Trick Flow heads....

[fryedaddy]

this topic is confusing,all the different answers to the problem,or is there a problem.leaves me scratching my head,but i will have to stick with this forums engine builders because of their years of experience.so what does a body do with a new set of tf heads,bolt them on or have your shaft pads machined? they might have made 700 hp out of the box,but how long will this engine last,or should i say will it have future rocker-valve problems?

[turbohunter]

Andyf it’s really interesting that you guys had a different outcome with the higher riser pads.
It would be neat to see a civilized/respectful discussion between all you great builders here.

[blykins]

Between Blair and me, I think we have at least 3 TFS builds, with 3 different brands of rockers.  All 3 required cutting the rocker stands down. 

The other user that posted here also had to cut.  That’s 4...

I would consider it a “must”.

[jayb]

I thought it would be informative to post some mechanical drawings of what good rocker geometry looks like.  The obvious difference is that with correct rocker geometry the travel across the top of the valve is reduced, and that brings benefits in terms of wear on the valve guide and reduction in friction in the valvetrain, especially if you are not running a roller tip rocker arm.  From the pictures I've seen the Trick Flow heads look like they come out of the box with rocker arm geometry similar to what is shown in the first picture below.  Will they run like this?  Sure.  Will they make power?  Of course.  Is it the ideal setup?  Not by a long shot.  This is why the rocker pads are being cut down by some of the folks here.  Longer valves would also solve the problem.  Since Trick Flow is offering the heads and the valves, it seems odd that they set it up this way.  Seems like a design or manufacturing mistake to me.  I hope they can get it corrected.

[Dumpling]

The fact that longer valves are needed seems to be blithely dismissed.  Don't longer valves weigh more, and doesn't that extra weight impact performance, particularly at higher rpm's, particularly with hydraulic cams, which may be the cam of choice for those purchasing 'out-of-the-box' bolt-on heads?

[MeanGene]

Maybe I'm missing something, but if the raised pads come with more beef and thread engagement, wouldn't that be an advantage, since that is a weak point on most aluminum heads? And cutting the stands, instead of the head, would fine tune the geometry without loosing the extra strength. Not sure why one would want to give up the extra strength by cutting the pads instead of just cutting the stands?

[machoneman]

I'll venture that since the heads have already been distributed to a number of sellers already (and more sit in TFS's own warehouse) it would be quite difficult to retrieve them all, re-machine them and redistribute them. It's too late to easily and cheaply fix all those heads now. Perhaps TFS will change the pad height on future castings as part of overall machining.

Btw, they also could easily slap a sticker on every box indicating a need to a.) closely check stem sweep, perhaps using a drawing like Jay did above b.) recommend either longer valves or pad machining.

Bet though they won't do this as its an admission they aren't direct replacements without actual machine shop (no shaded tree, backyard stuff here!) pad reduction intervention. 
 

[jayb]

Maybe I'm missing something, but if the raised pads come with more beef and thread engagement, wouldn't that be an advantage, since that is a weak point on most aluminum heads? And cutting the stands, instead of the head, would fine tune the geometry without loosing the extra strength. Not sure why one would want to give up the extra strength by cutting the pads instead of just cutting the stands?

One reason would be clearance between the rocker body and the head, or the end stand.  For example, if you tried to cut one of the Precision Oil Pumps end stands down, you'd probably turn it into two pieces and loose the benefit of the support out at each end of the rocker.  If you were running solid spacers between the rockers, maybe the spacer would hit the head with the reduced stand height.  The other issue would be fixturing in a machine.  How would you easily fixture all the stands so you took the same amount off each one?  It certainly could be done, especially if you used a rocker shaft for alignment, but I'll bet it would be more expensive than just cutting the rocker pad. 

[C8OZ]

I suspect they would address this about 5 seconds after someone starts marketing, "Rocker stands to make TFS heads a direct replacement."

[CaptCobrajet]

I know that is a generalized drawing there Jay, but in the case of the Trick Flow, the tip is actually pitched too far towards the exhaust side.  Depending on the arch of the rocker arm (if any), a longer valve will not necessarily do the same thing as a change in shaft placement.  If it was a "box" geometry that started with all 90° angles, up with one, or down with the other would accomplish the same things.  If the set-up exists with "other than" 90° angles to start with the remedies get kinda blurry.  Just for the sake of example....sometimes dropping the stand .200 might affect it more or less than a .200 longer valve, or vice versa.  They do have a longer valve, but it isn't "longer enough", and it would create other issues like installed height problems to keep making the valve longer.  The best fix for their deal is to lower the shaft, by whatever method suits a person's fancy.  I agree that it will work, it has minimal effect on power, and yes, it will wear the guides out quicker over time than proper placement. It also can be hell on a valve tip and rocker if not a roller, as Jay suggested.

Seemed to me that milling the rocker stands and changing the studs is the best answer.  The stands can be easily clamped in a Kurt vise and trimmed, and the studs can be bought with longer base thread.  After the fix, the deeper root is actually better........it just needs to be done.

One of the problems when raising the port roof when using OE style mounting is than we start to run out of threads above the port.  This doesn't happen quite as soon if the pad is taller and there are more threads left......just food for thought.

I think we shouldn't be too greedy about wanting an absolute bolt-on-no hassle situation when working with aftermarket heads.  A bolt-on OE garden variety FE head will flow about 230 on my bench on a good day.  That TFS that needs the stands milled will flow 308 here.  If all it takes is milling the darn stands a little, big deal.....just my opinion.....for 80 cfm, seems like a pretty good deal.

Valvetrain geometry can get to be an infinite discussion, because there are so many conditions that can require so many different remedies.  Sometimes, with really big camshafts with super high spring pressure, it is good to screw it up intentionally, in terms of the normal theory, to ease the burden past half lift, when ramps are stout, and spring pressure is high.  Other times, with less than .500 lift, the tip will barely change position through the whole range.  THAT is obviously what most of the street folks are looking for. 

Maybe Trick Flow should just put a note in the box that when building a high performance engine, one should verify proper valvetrain geometry.  I'm going to check it on all heads and all valvetrains.  Over time, I see some things over and over with certain combos of parts.  If you don't do it every day, you should check your individual situation out for yourself, or  work with someone who can check it for you.

[jayb]

I know that is a generalized drawing there Jay, but in the case of the Trick Flow, the tip is actually pitched too far towards the exhaust side.  Depending on the arch of the rocker arm (if any), a longer valve will not necessarily do the same thing as a change in shaft placement.  If it was a "box" geometry that started with all 90° angles, up with one, or down with the other would accomplish the same things.  If the set-up exists with "other than" 90° angles to start with the remedies get kinda blurry.  Just for the sake of example....sometimes dropping the stand .200 might affect it more or less than a .200 longer valve, or vice versa.  They do have a longer valve, but it isn't "longer enough", and it would create other issues like installed height problems to keep making the valve longer.  The best fix for their deal is to lower the shaft, by whatever method suits a person's fancy.  I agree that it will work, it has minimal effect on power, and yes, it will wear the guides out quicker over time than proper placement. It also can be hell on a valve tip and rocker if not a roller, as Jay suggested.

Blair, thanks for the clarification on that, I don't have a set of those heads so I wasn't aware of the alignment issue.

[blykins]

The obvious difference is that with correct rocker geometry the travel across the top of the valve is reduced, and that brings benefits in terms of wear on the valve guide and reduction in friction in the valvetrain....

Not to mention the amount of lift that you lose to unwanted movement.  Anytime you see a wider witness mark, especially with a roller tip, you are losing some amount of valve lift because the rocker arm is too busy making a lateral movement instead of pushing the valve down.   You already lose some to pushrod deflection, there's no need to compound it. 

Most rocker stands that I've messed with so far will take the .200" cut off the bottoms without issue, including T&D streets, and POP center/end stands. 

[MeanGene]

I know that is a generalized drawing there Jay, but in the case of the Trick Flow, the tip is actually pitched too far towards the exhaust side.  Depending on the arch of the rocker arm (if any), a longer valve will not necessarily do the same thing as a change in shaft placement.  If it was a "box" geometry that started with all 90° angles, up with one, or down with the other would accomplish the same things.  If the set-up exists with "other than" 90° angles to start with the remedies get kinda blurry.  Just for the sake of example....sometimes dropping the stand .200 might affect it more or less than a .200 longer valve, or vice versa.  They do have a longer valve, but it isn't "longer enough", and it would create other issues like installed height problems to keep making the valve longer.  The best fix for their deal is to lower the shaft, by whatever method suits a person's fancy.  I agree that it will work, it has minimal effect on power, and yes, it will wear the guides out quicker over time than proper placement. It also can be hell on a valve tip and rocker if not a roller, as Jay suggested.

Seemed to me that milling the rocker stands and changing the studs is the best answer.  The stands can be easily clamped in a Kurt vise and trimmed, and the studs can be bought with longer base thread.  After the fix, the deeper root is actually better........it just needs to be done.

One of the problems when raising the port roof when using OE style mounting is than we start to run out of threads above the port.  This doesn't happen quite as soon if the pad is taller and there are more threads left......just food for thought.

I think we shouldn't be too greedy about wanting an absolute bolt-on-no hassle situation when working with aftermarket heads.  A bolt-on OE garden variety FE head will flow about 230 on my bench on a good day.  That TFS that needs the stands milled will flow 308 here.  If all it takes is milling the darn stands a little, big deal.....just my opinion.....for 80 cfm, seems like a pretty good deal.

Valvetrain geometry can get to be an infinite discussion, because there are so many conditions that can require so many different remedies.  Sometimes, with really big camshafts with super high spring pressure, it is good to screw it up intentionally, in terms of the normal theory, to ease the burden past half lift, when ramps are stout, and spring pressure is high.  Other times, with less than .500 lift, the tip will barely change position through the whole range.  THAT is obviously what most of the street folks are looking for. 

Maybe Trick Flow should just put a note in the box that when building a high performance engine, one should verify proper valvetrain geometry.  I'm going to check it on all heads and all valvetrains.  Over time, I see some things over and over with certain combos of parts.  If you don't do it every day, you should check your individual situation out for yourself, or  work with someone who can check it for you.

Thank you- I was thinking with my Bridgeport mind, and had the same idea about putting the stands in an accurate mill vice, and keep the same setup for the next batch. The average wrap-around end stand thickness thing, a valid point, could be overcome with a little country thinking. In my mind, the extra beef and thread engagement is worth coming at it from a different direction

[TimeWarpF100]

I know that is a generalized drawing there Jay, but in the case of the Trick Flow, the tip is actually pitched too far towards the exhaust side.  Depending on the arch of the rocker arm (if any), a longer valve will not necessarily do the same thing as a change in shaft placement.  If it was a "box" geometry that started with all 90° angles, up with one, or down with the other would accomplish the same things.  If the set-up exists with "other than" 90° angles to start with the remedies get kinda blurry.  Just for the sake of example....sometimes dropping the stand .200 might affect it more or less than a .200 longer valve, or vice versa.  They do have a longer valve, but it isn't "longer enough", and it would create other issues like installed height problems to keep making the valve longer.  The best fix for their deal is to lower the shaft, by whatever method suits a person's fancy.  I agree that it will work, it has minimal effect on power, and yes, it will wear the guides out quicker over time than proper placement. It also can be hell on a valve tip and rocker if not a roller, as Jay suggested.

Blair, thanks for the clarification on that, I don't have a set of those heads so I wasn't aware of the alignment issue.

TFS Engineer did say the valve angles have been changed from stock.

[cjshaker]

We're not clueless, the stock stand height worked just fine for us. That engine made 700 hp and everything looked great. Those heads are a super nice design as were the other parts we used on that engine. The engine took a little more "fine tuning" than a typical Chevy or Mopar engine, but you kind of expect it with a FE engine. Especially when using a bunch of brand new parts. We had one of the first sets of TF heads as well as set #1 of the Comp rocker arms so stuff did have to be tweaked a little bit but we didn't have to machine the stands. Pushrod clearance was tight in several spots and the intake did end up on the milling machine a couple of times.

From the picture you posted, you can see that the rocker tip is off to the exhaust side at zero lift, just as Blair noted. And like Jay said, yes, it'll run and make power, but that is far from desirable in a geometry pattern. Defending the fact that it 'worked' only confuses people and will lead others to have problems down the road. So, it seems you guys were clueless. Sorry, don't mean to be rude about it, but the facts need to be set straight for people.

Given some of the benefits noted, it seems like they are a good set of heads, with the proper set-up and required work. A shorter stand means a shorter stud, and a shorter stud won't deflect as much, so that's a good thing. The sad part is that there are a lot of people who don't go internet-cruising to find out any and all issues. There are still a lot of backyard mechanics out there, and they will have problems. Pretty crappy business practice, IMO, for TFS to pass these off as "bolt-on". But that's what you get with businesses today. Luckily, we have the benefit of builders here who make us aware of these issues before we find out on our own...in most cases.