350/350 combo - undergeared?

[88v8]

This TR6 ticks many boxes for me, chiefly that it's all done and it's a right-hooker. Not quite true that there are no other TR6 V8s in the UK, but there certainly aren't many. Unmodded bodywork other than a raised rear edge on the bonnet, nicely trimmed.
It has much to commend it.
http://www.carandclassic.co.uk/car/C648305

However.... it's pretty clear from the Info Sheet created by the previous owner that it was built on the cheap. It has a standard TR6 rear end, and a TH350 or 400 box, seller couldn't say which. He seemed not to know that a B&M Quicksilver isn't a gearbox....
And he was rather evasive abut the overall gearing, but I reckon it's got to be about 21mph/1,000rpm.
This seems awfully low.

Now, I know I can put in an R200 rear end with a Goodparts kit. I want an autobox and I could convert it to a 700R4, but that will cost, and the price isn't exactly keen.

A crate 350 sitting at an 80mph cruise of 3,800rpm is going to eat fuel. How happy would it be at those cruising revs?

Ivor

[Anarchy99]

A th400 and a  2004r are roughly the same dimensions and you only have to modify most trans mounts a little bit to make them fit. It'll get you overdrive and if you already have a th400 it's a fairly straight forward swap, just a TV cable.

[Sidecardoug]

Ivor-  
         Basically the same issue as with my  TR6/Ford/C4.  Rear gears are a no-go. The TR6 comes with 3.69:1, the best the GoodParts can do is 3.54:1, IF you get a diff sourced from the Z car. The 700R4 or 2004R is probably your best bet.  If the exhaust runs alogside the driveshaft, a GearVendors overdrive almost certainly won't fit.  Without the exhaust in the way, you might be able to fit one with a bit of sugery to the tunnel cover.  The GearVendors overdrive is about $3000 US with the tailshaft adaptor.

    One thing to watch for with the 700R4, is that they don't like to be run in overdrive below 45-50mph, as the pump doesn't spin fast enough to maintain best pressure.  There are kits available to fix this, probably found
through Summit Racing or Jeg's.

 
Doug
.