removing the secondaries a compelling story
 

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Scope view at point of discovery the awwww Crap moment!!!!!
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Folks a lot of you know I am going through a motor rebuilding process. For those of you not in the know my car engine stopped dead in late May of this year almost at idle. Preliminary checks revealed Zero compression on Cylinder #2. I am sharing this as a documented failure on my 91 for the entire community’s info.

Here was the cause. One of the butterfly valves (#2 Cylinder)for the secondary’s snapped at the shaft screw point and fell into the head into the combuston chanmber and wedged a valve open. You can cleary see the fatigue at the screw point of the shaft. Scoring was seen on both the #2 and #4 pistons. This actually happened to me before on the other side of the motor when I received a CODE 61 Error. That time the parts did not go into the motor.

IMHO the debate is over. If you are doing any headwork or motor work remove the secondary system. Blades, Rods, actuators, reservoirs etc. Who doesn’t drive our car in full power anyway?

Just FYI and I hope this helps another brother out. This is a failure point but after 20yrs there are bound to be a few. Please heed my sage advise. GC

Re: removing the secondaries a compelling story
 

Correctamundo. We don't need no stinkin secondaries ! Yank them out and plug 'em up.

Re: removing the secondaries a compelling story
 

I also want to add my car was a daily driver with 122k Miles. No issues up to that point for almost a year the engine just died. It did restart but was obviously running like a drunken mule on 7 cylinders.

Re: removing the secondaries a compelling story
 

Thanks Cliff its all about helping out the membership. :cheers:

Re: removing the secondaries a compelling story
 

And Frank ought to know. BTW My heads are being ported, welded and Multiangled at this time. With Petes Intake Cams and a 380 bottom end with a Fidanza flywheel. OH Baby

Re: removing the secondaries a compelling story
 

Jez, that stinks Daryll! Pardon me while I reach for the bourbon to kill the pain.

Okay I got a question.......awe come on you knew this was coming...:p....:o

The only stress that I can identify is the suction caused by an intake stroke when the butterfly is closed......which is almost all the time if you live where I do....maybe I better start driving around in 2nd and leave it at 4th till I get to WV.....:dontknow:.....I mean how could this not happen, right?

signed:
the lost grasshopper ;)

Re: removing the secondaries a compelling story
 

Must be heavy throttle syndrome. ;)

Re: removing the secondaries a compelling story
 

:thumbsup: but I'm serious...what stress? It takes 8"Hg & they're open fully. They don't close until you back out enough that the ECM says okay, no more. The only stress has to be from the intake stroke when they're closed, right?

On another note: I do hope you get the worst case of permagrin that side of the great plains!:thumbsup:

:cheers:
Tom

Re: removing the secondaries a compelling story
 

Yank em!, I Lost maybe 1 MPG, picked up 11 RWHP, no more "extra stuff" to go wrong or worse yet blow the motor a GC found out

Re: removing the secondaries a compelling story
 

i'm assuming the 11hp was due to extra work like porting or something not just tossing the plates

Re: removing the secondaries a compelling story
 

Tom I concur. The fatigue could be vibration and heat realated and not pressure/tension alone.

I was skeptical as well but remember this has happened to me twice. Once to each head. :mad:

Re: removing the secondaries a compelling story
 

Actually third. This happened to each head. 2nd time was the charm

Re: removing the secondaries a compelling story
 

Well Kevin, Marc Haibeck was involved in Phils build. Im sure a little but of this and a little bit of that made 11HP possible for Phil

Re: removing the secondaries a compelling story
 

Dear Biff Valve treatment. :)

Re: removing the secondaries a compelling story
 

it all makes sense now

Re: removing the secondaries a compelling story
 

Already done or I never would have went with the Fidanza. My transmission is a Bill special it was B&B and Cyro treated by the previous owner. One of the key factors in my decsion to buy this car. It wasnt the rear wing lol. GC ;)

Re: removing the secondaries a compelling story
 

Hey Goldy - I had Marc take my secondaries off this last spring. Haven't notice too much difference as I screwed up my left leg last July and I cannot push the clutch in. She just sits in the garage waiting for the leg to heal. Real bummer:mad: BTW when you decided to get rid of the wing I want first chance at it...:) When do you think yours will be ready for the permagrin???

Re: removing the secondaries a compelling story
 

O:eek:M:eek:G:jawdrop: That would ruin my day. But aren't the throttle plate screws swedged just like the air horn throttle plates to make it impossible for those screws to back out? When I took my throttle body apart for powder coating the screws looked like they were screwed in through the rod then cut off and the tips of them looked like they had been melted. So if you back them out you will rip the thread out. And the screws were flush with the back of the rod so I could not just grind the swedged tip off and unscrew them without ruining the thread. That's why I had to tap them the next size up 8-32. I would think all the throttle plat screws would be the same. Unless of course some one had messed with them previously.

Re: removing the secondaries a compelling story
 

http://i301.photobucket.com/albums/n...o1970/thts.jpg
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Then I had to tap them the next size up and install new SS screws and grind them flush to where the wouldn't back out. But not so much that I couldn't back them out and not have to destroy the thread again.
http://i301.photobucket.com/albums/n...rottlebody.jpg

No Dag necessary.:icon_thum

Re: removing the secondaries a compelling story
 

:handshak: Good choice D !!

Re: removing the secondaries a compelling story
 

You are first in Line Bobby but I will be honest. Unless im smacked in the rear end it isnt coming off. The PO said it was actually struted to the frame. I hope you heal up soon. When im in town Ive been driving Pops 96 CE LT4 powered. NLT than 1 OCT is the target

Re: removing the secondaries a compelling story
 

They are... which almost makes this impossible (right?) but its happened twice and they seperate right where the screw centers the rods (both times). The rods appear to break at their weakest point where is where the screw centers it. Its entirely possible they were over tightened at the factory and after 20 years or Heat cycles, Pressure, vibration whatever they failed. Believe me the Driver side head when it failed a year ago we all thought it was a fluke. Well im a believer. The secondary system is outta there. GC[-X

Re: removing the secondaries a compelling story
 

Frank a thought just occured to me. Should I increase the porting to the TB say 63MM. Help me oh racing obiwan.

Re: removing the secondaries a compelling story
 

Wow, Daryll... certainly not just a fluke, after having it happen twice on your motor. I'm glad my butterflies have flown away :)

Re: removing the secondaries a compelling story
 

I'd ask Pete about that D. He has probably forgot more than I know.

Re: removing the secondaries a compelling story
 

I raised this question a month or so ago and Mark Haibeck said there was very little benefit in porting the heads. Did I miss something?

Re: removing the secondaries a compelling story
 

according to his website head porting is worth 35 hp...http://www.zr1specialist.com/HAT%20W...20upgrades.htm

maybe mark can chime in here

Re: removing the secondaries a compelling story
 

Here is the link for full pocket porting. I think I need to get my car to Mark and see what is truly done to the engine.

http://zr1.net/forum/showthread.php?...Pocket+porting

Re: removing the secondaries a compelling story
 

FYI, "pocket" porting refers to porting just a small area of the head. Basically the area behind the valve.

The way I read Marc's reply was that there is little to be gained in this on the LT5, and that the real gain from headwork comes in porting the runners. In fact, in that post, he refers to it as the porting goldmine.

Re: removing the secondaries a compelling story
 

Yes ;) All heads benefit from porting. The real question does the cost = the potential gain. Your mileage may vary. Mine are being done at a local shop very cheap due to my sons friendship with the owner.

Re: removing the secondaries a compelling story
 

Ok pics are back up. I should have the car back this weekend. :pray

Re: removing the secondaries a compelling story
 

:cheers::dancing:mrgreen:

Re: removing the secondaries a compelling story
 

Great News, Daryll!!

Re: removing the secondaries a compelling story
 

Yep I am so..... Ready

Just installed a radiator today on my POPs 96CE and put his new front a rear CE emblems on. Took the day off bonding with tools always fun.

Re: removing the secondaries a compelling story
 

Cost = gain? Yep, that IS the question. AND, education cost $$ too! How does $100+/rwhp sound? That's assuming YOU do the engine pull and reinstallment. - Like I said education ain't free neither!;)

My heads had to come off anyway, due to a valve problem. (I believe was there when I bought the car, possibly due to a bad injector.) I love the power the porting bought me - I love it - don't get me wrong. BUT, IF you're not racing, 400+ rwhp ain't too shabby at all, and enough to get the attention of all contemporary Vettes except the "Zs"...NOT too shabby at all for a little DIY plenum and IH porting + exhaust system! And, my biggest "seat of the pants" boost came at that point; a 60+rwhp lift for porting the plenum and IHs and installing the exhaust. The additional 26-30 for the heads was just the cherry on top, but the BIG bucks was in the heads, as the engine has to come out, the porting (not for the fient fo heart) has to be done, the cams timed, gaskets, etc, etc, pressure tested and repaired as needed...

P.

Re: removing the secondaries a compelling story
 

Yes, the work to port the heads is labor intensive
and therefore either $$$ and/or a PITA. But,
If I read the thread correctly, the question was
is it worth it to open up (port) the Throttle Body?
See post #23.
That's another issue. Waiting for opinions........

:dontknow::happy1:

Then see post #26. I think Marc H. was mis-quoted.
He probably said there wasn't much gain porting the
throttle body, but porting the heads is beneficial.

Re: removing the secondaries a compelling story
 

From all the folks I talked to the short answer was no not really. Possible gain if you are going the stroker route but if just top end porting with no stroker action below no was the uninamious response. I went with no reguardless It wasnt worth it to me unless there was significant gain.

Re: removing the secondaries a compelling story
 

I recently had this conversation with Marc. If I recall correctly, he felt the 63mm TB was worth ≈ 6 or possibly 8 hp, ± on a stock block.

I was thinking it would make more difference than that. The fully ported top end increases area of the runners by approx 19%. Coincidently, increasing the TB from 58 to 63 mm is also approx 19%.

Well, physics is an interesting study, in that flow and pressure and resistance, are terms that can be translated into electrical properties; i.e., Amperes, volts, resistance...for example.

Curious what would happen in electronics if a similar model were built, I set up a series circuit with two resistors; one representing the TB, and the other representing the rest of the ported top end. And, for a benchmark, I used the power gain of my motor having been fully ported except for the stock TB. Then I reduced the resistance value of the TB by 19% to see what the difference in power would be. Coincidently(?)...the answer was 6 hp!!!

I'm not drawing any hard won conclusions, but it was a bit of a surprise, if nothing else... Sure would like to have a dyno day and a pair of TBs; one stock and one ported and swap 'em back and forth a few times to see.

Just a thought.

P.

Re: removing the secondaries a compelling story
 

Wow Paul you are the only one I am aware off that has put a hp figure to it

Re: removing the secondaries a compelling story
 

That's a pretty cool ratio calculation- the next question is that if it does anything under the curve before 6000 rpms and if you have stock exhaust manifolds, for instance, will that bottleneck negate any further intake gains.

I guess the tb enlargement might still be left for last- or maybe at the same time you port the heads.