High Rpm Power Loss After Switching Back To 1.6 Rockers

[Dave2000GT]

I had installed Crane 1.7 ratio roller rockers when I did my GT40p heads a while back. Problem is, even after re-checking the torque/install on them several times, I could never get them to be quiet, car always sounded like a loud sewing machine and I couldn't learn to 'accept' it.

So today I swapped back in the stock 1.6 stamped rockers. Torqued them all to 20 ft-lb. Car started fine, drives good, is quieter, and to my surprise seems to have a touch more low-end power. However, once I hit about 4k rpm at WOT, it falls flat.. then picks up.. then flat... Am I getting valve float or something ? The heads already had the springs replaced, and with the 1.7 rollers I could rev to 5500-6000 no problems. Any ideas what could be causing this ???

 

[fords2live]

Were they adjustable? As far as the flat spot @ wot is not valve float, it'll just flat fall on its face and never pick up. It's a fuel issue, replace your filter if you haven't. THEN Check your pressure too. And the 1.7s give you more lift which gives you more top end. More duration gives you bottom end and more LSA gives you more of both basically.

 

[barnett468]

I had installed Crane 1.7 ratio roller rockers when I did my GT40p heads a while back. Problem is, even after re-checking the torque/install on them several times, I could never get them to be quiet, car always sounded like a loud sewing machine and I couldn't learn to 'accept' it.

So today I swapped back in the stock 1.6 stamped rockers. Torqued them all to 20 ft-lb. Car started fine, drives good, is quieter, and to my surprise seems to have a touch more low-end power. However, once I hit about 4k rpm at WOT, it falls flat.. then picks up.. then flat... Am I getting valve float or something ? The heads already had the springs replaced, and with the 1.7 rollers I could rev to 5500-6000 no problems. Any ideas what could be causing this ???

what push rods are you using?

did you run it with the 1.6 previously?

sounds like might be a tuning/computer problem to me.

 

[fords2live]

what push rods are you using?

did you run it with the 1.6 previously?

sounds like might be a tuning/computer problem to me.

I'm sorry but it's not a computer/running issue. A computer will only do what it's told. Unless he tried tuning on it independently, without a package tune like handhelds give, there is nothing wrong with the tuning. I do not mean to step on anyone's toes, but that is just wrong advice. Pushrod length would definitely change if they were adjustable. He did say he was running the 1.6s previous as well.

 

[barnett468]

I'm sorry but it's not a computer/running issue. A computer will only do what it's told. Unless he tried tuning on it independently, without a package tune like handhelds give, there is nothing wrong with the tuning. I do not mean to step on anyone's toes, but that is just wrong advice. Pushrod length would definitely change if they were adjustable. He did say he was running the 1.6s previous as well.

it is not advice it is just a though and it is not "wrong".

why don't you simply tell him exactly what is causing his prob then since you sound like you know for sure what is not causing his problem.

 

[barnett468]

/QUOTE]

what is your valve lash/preload?

 

[fords2live]

it is not advice it is just a though and it is not "wrong".

why don't you simply tell him exactly what is causing his prob then since you sound like you know for sure what is not causing his problem.

So then please, tell me how this computer/tuning could be of cause?!

Now, if you ment pull your codes to see what the computer TELLS you what's wrong. Then that would be a valid suggestion.

 

[Gearbanger 101]

You sure you stabbed your distributor correctly when you reinstalled it? Improper ignition timing will cause an issue like you described.

 

[barnett468]

I had installed Crane 1.7 ratio roller rockers...

The heads already had the springs replaced, and with the 1.7 rollers I could rev to 5500-6000 no problems.

So today I swapped back in the stock 1.6 stamped rockers.

once I hit about 4k rpm at WOT, it falls flat.. then picks up.. then flat...

This is not an obvious sign of a mechanical problem but that doesn't mean it isn't.

if you are running a computer, i would check the codes.

some of the things this suggests is:

fuel shortage

electrical miss like a failing coil.

 

[fords2live]

I'm not going to sit here and argue with ignorance. You make no sense. I've learned that sometimes people are too closed minded to understand a point proven. One last time. .

Fuel shortage: Yes, still has nothing to do with computers or tuning after he said it ran great with the 1.7s other than the clattering.

Electrical miss?: Never heard of it.

Ignition miss: No, nothing he has said points to ignition miss, nor does he have any symptoms.

Bad coil: No, A bad coil will not be that consistent with failure.

 

[barnett468]

I'm not going to sit here and argue with ignorance. You make no sense. I've learned that sometimes people are too closed minded to understand a point proven. One last time. .

Fuel shortage: Yes, still has nothing to do with computers or tuning after he said it ran great with the 1.7s other than the clattering.

Electrical miss?: Never heard of it.

Ignition miss: No, nothing he has said points to ignition miss, nor does he have any symptoms.

Bad coil: No, A bad coil will not be that consistent with failure.

lol, you obviously have very little experience with cars.

you make statements claiming what you "think" [thinking is a strong word to use in your case] is definitely NOT causing the prob but you have absolutely no clue what is, lol.

you are also unnecessarily abrasive but carry on.

i also see that no one has "liked" any of your posts yet even though you have been here well over a year but that's no surprise to me cause it's kinda obvious why.

 

[fords2live]

Grow up. Seriously. You haven't even attempted to back up your theories. Your more worried about finding how many likes I have?..

 

[mikestang63]

 

[fords2live]

Am I wrong though?

 

[mikestang63]

Am I wrong though?

Not going to get in the middle of this piss match.

Barney is a troll that mostly googles crap and posts tons of wrong and/or states the obvious. He is hated on the Corral and sad to say he found his way here.

 

[Gearbanger 101]

 

[mikestang63]

Lol more like

 

[Dave2000GT]

what push rods are you using?

did you run it with the 1.6 previously?

sounds like might be a tuning/computer problem to me.

Using the stock pushrods. Like I said, did the Explorer heads/intake/1.7roller rocker swap, got it setup and running mint. The 1.7's didn't need any shims, torqued fine at about 1/2 after zero lash, switched back in the stock 1.6 rockers, I DIDN'T MEASURE this time, but assumed it would be the same, and just torqued down.
Could the Crane 1.7s and stock rockers sit at different heights ??

I really don't think it's fuel or tune, since neither changed, ran fine the day (and months) before, after rocker change it didn't.

 

[Dave2000GT]

Here's another question (hehe)... if/when I open up the valve covers again, I was considering putting the 1.7 rollers back on... but just on the exhaust side, leaving the stock rockers on the intake. Is this a great idea or not ?

 

[fords2live]

Great idea. People definitely do it. Always good to make sure you get everything out of the cylinder. But I'm thinking you might wanna go .05 bigger with the pushrods. So 6.3" rods, shim kits are always good to have if you don't. Definitely count your turns with the 1.6s first tho. If it's more than 1/2 get some pushrods.