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Engine popping at high RPM.(5500-6400) Found the problem
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lun40119
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1967 Chevrolet Chevelle

PostPosted: Tue Jul 21, 2009 6:40 pm    Post subject: Reply with quote

How did you install a rocker arm incorrectly, and live to talk about it Twisted Evil Twisted Evil
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af2
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1933 Willys Coupe

PostPosted: Tue Jul 21, 2009 7:16 pm    Post subject: Reply with quote

This thread is pretty wierd? If everything checks good why is it popping at the dreaded ( valve float rpm) ?
My question is: An Honest answer needs to be! Does it go beyond that rpm now as we speak??
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lun40119
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1967 Chevrolet Chevelle

PostPosted: Tue Jul 21, 2009 7:29 pm    Post subject: Reply with quote

Thats funny. I had a guy tell me once that he had a broken plug wire on a chassis dyno, because it was down a shit ton of power, but he couldn't hear, or feel the one DEAD hole.
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squeeezer
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1991 Chevrolet Camaro

PostPosted: Tue Jul 21, 2009 9:08 pm    Post subject: Reply with quote

what the hell is goin on here secret






popcorn

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Ballaholic29414
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PostPosted: Tue Jul 21, 2009 11:50 pm    Post subject: Reply with quote

Well the bottom line is.

The exhaust valve on the number 2 cylinder wasnt opening up enough.

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lun40119
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1967 Chevrolet Chevelle

PostPosted: Wed Jul 22, 2009 1:02 am    Post subject: Reply with quote

Why, did you put it on the stud upside down????? I am friggen confused. If the exhaust valve wasn't opening up all the way I would guess you had a big problem fella..........Sounds like your ass dyno is broken!!!!!!!
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Ballaholic29414
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PostPosted: Wed Jul 22, 2009 2:24 am    Post subject: Reply with quote

Surprisingly they found 45hp and 45ft lbs of torque when I got it dyno tuned last month. My numbers looked pretty good too. I just cant wait to go to the track to see what kinda times the car will run now.

The stud wasnt upside down. the center part of the rocker that the stud goes through was upside down. My pops did that by accident and he noticed it when we pulled the valve cover off yesterday. He said he dont know how the hell he didnt notice that.

My 8th mile times were off by 1 tenth so hopefully finding that issue will put me where I needed to be. (meaning my times were 1 tenth off from the times the guy I bought the motor from was getting with it)

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clay
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1972 Chevrolet Nova

PostPosted: Wed Jul 22, 2009 6:04 am    Post subject: Reply with quote

I can't see that making a difference with the problem you are talking about. Here is my logic. If you installed the trunion upside down on the rocker arm, the only difference is that the nut won't have a nice flat surface to bear against. Now this could definately cause some reliability problems, but as long as you set valve lash in the normal manner, total valve lift will be the same either way. Now don't get me wrong, if this fixes your problem, I'm happy for you, and I'll file that in my weird stuff that happens mental file. Let us know. Clay
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I have done so much with so little for so long, I can now do anything with nothing.
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af2
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1933 Willys Coupe

PostPosted: Wed Jul 22, 2009 4:56 pm    Post subject: Reply with quote

I am still confused how having 2 threads V.S. 10 threads on the adjuster will change the ratio so much you have an exhaust that isn't opening? It won't happen.

If the springs were what they should be, you would have less threads left on the stud from pulling the 2 out when the valve was open and the rocker would be lying in the head.

With the setup you have you better have minimum #250 seat!
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Ballaholic29414
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PostPosted: Wed Jul 22, 2009 6:06 pm    Post subject: Reply with quote

Im not sure if that was the cause of the popping at high RPM, but I hope is was. It didnt start popping until after we pulled the heads off. So thats is why I am considering that rocker issue to be the solution. If its not fixed then ill get the valve springs checked.

It idles a lil better since we found that issue and adjusted the valves. The only way I can know if the issue is actually fixed is to take it to the track and that wont be to next week.

(a better idle coulda just been in my mind, but it did sound different after adjusting the valves and find the rocker issue)

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af2
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1933 Willys Coupe

PostPosted: Wed Jul 22, 2009 6:22 pm    Post subject: Reply with quote

Ballaholic29414 wrote:
Im not sure if that was the cause of the popping at high RPM, but I hope is was. It didnt start popping until after we pulled the heads off. So thats is why I am considering that rocker issue to be the solution. If its not fixed then ill get the valve springs checked.

It idles a lil better since we found that issue and adjusted the valves. The only way I can know if the issue is actually fixed is to take it to the track and that wont be to next week.

(a better idle coulda just been in my mind, but it did sound different after adjusting the valves and find the rocker issue)



Ok! We are way different.

I have to check VS pressure once in a while to rule out other causes.

That is #1 on my list and I have less than 50 passes on them.
A friend had 200+ passes on his 355 and was bitching about running 9.70's instead of 9.40's when I asked him what was the last time he checked V.S.? Short story he is running the 9.60 class with ease.
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Blown65
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1965 Chevrolet Malibu

PostPosted: Thu Jul 23, 2009 3:48 pm    Post subject: Valve Springs Reply with quote

We check our valve springs between rounds. Granted we run huge spring pressures but its easy. Get an on head valve spring checker. You don't really need to know the exact pressure as long as you can see if any one spring is going away or all are going down. Just make sure you keep good records.

2 cents
Corey

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af2
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1933 Willys Coupe

PostPosted: Thu Jul 23, 2009 5:08 pm    Post subject: Re: Valve Springs Reply with quote

Blown65 wrote:
We check our valve springs between rounds. Granted we run huge spring pressures but its easy. Get an on head valve spring checker. You don't really need to know the exact pressure as long as you can see if any one spring is going away or all are going down. Just make sure you keep good records.

2 cents
Corey


A good way to know the # is check the new spring on the Rimac tester then after it is installed see what the rocker mounted tester says.
That gives a pretty good starting point.
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10sec.et
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1969 Oldsmobile Cutlass

PostPosted: Thu Jul 23, 2009 6:25 pm    Post subject: Reply with quote

clay wrote:
I can't see that making a difference with the problem you are talking about. Here is my logic. If you installed the trunion upside down on the rocker arm, the only difference is that the nut won't have a nice flat surface to bear against. Now this could definately cause some reliability problems, but as long as you set valve lash in the normal manner, total valve lift will be the same either way. Now don't get me wrong, if this fixes your problem, I'm happy for you, and I'll file that in my weird stuff that happens mental file. Let us know. Clay
with the trunion upside down, you would not have the flat surface for the rocker nut to sit on making the nut stand up higher than the others. if, upon noticing this one particular rocker nut is taller than all the others, one were to assume its simply not tight enough and crank it down like the rest, it would hold the exhaust valve open and cause the poping at higher rpm.
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af2 wrote:
It seems we can look at our magical Balls and come up with a fix?

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lun40119
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Joined: 22 Oct 2008
Posts: 624
Location: Wisconsin
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1967 Chevrolet Chevelle

PostPosted: Thu Jul 23, 2009 6:46 pm    Post subject: Reply with quote

I would sure hope that "one" wouldn't just keep cranking on an adjusting nut, until the poly locks are equal. Even so, if the exhaust valve wasn't returning to the seat, he has more problems, than just a little pop at rpm. Not to mention the burnt valve. I was looking at some stud mounted stuff that I have in the shop the other day, and if you were to put them in with the trunnion upside down, I think all that would happen is the nut, or the trunnion would start to wear prematurely, and it would create lash. If was loose enough to effect the valve timing that much, wouldn't you hear it rattling????????????
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