HELP 1968 SBO tuning

Stupidquestionspro

Stupidquestionspro

Master Mechanic
May 23, 2019
310
43
Tampa Bay Area
The 68 350 I have I’ve been trying forever to get tuned right.

I’m not sure what cam was just told RV cam
MSD ready to run is set with light blue and light silver spring I believe all in timing by 2800?

I tried once to tune timing by a vacuum gauge and max vacuum had initial at 30 with 21 in the distributor and 10 on the can and as insane as this sounds I still didn’t hear any pinging maybe I’m deaf?

Currently It is set to 15 initial and 23 mechanical stop bushing with a 10 non adjustable vacuum advance that came with it.
I just reset the idle/air with the vacuum gauge and had mainly steady 19 though it took quite a few more screws out then expected I’m estimating like 3-4 on each side. The exhaust smells slightly of gas and while it stumbles slight with the vacuum unplugged it doesn’t die. The video is of these settings and the idle in the video is with the idle set screw completely loose. I wish I could get the idle lower but I’m not sure why I can’t.

I run shell 89 gas
Wish I knew the compression but no idea

Video starts in gear and towards the end I put it in park.


 
G

GPNX

Apprentice
Jun 6, 2016
97
18
are you doing all this tuning with vacuum advance canister attached? is your carburetor set up right or did you just take it out of the box and bolt it on?
 
Stupidquestionspro

Stupidquestionspro

Master Mechanic
May 23, 2019
310
43
Tampa Bay Area
are you doing all this tuning with vacuum advance canister attached? is your carburetor set up right or did you just take it out of the box and bolt it on?
Yes vacuum advance is connected to time vacuum and it’s been out of the box for a bit since then I’ve adjusted the choke
 
G

GPNX

Apprentice
Jun 6, 2016
97
18
vacuum advance should be disconnected until you get full mechanical timed right. if you google timing on the internet there is alot of things that can help you. basically i start at 32 full mechanical advance drive it wot listen for pinging the bump it up 2 degrees and keep doing the same thing until i hear denotation or feel lose of power. as for your carb i have never messed with a summit one. if they are like edelbrocks i don't think to highly of them.
 
Stupidquestionspro

Stupidquestionspro

Master Mechanic
May 23, 2019
310
43
Tampa Bay Area
vacuum advance should be disconnected until you get full mechanical timed right. if you google timing on the internet there is alot of things that can help you. basically i start at 32 full mechanical advance drive it wot listen for pinging the bump it up 2 degrees and keep doing the same thing until i hear denotation or feel lose of power. as for your carb i have never messed with a summit one. if they are like edelbrocks i don't think to highly of them.
Well I always set timing with the vacuum advance disconnected it’s the mixture adjustment I dont always bother to disconnect the vacuum advance right now my total timing without vacuum advance is about 38 and I don’t hear any pinging though like I posted when I set timing with a vacuum gauge and didn’t bother to check it I was somehow running 51 total timing without vacuum advance and didn’t hear any pinging so mostly my engine makes no sense because it never seems to follow the research I find
 
fleming442

fleming442

Geezer
Dec 26, 2013
6,840
113
So, from your other thread, the transfer slots should be almost square as these are the idle air feeds. If the throttle blades are too far open, you are trying to compensate with fuel, which is why the idle screws had to be backed out so far. Carb tuning is MUCH easier when the foundation is right!
1558636245438.png
 
Stupidquestionspro

Stupidquestionspro

Master Mechanic
May 23, 2019
310
43
Tampa Bay Area
Ok and the secondary idle adjustment which it’s called in the manual adjusts that?
 
Stupidquestionspro

Stupidquestionspro

Master Mechanic
May 23, 2019
310
43
Tampa Bay Area
I don't know didn't read it. It's usually on the primary idle screw where the linkage hooks up. Does it have 4 corner idle screws or just 2?
There is 2 idle mixture screws 1 fast idle screw and 1 curb idle screw and on the bottom of the carb is the secondary screw it was speaking of the only one I haven’t messed with so I’ll have to take a look at that one.
 
olds307 and 403

olds307 and 403

Comic Book Super Hero
Oct 14, 2008
4,747
113
Melville,Saskatchewan
As said time it with the vacuum advance disconnected and plugged. 15 base and 23 advance with the 10 degree can sounds about what Olds V8's like. Is it a factory 2bbl or 4bbl? My 9 to 1 Olds 350 likes 18 base, 18 mechanical and 12 vacuum advance off manifold. I consider adding another 5 degrees vacuum advance and it would probably like it.
 
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