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Rockers too high on the studs?

General engine tech -- Drag Racing to Circle Track

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travis
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Rockers too high on the studs?

Post by travis » Sat Dec 28, 2019 10:39 am

I’m measuring for pushrod length and something seems off here. It doesn’t seem to matter what length I set my adjustable pushrod measuring tool at...each time the tip pattern is nice and tight even if it isn’t in the center. I ended up getting a nice tight sweep pattern in the center of the tip with my comp 7703 tester set at 8.000”, which seems too long for this combo. I’m using light test springs and am just taking out the lash, being careful not to compress the lifter plunger or move the valve while the cam is on the base circle. Set at 8.000”, it seems that the rockers end up too high on the stud. What am I doing wrong here?

351w decked to 9.480”, Promaxx 9175 heads, Jones small hydraulic roller, PBM 1.6 rockers, Howard’s good link bar lifters (not the cheap ones).

58461412-BDB7-40F6-9E40-F9DD9ADE9E8C.jpeg
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Re: Rockers too high on the studs?

Post by Walter R. Malik » Sat Dec 28, 2019 10:50 am

travis wrote:
Sat Dec 28, 2019 10:39 am
I’m measuring for pushrod length and something seems off here. It doesn’t seem to matter what length I set my adjustable pushrod measuring tool at...each time the tip pattern is nice and tight even if it isn’t in the center. I ended up getting a nice tight sweep pattern in the center of the tip with my comp 7703 tester set at 8.000”, which seems too long for this combo. I’m using light test springs and am just taking out the lash, being careful not to compress the lifter plunger or move the valve while the cam is on the base circle. Set at 8.000”, it seems that the rockers end up too high on the stud. What am I doing wrong here?

351w decked to 9.480”, Promaxx 9175 heads, Jones small hydraulic roller, PBM 1.6 rockers, Howard’s good link bar lifters (not the cheap ones).


58461412-BDB7-40F6-9E40-F9DD9ADE9E8C.jpeg
Tip wipe pattern width is not the "be all, end all" requirement for acceptable valve train geometry; especially with a rolling tip rocker arm.
To me, getting the pushrod tip to be near correct is much more important. Usually finding the best compromise is necessary.

Your photo looks like a shorter SBC rocker arm on a SBF head as many companies box them as if they are the same; simply number them different.
A small block Ford rocker is about the same dimensions as a Pontiac, though.
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travis
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Re: Rockers too high on the studs?

Post by travis » Sat Dec 28, 2019 11:16 am

Walter R. Malik wrote:
Sat Dec 28, 2019 10:50 am

Your photo looks like a shorter SBC rocker arm on a SBF head as many companies box them as if they are the same; simply number them different.
A small block Ford rocker is about the same dimensions as a Pontiac, though.
Hmmm...that is possible I guess. These rockers came on a set of D0OE’s I bought years ago...and they had sbc valves and springs in them.

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Re: Rockers too high on the studs?

Post by CGT » Sat Dec 28, 2019 11:20 am

Longer than stock valves? Does the pushrod hit the rocker body at max lift?
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Re: Rockers too high on the studs?

Post by BlitzA64 » Sat Dec 28, 2019 11:27 am

Straub Technologies youtube video "Push rod geometry for engines" is the way I have done it for 8,000 rpm+ engines with no valvetrain issues.

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Re: Rockers too high on the studs?

Post by Steve.k » Sat Dec 28, 2019 11:35 am

I did the straub video method which was very interesting. I compared the video with my own method which I have used over the years that has worked for me. My own method consisted of what I personally liked for valve sweep. In the end the Straub method in video netted me a .005 shorter pushrod which you can see is very close. I did go with the straub setup.

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Re: Rockers too high on the studs?

Post by Steve.k » Sat Dec 28, 2019 11:37 am

travis wrote:
Sat Dec 28, 2019 10:39 am
I’m measuring for pushrod length and something seems off here. It doesn’t seem to matter what length I set my adjustable pushrod measuring tool at...each time the tip pattern is nice and tight even if it isn’t in the center. I ended up getting a nice tight sweep pattern in the center of the tip with my comp 7703 tester set at 8.000”, which seems too long for this combo. I’m using light test springs and am just taking out the lash, being careful not to compress the lifter plunger or move the valve while the cam is on the base circle. Set at 8.000”, it seems that the rockers end up too high on the stud. What am I doing wrong here?

351w decked to 9.480”, Promaxx 9175 heads, Jones small hydraulic roller, PBM 1.6 rockers, Howard’s good link bar lifters (not the cheap ones).


58461412-BDB7-40F6-9E40-F9DD9ADE9E8C.jpeg
?
Travis it looks like in pic the pushrod rod is to long. Thus the high height. It looks like at full lift your pushrod will be very tight to rocker body?

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Re: Rockers too high on the studs?

Post by turbo camino » Sat Dec 28, 2019 11:55 am

Walter R. Malik wrote:
Sat Dec 28, 2019 10:50 am
Your photo looks like a shorter SBC rocker arm on a SBF head
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Re: Rockers too high on the studs?

Post by 1972ho » Sat Dec 28, 2019 12:16 pm

It even looks like the retainer is touching the rocker.

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Re: Rockers too high on the studs?

Post by jed » Sat Dec 28, 2019 1:50 pm

Looking at the picture the pushrods is not in the pushrods ball socket. In the picture the push rod needs to be more out board.

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Re: Rockers too high on the studs?

Post by turbo camino » Sat Dec 28, 2019 1:57 pm

That's just what a 1.6:1 SBC rocker looks like, short and stubby. If it were a proper SBF part the pivot to tip distance would be longer, and the pivot to pushrod cup distance would be longer, and the rocker would be much farther down on the stud when the pushrod length was correct.

The reason it looks so jacked up is because those aren't SBF rockers.
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Re: Rockers too high on the studs?

Post by 77cruiser » Sat Dec 28, 2019 3:48 pm

The roller tips look real big.
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Re: Rockers too high on the studs?

Post by PRH » Sat Dec 28, 2019 5:29 pm

I guess the next question for the SBF guys is...... what’s the preferred “correct” length stud mounted budget friendly rocker for that type of application?

Looks like what’s in the pic has a lot of extra weight hanging off the pushrod side.
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Re: Rockers too high on the studs?

Post by travis » Sat Dec 28, 2019 5:47 pm

The retainers aren’t hitting, and the pushrod IS in the pushrod socket on the rocker. There is another rocker right behind this one, so it kind of creates an optical delusion.

These may very well be 1.6 sbc rockers. I thought I had a set of 1.6 ratio sbc rockers to compare but I can’t seem to find them right now. I’m ordering some new rockers so we’ll see if that solves this problem

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Re: Rockers too high on the studs?

Post by PRH » Sat Dec 28, 2019 6:04 pm

Two things I really try and stay away from are Chinese rockers and dampers.
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