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| Intake Manifold Question; A tale of two manifolds | |
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| Tweet Topic Started: May 22 2014, 08:49 PM (1,056 Views) | |
| perfesser | May 22 2014, 08:49 PM Post #1 |
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Elite Member - Former Metro owner
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I have a '91 Metro that had a '94 engine in it (until 3 hours ago!) I also have the original '91 engine that blew up. I am rebuilding a different '91 engine and should have it installed in a few days. Today I spent a bit of time prepping the original engine's intake and getting it ready to plumb up and install. When I took the manifold off the '94 engine prior to pulling it, I noticed a difference between it and the '91. So I went down to the workshop and checked the manifold that came with the '91 engine I'm rebuilding, and it had the same difference too. Notice the branch for #1 cylinder just before the end where it meets the head. ![]() What is this vacuum sensor screwed into the end of the dirty manifold? ![]() That vacuum hose runs to the vacuum distributor advance unit. Since the clean manifold is original to my car, and the vacuum distributor that was on that engine is now on the '94, I'm wondering if I need it. What does it do, and can I live without it? I have two other manifolds I could use, but I don't want to clean up another one if I don't have to. |
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| Bad Bent | May 23 2014, 01:12 AM Post #2 |
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Facetious Educated Donkey
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The hood sticker off my 1991 Geo. It's the gas filter. Gas as in vapor, not liquid (i.e. fuel). As in it is used for Vacuum Advance of the Distributor. ![]() Probably can't live without it if you want proper vacuum advance of the distributor.
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| perfesser | May 23 2014, 01:37 AM Post #3 |
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Elite Member - Former Metro owner
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If my manifold doesn't have a hole for it, I wonder where else they might have been getting this function from??Thanks for the sticker. My car doesn't have any of its stickers, either under the hood or on the door/frame. Edited by perfesser, May 23 2014, 01:39 AM.
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| perfesser | May 23 2014, 11:56 AM Post #4 |
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Elite Member - Former Metro owner
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The part in question is #15. It looks like I have 2 LSI manifolds and 1 base (which makes sense as the car is a base model and I'm using the original manifold.) Now to find out how the base was hooked up. The FSM is silent on that.![]() At this point, my options are to 1) figure it out, 2) drill and tap the base manifold, or 3) prep one from the LSI. Edited by perfesser, May 23 2014, 11:57 AM.
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| Old Man | May 23 2014, 12:33 PM Post #5 |
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gotta have it if you are using a vacumn advance distributor. |
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| mlillie | May 23 2014, 12:36 PM Post #6 |
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Member
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I would not cross change the non egr manifold to the egr manifold. To much of a headache. I like my non egr 91. I also believe there are some differences between the 91 & 94 throttle bodys.
Edited by mlillie, May 23 2014, 12:52 PM.
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| Bad Bent | May 23 2014, 08:55 PM Post #7 |
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Facetious Educated Donkey
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Do you have the old hoses? If so hook the old hose to the distributor and see how far it will reach around the TB and look for ports that would work. It is possible that they simply ran it without any advance.
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| Good bye | May 23 2014, 11:16 PM Post #8 |
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Does your clean manifold have EGR? If not I don't know what you have. If it does it is a California or Xfi intake. |
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| perfesser | May 24 2014, 12:35 AM Post #9 |
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Elite Member - Former Metro owner
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The original (blown) engine came to me with a manifold, but no TBI, so the hoses are no help in tracing routing. I don't really care at this point what the non-LSI manifold may be, because I cleaned up one of the LSI manifolds, which solves my problem nicely. I started with three manifolds. ![]() The one on the left is the non-LSI that I had cleaned up and prepped. The one on the right is from the '94 LSI engine I pulled yesterday. I am leaving it strictly alone as a routing guide. The car was running really well with it hooked up the way it was, so for the time being it's a 3D model. The one in the middle I stripped. It's the one I'm using in the rebuild now. ![]() It needed a bit of cleaning up, and then I took my Dremel tool to it to tidy up mold marks, etc. Some time later ... ![]() Once it's painted, the grinding marks will be much less visible. ![]() So now I am ready to move forward again. I've ordered a TBI repair gasket set. I'm going to rebuild it after all. I'll be picking that up tomorrow morning.
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| t3ragtop | May 24 2014, 01:46 PM Post #10 |
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Turbo3 and Twincam Tweaker
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the manifold in the middle of your pic was from a mk2 manual transmission car and the one on the right was from a mk2 automatic. ![]() the one on the left is from a mk3 (92 thru 94.) |
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| perfesser | May 24 2014, 03:43 PM Post #11 |
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Elite Member - Former Metro owner
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Other way around. The round TPS is from an automatic and the square TS is from a manual. In this case, the one on the right was taken off of a '94 engine hooked to a manual and the middle one came off a '91 engine that came to me with a flexplate, not a flywheel. The one on the left is from the original engine that came in my car from the factory. That engine is a '91 with a 5-speed on it.
Edited by perfesser, May 24 2014, 05:37 PM.
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| Good bye | May 24 2014, 09:28 PM Post #12 |
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It looks like all your manifolds have a place for EGR. My 49 state 91 manifold did not have a place to bolt an EGR valve on it. It came with a vacuum advance distributor and the #1 port vacuum hookup. I can take a picture if anyone cares. My car now has an extra cylinder and EGR with computer controlled spark advance. |
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| perfesser | May 24 2014, 10:35 PM Post #13 |
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Elite Member - Former Metro owner
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EGR was never my concern. The only difference besides the TPS/TS is the presence or absence of a vacuum port at the #1 intake branch. As far as EGR goes, my three manifolds are all the same. I cleaned up the '91 LSI manifold and made it purrty this afternoon. ![]() ![]() ![]() Now to tackle the TBI rebuild. I'll swap the TS from the '94 manifold for the TPS from the '91, and I'm doing a TBI bridge delete while I'm in there. Edited by perfesser, May 24 2014, 10:36 PM.
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| Good bye | May 24 2014, 10:42 PM Post #14 |
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That looks very nice, I am happy if the engine doesn't leak oil. I drive my car 60 miles every day so it is not very clean. However the 350 Chevy in my boat is clean, not too dusty out on the lake only on the driveway. |
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If my manifold doesn't have a hole for it, I wonder where else they might have been getting this function from??



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7:58 PM Jul 10