Engine Car Won't Run Right After Head/cam Install

Mstng93SSP · Jan 22, 2015

I installed GT40x heads, and an e303 cam in my 90 LX. Prior to doing this the car ran fantastic in stock form. No issues at all. After the heads and cam install the car will fire right up but it hunts for the idle, and will eventually stall. Occasionally there will be a pop in the intake, but it's rare. The timing chain was set up properly, and the heads and rockers too. Timing is set at 12 degrees (I tried 10 also no change). I have replaced all of the vacuum lines because I am suspecting a vacuum leak? The reason I say this is the power brake booster has zero boost. Pedal is hard as a rock. The lower intake went down with no issues. I have done it a hundred times. KOER codes are 21, 26, 41 (lean) and 91 (lean). Any help is appreciated. I am just sick as the car ran great before, and now it will barely idle.
Thanks
Chris

rbohm · Jan 22, 2015

i agree that you have a vacuum leak. perhaps the intake gasket is leaking from being installed incorrectly.

jrichker · Jan 23, 2015

Finding vacuum leaks

Revised 04-Aug-2011 to add pintle cap, PCV grommet & power brake check valve grommet to checklist.

There is no easy way to find vacuum leaks. It is a time consuming job that requires close inspection of each and every hose and connection.

Small vacuum leaks may not show much change using a vacuum gauge. The range of "good readings" varies so much from engine to engine that it may be difficult to detect small leaks. The engine in my first Mustang pulled about 16.5" of vacuum at 650-725 RPM, which I consider rather low. It was a mass market remanufactured rebuild, so no telling what kind of camshaft it had. Average readings seem to run 16"-18" inches at idle and 18"-21" at 1000 RPM. The only sure comparison is a reading taken when your car was performing at its best through all the RPM ranges and what it is doing now. Use one of the spare ports on the vacuum tree that is mounted on the firewall near the windshield wiper motor.

Use a squirt can of motor oil to squirt around the mating surfaces of the manifold & TB. The oil will be sucked into the leaking area and the engine will change speed. Avoid using flammable substitutes for the oil such as starting fluid, propane or throttle body cleaner. Fire is an excellent hair removal agent, and no eyebrows is not cool...

The vacuum line plumbing is old and brittle on many of these cars, so replacing the lines with new hose is a good plan. The common 1/8” and ¼” vacuum hose works well and isn’t expensive.

The PCV grommet and the power brake booster check valve grommet are two places that often get overlooked when checking for vacuum leaks. The rubber grommets get hard and lose their ability to seal properly. The PVC grommet is difficult to see if it is correctly seated and fitting snugly.

Fuel injector O rings can get old and hard. When they do, they are prone to leaking once the engine warms up. This can be difficult to troubleshoot, since it is almost impossible to get to the injectors to squirt oil into the fuel injector mounting bosses. If the plastic caps on the fuel injectors (pintle caps) are missing, the O rings will slide off the injectors and fall into the intake manifold.

Fuel injector seal kits with 2 O rings and a pintle cap (Borg-Warner P/N 274081) are available at Pep Boys auto parts. Cost is about $3-$4 per kit. The following are listed at the Borg-Warner site ( http://www.borg-warner.com ) as being resellers of Borg-Warner parts:
http://www.partsplus.com/ or http://www.autovalue.com/ or http://www.pepboys.com/ or http://www.federatedautoparts.com/

Most of the links above have store locators for find a store in your area.

Use motor oil on the O rings when you re-assemble them & everything will slide into place. The gasoline will wash away any excess oil that gets in the wrong places and it will burn up in the combustion chamber. Heat the pintle caps in boiling water to soften them to make them easier to install.

Diagram courtesy of Tmoss & Stang&2birds

Vacuum leak due to slipped lower intake manifold gasket...

Ask Nicoleb3x3 about the intake gasket that slipped out of place and caused idle and vacuum leak problems that could not be seen or found by external examination. I don't care what you spray with, you won't find the leak when it is sucking air from the lifter valley. It simply isn't possible to spray anything in there with the lower manifold bolted in place.

Mstng93SSP · Jan 23, 2015

Jrichker, Thanks for all of the advice. I appreciate it. At this point I suspect the lower intake gasket. Everything else was working properly (pcv, injectors, etc) on the car before the heads/cam swap. This must be a nasty leak as I have NO boost to my brakes at all. I am going to try the smoke method to look for leaks but plan on redoing the lower intake as it's not that hard and will give me piece of mind.

Mstng93SSP · Jan 23, 2015

I made a smoke machine this morning and hooked it on to the car. It appears I have a massive gasket failure on the lower intake gasket on the passenger side. There was smoke pouring out of there. I'm going to tear it down now and find out what happened. Thank you for all the help

Mstng93SSP · Jan 23, 2015

Yep. Gasket slipped down during install. My bad........

I'm just glad that's all it was.....hopefully.

[URL=http://s841.photobucket.com/user/Mstng93SSP/media/IMG_20150123_112913713_HDR_1_zpsu0607piz.jpg.html][/URL]

mikestang63 · Jan 23, 2015

what intake gaskets are those? The ports look too small for the heads and they look like paper ones. Can you get a set of Felpro 1250S3 where you are?

Mstng93SSP · Jan 23, 2015

Yes I realized that was part of my problem after I took it apart. My mistake 100%. The gaskets are wrong. I did manage to get a ford racing gasket set today that is supposed to be for the gt40 heads. Don't have part number with me but the gasket is larger and I can tell it will fit properly compared to what I used which was a stock 93 intake gasket set. Tomorrow should have it back together. Thanks for all of the help. Here is the gasket I got today. Disregard the fel pro box its on. It didn't come in that. Does this gasket look like its rhe right one?

*Edit The Ford Racing Gasket is actually a fel pro 1250. I guess they make the gaskets for Ford.

madspeed · Jan 24, 2015

dont forget to trim out the coolant ports and use rtv to seal them up

Mstng93SSP · Jan 24, 2015

Got it all back together. Runs GREAT!!!! Good power and sounds awesome! Lesson learned on the intake gasket. Thanks again for all the help.

Engine Car Won't Run Right After Head/cam Install

Mstng93SSP

You have a nice rear end there Dave.

rbohm

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You have a nice rear end there Dave.

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You have a nice rear end there Dave.

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You have a nice rear end there Dave.

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You have a nice rear end there Dave.

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You have a nice rear end there Dave.

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Engine Car Won't Run Right After Head/cam Install

You have a nice rear end there Dave.

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You have a nice rear end there Dave.

You have a nice rear end there Dave.

You have a nice rear end there Dave.

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You have a nice rear end there Dave.

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You have a nice rear end there Dave.

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