We need to know cam info like duration @.05 and lift before we can say what a good idle is. Ford makes several cams, so we still cannot really guess at this point. A mild cam with a vacuum leak will idle like a 255 duration race cam. Until we know more, a vacuum leak is still a possibility. I run a 242/248 duration@.05 with .64 lift solid roller Comp Cam and at 850 my idle vacuum is 11-12".

10" is very low unless you are running a REALLY serious cam or a bunch of valve lift. My car will hardly run if I rich it up or lean it out enough to hit 10" vacuum at idle.

 

Timing changes idle vacuum as well, more timing means more vacuum. The problem is if you just bump base timing to get solid idle vacuum then you may end up with too much timing and can detonate under load or diesel when you shut the engine off. Heads, intake and compression will also have an effect on idle vacuum. Plus you need to make sure you have the right size power valve, if it's rated too high and opening during idle it'll load the engine up and reduce vacuum and cause the PV to open more and dump more fuel etc etc. You also don't want to set idle for best vacuum, that can lead to improper throttle position uncovering the wrong amount of transfer slot.

 

Your original question asked if the 10 inches of vacuum was too rich. It is not really correct to say that the idle vacuum has any thing to do with rich or lean. They are somewhat related but you don't measure a rich lean condition with vacuum. A rich/lean conditin has more to do with the carburator.

 

Maybe my vaccum gauge is broken but the thing jumps like from 8-12 and it is not stable at all

i need to find the receipt for the cam so i know which one it is but i mean before i was able to get like 15 constant and now i can't even get close to that and it reaks of gasoline badly


This all happened after i flooded my engine one day and ever since then I haven't been able to get a constant 15" anymore but my vacuum gauge kinda sucks and the needle doesn't even rest at 0 unless i hit on it....


and now when i put my idle at 650rpm which the shop had it at originally it goes down to like 5-8" but they had tuned it before a while ago and it always ran real rich and ate gas


now really sure if the jumping is normal

i sprayed carb cleaner all around the carb and the carb spacer and there was no idle droppage so i don't think i have a vacuum leak near the carb.......

 

When you flooded it, did it backfire through the carb? I think you have a blown power valve.

 

Sounds like you could have a vacuum leak. Jumping needle is a misfire, more commonly caused by valve overlap (lopey cam) or a vacuum leak. I'm assuming you have a roller cam since you said it's a Ford cam, and roller cams generally don't have the nasty idle that aggressive flat tappet cams do. Like fakesnakes said, a Z cam will get crappy vacuum at idle, but you don't see too many people running those. So going off of that, sounds like you most likely have a vacuum leak.

I ran into a problem with my engine a while back where I knew I had a vacuum leak, but I couldn't find it for the life of me. I also figured out that cylinders 2 and 3 were burning oil. Turns out I had slightly overtorqued my intake, which caused it to bow inward, which caused the bottoms of the intake ports to lose their seal and suck crankcase gases and oil up from the lifter valley. Internal vacuum leak. Not saying this is for sure your problem, but it is something to think about.

Edit: Fakesnakes has a good point, a blown power valve would push the carb way rich, causing a misfire and low bouncing vacuum.

 

I have an edelbrock 1406 carb so what could be the problem since i read they don't have power valves?

my carb was rebuilt 2 years ago im not going to have to rebuilt the entire thing am I??



but yea definitely since i flooded the engine its been running really rich and i have never been able to get the vaccum anywhere near 15" at idle when before it was really easy to and it was constantly at 15"

 

Aha! Didn't know you had an Edelbrock. What's happening is that your low vacuum condition at idle is allowing the too-strong stock springs to push the rods up, dumping way too much fuel into the intake, which causes a super rich mix, which in turn causes a misfire, which further drops vacuum and perpetuates the situation.

What you need to do is switch to lower rated step-up springs. Use the 5" or 4" (of Hg) springs. This will keep the rods down during idle. Then you can tune your idle speed/mix properly, and switch back to a weaker spring if needed.

 

thank you for your help can i buy the spring separately or do i need to buy the tuning kit?

and i wont have to adjust change all the jets and stuff if i am changing the spring correct?

edit: because the carb runs pretty good at WOT and just driving it around and all that good stuff runs great

 

What you just said reinforces Tad's suggestion which I agree with. Here are the springs:

http://store.summitracing.com/partde...5&autoview=sku

Keep in mind that you still have a problem that needs to be fixed. It could by as simple as crap under the float needle. Did you recently change any hoses?