97 SC Cobra

Hello C5 FI,

I developed a louder than normal tick a while back and I finally got around to pulling the heads off the car. Two of my lifters are trashed and one of them has made a nice track around the cam. They were in one piece but you could move the wheel up and down on both of them.
All the pushrods all look ok, no mushrooming. Valve stems look perfect as well.
I have the stock rockers with a comp trunion upgrade. To me the pockets look worn in a bit but I’m sure some wear in there is normal? They’re not hogged out or anything.
Anyway it’s a mast head & cam ECS 1500 car that makes around 15psi. Small cam 223/235 .600 ish cam 115lsa. I know everyone seems to be headed towards the shaft mount set ups but most of them are pretty expensive and I just don’t think my car warrants it. It’s a pretty standard street car.
With that being said, replace the stock rockers with stock rockers and another trunion upgrade or is there a better option?
Thanks fellas🍻

mykream

I would stick with the stock rockers. An option to stiffen up the valve train would be to run the BTR shaft mount setup, or at the very least, run some PRW billet rocker pedestals and a CHE trunion kit.

I would move to a link bar style lifter like a johnson 2116 or at least a 2110r if you still want to run lifter trays.

97 SC Cobra

Thanks for reply. I did get some Johnson linkbar 2116 lsr lifters so I’m set there. I did email BTR about their trunion kit as well. Maybe I’ll give them a call. I cannot change my valve covers I already had to grind them a bit because these heads are a bit taller than stockers and the alternator just clears.

C5 Pete

I’d just replace with OEM rockers with the trunion upgrade.

Best of success with your repairs.

97 SC Cobra

Thanks for chiming in Pete. Your car is insane btw. 🍻

mykream

Now know this, with the 2116 lifters, you are going to need to be more conscious with the pushrod length.. You can not just throw a set of 7.4s back in the car. You WILL need to measure each valve for length,

Watch this video and it will show you how to do it correctly if you do not know. Do NOT listen to anyone that says count the rocker bolt turns to find preload or any of that nonsense.

C5 Pete

Thanks!

97 SC Cobra

Thanks mykream, I’ve watched a lot of them but not that one. Mine are currently approximately 8.1”. I don’t really get the turn method myself. Seems easy enough to find zero lash and add your preload from there. I’ll make sure to do a couple on each bank just to be sure. I know these Johnson lifters only specify 0.030 +- 0.005.

Appreciate the replies

romandian

PRW billet rocker pedestrals: how are these better than stock? reinforced? how.

btw, nice vid. however i wonder what kind of calipers that are, because you need to shim regular ones up to the axis of the pushrod, right?

mykream

They are a machined piece of aluminum as opposed to the factory cast rocker stand. The factory piece has a huge amount of flex/deflection and when measuring for pushrods, you can see up to 10 thousandths difference from one end of the rail to the other, possibly more.

Just holding the two in your hand and trying to bend them is noticeable. I could easily break the factory piece in half by folding it over on itself. The PRW, probably would need to mount one end in a vice and really lean into it.

What do you mean what kind of calipers they are? They are standard calipers. Measure the pushrod end to end, give a company like Manton, Trend, etc a call and give them your end to end overall length that you need once you have measured and added the lifter preload to it.

Most pushrods when sold as a stocked length like the standard 7.4" rod, are measured at gauge length, which takes into account the the radius of the ends. So when you mic them end to end, you will usually find it is probably closer to 7.4-7.5X long

brentsz06

trunnion upgrade for the stockers. and verify pushrod length.

romandian

every time i measure pushrods i shim up the calipers to the height of the pushrod axis. i was just wondering how they can do it without visible shims.

10 thou difference in what? the height? no, it doesnt correspond to my measurements, the originals are equal up to the accuracy of a digital caliper. the stiffness of the assembly comes from the pedestrals, so the modulus of the rails is irrelevant. btw, youngs modulus of cast and extruded aluminum is nearly the same. and fracture toughness as well as ductility is of no concern in this case. on the contrary it might be argued that a more ductile material might be softer and thus less appropriate for the application.

so i wonder, is this part one of the completely unneccesary "improvements" or am i missing something?