cam went flat overnight? HELP

Mustang78 · Sep 9, 2007

So last night i went out for a 3 hour drive around to the local towns and had a good highway run with a modded supra(won 2 outta 3, he jumped on me hard), when i got home there were no unusual sounds or ticks. The not more than 5 hours later i jump in the car, hit the key and immediately i hear a loud ticking. So i shut it off, pop the valve covers to find about 6-8 random rockers had at least 1/8" of play before it touched the valve..i re-adjusted those few and put the VC back on, fire it up and it still ticks. so i say to hell with it and take my truck. Today i pull the valve covers off to find 4 loose rockers on the drivers side(all the poly lock nuts were tight every time i checked), so i tightened that side and the noise from that side is pretty much gone but i cant tell because the pass. side is ticking badly. So i pull the right valve cover to find at least 4 loose rockers, i adjust everything 1/2 turn past zero lash again. The only problem being that on #2 and #3 exhaust valves they wont go to zero lash, the nut just gets tight..i discover the rocker arm is at the bottom of it's travel and wont tighten up anymore. So i leave them 1/8 turn loose on those two rockers, and tighten all the poly locks back up. to no surprise it still ticks...the only thing i can think of that would cause the rockers to sit lower is either the rockers got squished, or the cam wore out...i have less than 2K miles on this full engine rebuild. I'd like to hear some opinions on the matter, and maybe a suggestion as to what tests i can do before pulling the motor, again..
EDIT: i am running scorpion rockers, a 351w, GT40 heads, and 8.350" pushrods

~Mark~

Mustang78 · Sep 9, 2007

sorry double post

Mustang78 · Sep 9, 2007

when i turn it over(ignition off) the starter spins fast for 1 cylinder, like one has much less compression than the rest...i took it for a short drive and now it has a missfire on 1 cylinder, if not 2...i just finished shaving the heads because of a leaky headgasket, i reset the timing to 12-14 degrees also. there was no pinging at all, 89 octane and it ran fine when parked...F'd up sparkplug maybe? i just replaced them with the gaskets, they are the V power type for a 94 cobra. Any help you can offer would be much appreciated, this post is mostly a vent but i would like some opinions before i set this biotch on fire

~Mark~

408gt91 · Sep 10, 2007

sounds like lifters,they may be sticking. ive seen that before at high rpms my friend and i were racing and he reved at 6,000rpm and he had a couple stick on him,but a couple days later they were fine,so we bled them and retightend the rockers.

as for the cylinders ,ide do a compression test.

Mustang78 · Sep 10, 2007

i could go for that, but they adjust fine..the pushrod is physically lower than before. I revved to about 5,300 yesterday, that was the highest this motor has been...I drove it for about 15min after that to get home then shut it off. I'm thinking possible bent pushrods/F'd up lifters, or bent valves and pushrods from the head shave and slightly thinner headgasket i used. I left the 2 problem cylinders 1/8-1/4 turn loose in hopes that a short drive would free up the stiky lifters but it didnt seem to work. Tomorrow i will do a compression test and check all pushrods, if that doesn't get me anywhere i will leave all lifters with no load on then overnight, maybe they'll free up. Thanks for the input i appreciate it

~Mark~

Mustang78 · Sep 10, 2007

If i have to pull the stupid intake again(30.00 gaskets special order) i will find a stealth for it first, and get some of those anti pump-up lifters they sell. i should be OK using new lifters on a used cam, right? i know you shouldent mix em up but i dont have many options here

~Mark~

91 HATCH · Sep 10, 2007

Do you have screw in studs or pressed in studs on the heads the pressed in ones can pull out with high spring tension.You probably have them way to tight and the valves aren't closing either

NKau · Sep 10, 2007

Mustang78 said:
the pushrod is physically lower than before

If you are absolutely sure about that, then it is either stuck lifters, flattened cam lobes, or possibley bent pushrods. I'm assuming this is a flat tappet cam, and not a roller?

smallstang393 · Sep 10, 2007

before we start giving out diag's lets get the info
what kind of cam is this and spec's pls
then we can see what is is and can go from there before we tell what may be wrong

had same thing happen on a flatt tappet cam with 560'ish lift and i broke it in with both springs on it and lasted 500 miles and flatted cam and then done a rebuild
broke in with single spring then added
center spring and done fine

Mustang78 · Sep 10, 2007

here is the cam: http://northernautoparts.com/ProductModelDetail.cfm?ProductModelId=1696
and the springs: http://northernautoparts.com/ProductModelDetail.cfm?ProductModelId=13790

I'm 99% sure the pushrod is lower than before, i am using trickflow pushrods that are .080" thick(1 piece). I'm pretty sure i have a few stuck lifters otherwise it would have happened while i was driving. The cam cant be flat because i am using the base circle to adjust the rockers, not the lobe itself..and last time i checked i've never seen a cam's base circle wear out. i've gotta do some tractor work today so i'll mess with it tonight, Thanks for any input, i hope i got this thing figured out, what a PITA

~Mark~

Mustang78 · Sep 10, 2007

also this is a flat tappet cam with screw in studs(studs are not backing out i checked). I did not overtighten(overadjust) the rockers, i simply adjusted for the slack that happened while sitting..and since i did that i bet 1 or more lifters free'd up and now it's losing compression on that cylinder, right? I dont think my heads lifted up either haha(ARP bolts torqued to 105 then 115 on the intake side)

~Mark~

Mustang78 · Sep 10, 2007

anyone have a story about stuck lifters? i'd like to hear how it happened and how it was fixed if possible, Thanks

~Mark~

Mustang78 · Sep 10, 2007

i pulled the intake and found 6 stuck lifters..the rest are very hard to compress(i cant do it by hand using a screwdriver in one end sitting upright on the bench). I have about 200 miles on the motor since i did the head gaskets, and when i did that i was careful to drain all the water out of the system first(i just changed the oil a few hundred miles before this) so i wouldent have to change the oil..it was normal color, not milky like it would be if there was water mixed in. So i put everything back together and did not change the oil, maybe that was my mistake? it's still in good shape but feels very thick. I used pennzoil 10-40wt and i'll change the oil again before i start the engine with new lifters, hopefully tomorrow or wednesday that will happen

~Mark~

Black1987Stang · Sep 11, 2007

I was going to say lifters also, mine has a lifter tap sometimes, sometimes its bad, sometimes its totally gone, sometimes when I change the oil it will go away or get worse, it's weird. The lifter's are like a year old too, since like half out of 16 of my old lifters went out on me at the same time it seemed like, it sounded like a mess and had soo little vacuum at idle i dont know how it did run. The new ones have been doing it for a while, I know which one it is but I don't feel like changing it. Glad to hear you got it figured out tho.

Mustang78 · Sep 11, 2007

yup, i put a torch on the old ones with the clip removed and they sprung apart..i checked out the surfaced for corrosion and there was some white staining on the plunger, probably from a little water in the oil..and all the lifters were extremely hard to compress, there wasnt much gunk in there but i guess that's all it takes

~Mark~

NKau · Sep 11, 2007

I've had good luck putting a pint of marvel mystery oil into the engine oil, running it until warm, and then changing the oil to clean out lifters. Always do this to the old grain trucks that have lifter tick after sitting for 9 months.

Mustang78 · Sep 12, 2007

i changed out the lifters and all is well, i dumped half a can of seafoam in my crankcase also, after i changed my oil...the old oil was VERY thick, like 90wt thick..i used 10-40wt pennzoil just a few hundred miles ago

~Mark~

NKau · Sep 12, 2007

Mustang78 said:
i changed out the lifters and all is well, i dumped half a can of seafoam in my crankcase also, after i changed my oil...the old oil was VERY thick, like 90wt thick..i used 10-40wt pennzoil just a few hundred miles ago

~Mark~

Good to hear.

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