[71lemanssprt]

Have a friend that just gave me a 73 400 with press in 2.11/1.66 4x in decent shape ( spun rod being) with performer intake edelbrock carb hei dist.I am looking for mild to warm street performance in my 71 lemans sport ( storing the orignal 455) this is a aut car with posi track and rear gears in the 3.73 range I think any help would help thks matthew

[engineer]

too much gear with an auto. use 3.55 or 3.23 with Turbo 400. what cam do you have?

[71lemanssprt]

was hoping someone would recomend one . not wanting to go completely wild with this motor but want better than stock. also have headers

[GTO Noob]

Originally Posted by engineer

too much gear with an auto. use 3.55 or 3.23 with Turbo 400. what cam do you have?

Why would a 3:73 be too much gear for a TH400? I am currently rebuilding mine and I was looking at going to a 3:73 Posi as I have 3:23 in it now

[Thumpin455_GTO]

Well you could go with an XE274 cam, a set of ported D ports from one of the Pontiac gurus, an RPM intake (fits under the hood ok) Cliffs Qjet, and a nice set of headers.. that would make for a nice healthy 400 that has plenty of driveability and enough power to be fun.

A 400 high stall converter would work pretty well, and they are cheap. Or you could go with another one with a stall of around 2200-2400, I prefer a bit less gear for a driver. I dont often go over 3.55s, and I wont run a mild 455 with any more than that ever again. Most of my drivers keep the 3.08 area gears and I just build more torque for them, keeps the revs down on the highway.

[wh33lman]

First thing to do is to double-check the type of 4X heads you are using by checking the stamp on the underside of the boss by the #8 exhaust port.

Unfortunately for me, I have the 4X-4H 98cc, which are small valved (1.96/1.66) and were rated at 150HP for 2 barrel automatics, and (I'm guessing here) 175HP with a 4-barrel. (Those factory ratings would be at the crank, right??)

I was hoping that maybe the heads had been improved by the previous owner/builder, but a) being able to run cheap gas, and b) dyno results; indicate stock cc's and valves.

Good news is my combo did make 200RWHP/272RWTQ on the dyno. So a head swap is definitely in my future.

I'm looking for advice on how to get this combo to 400HP but I don't want to hijack this thread, so I'll start another with combo details. ...unless someone asks...