Howdy gents,

I'm building up a "400 tribute" 69 and am struggling with several upcoming decisions. If it's helpful to know, I am hoping for a car that has good driving manners but with some attitude. I don't expect to race it, though I'd certainly be happy to get on it and have it respond.

It's becoming very clear to this newbie that one needs to have an overall plan for the car when considering things like cam, trannie, rear-end, to name 3.

My problem is that this is my first shot at all this and I don't want to get too far over my head (too deep into the wallet) until I know that things are working out. For example, I'm rebuilding the 400 motor and clearly there are a million things that can go wrong. My feeling is that I should finish up the motor, do the break-in, and if everything goes well, then start looking at trannie and rear-end options.

On the other hand, there seems to be so much inter-relation between the cam selection and these other things. Am I making any sense?

Anywho, my question is really about my stock 2.79 rear-end. Is there any case to be made for running that in my project? Is it sane to just postpone that decision until after the motor is broken in or should I have resolved the rear-end question before even selecting a cam? Or must I have an overall plan for everything before buying any of the big-ticket items?

Thanks for your thoughts.
Tom

Speaking from experience. Change one thing at a time when you can. However pulling/installing the engine and trans at the same time is much easier.

Enjoy the car for a while between parts. When you change to many parts your bound to wind up with multiple problems.

As for the gears. You need to ask yourself how much traveling are you doing? Will you take it to cruises? Car shows in other states? Drag race? Will you ever put in a overdrive? I would hold on to the gears as thoes gears are becoming more and more in demand.

I have 3:36 gears and I'm thinking of going to 3:08s. I only get 11mpg and the rpm is about 2500 for 60mph. It would be nice to knock that down a bit.

Hard to go wrong use'n 3.23-3.55 gears.

2.79 are good for highway driving but probably wont give you the "attitude" you're looking for

I drove with 3.90 rear end this summer. Lot's of fun but by no means a cruiser. Ventured on the highway once. You could watch the gas gauge move in real time! 3600 rpm at 60 mph! Going with 3.55's next year!

3:23, 3:36, 3:55 ratios would give you the kind of performance you desire. When picking your cam go with a cam that will work well in conjuction with the gear ratio you plan to use. You will feel a great difference between the 2:79's & a 3:55 ratios. The best 4 speed to use is an M-20 wide ratio box.

I would do as you are, as you can afford upgrades, do them. Engine first, tranny & rear next. There are aftermarket posi units that can convert your rear to a posi.

Steve

2.56 works great for me.....yup, people can beat me off the line...but I usually get 'there' before them anyway...but using less gas

I've got the 2.78 rear in mine. I'm happy with the performance of it with just the base 350, but I'm more interested in cruising than performance.

HAHA, still don't pass many gas stations. If you are worried about gas mileage in these cars, you probably shouldn't have one.3

3.23 to 3.55 would give you a big boost in performance. Any higher than that and I think you would loose most of the cruising ability. Changing gears can wait until after you've got the engine built and back in, and you'll also really get to see the difference in performance between the gears.

There is a huge difference in a 2.78 to 3.36. My car came to life when I changed the rear to a 3.42. Nothing else changed and the car really woke up. I am now redoing the engine and body, so it will perk up a lot more with the higher compression I went with.

You should change the rear after you decide how the engine responds after rebuild. Then you can tell the tangible difference with each change. You may decide you don't need a lower gear depending on your needs.

My 69 conv. has 455 ,T400,and an open 279....At 70mph I run at 2800...Mine is a 4 day a week driver and some highway cruises... I don't bend it around corners ,but with 500 lbs./ft. of twist ,I can get on it pretty fine....On trips ,I get 14-15 mpg , with the top up...but who puts their top up ? Someday I may get a posi rear as I light up my one tire at stop lights at times....Bear

that sounds about right...mine has a 400, TH350, 2,56 rear I get about 14 mph at 70-75 mph ,top down, and just around 2800 rpms

Thanks for all the great inputs, fellas.

Bjorn, do you have a non-stock cam in your setup? My setup and yours are quite similar (400, TH350, 2.79s, assuming 4V for you) and I was thinking about keeping that arrangement until I could scrape the money together for a 200R4 and maybe 3.33s.

I'm mostly wondering how your girl there gets out of the hole. I figure with an overdrive, I can get the best of both worlds with a lower-gear rear-end, but until then, I'm curious how you like your setup.

Thanks!
Tom

Tom, I really dont know which cam is in it...engine had been installed by PO, I merely changed heads...the engine was out of a 72 , it was rebuilt...had 7J2 heads...I replaced with 5C heads from a 75, had milled to around 88-90 CC to get +-9.2- 9.3 CR...she gets out of the hole pretty well...but not as well as some of my other fgf friends with big 455s etc, LS1s...but it gets me to the destination ,usually quicker than them anyway ,as when you drive on the roads (I like cruising) the initial out of the hole doesnt matter , only how you get yourself thru traffic or how you drive on the highway...
an overdrive would certainly save some gas....(I added one in my TR6 as it was 3300 rpms at 70....but I found a great J-type OD tranny for it for $800)...if you find a good OD tranny for not too myuch money ,go for it...I just try to figure out how much you drive, how much gas you use, vs how much gas you save , what it costs you...then is it worth it , and how many years payback....if you save 5 mpg , spend $2000..it may take awhile to pay for it....thats how I look at it...so far 14 mpg does well for me...I drive 3 to 4 k miles /year
and yes a 4v, a Holley 650