cabech984

iTrader: (11)

I'm getting ready to install some PRC Stg 2.5 5.3L Cylinder heads that have 59cc chambers. I'm using gm mls head gaskets. I'm going to have 11.5:1 Compression ratio according to calculations. Is that going to be too much for 93 octane?

Also, whats the biggest camshaft you can run without having to flycut the pistons? I am going to check ptv clearance and all that stuff but I just want some advice before I dig into the project.

Chris

Grimes

iTrader: (3)

The cam you pick will affect the detonation resistance of the engine. If you are running a larger off the shelf cam, as a gross generalization, you can go for a higher static compression ratio.

What cam are you thinking of?

orangeapeel

iTrader: (18)

You will probably be limited on cam size if you arent running some sort of relief.

cabech984

iTrader: (11)

Thats what I'm afraid of. I have been reading 228 cams are on the safe side of things. I was planning on running the same custom cam my buddy's car has in it with the same heads. But I'm thinking his heads are 62cc and not milled versions like mine.

The cam in question is like 234int/240ex .598int/.608ex on a 112 lsa

orangeapeel

iTrader: (18)

I don't know if that will fit without flycutting. I do know that the 228r has been recommended when running those heads. I currently have it and love it.

cabech984

iTrader: (11)

Cool well I pm'd Matt from Texas-Speed. I have all the tools to check PTV and pushrod length, I'm just trying to do all the thinking before I dig in and get my hands dirty.

orangeapeel

iTrader: (18)

If I had a nickel for every time I heard someone say this....I would have like 20 cents. HAHA!

cabech984

iTrader: (11)

Well, this is LS1Tech lol. Where everyone digs into their cars and bites off more than they can chew!

bww3588

iTrader: (49)

what better way to learn than to delve into something and learn from mistakes?

orangeapeel

iTrader: (18)

I have never dropped a lifter during a cam install. *knock* Nor am I about to do it purposely to find out how this feels .

Haha!

SOMbitch

iTrader: (8)

I would be surprised if a 228 would clear with that much mill..... I was advised to run my 230/234 111+2 cam uncut with those heads when I had them.....

cabech984

iTrader: (11)

Matt from texas speed said they've had success with the 228r cams but to obviosly check ptv clearance first

cabech984

iTrader: (11)

Now to find a good cam to use without flycutting!

smg267

iTrader: (23)

If you install those heads only, Will you be able to drive the car safely w/o a retune? I only ask this b/c I have the heads sitting in my closet.

cabech984

iTrader: (11)

Would it even idle with all that extra air? If mine runs and idles, Id consider driving it to the tuner but thats it. I have HP tuners and access to some trailers so Ill only drive it onto the trailer. I wouldnt go hotrodding it or anything lol.

05MBMLS2

iTrader: (34)

Well if it helps,,,,im running the exact same out of the box 2.5 heads, same mls gaskets with a Comp custom- 224/230 .609/.604 on 113lsa cam and had plenty of room but obviously your going to want to check regardless of what people recommend.

cabech984

iTrader: (11)

Out of the box as in 62cc or 59cc? I'm gonna try with this cam that I have but I may go ahead and spec out another one.

vidal77boxing

iTrader: (15)

i ran PRC heads with 59cc using a 224r. The biggest you can prob go without PTV issues is the 228r.

05MBMLS2

iTrader: (34)

My heads are the 59cc ones out of the box.

cabech984

iTrader: (11)

You guys are making me want to keep this cam and just go ahead and check ptv!