Ok for some backgroud info i'm running a set of custom ground cams, they are for a turbo LS application. The cams have close to 12mm of lift, but a short amount of duration(about 15 degres greater than stock). i've been having trouble with my timing belt jumping. The 2 previous times(one which lunched 4 valves) it was chalked up to an onld timing belt....So a new one was bought and installed after we had to rebuild the head....

Please refer to this thread for more info
https://honda-tech.com/zerothread?id=222534


Holy friggin cow I'm about to set this POS on fire an roll it into the nearest congragation of innocent bystandards......This has me so pissed off right now. After a 3 day tear down a rebuild of the entire top-end of the car. It was fully assembled and ready to rock tonight. My friend gets done with it and takes it out for a test drive. He almost gets back to the house with it after a 2 mile easy slow drive, as soon as he clutched in to turn into my developemtn to car dies. Without a sound.

YET AGAIN my cams jumped time this time a full 180 from each other. And guess what I still have good/equal compression on all cylinders! Am I a lucky MF'r or what? Now I just have to use the 2nd chance to the best of my ability before I have to rebuild another head...or worse.

Please could some one tell me why my cams keep slipping? The cams have close to 12mm of lift and a low duration profile. I'm running Crower valve springs and Ti retainers. If let the tensioner pull all the slack out of the belt there still seems to be some left, so I have to coerse the pulley to take up a bit more by pulling on it. I think the cams jumped this last time because the tensioner pully bolt wasn't quite tight enough, but I thought I put enough force on it, I didn't want to snap it off. So this time I got out the torque wrench, set it to 40 lbs and hit the bolt with that.....

I know some of the DOHC VTEC guys have trouble with some of the high lift aftermarket cams, any wisdom there? Any other suggestions? I'm out of ideas right now. I don't feel like folowling the proper tightening sequence and torquing the tensior bolt to 40 lbs is enough. Am I wrong? I don't know if it has been a string of bad luck or what, but i'm 1/2 scared to take the car out for a test again. It never did this before I installed my new cams/valvetrain. but it costed my too much money to give up on.....

Tommorow i'm going to take off my adj cam gears and put the factory ones back on. Maybe that'll help some. I'm gong to the beach in 2 days and intend to be driving this car. I need some help fella's

Thanx for anything

~steven



[Modified by Speed PHreak, 1:55 AM 7/18/2002]

 

Hmmm thats a coincidence I'm having the same problem only my intake cam jumped 90 degrees and my valve train is completely stock, stock cams.

What kind of cam gears are you running??

Adi

If you wanna check out my post here is the link for it..
https://honda-tech.com/zerothread?id=224758

 

Not that I'd be of any help for mentioning this, but my belt didn't jump at all, but my engine almost completely lost compression in #4.

 

Newgsr: I'm running a set of Fidanza cam gears. I thought that they were a quality company, maybe not? I dunno Gotta start from scratch, stock is best when it come to troubleshooting. I'm gonna swap in the stock cam gears, and a new sping/tensioner pulley and go from there.....

In VTEC: Man that sucks, ever find out what it was?

 

Yeah see I had skunk2 cam gears and I also thought that they were a pritty goog gear well up on till now so I'm actually gona do the same thing.
I'm replacing the gears back to the stock ones and getting a new T-belt tentioner...

And so will just go from there...

Adi

 

Sounds like a plan to me, I didn't have any trouble out of mine when my valve train was stock, but now it's decidely un-stock. The was the cams are setup they don't really need any adjustment, so that fine by me. I'd rather have a top-end that doesn't eat valves more than I want 10~15 more HP.

Did you do a compression test on your engine yet? I'd suggest doing that before you take off down the road in it. I got lucky 2 of 3 times my cams have jumped and it didn't eat any valves. You car will run like *** or not run at all, if any of the valves are bent.

I was able to salvage my head, I only got 4 bent intake valves. With a little trading with some friends i was able to get an LS head to source parts from. 4 intake valves, a port job(why not), and 3 days later I was back in business.

 

have u read about the slotting your tensioner? make the slot longer so u can get more tension on the timing belt. ive read about people with jun3/toda C having probs like that, and they just slotted the tensioner to fix it.

 

Speed PHreak

I did a compression test and on a cold motor the compression was 130-135 across the whole board so I think I got lucky plus I'm running a Inline pro headgasket which gives me 2.7mm more clearance between the valves and pistons...

I think it should be fine I just got to get me a new tensioner belt and go from there all thou I think it was the cam gears that caused it but just to be safe I'm going with a new tensioner and stock cam gears..

On your car I can somewhat see why the belt would slip because of the upgraded valvetrain or should I say "valve springs" but still that stuff should not happen...

What would be your next step if you replace the tensioner and go back to stock gears and it still slips??? "which I hope doesn't happen!!!!!"...

Adi

 

Maybe "way" off here.... Buuutttt, are you sure it's not the pistons slapping into the valves, from lack of clearance between the two.

Just a thought....

 

Wouldn't that bend a valve? Not being an ***, or trying not too anyways. But why would it only do it after I take off down the road? I mean it'll sit, idle and purr like a kitten all day long. Even on acceleration it's perfectly fine, but when it is clutched in and the rev's drop that's when it jumps time. Any other time it's fine. Hell, we let it sit and run this past time all the way until the cooling fans came on, shut it off re-checked the tension(which was still tight as a drum). Then we cranked it up again after it cooled off a bit, checked, looked, and listen for anything wrong. Not a thing.

Only thing we can figure is wrong is that somehow we didn't tighten the tensioner quite enough and it moved. When I released it after it jump time the pulley didn't move, and there was hella slack in the belt. Both my friend and I were like WTF?

 

This same think happend to me on a full stock JDM B16. Mine jumped 3 times. \
It turned out the cams would seize In the head for a second and throw the belt off a few teeth. When it was disassembled the cam journals where scarred. but if you rebiult the head and the cam journals looked good then I am cluless?

The scarred cam journals can be caused by using the wrong tourqe specs on the cams ( too tight ) or no oil in the head.

 

There's no chance you guys were given the wrong water pump is there?

 

Ya know now that you mention it it did see some minor scarring on the journals. But I couldn't feel it with a finger nail. A shadetree test -- if you can't feel it with your fingers, but can feel a tug against your finger nail, it's about .010" of an inch. I didn't feel anything an rationed that it would be ok. Both times through I installed the cams, the cams were pre lubed with white lithum grease, and the journals/rocker surfaces had assembly lube applied just for safe measure.

All jorunal bolts were torqued down to 7ft/lbs(9.5 N/M) with one of these

A Snap-on Torqometer. Guaranteed to with-in +/- 2% accuracy. I've always used one of thse for those damned LS journal bolts, I mean 7 ft/lbs is a small amount you need something more accurate than a std torque wrnech to hit that.

No was am I gonna screw up a $600 set of cams becuase of impoper installation


[Modified by Speed PHreak, 7:15 PM 7/18/2002]

 

Mine did not look that bad eather!

I hope someone with more experience with chime in soon?

 

You definitely need to isolate which cam is doing the slip. May not be the one that has the bent valves.
Are you SURE on your valve to piston clearance. I know that it idles all day but things stretch and change at speed. If you only have a few thousandth clearance, something could be hitting.
Another thought. Could the distributor bearing be heating and binding up enough to sieze the cam and jump the belt?
Last resort. Back off all the valve clearance on both cams. Remove timing belt. Use a torque wrench to test lbs required to spin each cam in it's journals. Spin each cam with an air gun (using the center bolt). Feel for any funny vibration, sound or extra heat build up. Don't do this for too long as you don't want to run a journal dry. Let us know...

 

Replace Fidanze cams gears with stock gears

New tensioner and spring

everything seems to be in order now, close inspection of the aftermarket cam gear reveal that they are slightly mis-sized from each other.....

Update on how well it runs later

 

Speed PHreak

I'm glad you got yours fixed, I'm getting my new tensioner next week and I can' t wait to get my car up and running again..

Adi

 

Alright....here is the final situation. I ment to post this last friday when we got the car up and running but @ 3:30 in the morning I was just too damn tired. Ya guys feel me? Anyways, after getting some helpful insights from everyone here on H-T. I decided to replace the tensioner pulley/spring and switch back to my stock cams gears. That was the plan at least.

My friend and our 2 women were supposed to be grilling out, having a nice evening, and doing some wrenching all at the same time. Well my g/f arrives an hour late, and decided she wants to turn it into a fight (WTF is up w/ that?)......Of course I didn't care she was that late but she could've called..... So after an hour and a half fight she leaves, and I go back to work on my car.

We get the Fidanza cam gears off and the old tensioner pulley off. With the cam gears off I noticed that they weren't identical, one was ever so slightly smalled in diameter ....WTF!?. The old tensioner had a tiny bit of wobble in it too. Soo all that got replaced, however in the process we fucked up the tensioer spring, and guess what, the new pulley didn't come with a replacement......ugh. So it being 10:30 PM now, we have to devise some sort of tensioning alternative. We found and old brake spring and mod'd it to fit. I provides a good bit more tension than the stock spring too

All is set, we fire it up.......it runs like ***, timing way off, loping like crazy. Well damn. Com to find out I was off a tooth from TDC on the crank...Aight, belt off, belt on, one more time. Here we go....now she's purring like a kitten again. We let it warm up, give it a few revs, and then let it cool down. Tension check = good. My friend says he'll stay at the house and wait for to call incase it jumps time again.......so he can be waiting with the "tow vehical"

So, I roll out in it, taking it easy for the first 1/2 mile 2500~3000 RPM shifts. Everything seems ok, them she starts to over heat. I pull over and shut it off, turn the heat on an leave it running until my temps come down. After thinking about it and muttering a long string of obcenities, I remember I forgot to re-fill the radiator after we put the head back on on me fo sure.

I limp it back to the house, aside from over heating everything seemed to be running fine. Cams still in time, not mis-firing, no ticking, nice steady purr from the engine. I think she's gonna be ok. So we both hop in a roll out of the development to a back road, after a few easy drives back and forth, a few timing checks, and tension checks. We give it the So on the final leg back to the house I get on it a bit. Not much of a romp b/c I want to give the cams ample time to break in.(IE, the 300 mile drive to beach the next day).

Well my initial impression is this, the engine runs different. It seems to breathe a lot better. My spool time seems to be about the same. Though I did do a fairly nice port job on the engine. The engine no longer feels like it has the destinctive LS power curve, ya know peak at about 6000. Not sure how to really describe it. It does pull hard, without any signs of stopping. I've raised the redline on mine to 8K. Though over the past weekend it only saw up to 7500 about 3 times.

After the drive to the beach, the only race I got was against some bikes. I was rolling around at like 2 AM and saw about 4 bikes cruzing. I'm not sure on the engine size, but they all looked like the 900 ~ 1100 range. I'm not really sure on model either b/c most had custom paint jobs. So I deciced what the hell, lets find out if all the work made a damn difference. First time was from a 55 mph, 3rd gear punch ,against the lead bike. I pulled a fender all the way through 3rd gear, I shifted into 4th @ about 7300 or so......I guess out of habit. The guy on the bike looks over, give a smile, and falls back to his buddies. I'm happy i'm about to turn off, when I see 2 bike accelerate and flank me on either side. The one I just raced and another bike. Tthis time I slowed down enough to get into 2nd, as soon as a down shifted and the spool came up, I nailed it. I caught one bike off guard and lept a 1/2 car infront of him, the other was right one my door. I started to spin at the top of 2nd so I short shifted @ about 7K. I laided to 3rd and rode it all the way to 7500. I pulled a bit more on the lead bike, and the one I surprised continued to fall back.....I shut in down and shifted to 5th, 90 mph in enough for me. I got the big from both guys....

Although she wasn't running at peak performance. It does need some tuning with these new cams, and it was about 85 degrees and humid as hell. Even @ 2 in the morning, glad I took it easy in the 105 degree weather coming down

 

All Right

Good Job Speed PHreak

You have definitely brought my hopes up, now let me just install my new tensioner and go race some bikes too!!!!

Tanks for the write up and good luck with your car!!!!

Adi

 

Unorthodox Racing T4 Cam Gears are the single best, most dependable, and most expensive cam gear product.

If all you buy are products that are infallable, then you greatly reduce the spectrum of possible failure.

 

[dr. evil] riiiiiiigggghhhhttttt [/dr. evil]

I think i'll stick with my stock cam gears....they seem plenty reliable to me.

 

so i guess you got a 9 sec daily driver pulling on 1100 and all the next thing youll say is that you took a hybusa in a striaght line pull. Dream on and learn how to tension a motor the right way and stop ghetto-r riggin. Stick to stok, jet some real cam gears like JUN TODA SPOON the might be ugly but the use a stock gear with a mounted adapter so your timing marks will all lighn up. holla

 

Leave the guy alone

 

Glad you got your car back in decent running order

 

OK ****. Nobody asked you to ***** my thread. The car is a solid 12 second car on street tires. Though from a roll next to a bike where I don't have to worry about traction problems, why is it so hard to believe that it would pull on a 900 or 1100? Ever notice how well bike hook coming out of the hole? You don't spin the tire off on a bike or you'll wind up on your back.

Also, it's not my daily, nor would I want it to be. If you'll notice my sig I have 2 CRX's. Furthermore the only way I would attemp to race a 'busa would be for kicks. I am well aware that one of those runs 10's in the 1/4.

Why so harsh? If you would have read a bit you'd have found out that I tensioned the engine just fine everytime. I had no reason to doubt the cam gears to begin with. Fidanza makes some excellent products, I don't hold them responsible because everyone makes/has a mistake everyonce in a while. I was just unfortunate enough to get the a bad batch. The stock cam gears are now on the engine.

And as far as ghetto-rigging goes, unless someone looked no-one ever know the difference. I had limited resources and time with which to work with, I designed an alternative that worked better than stock for my setup. What does it matter anyway?



Thanks to everyone else who helped me out.