![]() |
|
![]() |
#1 |
71 Cheyenne SWB Fleetside
Join Date: Jan 2005
Location: Sarnia, Ontario, Canada
Posts: 403
|
![]()
hey, what is the timing suppose to be on a 71 350ci engine? 8 degree's advance or 4.. this is a stock motor.
thanks joel
__________________
![]() |
![]() |
![]() |
![]() |
#2 |
71 Cheyenne SWB Fleetside
Join Date: Jan 2005
Location: Sarnia, Ontario, Canada
Posts: 403
|
i think i found it in a book have here? 4 degree's sound right to you guys??????
thanks joel
__________________
![]() |
![]() |
![]() |
![]() |
#3 |
Senior Member
Join Date: Jul 2001
Location: Muskegon,MI,USA
Posts: 6,026
|
![]()
The recommended setting for timing is 4 degrees btdc for the stick shift and 8 degrees btdc for automatic.
We set ours at 10-12 degrees btdc unless spark knock occurs and then we back off a bit if needed. Jim |
![]() |
![]() |
![]() |
#4 |
71 Cheyenne SWB Fleetside
Join Date: Jan 2005
Location: Sarnia, Ontario, Canada
Posts: 403
|
you get more power from using 10-12 BTDC?
thanks joel
__________________
![]() |
![]() |
![]() |
![]() |
#5 |
Senior Member
Join Date: Jul 2001
Location: Muskegon,MI,USA
Posts: 6,026
|
Yes, you do get more power.
Jim |
![]() |
![]() |
![]() |
#6 |
Registered User
Join Date: Nov 2004
Location: New Lenox,IL
Posts: 306
|
I set my rebuilt 355 (350 Bored .30 over) at 6 instead of the "Factory" 4 BTDC.
__________________
1985 Chevrolet C-30 454 1-TON Dooley 1969 CHEVROLET CST-10 PICK-UP Good memories 1999 Chevrolet Z71 Ext. cab 5.7L Good Memories With a quart of oil, and a gallon of gas, she won't let no other car pass!!!. ![]() ![]() Last edited by CHEVY & GMC FOREVER; 03-31-2005 at 09:37 PM. |
![]() |
![]() |
![]() |
#7 |
71 Cheyenne SWB Fleetside
Join Date: Jan 2005
Location: Sarnia, Ontario, Canada
Posts: 403
|
is yours a manual transmission tho?
__________________
![]() |
![]() |
![]() |
![]() |
#8 |
got boost?
Join Date: Mar 2005
Posts: 123
|
first realize the stock advance curve is a compromise.if you are interested in good fuel mileage/good performance then, go read up on how to optimize your advance.
your camshaft duration has a huge effect on the required advance. as does the head design. a stock cam will have a mild factory advance curve that sometimes will continue adding timing all the way up to 4500rpm.not optimum! a good basic advance curve for a 350 is to set base timing at 10-12 degrees. have the mechanical advance all in by 300/3500 rpm for total advance of 36-39 degrees depending on your cyl heads & cam. i connect vacuum advance to manifold vacuum.this provides for a smoother, quieter idle, higher idle manifold vacuum & brisk takeoffs.not to mention it masks some of the lopiness from some cams. using an advance curve this aggressive can yield part throttle cruise surging. for this reason i highly recommend an adjustable vacuum advance. this will allow you to keep the mechanical advance curve & be able to "pull out" some of the part throttle vacuum advance. there is some good info on the net. try a google search for:"tuning ignition advance"
__________________
'70 chevy lwb w/'67 hood. 357 s.b.c. built, 4l60 w/vigilante lockup high stall converter, edelbrock pro-flo,brodix heads,comp cams rollerized w/ belt drive, one piece d-shaft, yada, yada, yada..... '82 honda v45 sabre"the black" ![]() |
![]() |
![]() |
![]() |
#9 |
71 Cheyenne SWB Fleetside
Join Date: Jan 2005
Location: Sarnia, Ontario, Canada
Posts: 403
|
hey,
thanks for the info chevibubba.. my vacuum advance is hooked up to the carb. should put it directly to the manifold? let me know joel
__________________
![]() |
![]() |
![]() |
![]() |
#10 |
got boost?
Join Date: Mar 2005
Posts: 123
|
there are two different sources for vacuum on a carb: one is above the throttle plates & is called ported vacuum.the other is below the throttle plates & is called manifold vacuum.
i use the manifold vacuum port or connect directly to the manifold where the tranny modulator line connects. you can use either port. the ported vacuum will not provide vacuum at idle. if you remove the vacuum advance line from the carb while the engine is running & it affects the engine you are connected to manifold vacuum.usualy increases idle speed. you can experiment with the ports & see which one you like best. just be sure to change your idle speed as needed when you change sources.
__________________
'70 chevy lwb w/'67 hood. 357 s.b.c. built, 4l60 w/vigilante lockup high stall converter, edelbrock pro-flo,brodix heads,comp cams rollerized w/ belt drive, one piece d-shaft, yada, yada, yada..... '82 honda v45 sabre"the black" ![]() Last edited by CHEVIBUBBA; 04-03-2005 at 12:22 AM. |
![]() |
![]() |
![]() |
Bookmarks |
|
|