head and cam swap
 

Hey everyone. Im new to this site but not too new to modding my stang. I have an 02 auto GT and was gunna do a head and cam swap this while shes in storage this winter. The current mods that I have are a JLT CAI, 70mm accufab TB and plenum, typhoon intake manifold, BBK ceramic LTs, BBK catted H pipe, Magnaflow catback, and 4.10s.

I was looking at installing Patriot Performance stage III heads with XE274AH comp cams. I know that the cams have a 0.5 valve lift. Will I have piston clearance with this setup? I have read about some people having trouble with clearance and needing to notch their pistons which I am really trying to avoid. I dont really know all that much about cams in general but hey...thats why Im here. Any help/advice/suggested head and cam combos would be appriciated. Thanks

Here is a thread with a link you might like to look at.
https://mustangboards.com/modular-4-...v-article.html

Now for the cams the Comp Cams 274 cams can not be run on a stock rotating assembly as there will be PTV contact. The biggest you can run is the Comp 270 cams.

The cam you are referring to is the 274H. Don't add the A since for Comp Cams, for the 2V cams, the A means .55" cams for PI heads. Also, scrap Patriot. Even their home made heads flow no better than stock heads (their SBC Chevy heads flow worse than Vortec heads). Instead, go to Total Engine Airflow or other reputable porters. You'll be way more happy w/ the quality and power. Also, depending what you want, you may not want heads that flow as much as the Patriots you're looking at. If you plan on staying NA and mostly street driven, go one step down, it'll help w/ the torque. But, if you are not planning on street driving or going FI, go big. As for the cam, why are you going w/ .5" lift? Is it because you don't want to change springs or are you worried about PTV? Either way, the cam you chose isn't going to be fun on the street since it's power band doesn't kick in until 2,000 rpm. The 270AH would be much better since the extra lift/smaller duration gives you the needed low-end torque but still gives you better top-end. Heck, even the 262AH might be better since even though the 270 is great, the 262 might better fit you. If you want to know what's best for you, give Comp, Crane, or Crower a call. They all have numbers for cam recommendations (just have the right info ready).

What is the cost vs. the HP gain?

Patriot heads
 

What's the deal with Patriot?? They have flow specs that show stock and thier stage I or II and they show improvement. Not saying you're wrong but.........How could it be that a CNC port job and bigger valves with a 5 angle couldn't flow better than stock??

1st off, dont believe everything you read, esp on patriots site....second, flow #'s dont meen squat, you need to know how were they flowed and at how many inches?
patriot has had a bad rap on there Modular heads over the last several years and imho, stay far away from them as there are to many other quality head porters/shops out there.....

I don't believe everything I read BUT
 

You still didn't answer the question. How could a CNC port job and bigger valves with a 5 angle valve job NOT flow better than stock. I'm not saying they're the best or that there isn't much better way to go BUT that it is not what I said. :)

why, because "bigger" is Not always better...bigger ports & bigger valves can actullay hurt performance by slowing-down the terminal velocity of the air thru the port, esp if the wrong camshafts are used, wrong intake mainfold and more, so it's NOT always about the #'s

Im a little confused. I thought that PTV contact depended on the valve lift of the cam, am I wrong??? I must be b/c the 270 has a .55 lift and the 274 has a .50 lift.

ps...awesome like for the head and cam install. Thanks

Its the lift and the duration of the cam as well. The 274 keeps the valves open longer so it hits the stock rotating assembly because the piston is up farther buy the time the 274 is starting to close. Where as the 270 has less duration and closes the valves sooner so they don't hit the pistons.

PTV is determined by duration, lobe centerline and the aggressiveness of the lift rate. the amount lof lift rarely comes into play.

This is incorrect, PTV occurs as the piston is coming up on the exhaust stroke and the intake valve is opening. If the intake LC is too low, the piston will hit the opning intake valve. This can be abated by retardign the camshaft but this will also reduce power...especially if the motor is a stroker of BB or the motor is using a single plane intake.

The exhaust valves will not hit the pistons becuase their diameter is much smaller than the intake valves.

if you want some good heads go to livernois motorsports or fox lake racing