According to '68 GM tune up specs all SBC's used manifold vacuum to the distributor vacuum advance. Not sure about big block. I've tried to set mine up this way and it runs like crap. Hard starting with the low base timing and rough idle due to over advancing. If I run ported with base timing bumped up, I can show it the key and it starts and idles nice. Even more responsive. Back when I was first in the trade we would always go ported when we could. So what are you running for advance and why ? Ported or manifold vacuum?
__________________
'68 Parisienne 2+2 Convertible Matador Red (Resale Red but not for sale).
My 62, when had the oem 283 was manifold vacuum, the new 350 with Edelbrock also has manifold both started really nice. The 62 vacuum can has a limit a peice of rubber hose on the pullrod simple but works It is limited to about 8* . 8-10 initial advance works nice. I used the old 283 dist. in 350 works very good. Was the vacuum pot changed, if so may be wrong one. Laurie
According to '68 GM tune up specs all SBC's used manifold vacuum to the distributor vacuum advance.
Are you sure??
Thanks
Randy
Ok Randy. I'm not positive but with initial timing at 4 BTDC and remove vacuum to adjust, I figured got to be manifold vac. I just checked an old Canadian Service Data Book and it shows spec at 8 BTDC which would be ported. The day I had the old scope hooked up I tried different ways. The engine really labors at 4 to go ported. I ended up setting it at 10 with ported which is where it was to begin with. One day next spring I'll have you over and we'll hook the scope up and set it your manifold vac way and my ported way and see which performs better. And who buys coffee.
__________________
'68 Parisienne 2+2 Convertible Matador Red (Resale Red but not for sale).
I always go manifold!! Set the 409 at 12 degree initial, with a new vac. advance "can" [ old one seized from sitting] and got 30 deg. full advance, then found out 9 ers like 14 degrees, engine came "alive" and had 34 total!!!!! Mileage improved greatly, on Hwy runs driving it "conservatively "
__________________
Some times I wake up GRUMPY, but today I let her sleep in !!!!!!!!BLACKSTOCK Ont.