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Old 10-29-2011, 06:43 PM
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dart head push rod clearence problem

I have a problem, of course... I have a set of dart platimum iron eagle heads that I have installed on my 355, all bolted on and was installing the studs and guild plates, I put in my push rods and BAM, the push rod hits the side of the head, this puts the roller rocker about 1/4 of the way off the valve tip, has any one ran into this problem ??? I am sure that I am not the only one to run smack head into this... do I grind the head alittle or do I need to get off set roller rockers? I also need to know about the geometry, the tips of the ones not hitting are just alittle off the center mark of the valve tip " forward" twards the outside of the engine. now I think they are to ride EXACTLY in the center of the tip. but the small amount? is this not the right push rod? thanks guys

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Old 10-29-2011, 08:57 PM
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Check the valve train geometry and it`ll tell you if you`ll end up having to grind anything.
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Old 10-29-2011, 09:10 PM
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well that was the reson for the question, the rockers are not on the tip of the valve, when I tried to move it for the correct geometry it hits the side of the push rod hole... and it seems to be only on the intake side of the center two on ether side of the engine. I have plenty of room under the rockers for the springs. and checked the push rod length and seems to be correct ( stock length) well I think so... the rocker is just forward of center on the tip. I am thinking that is ok??? I marked the tip with marker. and rotated the engine, and it marks just off center on the far side of tip.
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Old 10-30-2011, 07:06 AM
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You do know that they will be in different positions depending on what position the cam is in, say whether or not its trying to lift the valve.
You should turn the crank to get #1 on TDC between compression/power strokes.
Search for valve adjustment procedures.(you didn't say if you had a flat tappet, solid, hydraulic cam).
I'm guessing its a Chevy, so after adjusting #1 intake/exhaust rotate crank 90 degrees clockwise and adjust the valves on the next cylinder in the firing order(#8) (1,8,4,3,6,5,7,2).
See if things look a little more consistent.
ssmonty
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Old 10-30-2011, 09:05 AM
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Quote:
Originally Posted by jdsst1
I have a problem, of course... I have a set of dart platimum iron eagle heads that I have installed on my 355, all bolted on and was installing the studs and guild plates, I put in my push rods and BAM, the push rod hits the side of the head, this puts the roller rocker about 1/4 of the way off the valve tip, has any one ran into this problem ??? I am sure that I am not the only one to run smack head into this... do I grind the head alittle or do I need to get off set roller rockers? I also need to know about the geometry, the tips of the ones not hitting are just alittle off the center mark of the valve tip " forward" twards the outside of the engine. now I think they are to ride EXACTLY in the center of the tip. but the small amount? is this not the right push rod? thanks guys
The bigger intake volume heads can often use offset rockers and/or guides. The bigger the volume, the more propensity towards needing offset rockers there seems to be. So, my question to you would be, what intake volume heads do you have?

You may do well to avoid trying to hit the exact center of the valve tip w/the sweep of the roller- this is an oft talked about subject around here, and the consensus seems to be that the right length pushrod will give the narrowest sweep of the roller on the valve tip, and that's preferred over having it centered exactly.

In my experience it seems that when the roller is more-or-less centered that it will also have the narrowest sweep. But this might not hold true on all heads, and I'd be surprised if it did given all the differences there are in heads, pushrod lengths, rocker design, etc.

More on the subject HERE.

HERE is a list of valve train points to check.

Last edited by cobalt327; 10-30-2011 at 09:23 AM.
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Old 10-30-2011, 09:36 AM
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I found on my 400/408 this time around on my 230 Dart Iron eagle heads when i went back the push-rods were doing the same thing as yours (rubbing) not all of them and also noticed mine weren't riding on the valve tip correctly. And after i re-checked the Geometry and found i was like +250 to around +300 in length off.
And after determining this and ordering the proper length push-rods the don't rub anymore. Now i did the marker test to determine the proper length and it is in the center of the tip now, but i am going to re-check / do mine after reading what Mr Miller has posted on here and on his page just to make 100% sure that i have them at the best location for PERFORMANCE & WEAR). JMO

So making sure the Geometry is as close to or 100% correct is a very important procedure that need to be done and done in the correct manner if you want the combo to work properly together as a unit. JMO
Get a push-rod length checker and do it the correct way the first time.
Cole

Last edited by eloc431962; 10-30-2011 at 09:42 AM.
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Old 10-30-2011, 09:43 AM
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More on mid-lift rocker theory HERE.


Home made length checking adjustable pushrod.
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Old 10-30-2011, 11:02 AM
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ok... so I have a push rod length checker. and did the correct procedure on checking the length. and have that well worked out , my heads are 200 cc 2.055 int. 1.60 ex. 64 cc dart heads. the push rods on the intake side only , only on the center cylinders are hitting. this puts my rocker only 3/4 the way on the valve tip. I am thinking it will be ok to grind out the side of the runners , but am woundering if anyone else had to do this. Is this a common problem? why is this not on the notes from dart to watch for???? not cool to find AFTER you put the head bolts in and torque them down.
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Old 10-30-2011, 11:40 AM
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You using 5/16" pushrods?
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Old 10-30-2011, 11:58 AM
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There are some real experts on here, so take this as lightly. I have heard of people grinding the rockers with big lift cams? probably not a good idea.
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Old 10-30-2011, 12:41 PM
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yes I am using 5/16 pushrods. and I am not talking about grinding the rockers... the head where the pushrod goes through...the outside of the intake runners.
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Old 10-30-2011, 12:45 PM
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I would measure the thickness of the runner before doing alot of grinding, but it should work as I have done that before on the Dart IE. I generally use offset rockers on any high perf application nowdays,.
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Old 10-30-2011, 01:14 PM
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ya know, if I would of known that this was going to be a problem, I would of got off set rockers, I have looked all around and I have not found anything that says anything about this, or am I not looking in the right places? this would have been a good thing to know about ...BEFORE. sorry if I am going on about something that I should have known about, but I am on a learning curve.
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Old 10-30-2011, 02:48 PM
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And you may have to assemble and take it apart several times until its right. If its not right you will make junk out of you whole investment, so make sure its right. Are you using 1.6 rockers? because World heads say the guides must be modified for larger rockers. Not sure of the darts. I thought I saw a tool in Summit or Jegs just for the purpose of opening up those passages.
Make sure you have the right pushrods and geometry.
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Old 10-31-2011, 06:31 AM
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Quote:
Originally Posted by jdsst1
ya know, if I would of known that this was going to be a problem, I would of got off set rockers, I have looked all around and I have not found anything that says anything about this, or am I not looking in the right places? this would have been a good thing to know about ...BEFORE. sorry if I am going on about something that I should have known about, but I am on a learning curve.
The reason you're not hearing much about this problem is because it isn't a problem very often. But like w/anything mass produced, there can be tolerance stacking. When you consider the differences in the block castings and the head castings, problems are bound to crop up occasionally.

Why you? Can't say. Chances are the combination of the heads' tolerances and a misalignment of the lifter bores has caused the problem. This is why "mock ups" are done prior to final assembly. If it's just a few pushrods, I wouldn't hesitate to clearance for them as needed. Obviously attention has to be paid to the wall thickness where you are grinding, but unless it's off more than I think it is, this shouldn't be a problem.

Have you considered using adjustable guide plates, or even moving the guide plates you now have (the bolt holes are larger than the bolts, so the plates can be adjusted. And you can make them more so), or cutting your guide plates in two, and re welding them?

Good luck.

Last edited by cobalt327; 10-31-2011 at 06:37 AM.
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