My friend ordered a Trickflow heads and cam package for his 79 Z28 with a fresh 355 roller motor (out of an 80's vette). He got the roller cam part # TFS-31402001 and 1.52 Pro-Mag rockers. Lift numbers should be .535" intake and .545 exhaust with these rockers. The lifters he got are made by Crane. My question is how long of a pushrod does he need for this setup? thanks a bunch

Jason

 

I went through this with a set of the old TFS "Twisted Wege G2" heads that they don't make any more, or if they do you can't find it on their website and they act like they never existed.

Even the newer 23* heads still require "custom length pushrods" according to their own documentation.

I HIGHLY recommend you find someone who knows how to work an adjustable length puhshrod to check for proper length. Trick Flow's specs on their website were WAY out to lunch for our G2s (.200 too long)- and we were just running a plain old flat tappet stock cam- nothing as complicated as you are dealing with on a roller cam with aftermarket lifters and rockers.

You can call Trick Flow and ask them for a "starting" recommendation, but really, you had better check for yourself. Like I said, they were way out of spec on their recommendation for our combo.

 

mebanditws6: Included in the instruction packet that comes with the heads is a "rocker arm and pushrod" data sheet. On that sheet we list starting points for a bunch of common combinations.

Damon: We do not recommend using stock length pushrods as a default because of "tolerance stack up". As we all know, Any part that is mass produced has a working tolerance of +/- a certain amount.
Knowing that, We can all see there is no way that I or anybody else can definitively know what the exact length pushrod of a given combination is going to be. (Couple that with the fact that not all rocker arms are created equal, And you have an impossible to know situation. But, that is a totally different subject altogether...)

That is why we list starting points for checking purposes. Of course, We do not list a starting point for every single rocker arm made. So, For your combination, I would recommend setting your adjustable checking pushrod at 7.250" and go from there.

If the rocker arm wear pattern favors the inside edge of the valve tip (rocker arm stud side) your pushrod is too short.

If it favors the outside edge (Toward the exhaust header side of the valve tip), the pushrod is too long.

The wear pattern will be dead center of the valve tip & less than .080" thick when all is correct...

If you need to, Give me a call @ 330-630-1555 Ext: 6324. I am in the office from 9:00am-5:00pm EST....

 

Artie- no argument here. I have posted on subjects related to this on many boards, including nastyz28.com and thirdgen.org. You have responded on those boards as well, as I recall.

I agree completely regarding the necessity of checking for any given combo. Obviously, the one (and only one) engine I built using the Trick Flow heads didn't line up very well with the "starting" recommendations on pushrod length posted on your website.

To the good: Once I got the valvetrain sorted out the Trick Flow heads absolutely KICKED BUTT. They are VERY impressive heads when set up properly. In fact, they exceeded my expections in every way. I have said on other boards, and I say again here, I will put them up against the (more expensive) AFR heads any day of the week. They are VERY good heads.

Just in my situation the pushrod length was way off when using the recommended pushrod length for our combo. By more than I can explain due to "stacking tolerances." It was definitely either a rocker arm-specific issue or the recommendation on pushrod length was not well thought-out. Given that I didn't try different rockers I can't say for sure so I won't comment further. End of the day..... ANY performance engine should be checked for proper pushrod length. It's just not something that many weekend warriors know how to do, so they often rely on the recommendations of the manufacturer.

 

A side question, if I may, Artie- has Trick Flow abandoned the "twisted wedge" heads completely in favor of the straight 23* units for small block Chevys?

I notice in the latest Summit catalog that there are still "twisted wedge" heads being advertised for small block Fords, but not for small block Chevys.

Is the whole "twisted wedge" thing slowly going away or does it have a future. It seemed like a good concept to me in theory.

 

Damon: Yep, Sometimes setting up the valvetrain geometry will give you a few gray hairs. If you ever get the chance to compare center-to-center lengths of the various rocker arms out there, You will see that they are not all the same. This is one of the major reasons for differing pushrod lengths with so called "similar" engine caombinations.

The G2 TW heads were taken off the market in 2002. The biggest contributing factor to them being taken off the market is the 23* head. When we brought the 23* out, We were trying to steal away cast iron head sales. From the amount of those heads we sold/sell, I would say we did that in grand fashion. However, At the same time, We stole G2 head sales from ourselves (If that makes any sense..). Do not get me wrong, The G2 heads make great power (As you already know...), It's just a simple fact that the average gearhead does not want to do what is necessary to set them up. In comparison to the G2 head, The 23* head is a walk in the park (And it had a lower pricepoint as well...).

As for me, I wish we still offered the G2 head as there was tremendous potential in those heads...

The SBF TW head will never go away...

 

I have a set of the early G1 Twisted Wedge heads, and I've been satisfied with them. They've held up well enough, even though I did break a valvespring in '99. Artie told me some of the early heads had a defective lot of springs. The replacements have been fine.