PTV clearance questions
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Teching In
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PTV clearance questions I'm new to the whole engine building world and I recently bought myself a 2000 Camaro z28 m6. I've been thinking about slapping a cam in it. originally I wanted to go with texas speed's 224/228 cam, but now I think I want to go with their 233/239 cam. I was wondering if I will have any clearance issues with the 241 heads and if so would installing 243's help anything? I plan on getting some CNC ported 243's eventually either way
How are you picking cams? By specs or internet "knowledge"? Especially if your new I'd get with a cam guy and get one spec'd for your intended use. Having a dyno queen cam that makes great HP at 6,800 is a regret when you're bucking around town most of the time.
PTV should be checked with any decent sized cam. It's not the lift but duration and valve events that cause pistons and valves to meet violently. Maximum lift is when the piston is 3+" down the hole and doesn't come into play. Also one person using a combination and it works may not work for you if the timing of valve events is slightly different from a stretched chain, slightly different key slot or some other variable. We're talking 80 thousandths on an inch total clearance
PTV should be checked with any decent sized cam. It's not the lift but duration and valve events that cause pistons and valves to meet violently. Maximum lift is when the piston is 3+" down the hole and doesn't come into play. Also one person using a combination and it works may not work for you if the timing of valve events is slightly different from a stretched chain, slightly different key slot or some other variable. We're talking 80 thousandths on an inch total clearance
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Alright, it's somewhat of a summer dailyish type vehicle but I dont actually drive it everyday, it's a cruise car and I do some occasional street racing, I'm not so worried about gas mileage really but I figured with a good tune the car could be very drivable with that cam and I was planning on running a 112 lsa to drop the rpm band a bit
Something like the Tick SNS2, but custom, would be my choice with a 227/234 .614/.585 110+3 (LSL/XE lobes). That'll work well with stock type compression if you swap in 243s... which will boost your compression to 10.5:1.
When I was stock displacement LS1 I ran the Streetsweeper HT cam with a 111 lsa. I also have 3.91 gears but it was a torque monster that I tuned to near stock handling and idle and got 25 MPG highway. The right cam and careful tuning can have it all.
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So what's a good cam that is on the big side which will allow me to still retain low end torque along with causing no clearance issues with either 241s or 243s ported or not? I read a page on how to make the measurements and it just confused the hell out of me, if someone can simplify it for me that'd be great I'm trying to learn all I can so someday I can do a full build on this engine or possibly another LS
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"Easy way" is to take off the valve springs on #1, put checker (weak) springs on. Bring it up to TDC , put a dial micrometer on the valve tip, push the valve down until it hits the piston and see how much clearance you have. Repeat on other valve.
The other way is to pull the heads and put clay on the piston, install the old gasket and bolt up, turn the engine over once, pull the heads and see how thick the clay is after you carefully take it off without stretching.
The other way is to pull the heads and put clay on the piston, install the old gasket and bolt up, turn the engine over once, pull the heads and see how thick the clay is after you carefully take it off without stretching.
The real issue is the combo. It needs to work well with your intake, exhaust, heads, etc. if your mostly stock, don't go too big on the cam. Honestly, if you still have your stock intake and manifolds, hold off on the cam. I got that same advice from others on here and as I read up more and more I realize they are right. If the cam can't breathe, it'll be worse than a stock cam.
There is a sticky on here somewhere called "so you wanna make power" or close to that. You should read that thread before you do anything.
I'm on an iPad, so I can't get the link to paste right. The threads you should check out are
1. Cam guide sticky in this third gen LS1 section - top of the page authored by JRP
2. So you wanna go fast sticky in the newbie section - authored by Jaberwaki
1. Cam guide sticky in this third gen LS1 section - top of the page authored by JRP
2. So you wanna go fast sticky in the newbie section - authored by Jaberwaki
If you've got long tubes, you can handle a bit longer duration. I'd recommend sending your info to comp cams, eps, and tick performance to see what kind of recommendations they make. I bet they come in the 224-230 range on intake and 230-240 exhaust and 111-113 on the LSA.
just not hitting isn't the issue. its how close the valves are to the piston during rotation. For example under heat everything will expand a bit and you need to make sure when heat is applied there is ample clearance for expansion and hydrolic float of the valve and lifter combo. Just because they don't hit while turning it over doesn't mean they won't hit while turning 6k.
