1968 SBO tuning

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Gotcha well I still have an 18 bushing I just know the last time I timed via vacuum I accidentally ended up with 30 initial which is why I wanted to be sure I didn’t over do it with mechanical I also crazy enough at that time had 21 mechanical so I bet it was pinging like crazy I just couldn’t tell if assume


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d6fc96c8a98143daf0a00672ae811ef3.jpg
so my number 8 plug looks like this


dbe4bc9c974a6fc811a5ba3e8676e514.jpg
all the rest look pretty much exactly like this.

What’s going on with that cylinder when I changed the plugs last 8 also looked way different from the rest ideas?


Also just to b*tch for a second I hate the plastic coverings on the dang throttle cables when they come together and bind and then you have to spend forever trying to stop it or buy a new throttle cable [emoji2959]


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Currently I’m having a bit of an issue with that I have surging or hunting at idle with mixture screws out about 3 turns if I tune them for max vacuum then they are way out and my idle is super high as it is it idles at about 1000 in park with the idle stop screw not even touching timed to 30 base. It’s very annoying because tuning the carb and reading all the information I’ve found it still doesn’t act like it’s supposed to and I find it very strange.

Also with the mixture screws turned only 1.5 out it starts stumbling at higher base timing so I’m very confused because I obviously don’t want to be running crazy rich.


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If I have a vacuum leak it is very well hidden I was all over the place with the propane torch and the spray bottle and couldn’t find a dang thing.

Final end of day settings
28 initial as per the markings on the balancer
10 mechanical with homemade advance bushing. Having a hard time verifying that may just put in the 18 and adjust initial because I can’t seem to figure out if the mechanical is working
Advance can plugged into ported vacuum motor didn’t particularly like it on manifold vacuum
And idle screws out 2.75 or so

I didn’t hear any pinging. Maybe you will in the videos?

https://youtu.be/zSZwKi1CkFc idle in park and gear

https://youtu.be/OjxpROzDYDQ pulling into traffic

https://youtu.be/Mskl9QZ5wiI light throttle through the neighborhood in this video you may see or hear the stumble or buck or whatever it’s called I’ve been trying to get rid of right around 1500-1800 it’s so frustrating tried a bunch of different initial setting tried to play with the mixture none of it really had any effect and I’ve never seemed to be able to get rid of it

I know there is definitely still more to do so any help would be appreciated because I still for some reason can’t get the dang thing to do what I wanted.

Weirder than that my dial back reads a different timing setting than the balancer does and I verified the balancer is zeroed at tdc.

The only weird thing I noticed is on compression cyl 1 tdc with the balancer at 0 the rotor button is not pointing at the first plug it’s actually counterclockwise part way to the next which I can only assume is because it wasn’t a fresh distributor install?

Also weird part is I couldn’t use my dial back timing light to check my mechanical timing when I set it to 38 no matter how much I revved I had no marks then when I set it to 28 and revved it actually went to 18 then when I set it to 0 and reved timing didn’t change at all. Once again nothing I’ve found seems to explain that and another example of how nothing seems to do what it’s supposed to.

Just like if I tune the mixture screws for max vacuum they end up about 4 turns out and my idle ends up around 1300 or so with no way to reduce it and it’s obviously running rich at that point because leaving a vacuum completely open raises the idle further. Only around 2.5 turns out does the idle finally falter when a vacuum is unplugged.

Tuning this stuff sucks when you have no idea what you’re doing


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I don’t want to make a million threads so I’ll ask in this one

How do I find out if my heads were shaved by the machine shop since from what I understand it could be why no matter how many times I try I can’t seem to get it sealed right

I also was wondering if there is a such thing as an internal engine vacuum leak or something along those lines because I’m showing some symptoms of vacuum leak but no matter what I use or where I check I cannot find a vacuum leak externally




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When I had problems with my Edelbrock Performer (BBO), I was advised to set the intake in the valley dry, slide it to one side, and observe the gap. What I found was that the intake valley angle was off, and had to have it corrected at a machine shop. Edelbrock's stance on the matter was that the intake was designed to use the factory style gasket (turkey tray with lots of RTV to seal the gap).
 
The intake may be crooked, many Edelbrock's are out of box.
 
Thanks I’ll have to check that when I take it off though in the mean time can I measure the head to see if it was shaved or anything?

And can there be a vacuum leak inside the motor?


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