I've got a th350 rebuilt with a heavy duty b&m shift kit that I had installed the guy that rebuilt my trans told me I couldn't install the street and strip version as it already had a kit in it so he had to go with the heavy duty version he also removed the clutch plates that were wavey and I guess replaced them with flat ones to make it more stout so now with my 2200 stall and stock gears which I think are 273 it has a very solid hard shift and chips the tires pretty good and it now shifts at 4000 or more until I get the tac in won't know forsure.question 1 411 gears with spool going in today what to expect with rpms and drive ability question 2 when I was driving yesterday to the mechanic I noticed that when the car revs past a certain point right around my shift point it wants to stumble like maybe revlimiter or something timing is set at 36 total and 16deg .it spits spudders at the higher rpms . thanks for your help hope this doesn't sound stuipd

 

If you put a spool in it, any time you take a turn, you're gonna wanna go as slow as possible around it. If stock is 2.73 gears and you're putting 4.11s in, you are going to notice a big difference in acceleration and an increase in rpms

The hard shift can be explained by the shift kit. They are designed to make the shifts firm and quick which takes any comfort out of it. A stock trans slips and slowly changes gears to make it as unnoticeable as possible.

 

Question 1: Yes you're going to notice a huge difference in acceleration, higher rpm's on the road, and lower gas mileage on the highway.
Question 2: Does your car have an MSD ignition box? That system has a rev limiter, governed by the plug-in rpm "pill", rpm value is stamped on it. Or like I have on mine, an adjustable rpm module.

 

Agree with comments given. Shift kits shorten time between upshifts and provide more volume of oil to the clutches for faster upshifts. Next time you drop the pan for a filter change, you will notice an extra plate for this purpose - more volume of oil engaging the next gear quicker.

Be careful, with a THM350, the intermediate sprag outer race, ie. second gear network, could break and no second gear - the weak link. It will feel just like shooting a 12GA shotgun when it breaks at WOT. However, the fix is easy, drop trans, pull out oil pump and there it is on the back of the pump. Pull off the old one, and push on the new one, and reassemble Camaro.

Your stumble can also be a couple of items - worn/weak valve springs as the valve(s) not closing fast enough for the RPM, they can be replaced with heads on engine. The other problem may be worn spark plugs. As load increases, aka, more rpms, the combustion pressure in the chamber can cause a spark plug misfire - plug does not fire. Easy solution - change to newer plugs.

When you change gear ratio, keep the carrier for the differentiating the rear tires going around a corner. Now, since you suggest you have a 2 series gear, you may have to get another carrier for the 4 series gear, or get a 3 series carrier and use a thick ring gear. Do research.

The only stupid question is the one not asked.

 

I personally would never let anyone put a spool in a rear axle for any car I ran on the street. Not only will it eventually break an axle, but they're dangerous on the street. It can easily get your car out of control, and end up wrecking if you hit any traction issues with a spool. Do yourself a favor and get a posi unit, not a spool.
All good advice on the stumble. I'd also look at the general tune. Timing, carb, plugs, valve adjustment, etc. Since you don't have a tach, I'm unsure what rpm range you're shifting at, so not sure if the stumble might be valve float, if it's a fairly high rpm shift.

 

Thanks everyone for the info I found out what it was there was a vac leak to the trans below it runs good now thanks again