Hi all, I have an 85 Z28 with a stock Lb9 80,000 miles on clock as far as I can tell unmolested. Am currently replacing the lifters as they were seized, and valve guide seals as smokes briefly on startup. I got thinking if I'm this deep into it I might as well do the valve springs and fit 1.6 roller rockers.I need to know do I have to change my push rods as well and can anyone reccomend where to purchase this gear from thats reasonably priced in the US as I have to import it to New Zealand and need to be absolutely sure it will fit my engine ith no issues. Thanks in advance
Cheers Simon

 

Shouldn't have to unless they have cracking or excessive wear on the ends.

I would check local pricing ( or Australia ) 1st .
With exh rate and shipping cost from USA ( some places only use Fedex / UPS = Expensive ) there may be little difference landed

 

Stock springs should be available just about anywhere. As an "upgrade" buy a cheap set of eBay "Z28" springs. They are drop-in replacements for stock and give a bit more pressure, but nothing that would overwhelm a stock flat tappet cam or valvetrain components. Slightly more expensive would be a set of Comp 981 springs. Specs are just about identical to the eBay cheapies but they come from a known source and I haven't heard of any quality control issues with them (and have used quite a few sets myself).

1.6 rockers can be had in traditional aluminum body full-roller style (most expensive) or as stamped steel with roller tip (less expensive) or as just plain stamped steel with no roller at all (cheapest).

Please note that 1.6 ratio rockers all achieve their higher raio by moving the pushrod cup on the under side towards the rocker fulcrum slightly. Moves the pushrod closer, too. In some stock heads this can cause the pushrod to bind against the pushrod hole in the head. Bottoming out, basicially. Rarely an issue with aftermarket heads but stock ones that use the pushrod hole to also serve as the centering mechanism for the pushrod is where you need to keep an eye on this possibility.

 

Thanks for the info Damon.I see what you say about push rod clearance in slots in head, have to check them all once new rockers are in as there is not a lot room for the pushrods to move closer to the valves. I think I can get some Comp Cams Pro Magnum 1.6 rockers locally for a reasonable price. With these rockers I have to definately upgrade my springs but not so much as overstress my std LB9 cam and lifters- what I dont understand when researching valve spring specs is they all quote the lift the spring is capable of handling but is this lift value the cam lift only or is it the combined value cam plus rocker ratio? There is so much to choose from, I guess I should be looking at performance spring that will handle the extra valve speed of a1.6 rocker but not too stiff to look after the rest of the valve train, what spring pressures would you recommend?
Cheers Simon

 

which gasket dod you get for the intake manifold? Be sure to use some rtv when re-seating it. it's also a good time for a new icm since the distributor is out

 

Hi Z28NZ! I'm in Oz, I should imagine your parts sources would be similar to mine. First check local speed shops, like the equivalent of Robbos etc here - Chev parts etc here.

Next up there are bigger catalog warehouses like Rocket or Superplus, don't know NZ equivalents are though.

Or to get pretty much anything, go to Summit:

http://www.summitracing.com/

They will ship worldwide and they've got everything. Figure on paying about 70-80% of the value of your order in shipping, keep the items small, light and cheap. Ie don't buy heads or blocks this way! They have quite a few shipping options in their checkout section, none of them fun to pay! I have bought from them a few times, ship right to your door.

Or there's site sponsors here like Hawks Thirgden and Pro-Built Automatics who will ship outside the US.

I have noticed that local sources here charge around 180% of Summit prices for the same items, so it pretty much evens out.

If you change to 1.6 rr's, make sure you have enough retainer to seal clearance to handle the increased lift. Also make sure the springs chosen can handle the new lift before coil bind, and yes springs are rated for the valve lift - ie the cam lift times the rocker ratio.

Spring pressures for a stockish flat tappet should be about 90-110 lbs on the seat, 280-300 lbs on the nose.

 

Hi, gaskets are Felpro thru Northern Auto. Are the ICM's prone to failure? car was starting and running fine before I embarked on this work, or is this a timely inexpensive upgrade? Thanks for your thoughts

 

Hi Treefiddy thanks for the info. Have found a suitable spring kit locally priced okish which I will use. Will be getting injectors and a AFPR out of the US as there is nothing here and if I could get it, it would double the price! I have been purchasing motorcycle and car parts out of the US for3 years now and have found if you only purchase small items from suppliers that dont gouge you on the postage then there is some big savings to be made in NZ in the region of 50 to 100%. Yes you are right large items the freight would kill the purchase savings. You are in a better position than me as your dollar is considerably better than ours against the US! Hey! I'm originally from QLD but escaped along time ago!
Cheers Simon