Here's a picture of my Hex-Adjust which let go during the last run of the year!!! http://www.chevelles.com/showroom/TWC/Timingcoverinspectionopened.JPG

If you run one of these devices you might want to check it.

Any idea what caused the failure? Did the hex adjust eccentric come loose? I run this timing set in mine. While the engine is apart being freshened up I'm strongly considering replacing it. This is the second failure I've heard of. I talked to my machinist who is also a builder and he said he refuses to use them. He said he has only seen 1 failure, and his shop builds/freshens 300+ engines per year. However he said that one failure was enough for him as he stands behind his work and had to make it good.

if you're running one of those devices....throw it away and save yourself $2000+ dollars.

Yikes! I can just picture bent valves and pistons with dents in them.
:eek:

Originally posted by Motor Martyr:
if you're running one of those devices....throw it away and save yourself $2000+ dollars. Ok, what's a better alternative that still allows for easy cam degreeing, yet isn't $600+ like a jesel belt drive?

If you ever feel you have an idea on what caused it to break I am interested in hearing about it. I've been running a hex a just gear for 10 yrs. or so and never had a problem and wont be changing it anytime soon. This is the 2nd combo I have ran them on and I know of a few others with no problems.

If we all quit using things we heard of breaking once or twice.. we would all be walking .. S**t happens

Damm I got one in my motor too.....BLK64SS you make a good point.

Can't say what caused it.Motor had about 25 passes on it. It is a well built motor running about 550 H.P. to the rear wheels. I could have limited the damage had I reviewed my oil filter screen after the previous weekend's race as we suspect that there may have been some alum. filings in the screen then. The big screwup on my part was I knew the engine wouldn't idle properly the morning it let go. I wrote it off to a change in the weather rather than stopping and figuring it out to be timing. I did my burnout for my 1st qualifying pass and the car quit after a weak burnout. I pulled it back to the pits. It started again, we checked the timing, it was @ 20 degrees. We just started to adjust the timing and clank it stopped. This time the distributor wasn't turning so we knew we had a big problem.
It bent all but 4 valves, pulled one rocked stud and bent most push rods. No lower end damage, barings etc. are O.K. etc.
We can't tell what happened,the bolts sheared off so they didn't come loose. It looked like the adjust mechanism was what let go. Anyway I'm going to a Comp. Cam billet set.

OUCH!

When the timing set was installed, were the allen head bolts tightened properly along with locktite on the threads?

I always make sure I spray carb cleaner in the threads of the cam to clean out any oil...then blow through the holes to dry the carb cleaner, then install the bolts with the loctite. Actually, the last time I put it in, I even used a special locktite primer on the threads of the cam and the bolts before installing. Just took the cam out and everything was still tight.

That failure sure looks like a bolt failure to me, as in they loosened up...guess we'll never really know the ultimate cause though.

Originally posted by 10secBu:
When the timing set was installed, were the allen head bolts tightened properly along with locktite on the threads?

I always make sure I spray carb cleaner in the threads of the cam to clean out any oil...then blow through the holes to dry the carb cleaner, then install the bolts with the loctite. Actually, the last time I put it in, I even used a special locktite primer on the threads of the cam and the bolts before installing. Just took the cam out and everything was still tight.

That failure sure looks like a bolt failure to me, as in they loosened up...guess we'll never really know the ultimate cause though. Todd,

That's the exact same procedure I used installing mine. 250 passes on that timing set and not a problem. Just took it apart last weekend and it looked good.

Good Point. I didn't do the installation but it is possible that the level of care was not there. I posted this as a heads up for those running a Hex-adjust to check it as I too have heard of more than one failure. The shop that I work with building my engines has also installed alot of them and this is their first failure. Lucky me!!!
Good news is I have all winter to get it back together.

Have you popped the valve covers off yet? I'd be concerned about having a bunch of bent valves from that failure.

Do you have any idea of that circular groove was there in the cover from new? Or was it possibly made by a bolt(s) backing out and grinding into the soft aluminum?

It definetly sounds like an error during assembly. Cant blame the parts at all for that.

I'm curious if anyone knows of a belt, chain or gear system that hasnt ever failed ??

Originally posted by 10secBu:
</font><blockquote>quote:</font><hr />Originally posted by Motor Martyr:
if you're running one of those devices....throw it away and save yourself $2000+ dollars. Ok, what's a better alternative that still allows for easy cam degreeing, yet isn't $600+ like a jesel belt drive? </font>[/QUOTE]a jesel belt drive is alot less money then buying a new valvetrain!
Most Street/Strip motors dont need to do anything but install the cam straight up, or 1 or two degrees advanced to compensate for chain stretch.

Sorry to hear about your misfortune TWC, this is the 2nd time i've heard of this failure with those peices, and timing related symptoms prior to the big bang.

A 3 keyway cam gear :confused: . Sure you don't mean a 3 keyway crank gear?

Still, that doesn't help dial in the cam degreeing process...only gives 4 degrees advance or retard.

I guess I'm just not too fond of degree bushings and drilling out a cam gear.

I thought that maybe you knew of a timing set that allowed for accurate cam degreeing, but was a different design than the Cloyes...maybe like the Comp setup?

re-read my edited post, i've had a long day.

I used a 3 keyway CRANK gear to dial in my cam, set it to a 104 ICL, and was happy with that.

Point stands, that there arent too many street/strip motors that need at the track adjustability of the cam timing.

tw,
I have never seen a problem with one. Most of my racer customers use them with big cams and even stronger springs. By the way, the hex portion is not intended to keep the cam from moving, it is only for adjustment, and even then you have to back off the valve train or you will break it. The bolts and the pin are what keeps the cam from moving. I think 10sec made a good call....it looks like the bolts were hitting the front cover for a while ... they might have come loose. I have also seen a couple of cam pins come out and cause some major death and destruction. If the pin is "missing in action" that may be the problem.

Originally posted by 10secBu:

I guess I'm just not too fond of degree bushings and drilling out a cam gear.
That is the way I do it with my Cloyes double roller setup. :(
Is there anything I should be aware of that is bad doing it this way. I've never had an issue. I just install the "zero" bushing, degree in the cam, see how many degrees offset it needs to be installed to get my ICL, install the correct bushing, then check it again. I was thinking of the "hex-adjust" setup for next time after I read through Ken Jett's nice .pdf writeup on his engine build.

Oh, I agree that changing the cam degree at the track is a very low priority.

It's just me, but if I'm gonna take the time to put a degree wheel on the front of the engine during assembly, I want it degreed in dead nuts, or as close as my eye can get it (maybe 1/2 degree).

That's why I asked about alternative timing sets that allowed for accurate degreeing during setup.

Mines apart right now and has 100 passes on the chain set...no stretch was noticed, but if I need to consider changing, now is the time to look at what else is available.

Next setup is gonna require more spring pressure which will put more stress on the chain, so I'd like it to be as bulletproof as it could be.

Jim,

I've never used the bushing deal, but my understanding is you have to drill the gear from the back side and stop before drilling the whole way through the front. If you drill throught the whole way, there's nothing to keep the bushing from falling out.

As I said, never used them, but that is my understanding of their installation.

BillK brought up another good point. I myself never turn the allen adjuster with the valve spring tension on the cam. I always tend to degree the cam in with the engine on the stand and the heads off, so there's no resistance or tension on the cam pin/adjuster.

I guy that I put a roller in for his 468 had one of these things and I talked him out of using it again....ended up using a offset bushing ,now i'm glad we did ....i know he will be too! :)let me just add one more thing.Drilling out a cam sprocket is very elementary.The bushing is held in place by a retainer plate and staking if desired....I dont know of any bracket racer who ever changed cam phasing at the track....I've used this setup with a decent roller chain for many years ,never had a problem

Yes it looks like the allen head bolts backed out thats what ground the cover up and left debris in the oil filer the week before.

I have used the Hex-a-just for years with no problem loctite is a must when assembling.

I agree, it appears the bolts backed out,contacted the cover, and then sheared off.

TWC, ugly. Ouch. Always hate to see mangled metal. Good thing the carnage wasn't obscene and total.

Todd, the Crane cam bolt 'cover' I installed covered up the bushing.

What I wonder is what if the bushing slips in the bore, or does the tension hold it steady?

I actaully took a very sharp chisel and gently 'peened' mine in two spots. Likely wont hold if it wants to twist in the bore ( gently peened!), but you'll be able to visually see it if it moved. Anyway, to a novice engine builder, it didn't seem like it would stay put. Otherwise, it dialed in pretty easy by continuing to rotate the eccentric bushing in the bore.

I should do a "quick and dirty" timing test next time the covers are off.

Another vote for a bolt backing out.
I too have been using the hex adjust off & on for as long as they have been around & never had a problem.
Only thing I see getting broken with regularity is the little eccentric adjuster because some people seem to have trouble following instructions,,,,
You cannot use it to adjust the cam with a load on it.

So just exactly what is this thing? Seems like something to degree a cam by the discussion, or something..I don't know so just want some learnin'.

Here you go Taylor: http://store.summitracing.com/default.asp?target=productdetail.asp&p=331&N=120+4294925232+4294924497+300331

Another vote for the bolts backing out. A good case for a) locktite, b) french locks, or c) safety wire. It's an unfortunate failure that quite probably was not parts related.

My new Comp Hitech chain ruined my engine. bent pushrods, smashed lifters, valves, seats, guides etc

So i bought a fail safe Jesel belt.

It went loose. 3 bolts into camshaft was broken.

Bought a new set of bolts, i saw when it start wobbleing. Nothing hurt. But i bought better and longer bolts. Works fine now.

I have a question for those using Locktite to keep the cam bolts in place: why not just use a cam bolt lock plate (french locks)? Wouldn't that provide a whole lot more positive lock? I'll probably use both on my BBC build!

Originally posted by Rich-L79:
I have a question for those using Locktite to keep the cam bolts in place: why not just use a cam bolt lock plate (french locks)? Wouldn't that provide a whole lot more positive lock? I'll probably use both on my BBC build! The Hex-A-just uses allen bolts that are recessed into the cam gear. You really can't use a cam lock plate with how the cam gear is machined.

Originally posted by 10secBu:
</font><blockquote>quote:</font><hr />Originally posted by Rich-L79:
I have a question for those using Locktite to keep the cam bolts in place: why not just use a cam bolt lock plate (french locks)? Wouldn't that provide a whole lot more positive lock? I'll probably use both on my BBC build! The Hex-A-just uses allen bolts that are recessed into the cam gear. You really can't use a cam lock plate with how the cam gear is machined. </font>[/QUOTE]Ah, I see!

http://www.qis.net/~geislert/cam_gear.jpg

Another happy Hex-A-just user. I've run mine for 5+ years and have not had a problem (676 RWHP). I like the Hex-A-just for ease of degreeing the cam during assembly. I completely agree w/ Wolfplace and 10secBu that proper use of the Hex-A-just eccentric (unloaded valve train) and loctite are key to reliable operation.

Good luck,

Mark

I really enjoyed dialing in my solid roller with this set and have had no problem with it. I was also careful to clean the threads and loctite them. You could drill the allen head bolt with a 1/16 drill and safety wire them for ultimate insurance.

Any chance that the built in cam button on the 2 piece cloyes cover failed and might have gotten caught between the sprocket and the cover? This could shear the bolts off and account for the damage to the cover.It also appears that the cam gear is scored.

Doc

The circle carved into the cover around the cam button clearly shows that one or more allen head bolts backed out and lathed the groove before giving up.