[stevenjw]

Thanks! Again, very good suggestions, but I'm still in process of getting car right. Tach and Amps gauges are not working. Replaced leaky fuel line and fuel sender to get fuel gauge working. That was important. The speedo is way off, but was going to tackle that with trans swap. Column has nice aftermarket temp and oil pressure gauges that work. I'm going to get the others fixed when I have AC installed since these require behind the dash work.

Right now, I think a solid 700R4 will provide very similar (if not stronger) 1-2 while giving me a 4th 0.70 OD that should be OK with final @2.88:1 and @2300 RPM. I just need to make sure that the 700R4 can handle the HP/TQ and has a big enough stall converter. I was going to also have electric fans put in at same time as the tranny cooler and get rid of the flex fan.

I was planning on getting diags/dyno done at some point, but doing so first sounds like a good idea.

 

[MEJ1990TM]

The big difference between the LS-6 and LS-7 was the LS-6 had closed chamber large rectangle port heads, the LS-7 was open chamber. The LS-6 also had pressed in connecting rod pins, the LS-7 was free flaoting. The LS-6 rod was not the L88 rod with the Boron Bolts, but was a rod with a little less inspection and knearled rod bolts, (still 7/16),

I bought a LS-7 Crate Motor from Richardson Chevrolet in 1974 as a base for a Pro Comp Boat Racing motor, it was, for all general purposes, a L88 with a 4 inch stroke.

It even had the L88 cam in it, I think in later years they put the LS-6 cams in them.

For those that might not know, the term "LS-7" was more or less a made up monikor, as Chevrolet never actually put one in a Production Car. The smog motor era, which started in 1974, ended the thought of that.

In our SS APBA Boats, we used a Crane Cams grind that was essentially a L-88 copy with 112 degree lobe centers..........jackie

The LS7 didn't come with an L88 cam. It came with the ZL-1 cam. Had less duration, but more lift, than the L88 cam. It also had a point more compression ,and a cam roughly 20/30 degrees bigger than that of the LS6. They were both 454's, but very different.

Thanks! Again, very good suggestions, but I'm still in process of getting car right. Tach and Amps gauges are not working. Replaced leaky fuel line and fuel sender to get fuel gauge working. That was important. The speedo is way off, but was going to tackle that with trans swap. Column has nice aftermarket temp and oil pressure gauges that work. I'm going to get the others fixed when I have AC installed since these require behind the dash work.

Right now, I think a solid 700R4 will provide very similar (if not stronger) 1-2 while giving me a 4th 0.70 OD that should be OK with final @2.88:1 and @2300 RPM. I just need to make sure that the 700R4 can handle the HP/TQ and has a big enough stall converter. I was going to also have electric fans put in at same time as the tranny cooler and get rid of the flex fan.

I was planning on getting diags/dyno done at some point, but doing so first sounds like a good idea.

I have yet to run my LS7, but I really don't think it's going to like being lugged down to 2,300 RPM at all.

 

[jackie schmidt]

MEJ, the motors we bought from Richardson Chevrolet back in the early 70's did have the .540-.560 lift cam, with an advertised duration in the mid 330 to 340 range. I just always assumed they were an L-88 grind.
They called them "LS-7's", and they were in a GM crate. I remember they all had "special off road" written in spray painted letters on the crates.
We did not use the cam, as all we bought these motors for was the good parts. They had the good rods, good crank, that nice oval skirt piston, and the duel plain high rise intake that was really a nice manifold, the four bolt block, etc.

Heck, if I dug around in my storage garage, I probably still have one of those cams laying around. Back then, you couldn't give one away........jackie

 

[MEJ1990TM]

MEJ, the motors we bought from Richardson Chevrolet back in the early 70's did have the .540-.560 lift cam, with an advertised duration in the mid 330 to 340 range. I just always assumed they were an L-88 grind.
They called them "LS-7's", and they were in a GM crate. I remember they all had "special off road" written in spray painted letters on the crates.
We did not use the cam, as all we bought these motors for was the good parts. They had the good rods, good crank, that nice oval skirt piston, and the duel plain high rise intake that was really a nice manifold, the four bolt block, etc.

Heck, if I dug around in my storage garage, I probably still have one of those cams laying around. Back then, you couldn't give one away........jackie

If you want to give it away I'm your man. I'll even pay for shipping.

I didn't mean to make my post sound argumentative or anything. It sometimes comes across that way on the internet.

 

[CoolBlueGlow]

re: Original post - replacing the TH400 with a 700R4,

I get why you want the overdrive with the 4:10 ratio and all. While I'm no big fan of the way the 700R4 shifts, or of the TV cable arrangement's sometimes finicky nature, or the relatively brittle OEM hard parts, it's still pretty hard to argue with a 700R4 from an efficiency standpoint (more efficient power transfer than a TH400) and I understand that they can be made pretty bulletproof up to 700hp or so.

I dunno - I just like the TH400 feel. They shift so nice and they are so durned hard to break...but I do get your reasoning and think it has some merit.

I have a buddy who's putting a 700R4 in his truck with 4:10 this weekend, for the reasons you noted.

I guess my opinion is a reluctant "yeah, makes sense".


p.s. I understand that the 30 spline output shaft version is preferred. The 27 spline model debuted sometime in about 1982...I think and went through perhaps 86 (working without a net here). Anyway, I hear the 30 spline output shaft starts with more robust hard parts. Check me on that though, again - no net.
Cheers,

CBG

 

[stevenjw]

Still looking for opinions and will look for local shop (have dealt with some already) in earnest. I'm not looking to add any more HP or race this car. So as long as I'm convinced the 700R4 that I get can handle up to 600 HP and torque, then the only question remaining is if the LS7 is "going to like being lugged down to 2,300 RPM." I agree that any of the newer 6 spd trannys would be too low, but the jury is still out concerning use of a 0.70 4th coupled with 2400 stall and 4.10 rear. I'm still convinced that over 50 mph, the LS7 will do fine with a total ratio of 2.88:1.

I'll make sure to get as definitive answers to these two questions as possible before proceeding.

For now, I'm looking at Jackie's used setup and the following two online:
http://www.maddogtransmissions.com/700R4_4L60_Transmisson_p/l4 700r4-fslash-4l60.htm
http://monstertrans.com/store/products/700R4-Transmission-Super-Duty-2WD.html

All opinions are welcome! Keep 'em coming.

 

[stevenjw]

Previous owner got back to me and said the following. "converter I think is 3600 and gear ratio is 4:11 and def has shift kit but i dont know what kind".

 

[CoolBlueGlow]

Yeah, at 2,300 that LS7 "only" has about three times the torque of the typical four banger in the lane next to you...

Besides, with that ultra low first gear in the 700R4, you can use your Chevelle as a stump puller on the weekends, if you need to pick up some extra cash...



Cheers

CBG

 

[stevenjw]

Well, I've pretty much settled on going with a 4L80 with FMVB to avoid electronics (which can be easily added later). It solves any durability reservations I may have had with a 4L60 (700R4) since it the same 80 rating and first-third gear ratio as my 3L80 (THM400). I gain an addition 4th 0.75 gear which will lower my RPMs on the highway. It's the same as if I had a 3.08 rear. It's also the same OD as in the TCI 6x, so don't see why it won't work well.

I'm considering this one: http://www.maddogtransmissions.com/4L80_4L80E_Transmission_p/4l80-fslash-4l80e.htm

The price is within my budget (and a lot less than a TCI 6x spd). Opinions are still welcome on this choice. Does anyone have knowledge / experience with Mad Dog transmissions?

 

[stevenjw]

Well, I went full circle on this and have gone with a Gear Vendors solution. Seems like the cheapest, simplest and all-around best approach to add OD to a TH400. Minimal labor, basically just remove the TH400 tail, bolt up GV, change shifter knob (to add one with a button), and shorten the driveshaft. Retains the current setup with no surplus parts to unload. And no extras (new trans, shifter, electric speedo, dip stick, 'puter,...) to buy either, just the GV. Stronger than any 4L80 too since the stronger TH400 is still there. The separate GV is rated to 1200 hp (with better guarantee than any 4L80). It provides more gearing and the OD I was looking for too.

Guess I need to rename this thread.

I'll post more once I get the Chevelle back from the shop.

 

[Guest]

I must have missed this thread.

I am somewhat biased as probably one of the better known 4L80E builders but I have used both and I personally didn't like the Gear vendors.

Gear Vendor Cons:
Clunky and unrefined feeling (my biggest complaint).
Driveline angles would have required much more tunnel surgery than what most lead you to believe.
Too frequent oil changes needed.
No lockup converter

GV Pros:
Easy to install except the floorpan mods to do it right.
Already has provisions for a mechanical speedo.
Fairly tough unit.

4L80E Pros:
OEM designed and can retain OEM shift characteristics.
Tune from the drivers seat
Pretty much as tough as a TH400 (mostly based on a 400).
Fits easier, Little to no floorpan mods.
Lockup converter and better OD ratio than GV.

Cons:
No mechanical speedo,
somewhat more expensive than a GV.

 

[Munch69ProTour]

One other thing to add, the TCI six speed is a 4L80 with mods to make it a six speed.

 

[stevenjw]

Cons:
GV will cost me half as much as a 4L80 solution when all said and done and a third of the cost of TCI 6x, yet I still end up with 6 speed in essence.

I was assured that floor pan mods were not required, but we'll see. It's definitely required along with flex dip stick change for 4L80. As for clunky shifting, again, I'll find out.

 

[Guest]

Cons:
GV will cost me half as much as a 4L80 solution when all said and done and a third of the cost of TCI 6x, yet I still end up with 6 speed in essence.

I was assured that floor pan mods were not required, but we'll see. It's definitely required along with flex dip stick change for 4L80. As for clunky shifting, again, I'll find out.

I can assure you, to get proper driveline angles with the GV, you WILL be doing floorpan mods on a 68-72 Chevelle. I own a 1969 and I installed the GV into my own personal car. Without floorpan mods, it had a decel vibration from highway speeds. The driveline angles were not right, even with the GV against the floorpan. It needed to go up roughly another 1/2".

The 4L80E doesn't require any cutting of the floorpan on a 68-72 A body in my experience. Usually a bit of clearancing where the cooler lines go in and that's it. I've done a couple of these installs. I've also done them in 1st Gen Camaro's, 2nd Gen Camaro's, G body cars, 67-87 GM trucks, and other platforms.

You can easily use an OEM GM dipstick on a Chevelle with 4L80E install. Fits with not issues.

The GV is very clunky on a downshift. Upshifts are nice and positive.

I can definitely understand the cost portion and you've made up your mind, I'm just giving you some first hand, real world experience with the pros/cons of each install.

Let us know how your driveline angles work out with the GV.