puzzle pieces

[old_phart]

I'm building a new engine (318) for my '67 Fury III
I picked up a set of RHS heads (20301 LA-X) and am having a difficulty matching up the valve train parts.
I have a set of 1.6 PRW bushed with roller tip rockers.
Here's what seems to be the problem:
The RHS heads use 318 magnum valves and springs, but the rockers hit the springs and don't clear the spring retainers.

The question is what size (dia.) valve springs do I need and/or do I need to come up with a set of beehive springs. I've seen some advertised, but they don't specify whether they are for an LA valve train or a magnum valve train.

 

[has2bmopar]

The factory installed valve spring height should be... I believe 1.650", some aftermarket heads have taller springs installed at 1.800", the diameter on these should be about 1.44"-1.46".

The Magnum heads do not have cast in stands for your rocker shaft, and use the GM style individual rockers, but I would just suggest comparing specs. to check the spring diameter and installed height as they may be the same on your RHS LA heads.

I think the issue you may be having is due to the 1.6 ratio rockers that move your pushrod closer to the spring and thus changing your pushrod length considerably. Some aftermarket heads are also taller than the originals, also gasket thickness, block decking, head planing etc, make several variables, therfore I would always wait until you are ready for final assembly to check pushrod length.

You will likely have to get an adjustable pushrod within your length range, (Trick Flow makes a decent one) put your cam on the baseline on one cylinder and check your length with no preload on your lifter and the adjustment screw threads just protruding slightly on the underside of your rocker.

From this, measure your adjusted pushrod to get custom length pushrods. I had Smith Brothers make my last set, and I was quite pleased with them. Also check your pushrod side clearance through the lift range for both valves on one cylinder with the springs and valves removed if it seems that the 1.6 rockers are going to make things run too close. You should have a minimum of .080"-.100" of clearance as pushrods will flex. When you adjust your rockers, I would put about .030" of preload on your lifters... (assuming that you have a hydraulic cam).

Another thing to check before final assembly when putting big valve heads on a 318 is that the valves may not not clear the smaller bore block.

 

[old_phart]

I haven't gotten to the pushrods, yet...but I do have an adjustable test pushrod for that step. The problem is before that step; the rockers actually rub against the springs, which are 1.44" O.D. and yes, the 1.8" height. This is why I ask do I need to find a set of beehive springs to give me the rocker arm space?

 

[has2bmopar]

I am building a 360 and will be assembling it this week. I ordered Edelbrock heads with the 1.80" spring height also. The rockers that I ordered are from Mancini Racing and are the bushed style having no roller bearings like Hughes. They are a Harland Sharpe body made in the U.S. for Mancini without the machining for the bearings or the anodizing. I have had 3 sets of Hughes also, and one set of the Harland Sharpe for big blocks.

I don't believe the Chinese parts are made by CNC equipment, or they just stole or copied the wrong parts that are only compatable with the stock height valve springs, and besides purity/strength issues that could haunt you in the future, this may be the source of your current problems.