Trick flow 170 question

[frdnut]

My brother just ordered a set of trick flow 170s..When he opened the box on the instructions it has a warning about piston to valve clearance..It says the 61 cc chambered heads work with stock pistons up to .550L and that the 58cc chambered heads require special pistons?....What would be the difference between the two heads that would affect PTV clearance differently?..I assumed the only difference would be a slightly smaller chamber on the 58cc version?

[rickgto]

Never used the 58cc version but I'm betting they're simply the 61cc heads milled to 58. If that's the case, PTV would be reduced by the amount they're milled. That said, I don't understand why they're rated at a certain (safe) max lift rather than lift at tdc they'd be safe at with stocklike pistons. Cam design/timing dictates in/ex lift at tdc moreso than a max lift figure.

[66resto]

Here is a thread with the 61cc head, F cam (512 max lift) (post no. 12) and still had to notch the pistons.

No matter what the combination is and whether are not it has been successful for others with the exact same parts...you always have to measure and it may or may not requiring notching after you get them in there.

[88cougargt]

Always clay the pistons when changing heads and/or cam. Cheap insurance and only takes a few minutes.

[frdnut]

Originally Posted by rickgto

Never used the 58cc version but I'm betting they're simply the 61cc heads milled to 58. If that's the case, PTV would be reduced by the amount they're milled. That said, I don't understand why they're rated at a certain (safe) max lift rather than lift at tdc they'd be safe at with stocklike pistons. Cam design/timing dictates in/ex lift at tdc moreso than a max lift figure.

Yes I am thinking that must be the reason as well..Just seems odd to me that they would sell heads already milled down some..

[66resto]

Originally Posted by frdnut

Yes I am thinking that must be the reason as well..Just seems odd to me that they would sell heads already milled down some..

Not everyone wants to run the same compression. Hard to make a universal aftermarket part for all the different combinations. You'll have more PTV issues with a inline head like AFR than you will ever had with this head.

[blueovalfan68]

Trick flow... are all of their heads that "twisted wedge" design??

I think the special piston requirement is more of a result of the slightly different location of the intake valve as opposed to the combustion chamber size?

I could be wrong

Just my $.02...

[C0V3R]

It depends on the cam you run - my understanding is you can run up to their stage 2 cam (cant remember the specs) without p/v issues on most stock pistons

I am running their 60cc TW heads on a late model explorer roller block with TFS stage 1 cam and no p/v issues

[sportsroof69]

The twisted wedge heads give you better P to V clearance, than an inline head, even with stock pistons. That's why they're the only head that can use a 2.02 intake valve with the stock bottom end.

[66resto]

It also makes a difference how far your piston is down the hole, if any. Measure or run the risk of having a very bad day.

[cornholio]

Another tidbit.... if those have the "high ports" you will need to have headers fabbed...

That is unless I am behind the times, and within the last 2 years someone started making a set that fits. They did not and I had to have a set made out of California from Ford Powertrain...

[kwkenf]

170 are not High Port heads so standard headers will work.

[frdnut]

Originally Posted by 66resto

It also makes a difference how far your piston is down the hole, if any. Measure or run the risk of having a very bad day.

Yes I am fully aware we need to check the PTV clearance..I was just wondering what all the differences were between the two heads that trick flow felt the need to say one would need a different piston and the other was ok up to .550L

[sportsroof69]

I'm. It sure why trick flow gives a generic lift number like that. Duration actually has more to do with it than lift.

[cornholio]

Originally Posted by kwkenf

170 are not High Port heads so standard headers will work.

Thats good. Man was that a pain.