360 stroked to a 408

[Mark8117]

Need some help I have a 78 block set up for a stroked 408.  I am using iron 340-x heads and a hydrolic roller lifters and roller rockers.  It seems like the pushrods geometry is off.  They are not in a straight line.

As anyone used a similar setup and did you have to do anything special with the heads. 

[jimynick]

Is it possible you've got TA heads? They have an offset pushrod to clear the ports. There's lots of real TA guys here who know that stuff inside and out, so hang in and see if they answer. If they ARE, they'll pay for a nice set of aluminum heads to replace them. 

[Mark8117]

I don't think they are the T/A heads.  It looks like the lifters may be to tall and the push rod is not able to sit in the pocket of the lifter.  If I force it in there then the push rod rests on hole in the head that it slides through.  If they were 3/8" or so shorter I think they should be ok? 

Does anyone have what the height of the lifters should be?  (Hydraulic roller)

[RzeroB]

Need some help I have a 78 block set up for a stroked 408.  I am using iron 340-x heads and a hydrolic roller lifters and roller rockers.  It seems like the pushrods geometry is off.  They are not in a straight line.  As anyone used a similar setup and did you have to do anything special with the heads.

Nothing lines up in a straight line with the LA engine's valve train geometry - it's goofy since the day it was born because of the 59 degree angle of the tappet bores (see my post #19 of this thread http://www.cuda-challenger.com/cc/index.php?topic=90335.msg899081#msg899081). The taller roller lifters and shorter pushrods only accentuate the geometry problem. So, first I would make sure that the aftermarket roller rockers are in fact for the X-head. As we know, it seems like there are as many different rockers as there are heads with each one designed to be used with a specific head. If that's good look at the pushrods. The pushrod will need to be shorter than stock due to the increased height of the lifter. The lifter manufacturer instructions may give you a hint at how long the pushrods need to be. Or you will need to mock up your engine and measure the length yourself with an adjustable pushrod. You will also need to use the thinner 5/16" pushrods as the stock diameter 3/8" pushrods will be too fat. Finally you will need to clearance the pushrod holes thru the heads with a die grinder (or have a machine shop do it for you).

[72bluNblu]

How did you set up your pushrod length? Are you using adjustable rockers?

If you just re-used the stock push rods, but went with roller lifters and rockers, the odds of them actually being the right length are astronomical.

[Mark8117]

I have an adjustable pushrods now that I borrowed from a friend and that is too long.  In my research I think Tom is right that I will have to grind out some clearence in the heads.

I need to order a short push rod to measure with.  I am using a set on Comp 1.6 adjustable rockers.

Thanks for the help, very appreciated......

[HP2]

It is very diicult to get mopar small block rocker geometry spot on . Like RzeroB said, the pushrod angles are rather extreme and combine that with fixed height pedastals for the rockers and it can be a bad combo.

So, if your talking about the angles of the pushrods:

  They are not in a straight line. 

...there is nothing you can do about it except switch to a newer block with different lifter angles.

If you are talking about centering the rocker arm tips on the valve tips, then you may need to either shim or machine the pedastals to put the shaft at the correct height to center the rocker tip. Once this is done, then you need to find the correct pushrod length to match up all your new components.

[Mark8117]

The alignement issue I am having is down at the lifter itself.  Everything lines up from the rockers down through the head.  It appears I need to open up the guide holes in the heads themselves to allow the pushrod to sit down in the cone of the plunger on the lifter.

[72bluNblu]

The alignement issue I am having is down at the lifter itself.  Everything lines up from the rockers down through the head.  It appears I need to open up the guide holes in the heads themselves to allow the pushrod to sit down in the cone of the plunger on the lifter.

A picture of what you're dealing with would be helpful. What are the casting #'s on the heads you have?

[RzeroB]

The alignement issue I am having is down at the lifter itself.  Everything lines up from the rockers down through the head.  It appears I need to open up the guide holes in the heads themselves to allow the pushrod to sit down in the cone of the plunger on the lifter.

The geometry would be better if it was a Magnum block with the shorter integral roller lifters. However, since you are using a '78 LA block you have the tall roller lifters with a link/tie bar between pairs which makes the geometry problem more complicated. Are you using the skinnier 5/16" pushrods (I don't remember you mentioning the thickness of the pushrods you are using)??. The 5/16" pushrods will give you a little more clearance than the 3/8" ones. You mentioned using adjustable pushrods. I would use them only to mock-up the valve-train to get the correct pushrod length. Once the correct length is determined I would order up a set of pushrods in that length. Some manufacturer probably already has them in the length and thickness that you need. The rest of the clearance you are going to have to create with a die grinder on the pushrod holes in the heads. Go slow and careful and check the clearance through the full range of motion of the valve-train.