2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

intake porting and weird vac readings

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Old Mar 2, 2003 | 02:17 PM
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From: Caldwell,ID
intake porting and weird vac readings

ok I had a bad pulsation damper and so I put the screw back in and put Jb weld over it

that seem to have worked fine


but took a vac test of my manifold today

have around 15-17 on the primary runners

and only 5-6 on the secondary runners

it idles fine though or so it seems at least and I can even turn the idle down to about 500rpms without any real problems


so what gives

the only real porting I did was to the injector spot on the intake runners where the large bulge is and that is all
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Old Mar 2, 2003 | 02:38 PM
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Re: intake porting and weird vac readings

Originally posted by rxspeed87
ok I had a bad pulsation damper and so I put the screw back in and put Jb weld over it
that seem to have worked fine
This is the WRONG way to fix the pulsation damper. Replace the bad part.

but took a vac test of my manifold today
have around 15-17 on the primary runners
and only 5-6 on the secondary runners
it idles fine though or so it seems at least and I can even turn the idle down to about 500rpms without any real problems
You have an NA, right? The secondaries (5th and 6th ports) are closed at idle.
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Old Mar 2, 2003 | 05:19 PM
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From: Caldwell,ID
that is the secondary runners that I am reading my vac from. not the secondary ports.... how can you even read vac from the secondary ports???

yes I know it is the wrong way

new pulsation damper is the best way

but I need the car running and not leaking gas till I can afford to fix the part
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Old Mar 2, 2003 | 05:26 PM
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From: Mars
If you want it running go rip one off a junkyard car until you can get a new one. JB welding it is NOT even a semi-good solution. I doubt the guys at the junkyard will even know what it is.
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Old Mar 2, 2003 | 05:58 PM
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From: FORT WORTH, TEXAS,USA
That bit about the runners caught my eye. I never thought about doing that much less how you did it.

So I went out to the 87n/a and got a vacuum gauge on the primary runners(where I usually put my cruise control vac hose, and read 17.

Then to get on the seconday runner, I got on that vac pipe at the very rear of the manifold and read it there.

Both were the same, 17. Does this mean my engine is no good and I need to sell it to the lowest bidder??

And about the pulsation damper.......ah forget it. You've been ragged on enough.....but the best way to handle that, would have been to get some Locktite and screwed the screw back into the damper until you just felt some resistance. Then stop. Done. If one cranks on the screw he is twisting the diaphram, guaranteeing(sp) the destruction in the near future. That screw acts like a shock absorber and should be able to move outboard a tash. I posted pictures of a dismantled PD last year when they had the god damnedest long lasting sticky in the history of the forum. YOu might look at those pictures sometime.
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Old Mar 3, 2003 | 12:39 AM
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From: Caldwell,ID
I swear I posted to this


oh well


I know the best way to handle it is to put a new one on there

but I am broke and without a job right now so I do what I can.
with the car leaking gas it cost me too much money to drive it around. and if it burned to the ground that would cost me even more so this is what went on

what could go wrong though by not putting a good damper on there?




the whole reason I tested them twice was because the first time I did it and was like whoa 5??? that's not good

so I tested from another spot and that is how it came about
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Old Mar 3, 2003 | 03:05 AM
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From: olympia,wash
Originally posted by rxspeed87
I swear I posted to this

what could go wrong though by not putting a good damper on there?

it could fail,leak gas all over the motor,catch on fire and your car will burn up.[i suppose if you had a extinguisher near by it would just ruin a bunch of stuff under the hood]
do a search on "fire"....
~d
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Old Mar 3, 2003 | 09:00 AM
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From: FORT WORTH, TEXAS,USA
******I swear I posted to this******

Bottom line is that the reason I posted is to tell you that on my 87N/A both primary and secondary runners have the same reading.. I have no idea why yours are different. They should be the same. Either your technique is off or there is a blockage in the manifold.
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Old Mar 3, 2003 | 11:59 AM
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From: Caldwell,ID
Originally posted by wankelhead
it could fail,leak gas all over the motor,catch on fire and your car will burn up.[i suppose if you had a extinguisher near by it would just ruin a bunch of stuff under the hood]
do a search on "fire"....
~d
hehe this thing has been leaking for some time now... least over a month.

shouldn't the jbweld hold up though?

yeah I know it stops it from reducing the pulsations in the fuel rail but whats the big deal with it?
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