Twisted wegde heads Stage II cam PTV clearance?

[purevenm]

A buddy of mine has ordered/recieved a set of Trickflow Twisted Wedge street heads with a Trickflow stage II cam. He is running a stock block in his 93 GT.
Is anyone on here running this same setup? Did any of you have piston to valve clearence issues?
We were going to put the motor together this weekend but this issue was brought up and I thought I would check here first for some first hand knowledge and advise.


Thanks,
PURE VNM

 

[coops93meangt]

Hey I just signed up for the site and I'm the buddy

Here's a little more detail about the setup.

I just wanted to see if someone else was already running the exact same setup for a little extra piece of mind before I go through the motions of degreeing the cam and checking for piston to valve clearance. So anyone running this exact setup please comment. I think I have posted enough information below, but if you have additional questions before giving your input, please ask.

This is a 93 GT.

Setup will be as follows:

• I'm using the stock block, crank, and Pistons.
• Running a Trick Flow Stage 2 Cam with a Trick Flow Double Roller Timing Set. (.544"/.563" lift and 224/232 duration @ .050")
• Heads are Trick Flow Twisted Wedge with Trick Flow 1.6 Roller Rockers
• Rods are Trick Flow 6.75"

Questions I have are as follows:

1. Will I have any issues with Piston to Valve Clearance if I degree the cam straight up?
   
2. If there will be clearance issues is it possible or recommended to retard the cam enough to gain the extra clearance or would I be better off just going with a slightly milder cam to get me within the .540" threshold that Trick Flow recommends not exceeding when using stock crank and pistons?
   
3. How advisable is it to grind the relief on the stock piston to gain any extra clearance needed?

 

[2000xp8]

I don't remember for sure, but i do not think the II works with stock pistons. It's not only the lift that cause's the clearance issues, so simply going with a lower lift number may not cure anything.

You can get the isky notching tool if you had to, but if the heads are assembled it's a pita.

IMO, sell the cam, and go with a custom for your application, cost a few more bucks, but it would be worth it.

 

[strtrcr50]

fox lake link

How big of a camshaft can I really run with my Trick Flow Twisted Wedge heads on my stock shortblock?

It is more of a matter of duration and not lift numbers that matter in this situation. When the valve is open, the piston is on it's way down so lift numbers aren't the problem. The duration is the length of time that the valve stays open and is where you more than likely may get into trouble. In theory, you could run a .700" lift cam and not have piston to valve problems if is has a short duration. Also, you could use a cam with only .400" lift and if the duration holds the valve open too long into the stroke you would have contact. In our experience, we have used the Trick Flow Stage 2 camshaft with numbers at .544"/.563" lift and 224/232 duration @ .050" and have no clearance problems at all on a stock shortblock. Piston to valve clearance should always be checked during assembly, but just try to not to get "hung up" with lift numbers only......there is more to it than that.

 

[coops93meangt]

fox lake link

Yeah, I hear what you're saying. Hopefully purevenm and I will get around to degreeing the cam and checking the PTV Clearance this weekend and I can post up the results.

 

[5spd GT]

Peak lift has nothing to do with piston to valve clearance. A Trickflow Stage 1 camshaft is 2.156" down the bore at peak lift.

Anyways, advancing or retarding the camshaft can gain you a bit...although it compromises your performance and powerband.

Advancing the timing opens the intake sooner and closes the exhaust sooner. That will gain you some clearance on the exhaust valve, but you will lose clearance on the intake valve. Retarding the cam causes the timing to open the intake valve later, and closes the exhaust later. You'll gain clearance on the intake, and lose clearance on the exhaust. So changing the cam timing won't result in increasing clearance on both valves.

You need to see which one you need most...

Adjusting either way can shift the powerband +/- 200 rpm that direction...

The general rule of thumb is .080" on the intake side, and .100" on the exhaust side.

The exhaust side needs a little more clearance due to a couple reasons:

- Piston chasing the exhaust valve as it is closing (spring has less control).
- Heat expansion
- Chain stretch (retards the camshaft)

I do not think it is going to clear.

Good Luck!

 

[coops93meangt]

We tackled this today. With the cam installed straight up we were close on the clearance. Intake was fine and exhaust was a little too close for comfort. We retarded the cam slightly and have plenty of clearance on the intake and exhaust now. Guess I'm keeping the cam

 

[coops93meangt]

For anyone who cares, here's the results from the H/C/I upgrade...

Not quite the numbers I was hoping for but it's a damn good improvement over a stock setup as well as my baseline. C&S said I also have plenty of room to still grow with the current setup and tune.

Mustang Dyno Numbers
RWHP = 252 at 5400 RPM
TQ = 279 at 4300 RPM

Dynojet Numbers
RWHP = 290 at 5400 RPM

At the Flywheel
FWHP = 315 hp

Now the fun part...the drive home. Car idles amazingly and man does it have that pin you back to the seat power at Mid RPM. The power band deffinitely shifted due to retarding the cam but it shifted in a good way in my opinion.

Wanted to share...

 

[ls1beater4eva]

what intake are you using with your combo,injectors,t-body , whats your timing at?

 

[coops93meangt]

Intake is Trick Flow Street Heat
MAF is 75mm Pro-M with a straight through calibration
24# Ford Racing Injectors
TB is Accufab 70mm

To get it to turn over we set the timing to 10º BTDC, but I'm unsure where it ultimately ended up when he tuned everything. It doesn't look like he adjusted the Distributor much at all.