bfed 18 Report post Posted November 27, 2012 Just finishished installing 89 roller with AFR165, Comp XE266HR, Edelbrock Performer in 69 Coupe. I installed 2000 stall and reworked the C4. Need help with rear end. Rear wheels are Vintage 40 245/50R-16. Using car on street and strip. Quote Share this post Link to post Share on other sites
jholmes217 65 Report post Posted November 27, 2012 That intake, if it's the regular Eddy Performer will hold you back some. You should try a Performer RPM or Weiand Stealth. As far as the rear end gear goes, how much highway driving do you plan to do? Are you planning to take any long road trips? I had a 66 Stang with a warm-up 289 and a 4 speed with a 4:10 rear end. I would tach over 4000 rpm when going 60 mph, so I tried to stay off the freeway if I could and limit it to cruises around town . For longer trips, it went on a trailer. I would probably recommend a 3:25 to 3:50 gear for a dual purpose gear that won't run the rpm too high. Quote Share this post Link to post Share on other sites
cobra3073 24 Report post Posted November 28, 2012 Bfed, Your question brings up an oft-repeated question which on the surface seems pretty simple but a "good" response depends on several factors. Most notably, at what RPM does your motor make power or to put it in a better way, at what RPM do you want it to make power. On the street, a given motor may be required to do it at a relatively low RPM while on the track (1/8 or 1/4 mile) it would be TOTALLY different. There are actually formulas to determine each of these factors but it comes down to knowing three of four things to determine the fourth. They are: Rear tire diameter Transmission Gear Ratio (First Gear of the transmission Miles Per Hour (where you want to make the power) Rear End Gear Ratio Now I could give you the formula to do all of these but a better way is to go to this Site and "plug-in" the data. http://www.wallaceracing.com/calc-rgr.php Hope this helps. BT Quote Share this post Link to post Share on other sites
bfed 18 Report post Posted November 29, 2012 jholmes217, I agree I will need to upgrade the intake. I'm using the 2121 and AFR recommends the RPM Performer. I have been looking for a 3.50 for a couple of months. Seems Chicago area is dry. What are you using in your 69 with C4? Who did your Trans? Thank for your help. Bill Quote Share this post Link to post Share on other sites
jholmes217 65 Report post Posted November 29, 2012 jholmes217, I agree I will need to upgrade the intake. I'm using the 2121 and AFR recommends the RPM Performer. I have been looking for a 3.50 for a couple of months. Seems Chicago area is dry. What are you using in your 69 with C4? Who did your Trans? Thank for your help. Bill My car with the C4 still has the stock peg leg right now, and I'm not sure what ratio it is. I'll leave upgrading that to whoever buys that car. I'm getting ready to sell it so I can put the money into the Cobra Jet Mach 1. My trans was rebuilt by Transmission Sales and Service in Tacoma, WA. Does your car have an 8 or 9 inch rear end? Quote Share this post Link to post Share on other sites
bfed 18 Report post Posted November 29, 2012 jholmes217, I'm at the decision making time on the rear end. I have an 8" 3.00 in the car. I need to make the change like you suggested to 3.50 posi but not sure if thats the right call. Read that its not strong and shouldnt dump the money into an 8. any thoughts? Bill Quote Share this post Link to post Share on other sites
Mike65 475 Report post Posted November 29, 2012 bfed, I ran a 3.50 rear gear in a 68 J code GT Coupe & a C-4 auto I had many years ago & I would drive it on the highway & around town & I was very happy with it. Mike. Quote Share this post Link to post Share on other sites
cavboy78 28 Report post Posted November 30, 2012 bfed, there is all sorts of philosophies, experiences, factors, and opinions on how much power to run through an 8". My .02 say (for normal driving), its just a 289/302 paired with an automatic tranny and you would be fine with an 8". Currie makes some nice/beefy 3rd members with upgraded pinion support worth looking into. Assuming your center section is a 69-70, you already have the stronger case. If you're gonna put slicks on and a NOS shot, then i would think about a 9" upgrade. Quote Share this post Link to post Share on other sites
jholmes217 65 Report post Posted November 30, 2012 bfed, there is all sorts of philosophies, experiences, factors, and opinions on how much power to run through an 8". My .02 say (for normal driving), its just a 289/302 paired with an automatic tranny and you would be fine with an 8". Currie makes some nice/beefy 3rd members with upgraded pinion support worth looking into. Assuming your center section is a 69-70, you already have the stronger case. If you're gonna put slicks on and a NOS shot, then i would think about a 9" upgrade. I agree. If your going to put slicks on a run it on the strip on a regular basis, I'd go 9 inch. For mostly street and occasional strip, a 8 inch converted to posi/limited slip/locker should be fine. Quote Share this post Link to post Share on other sites
wfridolfson 10 Report post Posted December 3, 2012 bfed, I'm putting an 88 5.0 in my 69 fast back, did you keep the serpentine assy or did you go to a vbelt set up, i have the whole serp set up but have questions about the power steering pump hose hook up to original power steering assy, just wondering what route you took and how it worked Quote Share this post Link to post Share on other sites
