3.8 intake to 4.1

[johnjj728]

considering the 4.1 intake manifold and carb swap on my 3.8 buick regal. How hard is this swap? is it just a quick bolt in or does it take a lot of skill? How much horsepower gains?and is this still emissions legal? thanks in advance -John

 

[84ZZ4]

It's pretty straightforward. The most annoying part is getting a carburetor that will match up to all the linkages properly. I couldn't find one so I had to get clever--good thing I know my way around Quadrajets.

If you can find the right carb it should be a simple swap. I performed a lot of maintence while I was in there--replaced the valve cover gaskets, unclogged two oil return holes in the heads, replaced all the vacuum lines, decarboned the intake, etc. etc.

 

[86cut]

Just be prepared to lay the car up for a day or two.....I'm not saying that it takes that long to do, just that you might run into the unknown problems and have to go looking for parts or something like that...just be prepared.

The swap is actually pretty simple once you know what you are doing. Do what the guy in the above post said to do and change all your vac lines, etc. Get yourself a nice fel-pro gasket and make sure you have all your tools and equipment ready. You are going to need a torx head (forgot what size) for the bolt near the distributor. also, you might want to throw a spacer plate in between the carb and manifold, it supposedly gets better flow and keeps the carb cooler.

 

[Freddie's Buick]

Getting the proper linkage on the carb should'nt be a problem.
Remove the throttle plate off of the Duel-Jet. Now remove the two round plates off of the linkage. (Sometimes they won't screw off so one has to grind off the other side of the screws. They are stamped in so one can't remove them unless one grinds them flat with a Dremal tool.

The Duel jet's primary throttle plates are the same as the Q-Jet.
All one has to do is switch them. Ta-Da! Same linkage as before only they're now on a Q-Jet!

When you screw the plates back onto the linkage make sure you use a punch to stamp them down again. This is so they won't come loose and fall inside the intake and ruin your engine.

 

[84ZZ4]

Actually, the dualjet throttle arm works fine except for one little detail... there's nothing to attach the lever that opens the secondary throttle blades to.

 

[Freddie's Buick]

Oops.... Forgot....

 

[84ZZ4]

I was waiting for someone to do that swap and then complain that the secondaries weren't working...

 

[zeusjr73]

Originally posted by 86cut
Get yourself a nice fel-pro gasket

Do you use a 3.8 Intake gasket or 4.1 Intake gasket?

 

[86cut]

3.8