason to replace them. However, they should still be removed during the rebuild because there are filter screens located above each seat that should be cleaned. Attempting to use a large flat-blade screw driver to do so will often result in chipping/stripping the seat, so I generally try to find a metal dowel/nail close the size of the four holes in them, thread it through both sides, and then tap it with a hammer to knock them loose. I know you aren't doing the carb rebuild yourself and I want to think your rebuilder is competent, but it's a little trick that some people overlook that can really save some headaches (and stripped seats).
thanks to everyone for their input. I posted in the classifieds and I was fortunate enough to find just what I needed, thanks Trackdiaz. While searching for this part I found that the carburetor spacer had 4 different vacuum nipple arrangements for the 12A engine. There is a four nipple configuration, two different 5 nipple configurations and a six nipple configuration. So my advice to anyone looking for one of these is you need to make sure which configuration you need and what are you are getting. Attached is a picture of what I found.
03-26-22, 12:38 PM
