pro94lt

This car may be cursed I've been in a fight with it for a while now and I'm down to one final issue. It breaks up or does something really weird that I can't really describe only while in boost above or around 5k. I have new tr6 plugs gapped at .030. New delphi opti, and the engine is fresh with around 1k miles on it or so. It did not do this before my engine blew a head gasket and I used the same cam and lowered the cr down to around 9:1. With stock cr and only 30#ers and a fmu it did not ever do this. please give me some advise I don't know what else to do, from looking at my log my 02's are around .9 and my maf is at 455 at 5700rpm's. My fuel pressure is good while whatever you would call what's happening to my car and fuel filter is new. Please Help!

transammiller

iTrader: (21)

valve float? what springs do you have? how much boost are you at when it starts breaking up?

pro94lt

It could be valve float, I just don't know how to diagnose it or what to look for.It has a hot cam, shims rocker and springs that came with the kit. Broken spring? The car ran perfect before it blew a head gasket at the track.

It's only getting around 5psi when this occurs

Could you Please describe valve float

XtremeDime

iTrader: (16)

Do you have a wideband?

pro94lt

I do not have a wideband. Looks like I need one?

Bob@BruteSpeed

iTrader: (16)

The first thing and cheapest to do would be to replace the new sparkplugs with another set just to make sure you didn't get a bad plug. Bob

kaotic_ws6

FOR SURE! my buddy had what sounds like the same problem as you and it was the number 5 plug... good luck

pro94lt

I was feeling lucky and set my 100kpa in the extended timing tables to be around 20* at 6000 and added 20% more fuel as well, no change.

You think I should try another set of plugs? When I put my engine back in I installed new plugs, now anogher set, the engine now has around 1000 miles on it.

Could someone describe valve float for me and what will fix it?

darooke

iTrader: (13)

You need a wide band to check your a/f and What are your plugs gapped at? What type of plugs are you running? my guess it is either the plugs or a/f.

transammiller

iTrader: (21)

valve float is a serious instability in the valvetrain. also boost pressure will force open intake valve causing boost bleed and "float"

pro94lt

thanks guys

I Have found something... this spring after my rebuild I had some valves that somehow became bad, they were fine when the head gasket blew but became bad from the time it blew and when I put the engine back in. well two of the valves look to be shorter. from the top of the retainer to the top of the valve stem, their is a difference. My caliper has a flat surface on the end and a small rod will extend out, the two valves are around .025in shorter and the valves have rubbed into my roller rockers. I don't know if they became loose (seemed loose even for roller rockers) or if this difference in length makes a difference, well I know it makes a difference.

Now I need to either readjust the valves, give it a try or just get the correct valves or send them off to Loyd or AI.

Am I correct that since the valve is shorter than it is supposed to be than the angle of the rocker will be off regardless if it's adjusted properly?

If this is the problem and if it's valve float, you don't ever want to encounter it, it sends chills throughout your body!

What do you think???

pro94lt

I reajusted them and have the same issue. I noticed on one of the rockers it looks like the pushrod has left an indention in the rocker.

Any advise all I know to do now is put the proper(or I think) proper valves back in I just don't want to burn any more time and money for nothing.

pro94lt

I installed some new valve springs that have 130# closed pressure and are good to .600 lift, put some different rockers, it still does it. I really don't have any other Idea what to check or do. I just don't understand why it does it under boost, and not if it freely revs to 6k. sounds like a loose rocker and the engine goes haywire. Anybody,

MY99TAWS6

iTrader: (3)

I had problem like this several times. Each time it turned out to be wires. Burnt or not connected or defective. I know wires are not fun in the lt1 but that is likley the problem.
If you plugs are good its likely wires. If you can run misfire checks on scanner then likely see which cylinder pretty quickly.

pro94lt

well I have not replaced the plug wires, their not that old and have all checked out ok with no burns.

I now either need to just sale the car or keep on, I'm looking to getting a wideband but I noticed as soon as it breaks up my injector pulse goes down to 8ms or pulses per second, whatever it is(can't remember)

I thought my bypass valve was opening so I blocked it off and it still does it.

Do I need more fuel pressure? I've got the stock pump with the procharger inline pump

BadgeZ28

iTrader: (28)

I don't know much about the LT motors but I do see a number of comments about opti ignition problems. You might run this by the gang at CamaroZ28.com There seems to be a bunch of LT version owners there. You might need to put the car on a chassis dyno to locate the problem? Don't give up.

So.jerZ-28

iTrader: (20)

sounds to me like a bad opti. pull the cover & check your rotor & contact points. also common for the bearing to go bad which will cause spark issues @ higher rpms due to vibration.

pro94lt

Thanks guys

Well I thought that and have already installed a ebay opti, which never really worked right, now I have a brand new delphi opti and cap. So what are my options now?? and possible problems

bad new delphi opti

going lean with proper fuel pressure maybee a bad fuel pressure gauge? so the fix would be bigger fuel pumps.

Bad tune?

plug wires

bad new fuel filter

inlet colapsing?

All I know is it did not do this before I blew a head gasket and broke some pistons. took the block heads crank rods and new pistons to machine shop, they cleaned up the heads said they were fine(later to find out two valves somehow went bad from the time it blew to when I put them on) polished stock crank, My concern now is if they missed the valves, could they have messed up on ballancing. they did not get my flywheel.

flynbludream

iTrader: (1)

I had a similar problem. Turned out to be a spark plug wire that comes loose sometimes. Check to make sure your plug wires are seated well to the plug.

So.jerZ-28

iTrader: (20)

i have seen cracked porcelian on the plugs that cause it too, and seen bent pushrods causing the same problem (mostly in ls motors though)