Squirts11

iTrader: (14)

Plans have changed! Hell, two weeks ago I was thinking of just stepping up to a bigger cam, but after buying a set of stock 243 heads, Katech rod bolts, and developing the courage to possibly flycut...here we are.

The plans are to have the heads ported (stock-size valves?) and milled a considerable amount (shooting for around 11:1 compression w/ stock MLS gaskets, btw we only have 91 octane in OK). Based off varying info I've found/heard, I wasn't sure if this was around 61cc or 59cc...

Anyway....Looking for some opinions of whether or not flycutting could optimize the potential setup I'm shooting for, as I wasn't sure whether or not my FTI 3600 stall, 3.73 gears, and ported 243 heads, etc, would compliment a cam big enough to require flycutting.

Adding the following (in addition to mods in sig):

1. FTI 3600 stall/cooler
2. Ported/milled 243 heads w/ stock MLS gaskets
3. Katech rod bolts
4. ls7 lifters/trays
5. Dual springs/pushrods

Possibly adding (if necessary/advised):

1. Racetronics 255 pump
2. Comp cams rocker arm trunion upgrade


Any cam ideas/specs you guys think might be ideal for this build would be greatly appreciated. Let's get cookin!

allngn_c5

iTrader: (3)

Flycutting merely adds piston to valve relief / clearance. It will also drop your compression slightly. Wouldn't worry to much about it weakening the piston unless whoever does the cutting gets wacky and goes too deep. 11 to 1 compression should be fine with 91 octane. Your tune will play a role in that though. 11.5 to 1 compression might be pushing the ability of the fuel to resist pre detonation and will limit how much timing you can run due to trying to prevent pre det *knock issues.

Best of luck.

01ssreda4

iTrader: (96)

What are you really looking to do with the car?? Remember going crazy on the mill will really limit your cam choices. What rpms are you gonna have your trans shift at? You dont need a cam thats building power past your shift point. Thats counter-productive.

Paint_It_Black

iTrader: (1)

I want to comment about the valves. Stay with the stock sized valves.

I do not see the point of anything larger than a 2.0 on a stock bottom end.

1) Opening the throat to 90% already puts the throat cross sectional area at around 2.47 inches. That is already almost too big for a stock bottom end as the throat SHOULD be your minimum csa.

2) If they are ls6 heads off a z06, you have sodium filled or hollow stems. The valves are as light as you can get, why move up to a heavy stainless steel valve?

3) If you DO put a 2.02 or 2.04 or 2.05 valve into the port, if you DO NOT open the throat up to match it, you are killing HP. People should ask supplies who offer the bigger valve if they open the throat to match the valve, then MEASURE IT when the do get them.

4) Even if you do open the throat to match a bigger valve, the coefficient of discharge needs to remain the same or increase with bigger valves, or else it isn't worth it either.

Squirts11

iTrader: (14)

As mentioned, it's my daily driver, but I would like to take a considerable step up from my current cam (in sig). It rarely sees the track, but the car is driven fairly hard from time to time.

With regard to milling limiting my cam choices, that's why I'm willing to flycut. Basically, I'm willing to do what it takes to have my cake (compression) and eat it too (larger cam). I would absolutely flycut if the optimal cam choice wouldn't fit without doing so.

While the addition of the Katech rod bolts are more of a longevity/reliability upgrade more than anything, I feel it would be wasteful to not take advantage of them and shift in the mid-upper 6k range.

01ssreda4

iTrader: (96)

These are two areas that seem most important to me. I would research some cam dynos and see which ones are starting to fall off by 66-6700. I wanna say something in the low 230s is gonna be a good one for you. And with only a 3600 converter, I wouldnt want to go any bigger then this as well.

Squirts11

iTrader: (14)

They're actually off a 5.3l engine. Stainless steel valves

SOMbitch

iTrader: (8)

I would recomend a GOOD VJ and a bowl blend. I have seen 243's pick up 20+cfm done right.

fatmat80

since the heads are off of a 5.3l i would definately get those ported and polished..give tesas speed a call they have had great results with there 5.3s and the ms3 cam..Good luck with your build!!!

SOMbitch

iTrader: (8)

They are 243's......That is what comes on the newer trucks.......

lemons12

iTrader: (71)

I think you would see a substantial (enough to justify the swap) from going from your 3600 to a 4000.. The quickest 60' I see out of 3600s usually is in the mid 1.6 range... With 4000s the average is 1.5s minimum.

Also if it were me I would be concentrating less and less on the cam selection and look into a nicer set of heads.

With that said (and since I don't think you want to do either one of those ) I will give my input on the cam. Reason being is it won't change your driving manners and THIS is where you make power in a setup!!!

Even with milling I don't think you can/should go with a big enough cam required to flycut. Main reason is your converter, second is your heads/gears.
I think something in the low low 230 range .600 112 is about as big as you should go. That will make enough power to carry well into what your shift points will be as well as not be too much cam for the converter.
What intake will you be going with? An ls6 won't cut it 6000+Rpms..

Nitroused383

iTrader: (10)

62cc's will give you 11:1 compression with .051" thick GM MLS gaskets. This will take .020" of milling and limit your cam selection by quite a bit with out fly cutting. My 224 cam with .020" milled 243 heads and GM MLS gaskets has right at .070" piston to valve clearance on the intake. For a daily driver and that converter look into something in the 224-230ish duration range.

Squirts11

iTrader: (14)

Regarding the 4k converter, I've never actually driven a stalled car, so I'd rather not go overboard before I even know what I'm getting into (I do have a free restall if I end up deciding to go larger down the road).

I do actually agree with you about the potential hazard of over-camming my converter, in essence, taking one step forward and two steps back. I have entertained that thought, and would definitely like to avoid that pitfall. Hopefully the end product won't be held back by such a crutch (whether it’s the converter, cam, etc).

Also, the ls6 intake/ported stock TB are just temporary, as it will most likely be a Fast 90/90 (minimum) by the end of the year.

I thought the .051 factory gaskets were graphite, and the MLS gaskets were .060? I would love that extra/cheap compression bump from the gasket (while improving quench), but I thought the MLS gaskets were recommended over the graphite style for performance builds?

lemons12

iTrader: (71)

You wouldn't ever tell the differen around town and normal every day driving between the two. WOT there would be a definite difference, especially with a decent sized cam.
You will definitely want to get a FAST setup.

Nitroused383

iTrader: (10)

Scoggin Dickey sells the GM MLS gaskets for $28 a pair. I have personally measured the MLS gaskets and they are .051" thick, its what's in my car, I would know. Lots of bad info on the net. .0065" / cc, 64.5-65 cc stock, .020" mill = 62cc in my setup, once again personally measured. I never mentioned graphite gaskets.



I did remove a tad bit out of the chambers, but not much at all.

Paint_It_Black

iTrader: (1)

I am still recommending my original suggestion.

Squirts11

iTrader: (14)

That's interesting, as I bought those exact gaskets from SDPC for $28, part # 12498544, and their site has them listed as .057-.058 thickness, not the .053 listed or the .051 you've measured.

Is this amount of variance common when considering "advertised" compressed head gasket thicknesses?

Yes, that EPS 230/238 is looking rather appealing...

Damian

iTrader: (89)

If you're looking at going with EPS, talk to Geoff about his 226/236 cam. I think that would fit the bill nicely and probably won't require flycutting depending on the ICL he uses.

With automatics, I typically don't like to go over 232 degrees of duration on either side but then again I use older Comp lobes for most of my stuff. They work just fine. Another thing I consider when building an automatic car, especially with a 3600 and 3:73's is, it doesn't need a big lumpy cam to go fast.

02*C5

iTrader: (1)

I ran a 232/238 600/600 109. I ran this with 59cc chambers and had to do no fly cutting w/ 2.02 intake valve and a 1.60 exhaust valve. I also used Cometic .040 gaskets.

Squirts11

iTrader: (14)

What heads? Normally, I wouldn't think that setup would provide adequete PTV clearance unless they were aftermarket castings (taller deck, sunk valves, etc).