My 66 is stock 3 speed does anyone know if I convert to turbo 350 will I need to change rear end gears?
Hey I have a 84 that used to be a 3sp with the 252 6er blew it up went 350 350 turbo kept the stock rear end...I believe 3.07 and it worked out all right alot of fun from light to light if you may want to change if doing highway and be able to salavage some MPG out of it last I checked I was getting around 12
I had 4:10 with a TH350 and it topped out at 65 MPH at 3200 RPM. I'm now getting around 16 MPG with the same gears and a 700R4.
Most of those old truck have 3.73 or 4.10 gears in them. With a Turbo 350 you're are going to be better suited with a 3.08 gear or close to that. You may find with mine, as I did, that it I lack the confidence to dive into an old rear end and you can't find a single compitent mechanic to do it for you. My advice would be to just swap the entire rear end. Fast, easy, you can convert to 5 lug.
Thanks This forum is awesome! (I'm a newbie) Thanks and I appreciate the help. I might be crazy but I'm gonna fix up this bucket!
I don't think there is a SINGLE guy in here that didn't scratch his head and ask "What am I doing" when he started to restore his ride. Welcome to the forum!!!
If you go t350 your rpms will be higher than the 3spd, mpg loss. You could offset it with the 700R overdrive with lockup though. Or depending on where you live, if you don't want to change the whole rearend..........find some old school drag race speed shop locally. What is sweet about the old rear axles is that (if it's like my 57 belair) you can unbolt the axle flanges, slide the axles out and take out the ring and pinion carrier center section and go to a speed shop and have them dial in a new set of gears. OR....with my 57....I found another center carrier and had a 4:11 posi put in it and now I have 2 sets of gear ratios all set up. If I wanted to take the car on a long cross country trip and want the fuel mileage instead of the quickness I can change gears in 1/2 an hour.
Aimless: I'd like to hear more on that Silverado rear axle swap... especially the axle width from hub to hub. I've had a 71 rear axle in my truck- gives you the five bolts...but it is about 1 1/2 " wider, which can cause tire fit problems. And how did you Finagle the panhard bar? And advice to you DoubleL, the big danger is biting off too much at one time and getting discouraged and giving up. If you can drive her every few months you are more likely to stay in the game to completion... if that ever happens.
Billy, Sorry it took so long to respond. My silverado axle was, if I remember right, about an inch and a half increase. I was doing power front brakes at the same time and that moved my foot print out about an inch in front, but it was still proportionate. If you ever spend time under the truck with a tape measure, you learn fast that from hub to hub up fron is like 58 inches, and only 56 in the rear. I did a TON of measuring before the project, believe me. Anyway, the big mystery was solved when we discovered that all of the width added was in the pumpkin of the new axle. I ordered a kit from Classic parts that adapted any axle with 3 inch tubes to the arms. It came with a new bar and u-bolt mounts. First my cousing and I cut all of the shock towers off the new axle to make the tubes smooth, then laid both axles neck and neck. We measured the distance from the u-bolt mounts on the 65 axle to edge of the pumkin (using a home-made measuring device of nails taped to a yard stick) then transfered that measurement to the new one, MINUS 1/2 the extra width in the new pumpkin. We were down to measuring 1/32 of and inch!!! As far as the bar, a new adjustible one came in the kit too. That was a bolt on/weld in job. Also, don't forget to maintain the same angle on the new rear end. The new one should be rolled back about 10 degrees, as was the old one!!
Oh, by the way, due to my footprint increase, I too had to downsize my tires!! I went from 15x8 inch wheels and P275/65R15 (which had an overall width of about 11.5 inches) to 15X7 wheels and P255/75R15 (becoming close to 10. The results I got from a skinnier, taller tire were MUCH better.
axle width etc Hi Aimless, Thanks for the reply. I went back to my 66 axle assembly and had the axles altered to five bolt. I did not like the extra width, as I want to fit as much tire as I can under the back (17x8). So it seems that the silverado swap would have the same problems for me as the 71 swap did- i.e. too wide. I think there are compent ring and pinion mechanics here in Omaha, so guess I'll stay with my current assembly when it comes time for a posi installation. Gracias for the info...
