mtt14

iTrader: (1)

Well guys I have a stock ls1 I'm basically reringing and adding arp rod bolts. Now the cam I picked up from a member on here is a 235/243 .647 .623 111+3. I know it's a little big but it's basically an In between for the ms3/4. Now I was thinking of porting some 5.3 heads and slapping them on to up the compression since this cam would love some compression as well as the ported heads. I'm open to flycutting the pistons, I've never done it before but I will.

I was originally planning on doing a 100-150 shot with my stock 241's and this cam. But I'd rather just do the heads and be done mabye add a 100 shot which I have read since flycutting makes the pistons weaker that its not too good an idea.

The build is a complete budget build so I can't really afford anyone's heads right now so that options out.

So now guys the question is would ported 5.3's and my cam with valve reliefs be worth it or should I just stick with my stock 241's and the cam?

I also thought about getting some 243's but I figured some ported 5.3's would be better since they up the compression and flow better.

garygnu

are you resizing the rods for use with the arp rod bolts ?what size valve mite you be considering for the 5.3 heads ?could you sink the valve seats deeper for a better VTP.

mtt14

iTrader: (1)

Yes rods are being resized for Arp's and I was assuming that stock ls1 valves in the 5.3's would be better than the stock tiny valves they come with?

garygnu

figure out your valve clearance before you fly cut the pistons.what head gasket will you use ?maybe do a valve drop test with no springs on the head with the head bolted to the short block .

mtt14

iTrader: (1)

Well I haven't had the assembly balanced yet so I guess I could do a test fit with the 241's and see how it fits but it won't be the same ptv as the smaller chambered 5.3 heads.

But I'm using mls gaskets. Figured since I have to get the rotating assembly Balanced ill just go ahead and flycut now then have it balanced I know it's not removing much weight from the pistons but still.. Gonna have it balanced either way since I'm using a 5.3 crank.

Sales@Tick

iTrader: (3)

This is how we check P to V. We use a checking spring with a dial indicator set-up on the retainer to measure how much clearance we have before the valve hits the piston. We get the piston up near TDC and bump it over checking P to V to see where it's furthest away and closest and repeat with the exhaust valve.

And yes the clearance will be the same with the smaller chambered heads as long as the 5.3's have not been milled. If the 5.3's are sitting at the stock 61cc chamber volume and the 241's are sitting at the stock 67cc chamber volume the P to V will be identical. The 5.3's will probably actually have more clearance due to the smaller intake valve not having as much valve drop.

mtt14

iTrader: (1)

Ok good deal I guess with the ls intake valve added to the 5.3's PTV won't change too too much! I'm gonna do a before and after measure when the shortblock gets assembled of the stock 5.3 intake valves and the 5.3 machined for the ls intake valves!

Sales@Tick

iTrader: (3)

If you change the size of the intake valve to 2.0" you'll end up with very similar P to V as a factory LS1 has.