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Old 09-20-2013, 07:21 PM
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Pushrod problems

I have a chevy 383 stroker with 230cc dart pro 1 heads, 1.6 comp cam rockers, 7.8000 pushrods, comp cam number 12-250-3, gross valve lift intake .507 and exhaust .510. My rockers are hitting the head studs, are my pushrods too short? Or do i need offset rockers? Im also having a problem with keeping the rockers centered on the valve stem, the rockers go off to the left and the right...why is it doing this? How do i fix these problems, please help!!!

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Old 09-20-2013, 08:46 PM
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Those heads should have come with push rod guide plates, are they in place? that's not much lift, did you do push rod alignment and check the length/pattern on the valve stem when installing? Are the 1.6 rocker arms roller rockers?
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Old 09-22-2013, 09:18 AM
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Yes the guide plates are in and they are roller rockers. No i have not checked the length or pattern of the pushrods, i am in the process of doing that but the pushrods dont seem to sit straight between the lifter and the rocker. Also, the rocker seems to go left and right on the valve stems. I have had the motor built by a shop a few years back, the motor sat for a little while before i used it and i had come faced with this problem with the rockers hitting the head studs while i was doing a valve adjustment. The pushrods that came with the motor are 7.8000, do i need the bigger pushrods? I appreciate your response and help thanks.
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Old 09-22-2013, 12:01 PM
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Quote:
Originally Posted by ritzbitz625 View Post
My rockers are hitting the head studs.
Use long-slot rocker arms.

Quote:
Originally Posted by ritzbitz625 View Post
Im also having a problem with keeping the rockers centered on the valve stem.
That's the job of the guide plates. Maybe you need to begin with adjustable plates.
Dart 27001410 Dart Pushrod Guideplates
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Old 09-22-2013, 12:42 PM
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Thanks for your advice! Could you possibly be able to get me the part number for the long slot rockers i need and whether i should use 1.5 rockers or the 1.6 rockers that i currently have? Here's my comp cam number 12-250-3. What size pushrods do i need or should i keep the 7.8000 ones? I also already have the adjustable guide plate the same one as the link.

Last edited by ritzbitz625; 09-22-2013 at 12:48 PM.
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Old 09-22-2013, 01:01 PM
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Quote:
Originally Posted by ritzbitz625 View Post
Thanks for your advice! Could you possibly be able to get me the part number for the long slot rockers i need and whether i should use 1.5 rockers or the 1.6 rockers that i currently have? Here's my comp cam number 12-250-3. What size pushrods do i need or should i keep the 7.8000 ones? I also already have the adjustable guide plate the same one as the link.
Personally, I wouldn't use an extreme energy flat tappet camshaft in the first place, much less use 1.6 rockers with it. I'd go to full-roller 1.5 rockers such as Scorpion rockers.
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Old 09-22-2013, 07:08 PM
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My i ask why u dont like to use extreme energy cams ? And i have a graddle for the rockers should i still use them?
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Old 09-22-2013, 08:22 PM
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Quote:
Originally Posted by ritzbitz625 View Post
My i ask why u dont like to use extreme energy cams ?
An internal combustion engine is an integrated compilation of parts that work together toward a common goal. Easy up, easy down flat tappet camshafts have been used for years by the OEM's and those who rebuild engines because they are cheap and will work in most applications if certain precautions are taken at pre-installation, installation and post-installation.

There is a quality of camshaft lobes known as hydraulic intensity. That's the rate at which the camshaft lobe interacts with the crown of the lifter to initiate lift. There is a point of lift per degree of rotation of the lobe beyond which the whole mess comes to a grinding halt and some of the camshaft grinders, CompCams in particular, have run the hydraulic intensity right up against the wall with their "Extreme Energy" grinds. Any more lift per degree of rotation of the cam could result in the crown of the lifter digging into the lobe and the game would be over. I dislike anything that's designed to run on the ragged edge if it's intended for a motor that should last for a while, like in a street or street/strip motor. Full tilt race motor? No problem. Balls to the wall is fine because of the inspection and replacement of parts on a regular basis. But a street driver does not need the extreme hydraulic intensity. It needs longevity with a less intense lift and seating of the valves in my opinion. For the street, I prefer a cam with a difference of advertised duration to 0.050" duration of at least 60 degrees. (for instance, 280 degrees advertised, 220 degrees @0.050").

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And i have a graddle for the rockers should i still use them?
Like the old Sergeant used to say, "smoke 'em if you got 'em".

Last edited by techinspector1; 09-22-2013 at 08:29 PM.
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Old 09-23-2013, 12:50 AM
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Quote:
Originally Posted by ritzbitz625 View Post
What size pushrods do i need or should i keep the 7.8000 ones?
You need to use a push rod checking tool, which one depends on the range you need to check.

http://www.summitracing.com/search?S...hecking%20tool
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Old 09-23-2013, 08:02 AM
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Quote:
Originally Posted by ritzbitz625 View Post
Yes the guide plates are in and they are roller rockers. No i have not checked the length or pattern of the pushrods, i am in the process of doing that but the pushrods dont seem to sit straight between the lifter and the rocker. Also, the rocker seems to go left and right on the valve stems. I have had the motor built by a shop a few years back, the motor sat for a little while before i used it and i had come faced with this problem with the rockers hitting the head studs while i was doing a valve adjustment. The pushrods that came with the motor are 7.8000, do i need the bigger pushrods? I appreciate your response and help thanks.
The Dart heads you have use +0.100" valves, IIRC. This usually means the p-rods need to be longer as well. The exact length can be determined easily; this is covered in the link, "Valve train geometry" below.

If you have roller rockers, the roller trunnion takes the place of a long slot in a stamped steel type rocker. All the roller tip rockers I know of are also 'long slot', but it's easy enough to check the clearance w/a paper clip inserted between the stud and rocker if you have rockers w/a slot.

Also it's important to have the lifter preload set correctly before assuming there's a problem. If the rocker nuts are too tight, this will throw off what you're seeing and it'll look bad when it may not be bad at all.

To check the pushrod length the checking lifter need to be either a solid lifter w/the same pushrod cup-to-foot length as the hydraulic lifters you're going to use, or stacked full of small washers or filled w/grease to make them un-compressable. Using a checking spring can make things easier, but isn't mandatory.

Most times the supplied pushrod guide plates will be all you need. This isn't always the case when you get into some of the off shore head castings, but w/your Dart heads you should be fine. That said, you still have to check the alignment along w/the other critical areas to be sure.

More info on setting up the valve train:

Valve train points to check
Valve train geometry
Valve spring installed height
Adjusting hydraulic lifters
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Old 09-23-2013, 08:19 AM
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I see not all Pro 1s have +0.100 length valves. Only the heads that came w/1.55" springs come w/the longer valves. But if the heads were bought bare and assembled later, they could be longer valves. If you're not sure, measure them.

The Comp XE284H cam is "lazy" when you compare the lift to the duration. I wonder why it's designated as being an XE cam, maybe there's a lot of lift early in the opening event. In any event, be sure the springs are up to the task- the cam redlines way on up there so it'll take a fair amount of spring pressure to control the valve train. Same thing goes for the pushrods- stock isn't gonna cut it. You may get by w/the stock OD, but the walls will need to be much thicker to stiffen them sufficiently. If it were me I'd be looking for a bigger p-rod- walls and OD.

If you chose 7/16" studs, you most likely won't need a stud girdle. If for some reason you got heads w/3/8" studs, you just might need the girdle.
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Old 09-23-2013, 11:00 AM
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Quote:
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All the roller tip rockers I know of are also 'long slot', but it's easy enough to check the clearance w/a paper clip inserted between the stud and rocker if you have rockers w/a slot.
Use a length of solder to do this. It'll mash down flat without causing damage.
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Old 09-23-2013, 02:08 PM
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I checked my push rod length with a checker and im caught between using 7.900 or 8.000 pushrods what do u think?
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Old 09-23-2013, 08:01 PM
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I checked my push rod length with a checker and im caught between using 7.900 or 8.000 pushrods what do u think?
Go w/the p-rod that gives you the narrowest sweep across the tip of the valve, as opposed to a centered- but wider- pattern. Centered and narrow is best, but if you have to choose between a centered and wide pattern or off center a bit but narrower, go w/the latter. Obviously, the rocker roller cannot ride off the edge of the valve tip at any point.
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Old 09-23-2013, 10:37 PM
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Okay understand im finding that its centered but wide why?
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