New cam question
10-24-2011, 09:28 PM
#1
Teching In
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Join Date: Oct 2011
Location: Cleveland East Side
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New cam question I have a 94 z28, 383 stroker kit and current cam is 230/236 @ 0.050. I bought the car this way, and the day I purchased the car it ran like crap and couldn't get the old owner to get it fixed.
I checked compression, 6 cylinders tested at 175psi, one at 80 and the last at 0psi. I Pulled off the intake while checking on the head gasket and discovered that one roller lifter's guts blew up, knocking off one pushrod, hitting the one next to it, twisting the adjacent lifter 90 degrees and in turn chewing up the cam.
I recovered all the metal from the broken lifter(the small retainer clip in the lifter was the part that broke). I put two lifters back in place of the broken ones just so I could do a compression test and the 2 cylinders have compression. Surprisingly the car did run and turn over, but it ran like crap so I turned it off and didn't push it.
I am looking for advice; I was informed this is a pretty big cam for my 94 z28 (lt1 5.7 fuel inj). I would like to make the car more reliable. I don't think I can use a stock cam for this application. What would be a good sized cam for this car that will work well with the stroker kit? My pushrods and roller lifters are ok, can I get away with a cam and lifter kit or do I have to go full valve train? Im working on a budget so any help or advice is appreciated. The current cam is a hydraulic comp cam. I have seen a lot of kits from summit that give you a roller cam with tappet hydraulic tappet lifters but not many with hydraulic roller lifters.
Last of all once the new cam is installed, lash set and everything is put back together can I fire up the car without risking any major damage to the engine, or is it imperative that it goes straight to the tune shop without ever starting the car or turning over the engine?
I checked compression, 6 cylinders tested at 175psi, one at 80 and the last at 0psi. I Pulled off the intake while checking on the head gasket and discovered that one roller lifter's guts blew up, knocking off one pushrod, hitting the one next to it, twisting the adjacent lifter 90 degrees and in turn chewing up the cam.
I recovered all the metal from the broken lifter(the small retainer clip in the lifter was the part that broke). I put two lifters back in place of the broken ones just so I could do a compression test and the 2 cylinders have compression. Surprisingly the car did run and turn over, but it ran like crap so I turned it off and didn't push it.
I am looking for advice; I was informed this is a pretty big cam for my 94 z28 (lt1 5.7 fuel inj). I would like to make the car more reliable. I don't think I can use a stock cam for this application. What would be a good sized cam for this car that will work well with the stroker kit? My pushrods and roller lifters are ok, can I get away with a cam and lifter kit or do I have to go full valve train? Im working on a budget so any help or advice is appreciated. The current cam is a hydraulic comp cam. I have seen a lot of kits from summit that give you a roller cam with tappet hydraulic tappet lifters but not many with hydraulic roller lifters.
Last of all once the new cam is installed, lash set and everything is put back together can I fire up the car without risking any major damage to the engine, or is it imperative that it goes straight to the tune shop without ever starting the car or turning over the engine?
10-24-2011, 09:51 PM
#3
On The Tree
A pretty popular cam for the 383 engine is the XFI 280 from Comp and that may be what you have. It is a good cam but is known to be hard on a valve train because of the ramp rate. If care isn't taken in spring selection, your exact problem will occur. The valves can float.
You can probably get away with a cam and lifters but I'm going to bet that your springs have bit the dust. You'll need to get the pressures checked for sure. The Patriot Gold springs are a good deal and have the seat and open pressures required to handle most streetable cams.....even the 280 XFI, if that's what you have.
You didn't say what kind of converter you have. That is going to determine which cam would best suit your needs. Since you're on a budget it's OK to match the cam to the converter.
With even a mild converter a decent cam that will make good power from under 2000 to around 6000 is the Lunati 60121. It's ground on a 112 so it should be real injection friendly. I've used it on several mildish daily driver builds and have been quite happy with it.
The stock LS7 lifters will probably be your best choice for economy and performance. Many people use them and they may be what you have. If so just replace the bad 2 lifters. Also, check the lifter bores for any signs of cracking. When lifters turn sideways nasty things can happen. Not always but it's worth checking.
Good luck with the repairs. ---Gunny---
You can probably get away with a cam and lifters but I'm going to bet that your springs have bit the dust. You'll need to get the pressures checked for sure. The Patriot Gold springs are a good deal and have the seat and open pressures required to handle most streetable cams.....even the 280 XFI, if that's what you have.
You didn't say what kind of converter you have. That is going to determine which cam would best suit your needs. Since you're on a budget it's OK to match the cam to the converter.
With even a mild converter a decent cam that will make good power from under 2000 to around 6000 is the Lunati 60121. It's ground on a 112 so it should be real injection friendly. I've used it on several mildish daily driver builds and have been quite happy with it.
The stock LS7 lifters will probably be your best choice for economy and performance. Many people use them and they may be what you have. If so just replace the bad 2 lifters. Also, check the lifter bores for any signs of cracking. When lifters turn sideways nasty things can happen. Not always but it's worth checking.
Good luck with the repairs. ---Gunny---
10-24-2011, 10:31 PM
#5
On The Tree
And the head work done to it is????????
Headers, basic stuff.....ya' know? 
10-25-2011, 02:26 AM
#7
