critter

iTrader: (9)

Sounds fishy. My cam is 232 @ .595 and Comp said I needed 145 on the seat and 350 open. Unless your cam has very gentle lobes (which doesn't seem likely given the duration and lift) I can't see how you can get by with less spring than me. Sounds like valve float erased your .070 clearance and caused the pistons to get kissed and the head to drop.

CHRISPY

Did you clay the heads to properly measure P to V clearance?

.070 on the intake is NOT enough clearance.

Good Luck in getting it resolved but I am not sure if you have any recourse.


Chris

bigdsz

iTrader: (1)

I think he does have recourse, somebody had to suggest those valve springs to him. I said earlier that I thought the case might be made for valve float. The question is did the valves float at a reasonable RPM say less than 6,600, if that's the case I think you might argue that seat and open pressures were too low. If there was float at say ~ 7,000 RPM then somebody raised the rev limiter and over revving caused the float.

CHRISPY

If he bought and setup the combo how is it anyone elses fault? It wouldnt matter what springs you run with 70 thou clearance it is still pushing the edge imo.

QuietTahoe

Just $0.02 from a guy with over 24 years with my own machine shop and over 32 years in this business. If you have that big of a cam, you intended to spin this engine pretty high, so it's pretty inconsequential about who spun it to what RPM. I don't care what brand of valve springs you run or what seat and open pressures your running, once you pass 5000RPM the valve is lofting over the nose of the cam. I guarantee you it is not passing smoothly over the nose of the cam. I've see lots of Spintron traces and you rarely see a trace of a pushrod engine valve train that ever has the lifter follow ON the lobe over the nose. The lifters might bounce across the cam nose on occasion, but that actually causes more wear than the lofting. Anyway, that is why all good performance shops insist on a minimum .100" Pto V clearance and really like to see .120"! I sympathize with your problems. Most of us have been there at one time or another. Keep in mind that those pushrods flex and act like a pole vaulters pole lofting the valve. Not enough seat pressure and the valve bounces and can break the head off the valve. Too much seat pressure and/or too high a spring rate and the pushrod flexes more and causes more lifter lofting (sometimes with disasterous results). It's a fine balancing act and only real world experience while help you understand what is actually going on ( as opposed to a lot of "theory" that is freely tossed around). Unfortunately, tuition in the School of Hard Knocks is the highest tuition there is.

My best advice is don't try to take a little bit of a lot of opinions and build an engine. Go to a reputable engine builder, tell him what you want and take his advice and go with his combination. Believe me there are several different combos that will get you to the same place, but you must stay with one complete combo! This might sound harsh, but if your looking to place the blame anywhere, start by looking in the mirror!

-Joseph-

iTrader: (12)

For a race-only engine Intake can be run to .040" at the very min., exhaust minimum .070", thats from several engine builders that build engines that cost more than most of our cars.... You'd be surprised, some LS1 "street" cams have less then that though! (not any we sell though) Personally I'd prefer .080" intake .100" exhaust if possible. Clay is not accurate enough to check when you get that tight either, use a solid or shimmed lifter, adj pushrod and a dial indicator. I wouldn't trust clay in any increment below .100" at all.

SilverGhost

iTrader: (53)

after talking to mike on the phone for quite some time today there are some things he isn't saying on here that he said when answering some specific Q's from me that make me really wonder about this shop that had the car last.

I won't go into details as I believe the results from the GM tech's scanner are going to be the deciding factor on a lawsuit here(there IS grounds if certain info comes up on that scanner) and don't want to put anyting in public that should not be said in that light.

And why can't an A4 be over revved on the dyno(not saying this is what I think happened necessarily to this motor)..mike told me he watched them the first day manually shifting the car on the dyno and he asked them to stop doing that. if they did it again they could have over revved in theory.

Camaroholic

iTrader: (1)

(I know I said I'd shut up... )

I still don't buy the overrev on a A4 theory. Even manually shifted, you have the rev limiter. It won't go above that.

I bounced my old motor (stock longblock but with a cam and isky 235 springs... good to .558 lift ) off the 7000 RPM rev limiter all the time (ever dumped a clutch at 7k on slicks? weeeeee.... ). Then I handed the motor over to Coach, and he did the same (5.13 gears and 29" tires will bang a 7k limiter about 100 ft before the end of the quarter). The motor's still in great shape (he did break one retanier, but caught it before anything happened when Thunder put in the TRex). That's on a stock '98 motor with just a cam, valvesprings, pushrods, oil pump, and timing set replaced. 7000+ should be no sweat for a built motor, especially when it was planned to go at least there.

Ultimately the PCM has control over the electronic transmission and the rev limiter, even when manually shifted. Unless the shop was *really* negligent (mind numbingly so), I still don't buy it.

Now, if the shop was wrapping it up (7k+) in first gear on the dyno, I'd have to wonder why they were doing that, unless they were simulating the 1/4 mile on a Mustang dyno or something... I could, however, see the case for manually shifting through the gears to make sure that the pull is done in 3rd (and not letting the PCM drop it in to 4th). But you would not need to wrap it up to 6k+ to do that. Only making sure the rollers were spun to the right speed to hit 3rd for the pull...

Billiumss

iTrader: (11)

One thing I don't get is why you didn't try to get it to run on the street first? (Part Throttle Tuning)

A lot of people think that 'get it on the dyno right away', not true, drive around a bit and make sure it DRIVES before the dyno.

I don't think the tuner did anything wrong. The first pull he shouldn't have went over 6k anyways...

Your trying to find a place to put the blame, I'd say the engine builder. If he knew what he was doing, valves wouldn't have hit the pistons.


What is your full list of mods?

QuietTahoe

It blows my mind how many people on this site want to build an engine on or near the"edge" and then they want to blame somebody when it comes apart or doesn't run the way they want. If you take your parts to an enginebuilder and he suggests something different and you say "I all ready have my parts and this is what I want to do", then you have designed the engine and share some responsibility. Guys, the world of racing and high performance involves learning by what doesn't work more often than what does work. If you blow an engine in a race (or even on a dyno), and can't pop the top on a cold one and say "that's racing!", you shouldn't be messing with this stuff. The factories all sold factory "hot-rods" and they have often been sold without warranty. FYI general warranty in the High Performance industry is "60 seconds or 60 feet, whichever comes first. It's time to learn and move on!

1998redcoupe

Well the GM tech's scanner info came in and five simotanious codes came up at the time of my motors demise. The codes signify a motor seizing up and the info on the rpm's at the time will be on paper officially Monday. the motor was blown at wide open throttle and the reading from the MAF sensor revealed a unusually high RPM. Almost as if someone was shifting gears with their foot on the gas an skipped right into neutral. I love electronics. The tech said that based off the reading from the MAF sensor the RPM's had to be around 8500 for the amount of fuel the computer was trying to pump into the engine. Is that an over-rev? Guys I built a motor to spin around 7K I will not deny it and I also informed them to not turn more than 6000 until I felt the motor was broken in and would bring it back in a month for all out race tune. However no matter how much I would like one, I do not have a nascar motor capable of 9000rpm's and I never intened it to go this high. I will give you the official RPM's monday or tuesday after I talk to my attorney. I would really like to share with you everything but for fear of ruining a possible lawsuit I can not revielve my cat in the hat evidence I have. I also do not want to slander someone's company name for fear of myself being sued. When I feel I can say everything I will. Wish me luck.

11 Bravo

iTrader: (3)

The pcm won't lie. The shop overrevved it, cut and dry case. Sue their *** if they don't make things right. Good luck! BTW, I personally would not let anyone put their foot on my gas pedal unless I was right there. I know it won't help you, but live and learn.

Pro Stock John

iTrader: (34)

Only way I can imagine seeing an 8500 overrev with an A4 is if a person backshifted the car from 3rd to 2nd at WOT... I have never seen it happen but I could see where the overrev would happen faster then you could imagine.

My own opinion (though I agree with Quietahoe on a lot of his points) is that your spring pressure sounds inadequate, very much so for that huge cam. Biggest cam I have heard of in in a stock cube motor. Good luck, maybe get all your facts before you start blaming others.

MyLS1Hauls

iTrader: (2)

You can't just look at the MAF reading and guess the RPM. What was the specific MAF volume/frequency? You can't accurately guess the RPM. Sure you could calculate the theoretical airflow, but the VE at that rpm would be very low and that needs to be taken into account. Sure the PCM takes a snapshot if it sets a code, but it cant tell you everything. If the PCM did take a snapshot, RPM is included in this data. For it to have recorded information, there would have had to have been a DTC set...which would suprise me. Also, if you revved the motor to 8500, I'd be willing to bet that more than one valve would have been severely damaged.

CHRISPY

I dont know anyone who would recommend .040 on a hyd motor. Maybe 3 times that amount...

You would have freeze frame info when a DTC was set from overrev. It would show rpm there. Do not go by MAF readings to "guess" rpm...

SilverGhost

iTrader: (53)

The basic point is this. The shop swore up and down that they did not even START this car. They called Mike claiming they couldn't get the motor started so come and get it, and here is the PCM data showing they had the thing at WOT, regardless of what the rev's turned out to be.

I asked Mike some very specific questions abotu what the plugs looked like and from his answers I didnt' need any PCM info to say they were not only running this motor but were pounding the **** out of it with a very unsafe tune in it. Guys he said he couldn't even SEE the white ceramic anymore on the plugs, they were black..not just speckled, but black... we all know what that means.

NOSjohn

iTrader: (9)

Sorry to hear about your bad luck with motor building. I think we've all been at that point one time or another. I remember back when dirt was first invented. I was all excited to put a Nitrous kit on my just broke in 350. Damn, wouldn't you know I was in such a hurry that I didn't even notice the fuel solenoid was mounted backwards...dummy me. Fired the motor, ran great, tried to "purge" the kit, damn motor died and wouldn't restart. I think the problem was two-fold...sticking plunger and rev. mounting the damn solenoid. Well, I learned from that school of hard knock....good luck.

marc_w

So what if the second shop really DIDN'T start the motor, and the first shop is the one that popped it?

How can you prove it?

SilverGhost

iTrader: (53)

he was there for the first shop. a valve getting broken off in the motor is kinda noticable when it happens.

1998redcoupe

Sean was really busy today but will call when I have my computer print out in my hand and talk to you about it. Talked to my lawyer and he says it sounds like an open shut case with the computer info. Will call.