Thread: Setup Questions

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Hi everyone. Well, it didn't take real long, but I have reached the limits of my knowledge and so I am turning to you guys to double check me and let me know if I have lost my mind.

Originally I was going to drop a Ram Jet 350, a 700R4 tranny, and 3.73's in the rear end in my 'bird; but, as luck would have it, I actually got a pretty good deal on a new Pontiac 400 motor and TH400. So now I gotta figure out if I really want to put 3.73's in it or not. I'm betting no, because with 255 60 15's in the back and no OD gear, I'm thinking that it would probably be close to 32-3300 RPMs going down the freeway at 70. Maybe 3.08's would be a little more realistic for a driver?

Anyway, what do you guys think about this set-up:

- Pontiac 400 with number 16 heads, a mild cam (Comp Cams Part # 51-208-4). I'm not sure about the compression ratio, but I believe it is around 9.5:1. Anyway, I believe that with a 700 CFM carb, dual plane manifold, Headers, 2 1/2 inch exhaust, and the cam above, I should be able to pull around 360 horsepower at 5000 rpms and more importantly for me, a fairly flat torque curve with a peak of about 450 ft lb of torque at 3000 rpms.

- TH400, and as for the stall, Comp Cams says their cam will work with stock stall, but I'm thinking either a 2000 or 2500 stall here wont hurt and it would get me closer to my 3000 RPM Torque peak, but still be drivable on the road.

- 3.08 Rear Gears and 255 60 15's, which should run about 26-2700 rpms on the freeway at 70.

I believe based on the tea leaves I've been reading, all of this should get me into the low 13's or perhaps even high 12's. I think that is very acceptable for a driver. However, I guess I am pretty ignorant about determining what the optimal setup (compromise) with this motor, tranny stall and rear gear ratio would be for a reliable but very healthy ride. And I guess I'm not afraid to say it; so, please don't be afraid to tell me I am out of my mind if you think I'm off my rocker about any of this.

I would rather hear from you guys NOW that I've lost it. then to spend a bunch of time and money setting it up, and then scratch my head when it don't work, come here ask the question, and THEN get told that I have missed something very simple and all I need is more cash and time to fix it.

Thanks for all the help,
Firechicken

Richard,

Thanks, I gotta tell you that I really appreciate and respect your opinion. So when you say looser on the converter are you talking in the range of 2500-3000 or were talking about simply looser than stock?

Thanks again,
Dutch

Every thing looks good, but I would use a 3.23 or 3.55 gear. Nothing beats that off line punch!

Originally posted by DennyW
Just adding my opinion. I would probably got for the 51-223-4 cam.

Denny,

Thanks for the input. That might be a little more "lopey" than I am looking for; but, I'm not sure.

Truth be told, there are a pair of '68 Ram Air II heads (Casting # 96) on ebay right now with a buy it now price of $2500.00. A little pricy but not outrageous to a Pontiac guy for what they are. Anyway, I considered getting those heads and then using the 51-116-3 cam to build myself a ram air engine; but, in the end, I don't think it would be worth the money because the car wasn't originally a Ram Air car anyway, and the heads and cam wouldn't really be a perfect match anyway because the cam is actually for the Ram Air IV engine.

Thanks,
Dutch

Thanks guys.

For the gears, I might end up going with the 3.23's; but, before I go that route, I really have to make sure that I can get those 255 60 15's under the car first. Supposedly they'll fit; but, I am kind of suspicious about that right now. I really think it depends on how much "sag" there is in the rear end to begin with, and I don't know that I'm real keen on putting air shocks under there just to create the clearance for them.

In any event, if they don't fit, then I'll end up going with 225 60 15's (because I know for a fact that they will fit). This is where getting above a 3.08 gear ratio really starts to add on the rpms to a level that I'm not real sure I would want to be driving at for extended periods of time. I could handle it for the 60 mile round trip commute to work from time to time no sweat; but, hell, some of the car shows I'll be driving it to will be close to 700 miles away. 700 miles at 3000 rpms (3.23's at 70mph with those tires) ain't all that attractive to me and it will just burn a lot of gas along the way if you know what I mean.

I really hate it because I love good launches just as much as the next guy; but, I just don't know if it's worth it for my particular application.

All that being said, if the 255's fit, I just might go for it.

Thanks again,
Dutch

Oh believe me, if I can get the rpms down to a reasonable level, I will be going with the lower gear ratio. I've even thought of installing air shocks and using them along with a different set of larger tires for the long trips. (somebody else mentioned something similar to this in another thread.) Then once I get to my destination, install the normal tires and lower the air pressure in the shocks and go back to a "normal" configuration.

It just really depends on what I can get to fit.

Dutch