I have an 87 Z28 with LG4. I had an 84 H.O. with the L69 5-speed and loved it...seemed so much faster. I know there is only about 20HP difference and someone had mentioned the gears in the LG4 are different so that might be why it seems slower. I was wondering if a Turbo 350 trans would work with the 305 engine. I know the blocks on the 305 and 350 are the same, so I wouldn't see why not?

I'm planning on changing the engine out to a 350 hopefully soon. Have to work up the money first. But would there be any problems with that trans??

 

It's shorter (unless you get a 9" tailshaft version), requiring a longer driveshaft. You'll need an '82-'83 3-speed auto or 4-speed crossmember. You'll need some means of mounting the torque arm, either bracket that bolts to the tailshaft housing, or a swap crossmember that has the torque arm mount provision. You'll lose overdrive and probably lock up torque converter. 1st gear is a lower number ratio, meaning off-the-line performance will be reduced.

The TH700 isn't your problem, so don't try fixing the "problem" by replacing it. When you asked about the LG4 vs. L69, you were steered to the 305 thread on the FAQ forum. Your answer lies there, not with a transmission downgrade.

 

So the TH700 is an alright transmission? Is it strong enough...that is what I'm really concerned with. If I upgrade the motor to a 350, will the trans work with it?

 

The TH700R-4 is what the factory put behind 350's in 3rd gens, rather than the T5's.

I'm running an approx. 360 horse 350 with a TH700 behind it.

 

I don't know if I have a 350...I think it is a 305. When I bought the car, they said 350 but I don't think it is...it is a 1987.

 

unless someone put it in I'm pretty sure that is a 305.

 

The otehr trans won't really help. Mostly, all it will do, is take away the overdrive.

The thing to do would be to concentrate on what's WORSE about the LG4 car (note: the CAR, not just the LG4 itself), that makes it slower than the L69 CAR. The transmission is not one of those things.

The biggest differences between the 2 motors were the exhaust, the gears, the cam, the cooling fan, and the air cleaner. Attack the car in that order.

For exhaust, the ENTIRE LG4 system, from engine to bumper, needs to go in the trash. It is extremely restrictive. Put on a set of good-quality headers that are CHASSI-SPECIFIC, not universal; and when I say good quality, I mean, not just the cheeeepest thing that says "headers" on the box. I'd suggest SLP or Edelbrock TES, those being 2 that I've used and had good success with; there are others that might be better than the Edelbrock, but it's SO MUCH better than what's there, it hardly matters, as long as the motor is anywhere near stock. Whatever ones you get, have them ceramic-coated. Get the ones for L69, or if California-style rigorous emissions inspection isn't an issue to you, for a TPI motor (TPI doesn't have the EFE valve on the pass side, so headers for them won't be CA legal for a carbed car). Get a high-flow cat such as a Catco, and a 3" cat-back of your choice from any of a dozen or so reputable exhaust mfrs. Don't mess around with "true duals", having "custom" exhaust made, or any of that; it'll end up costing more, won't really work any better, and probably won't fit as well.

Get 3.42 gears or 3.73 gears for the rear.

For a cam, you'll need to figure out if it's a roller or not. It probably is, but buying parts based on "probably" in this situation is not a good idea. Whenever you find what kind it is, pick a cam (hopefully a roller) from one of the top-line cam companies, with about 210-215° of .050" duration on the intake, and 6-10° more on the exhaust, in the high .400"s of lift. Comp, Lunati, Crane, Crower, Isky are good places to look for a suitable cam.

The fan of choice is either a stock one from a TPI or L69 car, along with its wiring (tough to do); about a 94 Frod Taurus 3.8 one; or a Chrysler minivan one. Most likely, you'll end up having to wire it yourself. Quite easy really, we can help you with that.

The L69 dual-snorkel cold-air intake is the best one. However they are VERY TOUGH to find, at a price below the stratosphere. You can maybe make your own dual-snorkel setup, the hard part will be finding or making a pass side scoop. I cannot over-emphasize the importance of COLD AIR.

I didn't mention it; but once the engine has some rev potential, a torque converter can make a HUGE difference to the off-the-line performance.

I think, to be honest, that if the performance of that car is bothering you that much, you might be better off to just leave it alone, and keep your eyes peeled for a better car. The above list is a good solid $1500, and can EASILY be more. Might be more sensible to use the easy 2-step method to make your car faster:

1. Sell slow car
2. Buy faster car

Sometimes it's cheaper to get where you want to go, if you buy a more expensive car up front, and have to do less to it to get it to where you want it.

 

What if I just bought a new 350 and put a TH700 tranny...what would I need to do to the car after that? I was thinking of a turnkey engine, just dropping it in.

Upgrade cooling fan? Exhaust of course...What else?

 

Gears.

What trans is in it now?

 

I don't know....whatever was stock. 700R4?

 

Can you tell me a suitable Comp cam? Because there are so many on their website, I'm not sure which to look for...

*Would a Thumpr Comp cam work? http://www.compperformancegroupstore...ry_Code=Thumpr