New 700R4 Trans in '63 Riviera


Active Member
Well, I had Bob Bendtsen's Transmission (the guy who makes adapters for nailheads with a dynaflow to mate up to more modern transmissions).

After I got it, it seems the engine has to reach a high rpm to get moving. And that in gear it seems to search for gears when accelerating.

Well, I had Bob test drive the car today,and he thinks it's normal. For me ( who's had the car since '83), it "feels" like more slipping than the leaking dynaflow he replaced. After talking about rpms, he hooked up a tachometer while we were test driving it. The tach read around 2200rpms at 15 mph. He then said he put a 2000+rpm stall converter in it. Shifts did occur around 2200+rpms. Yet, for me to get going from a dead stand still, it's like there's very little positive engagement. When he was driving it, he had the throttle almost to the floor. He then said there could be fuel starvation (not true the engine runs great), and what I'm hearing is the flex-fan ( yes, I know this makes more noise than a clutch fan; the flex-fan has been in there since '92, and I know how the engine sounds under all kind of conditions. I also have a '73 Riviera GS stage 1 with a flex fan and a '76 Riviera with a clutch-fan. With both of those cars, there's a positive engine to transmission engagement, smooth shifting and in the '73, there is a flex-fan roar that I'm fully aware of.

I know the '63 thoroughly--- how it responds, the engine, the old transmission. I've had it since '83.

We agreed that he would have a different stall converter (~1500 rpms).

Has anyone else had experiences with Nailheads and 700R4 transmissions?


New Member
Tranny Troubles

One of the most important connections is between the trans and carb.
is the linkage a rod? or cable? If it is a cable you can get it to work by using a cam on the carb that changes the throttle pressure at a curve that corresponds to the trans.
Different carbs require different cam that the cable rides on.
it is tricky.
If it is a rod it will not work.

The torq conv should be stock, 2000 is a bit high.
I've run the 700R with a 383 chevy in a 49 Chev pu work truck for 18 years and it works just fine. it took some fine tuning, and the knowledge of a good trany guy.


Find a tranny guy that knows what he is doing real quick. It's all in the cable adjustment. You will burn it out if you keep driving it the way it is.
The 401-425 Engines As You Know Are High Torque At Low Rpm Engines. The Factory Torque Convertors On The 64-66 Th400 Trans Were About 1500-1600 Stall. This Does Not Include The High Stall Speed Used On The Variable Pitch Units In 65-66. Also Covertors Are Rated With An Input Of About 200hp And 325 Lbs/tq So When You Take A Small Block Chevy Convertor And Put A Buick With 445 Torque.... You Can See The Numbers Go Way Out Of Wack. It For Sure Also Sounds Like The Trans Is Indeed Slipping At A Clutch Unit And Or A Band. Just My Personal Choice.... I Would Have Left The Dynaflow In The 63. They Are Big And Built And Enginered To Handle The Weight And Torque Of The Big Buicks. Hope You Get It Solved And All Goes Better Soon.