I have a 68 327, 4-speed, with a 12 bolt 3.08 rearend that is basically stock. The heads are 1.94/1.5 "double hump, the pistons are flat top, and the cylinders have been bored .030". Distributor, carb, intake, and exhaust manifolds are also stock.
The cam that was recommended to me was a Mutha Thumpr Cam. (.489/.476 lift, .235/.249 [email protected]
Since I've installed it its been a nightmare to tune.
I am trying to stay as close to stock as possible (externally) so I kept the Quadrajet and rebuilt/modified it by doing the following: increased the down idle tubes, replaced the secondary butterfly bushings, put the lightest APT spring in it an at this point trimmed it.
The cam makes very little vacuum (7-9") and the APT was opening up all the way causing it to run extremely rich. Since I pulled the carb back down and trimmed the spring it is not running as rich, but still bad enough that I cant stay in the garage while its running (and the idle adjustment screws are out 1/2-3/4 of a turn).
I am having a really hard time tuning the engine. I have a spring kit and an adjustable vaccum advance , but have not installed them.
Currently I have 30 degrees initial timing and have taken a break from running the engine because I cant get it tuned, and the front end is being rebuilt so I cant pull it out of the garage yet.
I don't have power accessories or an automatic transmission so vacuum (for accessories) isn't a big deal to me right now.
Is there a way to tune these cams without the exhaust being so rich? If so, how do I do it?
I really want a nice sounding cam that has a lot of torque in the lower RPM range (<3800).
Would I be better to go ahead and pull the cam out and go with something else? If so which cam?
Any opinion or advice would be greatly appreciated.