Good Engine Advice Needed.

[2ndCIB]

I am planing on building a 350/700R4 combo for my 72 LWB. Plans are Edelbrock Perfromer cam and intake, 600 cfc carb, vortec heads, long tube headers. Current gears are 3.73 but plan on 3.42. This is going to be a daily driver. Any guesses on power and mileage? How big a headache is it to do the tranny swap? Thanks

[69halfton]

its really hard to guess power without cam specs. same with mileage. but with just a mild cam, and all that gear, you might be closing in on 15-16 mpg, if your lucky.

[Shyguy]

15 to 16 mpg sounds about right.

It also depends on your driving habits and high tall your tires are.

I don't know anything about 700R4 swaps, but I am sure some one that has done one will chime in soon.

Danny

[boundstaffpress]

700R4 swap will need a crossmember change for sure. Your drive shaft should stay the same, and even your yoke.
Speedo converter?
Detent cable?

[2ndCIB]

UMMMM.... Forgot about those things. Adding them to the list now.

[2ndCIB]

Planning on 275/60R15's 26" if I remember right.

[dan42]

3.73's are still a very common rear end in the brand new Chevys - the mileage will come from the tranny.

[jamesi20]

I can't imagine seeing much difference between the 3:73 and the 3:42 gears.If the 3:73 is in good shape,I would spend the money elsewhere.

[Billla]

Milage sounds right - I'd agree with Dan42 that the tranny will give the milage.

For power, I had something close to this engine already built in DD - figuring the CR at 9.1, I came up with 320HP@4500 RPM and a great torque curve with > 400 TQ available from 2000 - 4000 RPM. More complete information (in the Engine section, probably would lead to better assessment of power output.

[cdowns]

if your truck had the original shorttail th350 you'll need to shorten driveshaft use the same crossmember just move it back in the frame(holes are already drilled) you might need a longer speedo cable available at autoparts storethen you need tvcable and mounts as well as the lockup kit//its not that difficult of a conversion once you have parts/save the 373 and if you want to spend money in the rear get a posi and new seals

[chris71]

i would leave the 3.73 's for now, i did a 700 conversion a while back, 3.73's were awesome, off the line quick and could cruise at 80mph no prob. your speedo cable will work, the dust cover will work from a 350, the "detent" cable is different for a 700 its called a "TV cable", i believe the dipstick tube is different as well. i agree with cdowns, you need the lockup kit so the lock up converter will engage and disengage at the right times. you will also need a carburetor geometry correction kit. it is very important that you get the tv cable adjusted properly, since it controls line pressure and shift points, if this is done wrong your trans may only last a few months.

[Ole Blue 68]

I agree with Chris. Everyone I've spoken to says the 700 likes 3.73 or 4.11 gears.

[2ndCIB]

Now thats what I'm talking about! Thanks Billa, thats the power I was wanting. I think I will keep the 3.73'. My wife really likes it when her head bangs off the rear window at every stoplight!