Engine IAC adjust spacer plate factory settings

emba129

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Jun 10, 2012
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Hi all. I had idle issues on my 93 Cobra. I found it to be associated with the IAC adjustment plate. Bad gaskets I believe. Idles pretty good without it installed.

I removed it, gave it a thorough cleaning. Bought new gaskets and now I need to put it back to factory settings. The installation instructions from Ford say that it comes from Ford preset at maximum airflow for engine applications of 5.0L displacement or smaller.

The plate required a good cleaning. I removed the two set screws fully and cleaned everything thoroughly. I see that both set screws had blue Loctite indicating to me that they were factory set.

I’m going to reinstall it. Does anyone know what the initial settings are for the 2 set screws for a factory 5.0? I want to get back to baseline so I can tweak to get the best idle with the plate. The car has a mild aftermarket cam so I want to reinstall to get the optimal idle

Thanks all
745C3FC2-0ED2-4A75-B5CD-15ECCD994A33.jpeg
 
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dgollem

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May 5, 2004
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Waldorf MD
Not sure about factory settings but I added one to my car years ago because I could not tame the surging idle issues. The plate helped out a lot but required some tweaking. If it idles ok without it that's the factory and the way to go. The idle plate is a work around. If you put it back on just tweak the screws until it idles where you want it, not that hard but patience is the key because it does not negate the IAC it just allows extra air to enter to increase idle. Adjust then wait a few minute or two and see how the idle reacts, repeat until satisfied.
 
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emba129

Member
Jun 10, 2012
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Turns out it DOES need the plate. This Cobra has an aftermarket, relatively mild, CAM (not sure of the specs on it) Without it I had slight surging idle (800-1000). I put it back on with new gaskets. Started out with the screws all the way closed. Backed the inboard out 2 turns and the top one 1.5 turns. Idle smoothed out perfectly. Did a Base Idle Reset and it runs like new :)

Thanks all
 
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7991LXnSHO

wanna catch the space herp
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Sep 1, 2010
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In theory, this is doing the same as opening the throttle a little more at idle, but without having to slot the TPS to get it back into range with a big cam.
The base idle reset steps works fine for my current combo. But I have one of these in my parts box in case it does not with my next engine and I do not want to learn how to tune a new computer system.
 

emba129

Member
Jun 10, 2012
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I tried to increase the idle the same way with the idle screw and to get it to smooth out the idle was at 1200. The fine tuning of the plate allows me to get it to around 900-1000 for a smooth idle. Also, I’d doesn’t hang between shifts, which is good.
 
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dgollem

Active Member
May 5, 2004
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Waldorf MD
Glad it worked out for you. Sounds like the same solution I arrived at, I could always get the idle better with the plate than without. Mine has been in use for more that 20 years now.
 

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Willybill32

But at least it's tight!
Jul 16, 2019
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Lexington, KY
Working for Ford I installed many a plate
Took off almost as many
I agree very few stock engines can benefit
The Lightning was one
They came about for the 85 fuelie Tempo surge
@manicmechanic007, my ‘86 (5.0, E303 cam, TFS TW heads, shorty headers, 24lb injectors, MAF, etc.) bucks a lot below about 1,200 RPM, making it difficult to drive in parking lots, etc. My tuner says it’s all happening before the TPS says the throttle plate is open. Would one of these plates maybe help with reduce the bucking?

Bill
 

Dan02gt

mazing how much gas smell came from that tiny hole
10 Year Member
Mar 2, 2003
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Greenville, NC
@manicmechanic007, my ‘86 (5.0, E303 cam, TFS TW heads, shorty headers, 24lb injectors, MAF, etc.) bucks a lot below about 1,200 RPM, making it difficult to drive in parking lots, etc. My tuner says it’s all happening before the TPS says the throttle plate is open. Would one of these plates maybe help with reduce the bucking?

Bill
I doubt it will help much at all. E cams are known for low speed drivability issues.
 

90sickfox

Wasn't a pretty sight...and I've got big hands
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Mar 2, 2015
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I drove an E cam for years. In a 302...a 306...and a 347. I didn't have any drivability issues with it and it always baffles me when I hear people say it. I ran it EFI and carbureted. The same exact camshaft. Something I did do was clock the throttle body so the IAC was on top and the linkage was at the front. I don't have any pictures ( I don't think ). This was an old trick for surging idles back in the day. It was like that when I bought the car so I kept it that way. I still have the bracket that the gas cable bolted to somewhere.

I loved that camshaft in my 347. It was mild for it but pulled hills with no problem. It also pulled the car north of 160mph. ( something I'd never do again in a fox )
 

Dan02gt

mazing how much gas smell came from that tiny hole
10 Year Member
Mar 2, 2003
885
431
113
Greenville, NC
I drove an E cam for years. In a 302...a 306...and a 347. I didn't have any drivability issues with it and it always baffles me when I hear people say it. I ran it EFI and carbureted. The same exact camshaft. Something I did do was clock the throttle body so the IAC was on top and the linkage was at the front. I don't have any pictures ( I don't think ). This was an old trick for surging idles back in the day. It was like that when I bought the car so I kept it that way. I still have the bracket that the gas cable bolted to somewhere.

I loved that camshaft in my 347. It was mild for it but pulled hills with no problem. It also pulled the car north of 160mph. ( something I'd never do again in a fox )
My dad had a E cam in a 90 GT with a GT40 top end and it ran great. A buddy had one in a 93 with Edelbrock aluminum heads and Trick Flow intake. It had all the issues people talk about with E cams. We fought with it for about a year trying to deal with the idle issues and low speed bucking. He finally got feed up, ripped it out, and installed a Steeda #18. Just like that all his issues went away. It seems like issues with them are really hit and miss. With so many good cams on the market for reasonable prices, I don’t see the point of fighting with one.
 
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90sickfox

Wasn't a pretty sight...and I've got big hands
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Mar 2, 2015
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My dad had a E cam in a 90 GT with a GT40 top end and it ran great. A buddy had one in a 93 with Edelbrock aluminum heads and Trick Flow intake. It had all the issues people talk about with E cams. We fought with it for about a year trying to deal with the idle issues and low speed bucking. He finally got feed up, ripped it out, and installed a Steeda #18. Just like that all his issues went away. It seems like issues with them are really hit and miss. With so many good cams on the market for reasonable prices, I don’t see the point of fighting with one.

I agree with you 100%. Aftermarket cams have come so far over the years. I wouldn't run an E cam again unless it was given to me. All the alphabet camshafts are a bit archaic. I have a comp cam xe282hr now and like it. It's a low vacuum at idle type of grind which could cause bucking and such at lower rpms but I don't have that issue with this cam either. My next one will be custom made. If I had a cookie cutter build I'd use a cookie cutter camshaft. There are proven dyno numbers for most basic builds with off the shelf camshafts. My comp cam isn't the best for what I'm doing and my engine is a special POS. Next time it'll be an aftermarket block and custom camshaft.