Got a good one...AL heads + roller rockers = runs like crap.

[Mustang5L5]

Ok, slapped some Tri-state knock-off Aluminum cylinder heads on my buddies 5.0 today. Since they were stid mount we also bought some 1.6 Crane roller rockers for them.

Motor is an '85 short block with a TFS Stage 1 cam, MAF conversion, 24# injectors, Edelbrock Intake and other typical bolt ons....resting in an '88 LX.

We slapped the heads on no problem. Torqued down properly and everything. Everything went smoothly except we had to slow down for the roller rockers. (more on this later)

Got the engine fired up and found it would fire up and stall. Did this nonstop. Just a rev to 2000 and stall. After some time we found we can make the engine run by disconnecting the MAF meter. We'd unplug it and the engine would start and run, although it would lope slightly. I wouldn't call it running fine though.

If we plugged the MAF back in, the engine would stall.

Next we discovered we had ZERO vacuum. I pulled the hose off the line goingo to the vacuum tree and it was barely sucking when we managed to maintain idle. With it plugged in there was barely enough pressure to use the brakes to hold the car at idle. Also, not enough vacuum to even work the HVAC controls.

We called it a day after that.


Back to the roller rockers. The bacic gist of what i got was to rotate the engine to a location where both valves would be closed. This was pretty to do. I'd hand tighten the nut down til the pushrod had no play in it at all, and then i'd go 1 turn more to preload.

Now we'd find that while adjusting the other rockers, the ones we did first would "loosen up". There wouldn't be any up or down play, but we could wiggle them side to side where we couldn't before. After a few more tries at adjusting them we then found that the lifters had some play in them and would could compress slightly. SO for all we know they could have bled down.

Could we have a valve hanging open?

Motor is hard to turn over with a rachet, but what has me puzzled is that we have basically no vacuum.

So any ideas? We are gonna crack into it again Monday and i think we should re adjust the rockers.

 

[Mustang5L5]

Ok after searching around for an hour or so i want to say it has to do with the rockers.

They are Crane Enegizer series 1.6 rr's. Like i said before, we adjusted them a few times without realizing the lifters were bleeding down. We thought they were coming loose. Also, we used stock pushrods.

First thing i'm going to do is readjust the rockers and go from there. Hopefully i'll get a straight answer on pushrods before monday as well.

Would valves hanging slightly open cause a motor to have little vacuum at idle??

 

[Grn92LX]

Mike, stud mount rockers require hardened pushrods. Stockers aren't what you want to use. Also measure for length when you change them. Are you setting the rockers in the right order? Twist the adj nut til the pushrod first won't spin, then go another 1/4-1/2 turn.

Could be a rocker adjustment issue or a bad vacuum leak. My engine ran like garbage when I first swapped it in and got it running and the problem was a vacuum leak.

 

[TheBocSez]

When you adjust stud rockers, you should use the intake closing / Exhaust opening method.

Go cylinder by cylinder and rotate the engine in its normal rotation. Watch the rocker arm of the cylinder you are adjusting.

When the exhaust 1st starts to open, adjust the intake valve.

Rotate the engine again and when the intake valve completely opens and just starts to close, adjust the exhaust valve.

There are 2 methods I have heard of for the adjustment. 1st is tighten the lock nut slowly until you feel resistance in the pushrod. When you feel resistance, you are at zero lash. Turn the adjusting nut 1/2 to 3/4 turn and lock it down, you are done.

The second method I have heard of is to watch the rocker. when it 1st starts to push down on the valve, make your final adjustment with 1/2 - 3/4 turn.

Regarding pushrod length. I am having the same issue. The stock pushrods are too short. I ordered a set of Crane pushrods from Jegs that are .117 longer. The description states that they are for vehicles using the stock hydraulic roller lifters and Crane aluminum adjustable roller rockers.

The part number at Jegs is 270 36623-16

 

[TheBocSez]

Here is a link with a better description.

http://forums.stangnet.com/showthread.php?t=542361&highlight=adjusting+roller+rockers

 

[Mustang5L5]

Ok thanks, i think this may be the issue.


Back to the rocker adjustment. I was noticing that when i spun the engine until the exhaust valve started to open, the intake valve would still be slightly open. Do i still want to make the adjustment here or when the intake valve is fully closed??

 

[txstang84]

it's not the rockers that require the hardened pushrods, it's the guideplates-when stockers rub up against the plates they shed tiny metal flakes...

 

[txstang84]

here's crane cams link for adjustment...

http://www.cranecams.com/?show=faq&id=3

here's their link for cking pushrod length

http://www.cranecams.com/?show=faq&id=6

hope these help

 

[88_GT_5_oh]

Ok thanks, i think this may be the issue.


Back to the rocker adjustment. I was noticing that when i spun the engine until the exhaust valve started to open, the intake valve would still be slightly open. Do i still want to make the adjustment here or when the intake valve is fully closed??

make sure the vlave is fully closed..... it took me 3 times to get it right the first time i did mine, i kept having one or 2 rockers that would still "rattle" go slow and use the info that was provided above. once you feel slight resistance, go 3/4 of a turn more and lock them. thats how i got mine to work

Here is a link with a better description.

http://forums.stangnet.com/showthread.php?t=542361&highlight=adjusting+roller+rockers

YES! i made that thread last year and those replys are what helped me

 

[Mustang5L5]

Thanks guys i've been reading up on this all day and think i know that the problem is related to the valves.

We will have to get new pushrods and figure out what size we need for them.

Just to clarify one last time on the pushrod adjustment. I've read the same thing in other posts and juist want to make sure.

Adjusting the exhaust valve is easy because then the intake is almost closed, the exhaust valve is closed.

Now adjusting the intake valve, i often read to rotate the engine until the exhaust valve just begins to open. Now when the exhaust valve on this engine just begins to open, the intake valve is still somewhat open. Do i adjust here or do i continue until i see the intake valve fully closed?

That's the only part i'm confused on?

 

[txstang84]

hmmm, that's wierd if the exhaust valve is just beginning to open and your intake valve is still somewhat open you must be running a top fuel dragster cam, LOL jk

are you sure you don't have that the other way 'round? i.e., adjust the exhaust vavle just as the intake is coming open?

 

[Mustang5L5]

It's a Trick Flow Stage 1 cam...nothing too wild.

Looking at above picture, Intake is valve on right, exhaust on left?




Lol, i told my friend to stick to GT-40P's. Oh well

 

[bluevenom867]

Thats the slight valve over lap txstang84.

You turn the push rod with your fingers while tightening the rocker adjustment nut (poly lock) until you cant turn it any more with light pressure (i.e dont be putting pliers on it and saying it still turns,lol).Then give it a 1/4-1/2 turn.

I will say you need to turn the motor over to get the lifters to pump up befor adjusting them.

 

[txstang84]

...Adjusting the exhaust valve is easy because then the intake is almost closed, the exhaust valve is closed.

Now adjusting the intake valve, i often read to rotate the engine until the exhaust valve just begins to open. Now when the exhaust valve on this engine just begins to open, the intake valve is still somewhat open. Do i adjust here or do i continue until i see the intake valve fully closed?

That's the only part i'm confused on?

yes, you are correct about valve placement, exh on the left, intake on the right...

yea, I know what overlap is-that cam should have about 70* of it, but the way I was reading it was; to adjust the intake valve, wait until the exhaust "starts" to open...when the exhaust valve is starting to open the intake is still at least quite a ways from being open, as the exhaust is only beginning to open, which means the engine is coming away from power stroke into exhaust stroke, now when the exhaust valve is starting to close, ok, I'll believe that...

but if your adjusting the exhaust as the intake is beginning to open, then yes, the exhaust will still be slightly open for several crank degrees

besides, that's what crane cams says about adjusting them... to adjust intake, wait until exhaust valve begins to open and it's always worked for me...

 

[Mustang5L5]

but the way I was reading it was; to adjust the intake valve, wait until the exhaust "starts" to open...when the exhaust valve is starting to open the intake is still at least quite a ways from being open, as the exhaust is only beginning to open, which means the engine is coming away from power stroke into exhaust stroke, now when the exhaust valve is starting to close, ok, I'll believe that...

But that's the thing, when i rotate the engine open and the exhaust valve just "starts" to open, the intake valve is not quite closed yet. It's still slightly open. Should i adjust here, or should i continue until the intake valve is completely closed before adjusting?

Reason i ask is because when the intake valve closes, the exhaust valve isn't *just* starting to open, it has been open. This is the part that's confusing me as i am unsure if they purposly want me to adjust with the intake slightly open or should i ignore the directions, rotate until the intake closes and adjust?

I just want to be 100% sure before my friend tries this again tomorrow ( i won't be there until later)

 

[txstang84]

Dude, are you rotating the engine clockwise or counterclockwise? if, when the intake valve is closed the exhaust is already opening, or open, that tells me you're rotating the engine backwards...

 

[Mustang5L5]

Ugh, we spun it backwards...don't ask how that happened and i can't beleive i didn't catch that at the time

Ok i think I have this all squared away now. I wish i had a chance to do this investigating beforehand as that's how i like to do projects, but like i said before, i was just assisting in this, and i took it upon myself to do my own research on SN

 

[txstang84]

LOL-cool deal, I was just making sure I wasn't going crazy...

 

[Mustang5L5]

Haha, with all the stuff we were trying to check and clearance beforehand you'd think at least 1 of 3 guys used to working on 5.0's would have caught that we were spinning the motor in the wrong direction!!

 

[txstang84]

well, if everyone's in the same frame of mind, and maybe even frustrated, simple mistakes often happen-I've been prone to it as well...after we all sit down, have a beer, and talk about something else for awhile, we usually get our wits about us and figure out what the problem is...