tim burks

well guys , after lurking the forums for a bit, I decided to join up. im a complete noob to the ls engine and Im doing my first ls swap as we speak into my 87 s-10 blazer. im completely lost on how to select a cam for these engines and was looking to yall for help. I have a stock bottom end LQ4with the 9.4-1 comp dished pistons,l92 heads with .650 springs, gmpp carb intake and probably going with 780-800 cfm holley. truck weighs roughly 3400, got 3.73 gears, turbo350 with 3800 stall. gona be mostly a weekend driver with street and strip in mind. can yall point me in the right direction? was looking at the stock 454lsx cam but just don't know.

speedtigger

iTrader: (16)

Welcome to the forum Tim! I think you will find a lot of helpful people here willing to share their experience.

For your cam selection, it just depends on how involved you want to be in the process. If you are a scientist type and like to get into the details, we have a lot of great resources here. In fact, I am creating a thread sticky on this very topic:
https://ls1tech.com/forums/carburete...ft-thread.html
The post below is specifically geared for people who are trying to get a feel for camshaft selection.
https://ls1tech.com/forums/18356780-post2.html

If you would rather just have an expert create a cam specifically for your application, we have multiple great vendors here who can do just that. Here are a few:
Martin @ Tick Performance
Geoff @ Engine Power Systems (EPS)
Brian @ Brian Tooley Racing

Or, if you just want to share ideas with the members that is cool too. As for the specific cam that you listed, I think you will find that a poor match for what you are up to. That cam might not a bad camshaft in a 6 liter with good compression if you advance it 4 degrees, but even then it is going to want a 4000+ converter, 7200 RPM shifts and will require you to fly-cut valve reliefs into your pistons.

tim burks

thanks for the heads up on that cam. I don't wanna get into cutting the pistons, and want to keep my shift points around 6500. Ive called Brian tooley already, just waiting on the call back.

tim burks

comp recommends a 231/247 @ .050 with 617/624 lift on 113. hows that sound to yall? part number 54-469-11.

tim burks

now another comp cam rep suggested cam 54-459-11 specs are 231 intake 239 exhaust @ .050 with lift of .617 intake/.624 exhaust. I don't wanna get into cutting valve reliefs in the pistons. so which would yall choose?

speedtigger

iTrader: (16)

Is that intake single plane or dual plane?

tim burks

it is a single plane

Sales@Tick

iTrader: (3)

This is what I would suggest if you do not wish to fly-cut:

227/239 .638/.621 110+4

This would work well for a weekend driver with your vehicle weight, stall speed and rear gear ratio.

speedtigger

iTrader: (16)

The thing about virually any cam that Comp Cams is going to have in their catalog is that it was designed for the factory fuel injection intake manifold. Your single plane LSX manifold has much shorter runner, so the ideal valve timing for a given RPM range is different. In looking at the 231/239 113+4 cam's valve events (via this great online camshaft calculator)

IVO is 6.5 ° BTDC
IVC is 44.5 ° ABDC
EVO is 56.5 ° BBDC
EVC is 2.5 ° ATDC
Overlap is 9 °

Notice the events in red. Cam experts will tell you that the most important valve event is the IVC (intake valve close). For a single plane intake manifold this event must happen sooner. For a < 6500 RPM shift point, that will need to be about 40.5 degrees ABDC IVC or less according to the examples I have seen. The 44.5 degrees ABDC IVC in your 231/239 113+4 cam would make for a very lazy midrange and a cam that wanted to spin to 7200 RPM to find it's area of efficiency. So, for what you are doing, it would be a dog.

The other event that I have highlighted in red is the EVC (exhaust valve close). This particular valve event is often used to manage and adjust overlap. Single plane intake manifolds are inherently weaker in the low RPM and midrange power compared to a factory long runner EFI intake manifold. But, adding a reasonable amount of overlap can improve midrange power notably. So, stretching the exhaust valve close from the 2.5 ATDC listed above to 6 or 7 degrees ATDC will help achieve that needed overlap and bolster midrange and upper RPM power.

So, if you make those modifications, you end up with a cam like the one Martin suggested and likely similar to the one that Brian will recommend.

tim burks

thanks for saving me from buying the wrong cam. Martin, would that cam still make 550hp at the flywheel? Thats my goal.

Sales@Tick

iTrader: (3)

If it has good long tube headers and free flowing 3" exhaust it should. Square port headed motors with an aftermarket camshaft normally make 525-575hp at the crankshaft.