Hi Luke, welcome aboard! I don't know if this Jeep is like the one you are working on--but see my post on page 2 of the forum called "first real groove 91 Jeep cherokee" Pics there, A look at this post might help ya. TracyG

Hi Luke!

I have found something occuring on a regular basis with new Gadgetmen. It appears most are getting locked up on the "15 to 20 Degree Angle" thing. Trying to keep it to that angle will cripple your results.

Here's the deal... At LEAST 15-20 degrees. While I wouldn't go to 45, 30 is just fine. The angle on the bits is a minimum.

You have to think in flow rates and momentum. As the air enters the engine at speed, if the angle is too shallow, the air jumps over the ledge, and leaves a boundary layer behind it. It is supposed to slide into The Groove. This allows for full creation of the second ball, the magic ball, the reason why The Gadg4etman Groove creates the amplified waveform.

If you cut The Groove too shallow, you will see improvements in power and emissions and maybe operating temps, but the mileage increases will be minimal if not non-existent. Just ask Aron Cheek,he'll tell you.

Anyway, remember the three rules and "Have a Groovy Day"!

Ron

This is GadgetmanNebraska, welcome to the groove family.

What Ron said is very true, just follow the angle of the throttle plate, but remember that the shaft has to bottom out against the throttle bore for the best results.

I have had this experience even after 72 grooves I've performed on a number of different vehicles.

After correcting this issue a jump in horsepower and mileage increases has been realized.

Happy Grooving and again welcome to the gadgetmangroove family.

If you need any help please don't hesitate to call.

GadgetmanNebraska Aron Cheek

Good news. Thanks everyone for your comments. When the TJ returns home, I will fill and re-do. In the meantime, I will occupy myself on my other vehicles, and will start posting pictures and results.

Happy Easter, everyone.

Luke

Thanks Ron for your wisdom this past weekend! Yes, the 2 grooves we checked were not deep enough and angle was incorrect. I will be filling in as time allows. Play by the rules of modification - Do the Mods, Do the Mods, Do the Mods and experience will be your friend!

Scott Castleberg
Pellston, MI
Gadgetman Michigan

Hi Tracy, I am guessing that my 98 Cherokee 4L will be similar and the 98 2.5 L Wrangler that I was working on looked identical, which leads me to my question or observation:

On the 2.5 L, the TB to manifold gasket inside diameter was wider than the inside diameter of the TB bore diameter. I don't have the exact measurements here, but the difference was close to 3/8 to 1/2 inch difference overall, or close to 3/16 to 1/4 inch when centred. I closed off the IAC opening, bored 2 holes on each side of the original site of the opening, and then cut a channel on both sides. On my first cut, I did not take into account the gasket size, assuming that it was the full width of the TB base, which it wasn't. If I left it like this, the by-pass airflow would have exited into the manifold at the first edge where the channel would not have been covered, or right into the zone where the groove was cut. The IAC would have worked as per normal, but would have been interfering with the potential improvements of the groove and I would have not accomplished a thing.

I noticed this when putting on the gasket, so I filled the the channels, marked where the gasket actually sat and re-cut accordingly. The gasket itself is quite narrow and so didn't allow very much room for error. I used a 1/4 inch diam. cutter, but should have gone narrower, as I only had at some points, a 1/16" contact surface for the gasket to seal. I put it on and did have some vacuum problems. I took it off one more time and ended up cutting a 4x4" by 1/4" aluminum plate, cut a hole 1 7/8" diam (same size as the TB bore), made a full plate size gasket for between the TB and plate, and the original gasket between the plate and the manifold to compensate for my wider than adequate channels. I did have to adjust the cables (trans and throttle) so the rpm shift points were not out of whack. I know wouldn't have had to go to this extent if I had a very accurate cut between the prescribed areas of the gasket sealing area and of course checked where the gasket laid from the beginning. The surface area of the intake mating surface is raised and offers very little overlap for just a larger diam. gasket: thus the plate.

On your jeep, I see that you cut the channels very close to the inside diam edge of the bore. You must have had a wider gasket, as the gasket I had on my jeep I think would have not covered the channels.
Let me know how that worked for you.

Again, I will send pictures on the 2.5L jeep when I re-cut the groove after it gets back home.

Best regards,
Luke