Just curious what type of additional valvetrain harmonics you guys picked up over your stock cam. I had a TSP 231/237 and from what I understand the lobes (lunati) are more aggressive than the cam-motions are. However, I have picked up a considerable amount of valvetrain noise going to an overall less aggressive cam. Anyone have any experiences similar to this with a futral cam? The harmonics I'm speaking of are from 2800 and up and vary as rpm increases. Thanks for the input guys!

 

The same thing was asked a few days back about Futral cams as well.
My input on that is lifter preload. I think it has to do with base circles and that 7.40 p-rods are a little short.
on my XE-R lobes, I reduced that "sewing" effect with .025 longer p-rods.
I run 7.425's.

 

F10 on 112 LSA here. No harmonics at all. Valvetrain noise is VERY quiet, but I have Yella-Terra rockers, which I think were a great addition to my setup. I have ZERO "sawing machine-like" noises.

I must say that I have a slight "whine" or "whistle" at WOT...I'm thinking it's either a very small exhaust leak (I have MACs) or it's normal...

 

GMCVT, what's your comparo between the two cams? Noticeable gain in low and midrange with the F10 over the 231/237 (you should have noticed)? How much high rpm power did you lose?

 

Am I the odd one out and love the sewing machine sound? It reminds me of my pops olds muscle cars for some reason.

 

What length PR's are you running?

 

I originally never gave much thought to there being a base circle difference between the TSP and the Futral and it seems that most people are using 7.4's on the Futral cams. I looked on Alan's website and they dont even list 7.425's. They have 7.4, 7.35 and 7.30.

 

In my opinion, and remember I have a GTO with more weight than an F car, there has been a HUGE difference. Lots more bottom end and I dont have the thing tuned yet. As far as top end is concerned, I dont know yet. (See previousl sentence )

 

I got mine a Thunder

http://www.thunderracing.com/catalog...vid=3&pcid=106

 

Thanks for the link. I dont think I communicated my thought process . The point I was making was that if this was a common issue with the BC of the Futral cams, wouldn't you think they would offer the longer rod?

 

yeah, I thought about that many times.
Base circle is relative to lifts used, so I guess they simplify things for mass sales.
you'll notice that this is an issue with non adjustable rockers, but with adjustables you can absorb these differences.
Beeing on this board for awhile, I've read many "noisy" posts, "lifter failure" posts etc.. most due to improper preload on lifters and/or poor geometry.
As a matter of fact, I have 4 sets of Comp p-rods (from 7,350, 7.400, 7.425 and 7.450). Those are what I use to get the closest preload with stock rockers when I change cams.
I just haven't got myself to spring for a set of adjustables yet (they all have clearance issues). The ones I like the most are CRANE "Gold" but with milled heads (or aftermarket castings), you run into the same situation.
This is what I do sometimes >>>
As a matter of fact, I'm going with a TSP 232/234 113LSA+0 soon (Torquer Rev 2) and I think I'll be doing some more head bashing.

 

I'm using stock-length 7.400" Comp pushrods

 

Well, the one thing I haven't done is check the preload. Check me on this, 0 out the lash and turn the bolt 1/2 turn. At that point it should torque @ 22lb ft. and of coarse this is done on the base circle. Is this method correct? Seems to be the most common method that I've found in searching.

 

This is from www.ls1howto.com
I did it exactly as written and I have ZERO harmonic problems.

To determine the right preload:

Once the rockers are sitting in the right place, use a 10mm socket and extension but NO SOCKET WRENCH, and finger tighten the rocker arm bolts until both of the bolts get too tough to spin with 2 fingers. You can take your index finger and try to spin the pushrod under the rocker arms as well, and it should have some friction on it and just barely spin, if spin at all. This is called "Zero Lash" and it is where there is no preload on the lifters....the lifter is touching the pushrod, the pushrod is touching the rocker, and the rocker is touching the valve, all without putting any pressure on the lifter.

NOW, get your socket wrench out and attach it to the 10mm socket+extension you were using. Without turning the bolt AT ALL, place the wrench in the 12 o'clock position. What we have to do is count the bolt turns until the instant the bolt gets hand tight. Turn each of the two bolts 90 degrees clockwise, then set the wrench at 12 o'clock and repeat (do each bolt one 1/4 turn, and keep alternating).....each 1/4 turn per bolt seems to equate about 10-12 thousandths preload (this is a very rough guess!).

If you get MORE than 1 full 360 degree turn on each bolt, remove the rockers and install the shims on the bottom of the pedestals and repeat this process to check the new preload. The shims seem to reduce the turns by approximately 270 degrees. You must install a shim on BOTH bolts, not just one or the other. If you got LESS than 1 full 360 degree turn then you are ok to leave the shims out!

Every car will be different so make sure you check this! You want the smallest number of turns you can get, as long as you have at least 1/4 or 1/2 full turn of preload in there once you are all setup. If you get to the point where the bolt is tight yet you can still spin the pushrod (without using shims), then your pushrods are either too short, your valves are too short, or you have some strange valvetrain geometry. You MUST have some preload or it will be OBSCENELY loud and run very poorly. Longer pushrods may fix your issue in this case.

 

You shim the stand to adjust geometry, (wipe test) will determine if your valve tip wipes are centered.
Once your geometry is correct, then you adjust your preload via p-rod length.
Since stock rockers are non adjustable, to get exact preload would be a miracle.
22ftlbs and no finiking with turns.
Most likely you should end up with a p-rod that gives you a preload closest to, without going over .060 >.080 (hot)

BTW this is a thread that might interest you.
https://ls1tech.com/forums/generation-iii-internal-engine/370412-lost-power-incorrect-length-pushrods.html

 

Please dont take this the wrong way but are you sure thats not backwards. Back when I used to be into Fords, I built my fair share of 302 and 351's. Ford Motorsport heads used bolt down rockers. We always purchased a shem pack to set the pre-load. Later on when I used aftermarket stud mount rockers I had an adjustable PR kit. I would always adjust the lenth of the rod to determine where and how wide the rocker tip would sweep the valve stem. Did I have it backwards? I'm going to go read that thread now. Thank you!!!

 

The wipe test on pedestal rockers has nothing to do with p-rod length.
wipe test will determine if your rockers are at proper height
Wipe test determines correct geometry and preload to a certain degree, p-rod length only affects lifter pre-load (this is because we run hydraulics, ie LSx specific with pedestal rockers).
Now that you know that your geometry is correct, you need to measure your lifter preload to determine what length rod you should run.

Now with stud mounted rockers (Comp Magnum) for expl, your method is correct.

 

Gotcha, I'm really cornfused , so last night I went out and put two rockers on base circle, 0'd the lash and I had to turn the bold 1 to 1 1/4 of a turn to hit 22lb ft. To me, that means that I need a shorter pushrod. The pushrod is sitting higher than it should which would require more overall turns to get it to 22 lb. ft. Am I wrong?

 

It means you need a longer p-rod. If it takes you more than 1 turn (360*) to reach 22ftlbs, then your p-rods are too short. (assuming your geometry is centered).
But that is done with motor warm and lifters pumped.

 

I have an F10 on 114 in my forged 346 with AFR heads milled .020 and Comp non "r" rockers and i use a 7.400 pushrod and it's not that noisy at all. My comp 216/220 .579 .589 114 was a TON louder in regards to a sewing machine noise.

If you want I have a pushrod length checker that I bought from thunder and I can mail it to you if you want to borrow it.