I realize theres no sure way to tell until you have the parts assembled and check the piston to valve clearance with some modeling clay, but can any of you experienced guys give me your best guess as to whether the pistons would require fly cutting with a 230/232 592/595 111 cam and 243 heads milled to 59cc, using the factory.053 thickness gasket?

 

anyone?

 

my guess is you would be safe.

 

I have AFR heads and I was told they locate the valves a little closer I did not have clearance. I do have a new cutter if you are interested PM me. (I went with new pistons that had reliefs in them)

 

I appreciate the offer, but Im not planning on getting into fly cutting the pistons on my mild street build. If it would be required, Ill just go with the 64cc heads

 

My advise to you is check and see for sure, but I had the same set up with 241 heads and no fly cutting needed.

 

agreed...Ill absolutely be checking regardless, but Id prefer to at least have a good idea ahead of time as Ill just avoid the 59cc heads completely if there is a good likelyhood that the pistons would have to be machined

 

Assuming you had stock 243s, couldn't you 'theoretically' check your current p2v clearance to know how much room you have now and then calculate how much cutting it would take to get to 59cc on 243s and see if on paper you're safe without fly cutting? If you have 241 heads, then you would also need to calculate the difference between stock 243s and 241s.

But you'd still need to check once the new heads are on to be safe.

 

well, the material removed is .006 per cc times 5cc reduction from 64 to 59 gives you about .030 of material. Im planning on measuring the current PTV clearance on the stock 243s, but Im not sure that you can simply subtract the .030 from the factory clearance to come up with the theoretical PTV clearance....I need to look into it further

 

I don't think you can just subtract like that and get the exact difference but it may get you close so you can decide if it's even worth finding out for sure.

 

yea Im sure theres more to it than that....my LS rebuild book says that PTV clearance should be .100 inch for the intake and .125 inch for the exhaust with a bare minimum of .080 and .100. I just got off the phone with the guys at Scoggin Dickey, who sell the 59cc 243 heads new, and they said that I "shouldn't" have any issues, but again, no guarantee until I get them and double check

 

Well I've flycut several motors. I have a couple questions for you.....

What is the centerline of the intake and exhaust ??

Who is the cam manuf ?? and why wouldn't they know the answer ??



Here is a simple run down of what you need to know.....
1) piston out of the hole ?? Probably like +.006"
2) lobe design to figure PTV @ TDC (Comp master catalog)
3) head gasket thickness ??
4) valve drop ?? The distance from the valve closed to the deck of the motor/head.


Flycutting can easily be accomplished while the motor is together.


Good luck with the project.......



Thanks..........and for the record, this cam looks tame enough for no flycut but depends on where you decide to install it.

 

Well, Ill try to answer as much of that as possible:

The cam is a comp cam and its an old MTI grind, otherwise known as their "V1" cam....that was before MTI went out of business a few years back. The cam has been installed in the car since 2008. I unfortunately did not do the install as I was deployed at the time so I dont know the specifics other than the grind and the springs used.

 

Do you have the cam card ?? Without the intake centerline it may not be as accurate.

To give you an idea, this cam would be a max cam without flycutting
234/238 .602"/.604" 113+1 w/EPS lobes.

I'll see if I can find you lobes in the comp master.


Thanks.........FYI, I've ran this cam without flycutting......231/234 .643"/.598" 111 LSA

 

Unfortunately the cam card, along with many other personal possessions, fell victim to one of many military moves

 

I looked them up, they are XE-R lobes.
The intake is .080" @ 106* CL or .065" @ 110* CL. x 1.7
And the exhaust is .083" @ 106* or .069" @ 110* CL. x 1.7

Are the heads off the car ??

.

 

the factory heads are currently on the car....Im trying to determine if these 59cc heads are worth buying tomorrow assuming they're in good shape when I go look at them....they only have 500 miles on them since new, so I dont anticipate any problems as long as fly cutting wont be required.

And thank you very much for the help

 

So lets just pick the 110* CL to figure with, I highly doubt your tighter than that.
So @ 110* CL your intake is at .065" x 1.7 = .1105" of lift @ the nearest point to the piston in the stroke.
So you know this.....
1) piston is +.006" out of the hole
2) head gasket is .053" minus the + .006" = .047" effective quench.
3) so when you look at the head tomorrow you need to measure from the deck to the "nearest" part of the valve (that will tell you your valve drop). Just use a machinist square and a dial caliper or a steel rule to measure the distance.

So recap, take your measurement tomorrow + .047" = your total area. Minus the minimum .080" = your total area available for valve travel. Then subtract it from your .1105" to see if a flycut is in your future.

Remember the intake valve chases the piston the the piston chases the exhaust valve.

Remember .100" exhaust and .080" intake are a minimum PTV for a street car.

Then do the same with the exhaust numbers @ 110*....

Post your measurements and I will help if you would like. I'm tired right now and the numbers are looking fuzzy....lol

Keep us posted.



Thanks........

 

LS, thanks very much for all the help, you've definitely gone above and beyond and I appreciate it. Ill keep you posted after I take a look at the heads

 

I just installed a 232°/234° XE-R cam in my LS1 with stock pistons and AFR 205 heads milled to 59cc. I measured ~.035" p-t-v clearance for my intake valve. My exhaust valve had .130" clearance, so it was fine. I bought a Lindy Tools in-head plunge cutter and notched all 8 pistons an extra .060" within 1½ hours. While I had the luxury of the engine being on a stand, it could easily be done in-car. Don't be intimidated by notching pistons. Pick the best parts for your build and then do the required work to make them work.