Logo
FULL SITE MENU

What did I do wrong?

M

magnum350

Member
I put a set of intake gaskets on my '94 350 mag/alpha today and now its running like crap. Runs rough and doesn't sound right. As far as I can tell, everything is hooked back up as it should be. Timing is set at 8 deg BTDC using a light, and I'm holding 18 inches of vaccum at idle. Help me out here guys.

This is what it sounded like before with it idled up a touch:



This is what it sounds like now:



Also, my starboard exhaust riser gasket was leaking, so I ordered a new one from sierra.
This is the one that it had on it:
b239d326.jpg

This is the one I put on it:
148d5119.jpg

What is the purpose of the restricted gasket? As of this second it has the 2 different gaskets on it, but I wanted to find out what the purpose of each one was. I can tell ya the exhaust riser is ice cold now, even with it running. lol
 
You could pull the plugs to see if one or more are fouled. Or, you are down to letting it idle and remove one plug wire at a time to find the dead cylinder...perhaps a bad plug wire. Your intake gasket may have moved...I use a propane torch on a low setting and move it along the intake gasket edges and carb base to find a vacuum leak; when the engine revs you found it...yeah, I know you said you had 18 inches of vacuum. What if it will produce 20"?
 
Last edited:
yeah, I'm gonna pull the wires with it running to see if I can find the dead cylinder(s) and go from there.

The torch is just on and not lit, correct? lol
 
I have seen this problem several times,could you give me more info on why you replaced your intake manifold gaskets, and what type you replaced them with.
 
magnum350 said:
Also, my starboard exhaust riser gasket was leaking, so I ordered a new one from sierra.
This is the one that it had on it:
b239d326.jpg

This is the one I put on it:
148d5119.jpg

What is the purpose of the restricted gasket? As of this second it has the 2 different gaskets on it, but I wanted to find out what the purpose of each one was. I can tell ya the exhaust riser is ice cold now, even with it running. lol
Click to expand...

Ayuh,.... Ya used the Wrong riser gasket too,....

Ya need the restricted gasket, or yer gonna have localized Overheating...
And,...
Ditch the green paper gaskets, 'n get a set of Mercruiser gaskets made of metal, 'n graphite....
 
magnum350 said:
Ok, how do I do that...?

Pull one wire off at a time with it running to see which one doesn't make a difference?
Click to expand...

Look at the top of the distributor cap. There will be two sets of numbers. One set for standard rotation and one for reverse rotation. They are marked STD and REV. You want to use the STD mark. Find number one and follow the ignition wire to see what spark plug it is attached to. The intake manifold is marked with cylinder numbers right next to the cylinder head.

After you have determined that the wires are on correctly, then you can pull one at a time to see which cylinder is not firing.

Also do as Bondo said and get the good Mercruiser gaskets.
 
Back
Top