Hey, Guys!! Hello! I'm new to this site , but not new to Buicks.......mom had 70' GS 350 back when I was still a pup and I never forgot how much my eyeballs fluttered when you mashed the throttle!! Anyway, now I have a 71' and it has a 455 from a 70' 'Lectra w/ 400 TH (I know.......welcome to the 510 club, huh?) and I have heard two different stories on how to hook up the vaccum advance to carb............is it supposed to be constant vac or progressive on this engine? Any and all answers will be greatly appreciated!! Thanks in advance (no pun intended, really!!!)!! 1971 GS455 ahem...."bone stock" jammon455
Stock was ported vacuum. On a stock motor, ported will work just fine. If you change the springs in the distributor to bring in your advance earlier, you need to limit the amount of degrees in the vacuum cannister to 8-10*. If you do not, there will be too much advance at cruising speeds, and it will ping when you romp on it. Bringing in your advance earlier can really wake up a motor, and it can enhance the low end when you have a cam in the engine. Also running your vacuum advance from manifold vacuum gives you extra advance at idle which further enhances throttle response, and can help engines that tend to overheat when idling. Bottom line, if you leave everthing stock, run ported, if you modify the advance curve, limit the vacuum degrees and run manifold vacuum. Both ported and manifold vacuum will go away at WOT.
Thanks guys!! This baby is stock and will remain that way............looking to replace what the build sheet indicates, 350HP from factory, but WILL build that one!! I have the vaccum advance already hooked up to a good source I now know! Thanks again! Isn't it fun to zip past most street machines just as they think they've got the edge??!!! The 455 is awesome as a street sleeper when ya' don't have any badges on yer car yet! I'm still restoring the body and some of the interior so I stripped the chrome and drive it occasionally downtown. Most youngsters haven't a clue as to what it is, but they remember it after a blast down the avenue! LOL
