One other question I have is a few replies up you mentioned something about blocking off ports on the carb to see if it made a difference.. Because any unused port/ports on the carb should be completely plugged off. The vacuum readings look better and more stable using the big port on the carb don't they? But unless you have a larger cam in it, i'd say they are a little on the light side of things, which adjusting the timing a few degrees one way or another can help that. Also though, tweaking your air/fuel screws and idle speed screw can have an effect on the vacuum readings as well. once you get it close its somewhat about splitting hairs to get it fine tuned. But, on the plus side if you have a vacuum gauge it's one of the best ways to fine tune an engine! Tune it for the best vacuum at idle and the rest should fall into place. I tend to disagree with the notion you shouldn't be able to fire it up and within a few seconds drive away if you choose. My 500hp 10.5:1 468 running 110 octane with an 850 Demon on it I can fire it up cold, back it out of the garage and drive away. and it has the Heat cross overs on the heads blocked off. I think something is just a little off with the timing and/or carb that a little tweaking can cure.
Here is the info off my cam card: I do not feel its a large cam but once again I am not versed well enough to say for sure. and I was thinking they are on the low side as well. Currently my timing is set at 14° initial. I am guessing it would like some more as before this I had it at 12° and it was just ok but not nearly as it is now.
speed pro cs-1013r cam and lifters.
- 2000-4500 RPM Range,
- 288 intake/298 exhaust Adv Dur,
- [email protected] 214 intake/224 exhaust,
- Valve Lift 443 intake/465 exhaust,
- Lobe C/L 112
And yes, all of the ports on the carb are used. passenger side runs to the dizzy, driver side runs to a "T" which connects the HVAC and the transmission module, the center is the PCV, and rear is brake booster, the other additional on the manifold is plugged with a NPT plug.
I am 100% with you on things are just a little bit off, be it a combination of timing and those mixture screws (pretty sure the original shop adjusted my TV cable, then bumped my timing up 2° and returned the carb back to out of box adjustments and called it "tuned"). I am pretty un-easy adjusting these pieces at this point, as this thing has me second guessing everything now. The way I see it so long as oil is warm enough to flow with a proper pressure through the engine it should be able to be driven no matter the outside temp. Granted maybe not immediately down a drag strip, but down around the block off to work should not be a problem. This is how my old carbs worked and I never had a problem nor did I ever need to adjust them, they came with the trucks and worked great.
Since I'm not 100% confident on my tuning ability I made an appointment with a restro shop to see what they think about it and what they can do with it. I'll be sure to pass along the info I've found here, being the first time I've had a vacuum gauge I have no idea why I haven't bought one before now.
