Cam selection
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Joined: Aug 2011
Posts: 413
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From: Plaistow,NH
Car: 92 Camaro Z
Engine: LS 5.3 LM7
Transmission: Built TH350 with 3200 stall
Axle/Gears: 4th gen, 4.10
Cam selection
I recently got my rebuilt engine running but i was always having one problem or another getting it run right or make any power. It turned out a cam lobe was flattened. When the engine was assembled I think I tightened the rocker arms too much and flattened the lobe. Two of the pushrods were bent as well.
In any case I need help with my next cam selection. I don't believe my last cam was the right fit and may have contributed tk it's demise.
Here's what I have now
Sbc 350
906 vortec heads
Holley 750 carb
Exelbrock dual plane intake
Summit CD ignition
Hypereutectic flat top pistons
Comp cams 286h cam.
1.5 rockers
Comp cams beehive springs
4.10 gears
2800 stall
Built up 700r4 rated for 400hp
In any case I need help with my next cam selection. I don't believe my last cam was the right fit and may have contributed tk it's demise.
Here's what I have now
Sbc 350
906 vortec heads
Holley 750 carb
Exelbrock dual plane intake
Summit CD ignition
Hypereutectic flat top pistons
Comp cams 286h cam.
1.5 rockers
Comp cams beehive springs
4.10 gears
2800 stall
Built up 700r4 rated for 400hp
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Joined: Dec 2012
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Car: 1991 firebird
Engine: TBI 305 (built)
Transmission: T5
Axle/Gears: 4.10
Is this a flat tappet or roller ? Did u break the cam in at 2500 Rpm ? Use good break in oil with zddp ? ... If u wiped out a lobe the whole engine is gonna b full of metal shavings ! Might as well start over ..
Thread Starter
Joined: Aug 2011
Posts: 413
Likes: 1
From: Plaistow,NH
Car: 92 Camaro Z
Engine: LS 5.3 LM7
Transmission: Built TH350 with 3200 stall
Axle/Gears: 4th gen, 4.10
Re: Cam selection
Flat tappet. Hydraulic lifters.
The cam was already broken in. It was the only part I kept from the original block when I rebuilt it. So far I have ripped almost everything out of the way to get in there and take a look. I haven't seen any metal shavings in the lifter valley or anywhere else yet.
The cam was already broken in. It was the only part I kept from the original block when I rebuilt it. So far I have ripped almost everything out of the way to get in there and take a look. I haven't seen any metal shavings in the lifter valley or anywhere else yet.
Joined: Sep 2005
Posts: 27,866
Likes: 2,428
Car: Yes
Engine: Usually
Transmission: Sometimes
Axle/Gears: Behind me somewhere
Re: Cam selection
Drag a magnet through the places where oil pools up .... you will.
Worse yet, there's metal in the passages in the block. Always is when that happens.
The block needs to come apart and have rifle brushes run through every passage. The vat alone doesn't do it; metal doesn't dissolve in there.
Vortec heads need a cam with a bigger exh lobe than int. BADLY. That's what makes em so good; they moved the ports and that gives em all this great FLOW, but the exh port is the same sucky thing as has been on SBC heads since 1955. It needs all the help it can get.
Consider a roller cam this time; might seem like alotta $$$$; but then again, what you're dealing with now, isn't so cheeeeep either, and the odds of it happening again are pretty high. I'd suggest something along the lines of the Comp XR276HR.
Worse yet, there's metal in the passages in the block. Always is when that happens.
The block needs to come apart and have rifle brushes run through every passage. The vat alone doesn't do it; metal doesn't dissolve in there.
Vortec heads need a cam with a bigger exh lobe than int. BADLY. That's what makes em so good; they moved the ports and that gives em all this great FLOW, but the exh port is the same sucky thing as has been on SBC heads since 1955. It needs all the help it can get.
Consider a roller cam this time; might seem like alotta $$$$; but then again, what you're dealing with now, isn't so cheeeeep either, and the odds of it happening again are pretty high. I'd suggest something along the lines of the Comp XR276HR.
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Joined: Jul 2011
Posts: 2,529
Likes: 0
Re: Cam selection
Drag a magnet through the places where oil pools up .... you will.
Worse yet, there's metal in the passages in the block. Always is when that happens.
The block needs to come apart and have rifle brushes run through every passage. The vat alone doesn't do it; metal doesn't dissolve in there.
Vortec heads need a cam with a bigger exh lobe than int. BADLY. That's what makes em so good; they moved the ports and that gives em all this great FLOW, but the exh port is the same sucky thing as has been on SBC heads since 1955. It needs all the help it can get.
Consider a roller cam this time; might seem like alotta $$$$; but then again, what you're dealing with now, isn't so cheeeeep either, and the odds of it happening again are pretty high. I'd suggest something along the lines of the Comp XR276HR.
Worse yet, there's metal in the passages in the block. Always is when that happens.
The block needs to come apart and have rifle brushes run through every passage. The vat alone doesn't do it; metal doesn't dissolve in there.
Vortec heads need a cam with a bigger exh lobe than int. BADLY. That's what makes em so good; they moved the ports and that gives em all this great FLOW, but the exh port is the same sucky thing as has been on SBC heads since 1955. It needs all the help it can get.
Consider a roller cam this time; might seem like alotta $$$$; but then again, what you're dealing with now, isn't so cheeeeep either, and the odds of it happening again are pretty high. I'd suggest something along the lines of the Comp XR276HR.
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