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I spoke with Bryan Tooley today and I asked him how much I could mill my heads using his Btr stage 3 cam, 231/242 112+. He said I could go .025 and still have ptv clearance with stage 3. Said he's seen this combo plenty of times at his old cylinder head shop.
He said the ptv difference between the stage 3 and stage 4 is .025 and that you can not mill 243 heads with the stage 4 235/242 111+3
He also said the Intake centerline largely affects how much you can mill your heads.
The 232/240 just might not make it with heads milled .025 (im assuming) i definately want to mill .020-.030 to try and get close to 11.5:1 compression
You think a 228/236 110+2 will clear a .030 mill? If so, I think I'm gonna go with this...as it has 12 degrees overlap and theoretically should give great low end torque and allow a big bump in compression.
Some are more brave than others when it comes to pushing the limits of valve clearance. I have told you what the actual valve clearances are with different cams in previous posts. I have also shared what I consider to be safe.
If you want the additional compression and a cam with some thump, here is what I consider to be a strong performing safe compromise:
10 degrees of overlap with the right lobe centers for maximum valve clearance and good compression from milling the heads .020".
This combo will have the idle you want, a stout compression ratio, great torque in the mid-range and will behave better than the combos with 16 degrees of overlap.
This will give you an idea of what it might idle like:
That vette sounds wicked! 230/238 112 sounds perfect. Is there any way you could advance it or a slightly lower lsa with .020 mill? Or is that it 230/238 112.
I wish i could download that cam timer! I use the wallace racing mill calculator and it says that with a .020 mill, my compression would be 11.28:1. Is that about right?
I think we've got it narrowed down to the cam I'm going to order, just seeing if it can be tweaked a hair...or not.
That vette sounds wicked! 230/238 112 sounds perfect. Is there any way you could advance it or a slightly lower lsa with .020 mill? Or is that it 230/238 112.
I wish i could download that cam timer! I use the wallace racing mill calculator and it says that with a .020 mill, my compression would be 11.28:1. Is that about right?
I think we've got it narrowed down to the cam I'm going to order, just seeing if it can be tweaked a hair...or not.
The combination of camshaft and compression ratio that I came up with above is a balance. If you narrow the LSA or advance the camshaft more, you would have to mill the heads less in order to maintain the same piston-to-valve clearance.
If you want, I can send you an excel spreadsheet that will calculate the valve events for you like the Cam Motion Cam Timer. Just PM me your email address and I will send you the file.
I was looking at that cam timer and its a 230/238 with 112 and 3 degrees advance.
So is that a 230/238 112+3 ?
Yes. That is it. You can order this cam under grind number: XA230/365-238/355-112+3
Originally Posted by Fullblast
I believe that compression ratio is 11.32 for a .020 mill. How do you come up with that? Is it the dome relief of -2.0 ?
The -2 CCs is for the ring land area around the circumference of the top of the piston. Most people overlook this. My calculations above come out to 11.32:1 when milling .020".
Do you have your heart set on a custom cam? A popular YouTube car reviewer drove an LS2 GTO with ported 243s, Vengeance VRX5 off the shelf cam, and supporting mods/bolt ons that made 495 rwhp and seemed quite streetable. This cam is a known performer in daily drivers.
Do you have yokmmpur heart set on a custom cam? A popular YouTube car reviewer drove an LS2 GTO with ported 243s, Vengeance VRX5 off the shelf cam, and supporting mods/bolt ons that made 495 rwhp and seemed quite streetable. This cam is a known performer in daily drivers.
I'm set on milling my heads to increase compression and I need a streetable cam that keeps my low end torque and under the curve power and ...has a nice chop to it.
The Vrx5 is 236/238 113+2 That has 10.5 overlap....with a loss in low end torque and a bump in top end and peak horsepower. Plus I can't mill the heads with that cam. I would also have to change my 3.42 gears to compensate.
A 230/238 112+3 will have more low end grunt and the power will come in sooner than the Vrx5 and it has 10 degress overlap as well.
My 228/232 112 is a great torque and midrange cam but I want a bit more chop and near the same driveability.
I pulled my cam today and a lifter got stuck and scarred up a lobe on my 228/232 112 cam. So I definitely need another one.
Not trying to beat a dead horse here....but I sent the heads to the shop and they're being milled .030. I want at least 11.5:1 compression. And since i need shorter pushrods...I may as well.go all out.
I dont think.the 230/238 112+3 cam will work with a .030 mill.
I really want to keep my punchiness and midrange....so my tuner said a 228/228 or 228/232 is my best bet and he said he could make that cam chop hard with his tune. But i want more overlap...
Will a 228/236 111+ 3 work with a .030 mill?
Since it has 10 degrees overlap....will it sound the same as a 230/238 112?
Your not beating a dead horse if it is your car. Now is the time to make sure you get exactly what you want.
The challenge in this case is that overlap vs compression is limited when using stock pistons that do not have valve reliefs. The reason is that overlap happens when the piston is at or near top dead center. This means that as you mill your heads, the IVO and EVC valve events, and consequently overlap, must be reduced to maintain the same valve clearance that you enjoyed with less milling.
So, now you are going to end up with 228/236 113+3. This will have 6 degrees of overlap. It will still lope, but not as much as the 230/238 on 112.
As you an see, unless you are willing to either fly-cut your existing pistons or put in a forged piston with valve reliefs, this is a game of sacrifice. If you mill the extra .010" to go from 11.3:1 to 11.5:1 you give up room for about 4 degrees of additional overlap.
Pick your poison.
Now, with all of this said, if it were mine, after the heads are milled and installed, I would measure the valve drop to be absolutely sure of how much clearance I had before ordering the camshaft. This is just a good way to eliminate variables that could cause you problems or stress.
Would 228/236 111+ 3 with 10 degrees overlap work with a .020 mill? Or does it need 111.5 or 112 lsa?
That sounds like the perfect grind for me if it will fit.
My last cam had 6 degrees overlap....so it may sound similar to 228/236 113+3 if I am not mistaken
The 228/236 111 +3 should fit with .020" milled. It would be slightly "torqueyer" (if that is a word LOL) than the 230/238 112+3 but I would not choose that. Closing the intake valve that soon on pump gas with 11.3:1 might start to get a bit fussy and give you some spark knock at low RPM. This is especially a consideration in a car with a manual transmission. I think you will find that a slight later IVC will still give you plenty of torque in the LS2 at that compression ratio. I am not saying you are, but don't worry about that lobe center angle number. It is a relative number and can be very misleading. If you absoulutely must have a camshaft on a 111 lobe separation angle, you could go 230/234 on 111+2 and it will do most everything you want.
Last edited by speedtigger; 06-27-2016 at 01:11 PM.
I spoke with Pat G and he told me he could tune a 232/240 11+3 to where it drives with no bucking or surging...but since I'm milling the heads .020 i either have to go with the 230/238 112+3 or the 230/234 111+2. Will the tighter lsa cam bring the power in at a lower rpm? Will that cam provide more torque?
Also What length pushrods will I need with milling the heads .020? I have 7.40s now. Thanks
I spoke with Pat G and he told me he could tune a 232/240 11+3 to where it drives with no bucking or surging...but since I'm milling the heads .020 i either have to go with the 230/238 112+3 or the 230/234 111+2. Will the tighter lsa cam bring the power in at a lower rpm? Will that cam provide more torque?
Also What length pushrods will I need with milling the heads .020? I have 7.40s now. Thanks
Actually, these two camshaft are identical with the exception of the exhaust valve open.
I think would find that you would not be able to tell the difference between the two. On a dyno you would likely see that the 230/238 112+3 camshaft would make slightly more power at higher RPM than the 230/234 111+2. And maybe, the 230/234 111 might have slightly better very low speed torque. But, any difference between the two would be so small that you would not notice in driving. So, if you just like the way the numbers sound, you could get the 230/234 111+2.
I would measure for pushrod length with the pushrod measuring tool after he engine is assembled. It will save you grief. 5/16" diameter, .080" wall are fine for your application.
For lifters, I prefer the Johnson lifters, but I realize they are more expensive. Either if the other two should be fine for your application.
Since I'm milling the 243 heads .020, what length pushrods will I need now? I was told I will need shorter ones.
I'm using stock rockers with Smith Bros trunion upgrade.
Also, I haven't made up my mind whether to go with Ls7 lifters or the Morel street series.
Also...is there a big advantage to pushrods thicker than 5/16?
I'm using a 230/238 112+3 cam.
I'm using a Pat G spec'd Cam Motion 230/238 626 lift 113+3 110 intake centerline with 8 degrees of overlap. The heads will be a set of LS3 ported and milled .030"(64.8cc) with .040' cometic gaskets. I will have to flycut the pistons and use 7.350" pushrods. My car is a 06 GTO M6. Hopefully this combination will haul a**. All parts are bought, need to ship heads out to get worked. My schedule is to have this completed in October.
I lost my old phone and had my email and password to the site saved and i cant log into my Fullblast account. Can a moderator help me get back into it? I can not access my email that ls1tech was linked to.
On another note....I got a sweet deal on a Tick Sns stage 3 cam motion cam. 235/243 111+2.
I had to hold off on the build for a few months but i have most of my parts now. I got tick 7.40 pushrods and a melling HV oil pump. Either way, i will check with a pushrod checker once assembled, just wondering if anybody has used this combo without flycutting
My 243 heads are still sitting at the shop and was wondering is there any way i can mill the heads .005 or .010 and use the sns 3 cam and keep my 7.40 rods
Eli at tick told me that should not be a problem, but they have never actually measured the valve clearance for that cam, but he said their Polluter cam 239/244 had .050 clearance. I wasnt sure if that was the ls1 polluter with 112 lsa vs the ls2 with 111 lsa though.
Last edited by Fullblast1; 12-04-2016 at 10:25 PM.
06-15-2016, 08:32 PM
