[Sun Tuned]

1/2", and romulus...I'd like to talk a little more but it will have to be later tonight...chasing little ones around. Got a few tips on some things for you guys. As if I hadn't run my trap enough already. Nobody's asked me to do a tech session before so I'll use this as my soapbox instead.

[romulus]

Sun Tuned,

The soap box is yours! When it comes to Pontiacs, too much info is never enough. When the wife comes home, the first place she looks is the garage. At least she knows where to find me......

[Sun Tuned]

romulus,
Question #1....Yes
Question #2....An opinion. Mine is Yes, but it's just that an opinion. Like elbows....everyone has a couple.

The 10-32 screw trick is about the easiest and best I've seen to date. However, let me add a little "stew" to the pot. On circle track cars, it was taught to me to do the screw trick. Now why you ask, if the cam limits it and all that?? Well around these parts all the local circle track folks believe that they have to have the engine turn somewhere in the neighborhood of 476,850 RPM, or " something ain't right". RPM on some of these things will realistically run in the 8000+ range. Somewhere around 8400 the center cam begins to lose its hold on the advance weights and will allow excess advance. Delco didn't design the HEI to be spun quite that high in Grannys Chevy wagon. Wellll, now we gotta come up with something else. We need some "hep"(help for you yankees) as Mr.Bonner always said.

Now fellas, this screw deal plain works, but there are some tricks to incorporate to make it a better mousetrap.

1. Use the screw head turned or filed down works well, but you file past where it needs to be and file some more. Just enough to be able to use a little piece of 7/64ths vac hose as a sleeve to act as a tiny shock absorber. Works pretty good, but takes a little time to make. Use a little glue to make the damn thing stay put.

2. You can also, but not in conjunction with 1 above...use same screw with stop filed about .001 smaller than actual full adv of the weights as travelled to the mechanically levered flat end of the cam. In other words the cam is fully advanced when the weight tails are at the flattest portion of the cam. Now file the screw until it just allows this to happen. That should be full advance and the trick is to file about .0005 or .001 more off it . This allows the full advance plus about 1 dist degree extra after the cam is supposed to be done. You kill two birds with one rock here, because you are letting the cam do its job like I described above earlier and you still have a mechanical means with which to phisically stop the thing in the event of a f*** up. The 3rd thing this allows is a better way to not induce a bounce into the equation and lets the cam actually do its job. It's like an insurance policy for the cam for those that don't trust it or those that are trying to wind the thing into orbit or think they got an atom splitter under the hood. Gotta do a little thinking to implement it though but you already got the hard part figured out. But seriously guys, trust that chart I got at the top it's not there just to jack with everyone, it's there to help and be used as a tool. ST.

[romulus]

Sun Tuned,

Thanks for the great tips! Some pretty good humor thrown in as well. You had me laughing so hard that I woke the wif up I've found its always wise to keep the war department happy
Seriously though, I am probably just paranoid, but I like the warm fuzzy feeling of the extra stop, and your tips just make it better. Looks like the small lathe at work is going to see a little side job I'm guessing some small pieces of shrink tubing will also do the trick. When you get time, please drop me an E-mail. I'm interested in one of your advance kits. I have a feeling that the #389 cam I have brings the majority of the advance too early in the curve.

Thanks

[Bad Karma]

SUNTUNED Please see my thread:http://216.178.81.108/forums/showthread.php?t=451765

[72LuxuryLeMansLa.]

bump! SunTuned linked to this thread so I thought I'd bring it back to the top for quick reference.

Karl

[ta man]

BUMP again.

[Cliff R]

"How do we minimize, or eliminate HEI timing bounce with mechanical advance?"

Try installing a factory link belt type timing set instead of a double roller type. Even better find one with a plastic coated aluminum top gear and run that engine on the dyno thru an entire pull while following it with a timing light.

Then test the same engine with a Rollmaster or Cloyes true roller timing set on it......let me know what you find?.......Cliff

[Sun Tuned]

Ya Smokey yunick already covered these things many years ago already.

[Cliff R]

Going clear back to the mid 1980's or so I was working with a guy who own and campaigned Stock Eliminator Chevelle 396. The car absolutely got it done for what it was, 396/325HP application, cast crank, two bolt mains, oval port heads, etc. Pretty early in my learning curve but he pulled the engine for "freshening" up one day while I was at his shop. For the most part he kept pretty quiet about what was used in it. When he pulled the timing cover off there was a stock link type timing set on it with a plastic top gear. It was in MINT condition and literally looked like it came right out of the package. He told me that he had been using the same timing set for many years and just kept putting it back in service.

I asked him why he used it, he said it was quicker than any type of "double roller" set he had tested. I asked him why, he said something about less "spark scatter" or something to that effect. Then he pointed out how the stock timing sets have constant tooth contact and the plastic top gear has further benefits of absorbing some of the harmonics between the parts, etc.

I've been using them exclusively in my own engines since then, and the one time I deviated from that deal and tried a Rollmaster it worked fine for quite a while, then failed and had to be replaced.

I never got the nerve up to use the plastic top coated aluminum gear variety, and have been buying old style sets off Ebay for my own engines like the one in the pic below. I'd also add than I stand beside ALL of my engines in the dyno room on the first couple of pulls and watch the timing marks to make sure they are exactly where we want them. The engines where I use the stock type sets are smooth as glass all the way thru the pulls. Where we use the "high end" double roller set-ups there is always a little "bouncing" around of the timing marks. Not enough to be alarming or for anyone reading this to go the direction of a stock set, but the marks for sure move around a tiny bit more.....FWIW.......Cliff

[prostreet64]

Cliff, that is an interesting bit of info; one of those times when the 'best' results are seen when doing something that is counter-intuitive, My son and I ran into that kinda deal many years ago when comparing different air cleaner setups and found that for our combo, at least, we ran quicker with the 4" open element air cleaner rather than no air cleaner at all. Always a good thing to test the waters no matter what the prevailing practices are at the time.

[Cliff R]

I'm certainly got going to come on here and pound my chest and tell anyone or everyone to use the stock Cloyes or Melling T/C sets as there is NOTHING at all wrong with the higher end Rollmaster and Cloyes stuff. They also offer very easy cam degreeing vs having to mess with offset cam and or crank keys.

Then you'll run into a few folks who are stock parts "haters" and tell us these parts stretch out like crazy and fail miserably compared to true-roller/billet sprocket stuff, etc.

Even with all that said, when it comes to making the most power it's often the attention to details and small things that separate one very close engine build from another. If you pick up 1-2hp here, and 1-2HP there, and do it a dozen or so times during the engine build, when you add it all up your build makes more power and runs quicker than the guy who didn't take advantage of everything that was available.

Case in point. A few years back one of my customers did a very "basic" 455 build trying to duplicate my old iron headed 455 that was part of the KRE head testing articles in HPP and Popular Hot Rodding magazines.

He did a 455 about the same year, flat top pistons, mildly ported 6X-4 heads, Crower 60919 cam, etc.

He took it to the same dyno with the same carb/distributor (set up by me) and instead of making 455.4hp and 540tq he made around 490hp/499tq.

I asked him a few questions. Instead of using the 60919 cam he chose a "modern" cam with about the same .050" numbers and tighter LSA, because Comp Cams told him it would outrun the "old" 041 clone everyplace.

He did NOT zero deck the block and didn't use a 039" thick head gasket either. He did not use high the same Ford 1.73 rockers that I did. He did not open up his intake manifold like mine. Didn't back cut the valves, nor did he check pushrod geometry he just bought stock length pushrods.

So, failing to really "duplicate" my engine he just built one with similar parameters and it came up WAY short on power everywhere.

Bottom line and morel of the story, when trying to duplicate a very popular batch of chocolate chip cookies, use the same ingredients and don't leave anything out!........FWIW......Cliff

[Cliff R]

PS: just noticed my typo here:

"He took it to the same dyno with the same carb/distributor (set up by me) and instead of making 455.4hp and 540tq he made around 490hp/499tq."

My engine made 455.4hp and 540 peak torque.

His engine made 390hp and 499 peak torque.

My engine made the peak HP at 5400rpms

His made peak HP at 4900rpm's.

At 4900rpm's his torque output was clear down to 412ft lbs.

My 455 was making 486.4 ft lbs at 4900rpms.

Sorry for the confusion but I think anyone reading my comments will get the point and realize that very similar engines can have dramatic differences in power output.........Cliff

[Stripes]

Tested your data and its right on. Thanks so much!