73-454

I have a 73-454 I was thinking of swaping the turbo 400 with a 700r 4-speed , The local performance shop said i would be wasting my money on the swap. He said it only make sense on a 350 vette. The big block would not benefit from the extra gear. Any thoughs

ColinOpseth

the 700r4 won't take the beating imo..well, it could but it'd cost you a pretty penny..

for the money you'd spend i would get a 200r4 because it's close ratio..

and yes, you car will benefit from a 700r4. 1st gear is very low which makes for extremely smokey burnouts ;)

you will notice a huge difference in gas mileage, upwards of 3-5mpg i'm sure (on a big block that could mean as much as 25%)

just my $0.02

later!
Colin :cheers:

daniel77350

25% on a big block? why discriminate? my small block gets 12 MPG....3 MPG is 25%....I think that'd be more like 40% on a big block. :jester

Anyway, I agree, I hear the Trubo 400 is a pretty touch little bugger.

As for smokey burnouts. Gas miliage is good as long as you can keep it out of the secondaries. :nono:

Daniel

Golden80

If I had the $$$$ I'd get a 4L80E. It's basically a Turbo 400 with an overdrive. The ratios are excellent and you can put some nutty gears in the back and still get halfway decent gas mileage. Someone on the forum said that Bowtie Overdrives could make a cross-member to mount it. The big issue is $ though. I think the tranny would run about $1700 along with a $800 computer to shift it.

Matt

Stingy74

I think turbo 400's were the reason mid 70's Corvette's were slow. C'mon, L-48's, 3.08 gears, and a power robbing th400? That's a receipe for slowness. Also, I apologize if I just dissed your car. I didn't mean it that way. I'd probably have a th400 in a dedicated drag car but I wouldn't think twice about a 200 or 700 on the street. First off they both have lock up converters. That's probably a 20 horsepower gain right there. I've also heard that there's 25-30 horse being robbed when using a 400 to say a 350. I dunno, I like my 700 but the more I think about it the more I want a 2004R. No sappy stories about them being too weak either, there's some 9 second turbo Buicks using those.

Tom73

The first question to ask is why? Are you doing it for gas milage? The cost of the conversion would buy a lot of gas. How much do you drive the car? The conversion will pay for its self a lot quicker in a daily driver. The gas savings in a weekend driver will probably never recover the conversion cost. What about the original or matching numbers issue? Store the TH400 and reinstall later? Factor that cost in. Also factor in the devaluation of the car if it is not converted back.

Lots of things to consider.

tom...


[Modified by Tom73, 11:19 PM 12/10/2001]

Shark Racer

It was my understanding that the 2004R was weaker than the 700R4.
Also, the 700R4 that BTO sells for $870 is supposed to be strong enough to handle a car that'll turn 11's.
-Steve