Ok guys...

She's a 96 Lt1 Z28 with just north of 150k miles.

Prior to the build she ran great, running +/-8.9 at +/-80mph in the 1/8th mile @ Immokalee in SW Florida.

All I wanted was to bump the ET a tad and found a set of used Hooker LTs on the web for way less than retail and while the passenger side bolts slid right out, the driver side came up with three snapped bolts which turned into yanking the motor and a complete tear down...

As it stands now, as of last night the short block was completely boiled and rebuilt; honed cylinders, new bearings, polished crank, pistons reused but refurbished, new rings... Also the heads were boiled cleaned resurfaced and a three angle grind on the valves.

The Machine shop recommended an Erson cam and after a brief discussion said he'd get one with lifts just ove .500 and duration on the order of +210... the idea was to keep it within the existing stock tune on the PCM.

When I picked up the engine and cam, the grind was only .480 lift and <.210 duration... w/108 LSA . After agonizing I checked around found that while the grind was hotter than the stock 96 LT4 cam it was way short of the Hot Cam everyone talks about... I wanted hotter than the Hot Cam (within the bounds of good taste, of course) but was talked out of it, then given a much softer grind.

Inevitably, called CC, told them I wanted >/= 50 hp over stock and they suggested the 7-466-8 grind, @.050 218/570 224/565 -113- LSA with Part# 941-16 1.255 Hi-perf' valve springs, #750-16 1.250 retainers and #611-16 11/32 super locks.

I bought all that and replaced the Erson springs that the Machine shop had just put on.

But I used the new Erson Lifters, soaked them in oil and put 'em in and eagerly set on the 1.6 Comp Roller Rockers and the new Push rods...

Which is where the stress comes in; I bought stock replacement push rods; they're chromoly, but what I can't seem to get a straight answer on is: are they suitable for the new cam and 1.6 RRs? I went ahead and bolted down the intake but if they're not suitable, I'll yank it off; I'd rather do it now than after its back in the hole.

Also I'm concerned with the Comp Springs, they're considerably thicker than the ones that came with the Erson and when we were replacing them, noticed that they didn't "squish" as far down as the Ersons... I just read a thread in the "Advanced" section where a guy is having a trainwreck in his valve train and it sounded like to me that his cam was pushing against a valve train with insufficient "squish" on the lift. Which: I WANT TO AVOID!

Also... I've picked up the B&M Holeshot 2400 Stall Conv', which I expect will be throwing more pressure on the system than the stock config.

Anyone with experience in this that can give some advice?

Thanks,
OVA1

 

Pushrod length needs to be checked with everything bolted together. There is no "set" answer. With all that lift, the springs need to be checked for coil bind.

After you get it together, hopefully you plan to have it tuned. Trying "to keep it within the existing stock tune on the PCM" was not a good idea. Trying to do that with a cam ground on a 108LSA made the idea even badder. Even a stock engine will see 10-15HP with a simple mail-order tune. You will need at least a mail-order tune to have an engine that is streetable, and produces the power its capable of.

 

Whole thing is a trainwreck. The stock valvejob is good, not sure what condition it was in at 150K but I would likely still trust it over "billybob's machine shop" down the road.

I might have stuck with the Erson grind over that Comp one. When you call Comp the average guy will get someone completely clueless who does nothing more than read their online catalogue. The springs they sold you wont control that poor choice of a cam either and as Fred said do not even try modifying the engine without doing the computer too. He made a good point on coilbind too, stock installed height is roughly 1.700 the valvejob likely made that a little taller but seeing as coilbind is 1.100 and you are subtracting .570 lift from a theoretical 1.700 installed height things look dangerously close. Like I said though those springs wont control that cam anyway.

I know it is all bad news but would you rather hear it now or try and figure out why the engine self destructed later.

 

I'll bet that 108 number was not lobe sep but ILC meaning the centerline of the intake lobe of the cam.

Just assemble one cylinder up with the pushrods and rockers adjusted and watch the motion across the tip of the valve as you turn the motor by hand slowly (easy with the spark-plugs out.). If the rocker tip stays over the center 2/3s of the valve through the whole cycle then the pushrods will work OK. You also failed to mention if you were using guide plates, if you are make sure they position the rocker over the valve properly.

 

108 is a useable LSA especially at smaller duration like that. Matter of fact would be a whole lot closer to right than the 113 XFI garbage he got to replace it.

 

Thank you all for your responses...

Frankly, this is maddening... I called CC and double checked and they claim the springs will handle that cam... way beefier than the Erson springs, but as a rookie I am swimming in the black hole of ignorance on all of this. Frankly at this point I'll be lucky to avoid a divorce.


But thanks nonetheless for the input fellas.