have a 90 formula 5.0 5 speed.stocker except 3" cat back pipe with magnaflow muffler,high flow cat and high flow air intake.can I run a lt4 hot cam with out changing anything?like valve springs,intake or anything like that?.or better yet whats the max lift on the stock heads??

 

That would be a pretty nice cam for that motor, but the valve lift even with 1.5 rockers would be borderline on stock heads, as its around .480 or so IIRC. Would require some tuning and probably L98 or LT1 sized injectors as well.

 

How about on an L98...because im thinking of putting a LT4 hotcam in myself. But i have the L98, what rockers and valve springs should i run? Anything else i would need? I know ill need a tune but thats computer, i need to know what i can run on the engine. I want a nice daily 300hp lol =]


Its for the 1989.

 

If I get a chance I'll mock up some L98 heads (the iron 083's) in my shop tomorrow and post the measurements.
I'm trying to get the exact valve events for that cam in another thread here.
You wouldn't happen to have access to an actual cam-card for this camshaft would you?

 

Same things would apply for the L98, as its not really any different than the LB9 in the valvetrain area. Use the springs that come with the Hotcam set. Roller rockers would be a good idea too, as those springs are stiffer than the stock L98 springs, and the stamped rockers may or may not bind with the lift of the Hotcam. Make sure you actually check to see that the heads can handle the valve lift of the LT4 'stick before you start it.

 

Lift with 1.5 is like .492.Says it in the thread just above or below this one.
I would go ahead and do the supporting mods for the cam swap if I were you.You`re prolly gonna have to.

 

??

Max lift with stock heads and springs is around .470". You can use Manley 22410-16 springs and 23652-16 retainers with stock heads to get a max of about .525" lift.

But I wouldnt use that cam with stock heads. It'd be like trying to get a fire hose worth of water thru a straw. And yes it will require a custom chip. That cam is better suited to aftermarket heads that flow better.

I also dont recommend a cam swap on a stock engine. You have to remove all the intake and the front of the engine, that it makes no sense to put the stock stuff back on. Replace the stock stuff with better flowing aftermarket stuff at the same time. Then at least it would be worth it.

 

The results of my mock up testing are below.
I found that swapping to the 4.3 Vortec or Vortec V8 retainers gives a lot more retainer-to-guide clearance. The install height does decrease a little though so you'll have to measure what you actually get after the swap to determine spring compression to bind.


Install heights (with all stock gear)

416 Intake "stock": 1.707"
416 Exhaust "stock": 1.727"

083 Intake "stock": 1.712"
083 Exhaust "stock": 1.722"
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Retainer travel limits (with all stock gear)

416 Intake "stock": 0.481" (with 0.150" seal)
416 Exhaust "stock": 0.500" (with 0.120" seal)

083 Intake "stock": 0.452" (with 0.150" seal)
083 Exhaust "stock": 0.481" (with 0.120" seal)
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Install heights (stock valves) using retainers from the 4.3L chevy V6 (no oil shields)

416 Intake: 1.695"
416 Exhaust: 1.677"

083 Intake: 1.695"
083 Exhaust: 1.672"
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Retainer travel limits of stock valves using the 4.3 retainer (with 0.150" seal)

416 Intake: 0.567"
416 Exhaust: 0.590"

083 Intake: 0.546"
083 Exhaust: 0.550"

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