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1975 Plastic fantastic aka Corvette

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  • I'm not 100% I follow why a 302? Five liter class? A 302 track car makes me think Muncie close ratio for some reason, with 3.23's. I'm coming up with [email protected] mph, and [email protected] at the top end of fourth on a 27" tire
    Flying south, with a flock of bird dogs.

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    • Originally posted by Beagle View Post
      I'm not 100% I follow why a 302? Five liter class? A 302 track car makes me think Muncie close ratio for some reason, with 3.23's. I'm coming up with [email protected] mph, and [email protected] at the top end of fourth on a 27" tire
      less mass, higher rpm
      Doing it all wrong since 1966

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      • How many million RPM's? 327 will rev pretty happily... most of the 3.0" Ford guys reach for a 3.25" stroke right away.

        I'd think a forged crank will be easier to find in 3.48?
        Last edited by Beagle; December 26, 2012, 09:02 AM.
        Flying south, with a flock of bird dogs.

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        • If it's the same 302 I had in my '69 Z28.....that mutha loves high revs.

          I ran 4.11's in the rear........even then it sometimes felt like you were
          taking off in second gear.
          Thom

          "The object is to keep your balls on the table and knock everybody else's off..."

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          • Good idea on the tie bar between the bolts. You need more velcro on your carpet.
            Escaped on a technicality.

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            • Originally posted by TheSilverBuick View Post
              Good idea on the tie bar between the bolts. You need more velcro on your carpet.
              more velcro?
              Doing it all wrong since 1966

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              • A pun on the zipper comment.
                Escaped on a technicality.

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                • On an independent rear suspension your camber will change, much like an IFS, as the suspension cycles up and down. There is also the chance that your toe setting will change, even though you don't have a steering arm influencing the arc.

                  However, until you replace your worn parts, you're just chasing your tail.
                  I'm still learning

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                  • Originally posted by SuperBuickGuy View Post
                    less mass, higher rpm
                    Yes... but, what usually determines the maximum rpm isn't the amount of mass swinging around, it's the rod bolts or valve train.
                    I spun my stock bottom end 350 (but with decent rod bolts) 7200 every time I hit the burnout box for a couple years, then put that bottom end in my truck for another year... and sold the truck with a perfectly fine running engine.

                    If you just like the rpms, the stock heads will do it easier if they don't have as many cfm's going through them... so the shorter stroke/ few cubes will spin easier in that respect.

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                    • Originally posted by TheSilverBuick View Post
                      A pun on the zipper comment.
                      Doing it all wrong since 1966

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                      • Originally posted by yellomalibu View Post
                        Yes... but, what usually determines the maximum rpm isn't the amount of mass swinging around, it's the rod bolts or valve train.
                        I spun my stock bottom end 350 (but with decent rod bolts) 7200 every time I hit the burnout box for a couple years, then put that bottom end in my truck for another year... and sold the truck with a perfectly fine running engine.

                        If you just like the rpms, the stock heads will do it easier if they don't have as many cfm's going through them... so the shorter stroke/ few cubes will spin easier in that respect.
                        Sooo... if the mass was less, it wouldn't positively impact both the rod bolts or the valvetrain?
                        I'm still learning

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                        • Originally posted by Bob Holmes View Post
                          Sooo... if the mass was less, it wouldn't positively impact both the rod bolts or the valvetrain?
                          Less mass = less stress on internals... as for valve train, something nice and simple like a Jessel valve train should do nicely :D

                          so
                          in other news, the original seats are back in the car - it's going to be easier to put holes for the harness than make the aftermarket sets fit... ah well

                          And

                          talked to the Corvette guys at Dean's Classic cars - he says I've completely lost a retainer in the rear differential




                          so on the inside of the spider gears, there's a keeper - they are a known wear item, and if it gets bad enough, it simply wears away - thus there is nothing holding the top of the tire from cambering to the outside. Now comes the time to conclude the discussion about gear ratios.... I can get a 2.73 unit for 300, or rebuild mine for 600 plus shipping.... or maybe even both... dunno

                          *if anyone is interested, a guy wrote a paper on Corvette differentials here - http://forums.corvetteforum.com/c3-t...ild-paper.html

                          he is in his early 20s, was 18 when he started on his 'vette....
                          Last edited by SuperBuickGuy; December 26, 2012, 08:49 PM.
                          Doing it all wrong since 1966

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                          • I'll throw this out there as food for thought, and it is relevant to Yellowmalibu's comment regarding cylinder heads. Years ago I threw together a "hand grenade" 327 out of mostly used parts and junk. Used short dome F.I. replacement pistons, a 307 crank (way under balance), didn't replace the rod bolts, didn't balance it. Early power pack style heads-small ports, small valves, 57cc chambers, a Chevy Z28 off road cam and GM Z28 valve springs. Victor Jr. and a 650 Holley. I went in a 75 Camaro that was full weight except for a glass hood with a 10" converter and a 4.10 gear. Ran 12.30s @ 108mph. Perfectly happy driving around town and at highway speed. Sounded like a full on race car at a stop light. When the motor hit 4000 rpm it was like flipping a switch-it came together and just took off. Buzzed it to 7200 because that was all the balls I had, but acted like it wanted to keep on going. That motor that should have blown up ran for years. Final compression was 11.8:1 and it was perfectly happy on pump gas. It was a hoot to drive, and I'm assuming that the purpose of your car is basically to be fun to drive. High rpm small blocks are cool.

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                            • Hot Rod February/March 2009
                              http://www.hotrod.com/techarticles/3..._engine_build/
                              http://www.hotrod.com/techarticles/3...yno_test_tune/

                              punch line - 550 hp @ 5400, 23.5 mpg in an A-body....


                              of course, cheap doesn't belong in this sentence - $2400 for the crank.
                              Last edited by SuperBuickGuy; December 26, 2012, 10:07 PM.
                              Doing it all wrong since 1966

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                              • new differential

                                2.73 gears..... posi is in good shape, needs a left yoke; or simply a shim....we'll see which one I go with....

                                So I dinked with the car tonight, working on tuning it.... I've come to the conclusion I think I made a mistake by putting the 1.6 ratio rockers on it.... it won't idle under 1400 rpm, even with the rockers at 1/8 turn past zero lash..... ah well, I can fix this pretty easily
                                Last edited by SuperBuickGuy; December 27, 2012, 10:43 PM.
                                Doing it all wrong since 1966

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