I am having some minor teething woes with my freshly rebuilt 304. Its making a valve train ticking noise and after replacing lifters and checking everything else I am convinced the noise is coming from the fact that it has original pressed steel rockers and bridges which may be too worn as well as pushing the limits of there intended use by Holden. Therefore I am looking at trying to fit a set of adjustable Yella Terra roller rockers which are apparently just a bolt on job, P/N: ST2033. Now before I bolt them on, I want to check a few things like spring coil bind and pushrod length to make sure I achieve correct rocker geometry. I am pretty comfortable with how to go about getting the right pushrod length (install checker spring, use adjustable pushrod etc) but I am after some guidance on spring coil bind.
My engine specs are as follows:
Holden 304 V8
Crane hydraulic camshaft, H286 with an advertised lift of 0.496" for both intake and exhaust at 1.6 rocker ratio. Recommended valve spring is part number 99848-16
Original cast iron heads (unsure on if they are pre or post pollution but I don't think this will make a difference)
Valve springs fitted are W1682-16 which I think are the same as the recommended part number 99848-16. Can anyone confirm this?
Valve spring part number 99848-16 has the following advertised characteristics:
Seat pressure 114lbs @ 1.7"
Open pressure 340lbs @ 1.2"
Spring coil bind occurs @ 1.153" therefore maximum allowable valve lift = 1.7 - 1.153 - 0.06 = 0.487"
So am I right in doing the following calculation for what the new valve lift would become with the YT RR:
Base cam lift = 0.496 / 1.6 = 0.31"
New valve lift = 0.31 x 1.65 = 0.512" which is greater than the maximum allowable valve lift for this spring
My question, is this approach correct? If so, what do I need to replace to get back into a safe operating range of the spring? Can I simply use a +0.05" retainer, effectively increasing the installed height of the spring? Or will this effect the spring seat pressure too much and cause other issues?
Anyones help on this one would be greatly appreciated