What can be causing my valve float? Springs are the Crane 10308, its a hotcam, 1.6 SA promags.

I did a quick search on Bing, read how with the supplied shims the springs can "walk around"? I'm not disappointed in the numbers by any means, but I feel like I'm cheating it, the guide Stealthformula wrote up for cams says for best performance to shift around 6100, well I've been shifting anywhere from 5600-5800, because well I had the dip at 6k when dynotuned about a year and a half ago, well on the dyno this weekend you can see how choppy its getting above 5600 or so.

 

Did you install the correct pushrods? ISnt this the car that you had replaced headgaskets on and did you or did you not machine the block? Are the rockers adjusted correctly?

 

are you sure it's valve float? a high rpm miss can cause these kinda problems. I run a much bigger cam with the same spring kit and have zero valve float problems, not to mention my springs are pretty old too

 

Not convinced its float.
This is valve float (red line):

 

looks more like a high rpm miss, especially since the A/F is fairly irratic

 

what springs were you running when you were having value float?????

 

Not valve float. Fuel or ign. related. Power never recovers after the valves start to float.

 

Fuel wise I have 36 lb. injectors, Walbro/Racetronix setup. Fuel Pressure gauge reads 43-44 PSI at WOT, 38ish at idle. What can I test in the ignition system, maybe the coil is getting weak?

I am curious about the pushrods, how much does a pushrod length tool cost and operate?

Rob this is the_Merv's old motor. When it got to me it had the springs from the hotcam kit on it, then I swapped to the 10308s. Which is why I thought it strange when I was told it looked like valve float, I was thinking I had gone overkill with the springs honestly for a hotcam. I did do headgaskets on my Mom's car not too long ago, but not this motor.

Wish I could find my sheet from the dyno tune, it doesn't look as bad then, so perhaps something ignition wise is getting weak?

 

pushrod length checker is like 10-20 bucks from summit

high rpm miss can be a number of things.
-faulty coil
-burnt plug wire
-bad plug(s)
-faulty opti
-faulty icm
-bad ground

personally one time I had an ICM that wasn't properly bolted to the coil bracket cause a high rpm miss I was chasing forever. among many other random high rpm missfires I had to track down

 

That dyno run was with PAC 1218's. A buddy had the same cam and springs and had the same problem and that graph showed the same thing.

I ran some PSI LS1 beehives, they floated too. Ran some Manley beehives and the float was cured but 4 busted in less than week. Turned out to be a bad batch according to Manley. I am now running Patriot extremes dual springs and the float went bye bye.

My cam with the XFI lobes simply can not work with beehives and rev to 6.7K RPM.

Looks like the OP's MAF tables are fugged according to the A/F.

 

I also had just put in a fresh set of TR55's and some MSD wires. I checked the day prior, none of the wires are melting on headers, mileage is unknown on the Opti or coil.

 

So I took my chart with me down to a shop that produces 700-1000rwhp Mopars on a daily basis. They said it looks like a potential fuel issue, as the A/F goes leaner in the choppier areas. I've got 43 PSI at the rail though at WOT, I'm going to double check when I drive it again later to make sure. Could I have an injector getting weak or something?

 

Is it just not cool to talk about actual technical issues in the LT1 section all of a sudden or something?

Here is the even worse thing that makes me uneasy. What if its just in the tune itself, I could be out money to have someone else tune it. If its not in the tune, the tuning time would be wasted. Looking for ideas here. Anyone else's chart ever come out looking like that at some point?

It doesn't really feel like there is any miss or anything at high RPM. Maybe I can get some footage this weekend of the fuel pressure gauge at WOT, shot of the tach, etc.

 

Everytime the power dips at the end of your pull, the a/f spikes rich, not lean, so I'm not sure thats a fueling issues, sounds more like a spark issue.

 

BTW, 10308-1 isn't the part number of the springs, it's the kit part number.

You have to drill down to find the spring part number and find the specs on the springs. Then you can see the recommended installed height, spring rate, coil bind height, etc. I had to go through all that a few years back and it did take some searching.

Jake

 

The springs in the Crane kit are part number 99893.

 

here is what my ignition issue looked like on a dyno. the harness to the opti was loose and wet along with 2 bad plug wires. my air fuel just took a nose dive instead of having a seizure like yours did.

 

So looking at the ignition side for troubleshooting, what is likely causing this? Should I have the ICM tested, is there anyway to test what the coil is putting out? I do have a spare ICM and coil laying around, I suppose I could slap them on and maybe hit that Proven Power place in Tampa, I guess I would hate to just keep paying for runs, I'd like to try to figure it out first.

How much a variation is there usually in the A/F? Obviously it shouldn't be going all over the place like mine is.

 

i will have to post up my dyno sheet, it looks very similar to yours and the guys at the dyno said it was the springs i am using???? i personally didnt think it could be the springs because when i had it dyno tuned it looked really smooth even though they had smoothing on 5. if yours was ignition related, i am going to start there.

 

Here's my dyno sheet. as you can obviously see, it falls on its face and is jagged like hell. the tuner and the mechanics at the shop said it was the valve springs i have but i hope not cause that job sucks!!!!


What do you guys think????????????????????