Straight cut or helical?

66brm · Posted: Fri May 29, 2015 7:32 pm Post subject: Straight cut or helical?

Ok here goes, what would you do?

2110cc 82 x 90.5
CB2288 cam (FK-8 )
CB 1.4:1 rockers
Aircooled.net L5's with dual springs
CB lightweight 28mm lifters
Comp 9.25:1
Double thrust cam bearings

Car is a 64 with 4.12 diff, stock gears street driven on a semi regular basis

Straight cuts or helical cam gears? The reason I ask is not for the noise etc but for longevity of the bottom end, I want to get as much life out of it as I can.
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fivelugshortaxle · Posted: Fri May 29, 2015 7:38 pm Post subject:

No side load on straight cut gears. Go with the streight cuts
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youngnstudly · Posted: Fri May 29, 2015 8:08 pm Post subject:

I wouldn't do the straight cuts on that engine, especially for a street car. I don't see where you're going to get a ton of extra life from this engine by using them. IF the cam was much more radical than an FK8, I'd agree with the post above, but it's not.
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Fall23 · Posted: Fri May 29, 2015 8:21 pm Post subject:

This is how I see it. Bigger engine, High lift cam and rockers with great heads. Nice CR ratio. SO why let yourself down with helical. If you look at 80%+ builds out there including mine, never had a problem. Straight cut gears. High revs better performance. Go good quality all the way.

58 Plastic Tub · Posted: Fri May 29, 2015 8:39 pm Post subject:

Don't mind the whine? Go with straight-cuts.

Want to hear stuff besides the cam gears? go helical.

K8 will still be fine with Helical gears.
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67jason · Posted: Fri May 29, 2015 9:18 pm Post subject:

i run CB straight cut gears with a fk7 in my 2180 daily driver. the whine is pretty much non existent.
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jason · Posted: Fri May 29, 2015 9:31 pm Post subject:

I'd say the springs are the deciding factor. Single hi rev, helical. Dual, straights. You could still do helical if you don't have crazy spring pressure but said you don't mind the noise so I'd do straights. Mine aren't that loud, more noise from the exhaust and what not.

stanthedog · Posted: Fri May 29, 2015 9:39 pm Post subject:

I agree with Jason and 67Jason. I cam only here my magnums at idle. anything over that and it's all exhast Very Happy

67jason · Posted: Fri May 29, 2015 9:41 pm Post subject:

vwracerdave · Posted: Fri May 29, 2015 10:08 pm Post subject:

You absolutely DO NOT need straight cut gears until to you go with Chevy style K-800 springs or larger. Straight cut cam gears are one of the biggest pimped & whored out part to get extra money out of you. All the worry about extra side loads is crap I'll bet there is less then 1/10 or one HP difference. Get helical gears and spend your money on something else. Anybody that tells you that you "Need" straight cut cam gears is throwing your money away. Having said that you will not hurt anything by using them. I run helicals in my 2165 street ghia with an FK-8 1.4 rockers and it sees 50% drag racing.

How loud straight cuts are is completely dependant on how the case was machined from the factory. The noise level is dictated by how the centerline of the cam is machined into the case in relationship to the crank centerline. This is why the factory had +/- cam gears

How long helical gears last depends on what quality you get. Cheap assed Chinese shit won't last as long as good quality parts no matter which you get. There are junk brands of straight cuts that I would not put into a stock 1600. Buyer beware stay away from EMPI shit. If you can find them get the Bugpack "Made In USA" $35 helical cam gear.
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deadkombi · Posted: Sat May 30, 2015 6:37 am Post subject:

Straight cuts, they sound great...

fivelugshortaxle · Posted: Sat May 30, 2015 6:56 am Post subject:

Quokka42 · Posted: Sat May 30, 2015 7:08 am Post subject:

If you have a loud exhaust, and you are young and inexperienced in mechanical matters, get the straight cuts. They won't give your engine any benefits other than bragging rights, but they might impress the other young guys (and you obviously won't be the type to have women in the car.)
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Clatter · Posted: Sat May 30, 2015 7:47 am Post subject:

I totally agree with 'vwracerdave' on the straight-cut thing.

Consider this..
The factory used various different sizes of cam gears for a _reason_.
There are variations in the distance between crank and cam tunnel centerline.
Unavoidable...

So,
If you buy straight-cuts, you get one size.
It's either correct for your case, or it's not.
Too tight, and things will seize, so they typically make those straight-cuts in a slight undersize.
Too loose, and the gears become 'clackers';
Instead of whine, or silence, you get backlash that you hear as a clack-clack at idle, teeth smacking each other.
Which, IMHO, doesn't sound cool at all.
Can't help but think it doesn't do your valvetrain any favors either; Especially at a performance level that warrants straight-cut gears.

My experience is also that the Brazilian cases found often lately tend to have a bit more distance between main and cam tunnel, more requiring oversize gears.

Different brands of gears are known to have slightly different sizes, too.
Magnums, CB and CE and such will be closer to a true '0', while the cheaper China 'Dyna Gear' and Empi will tend to run a tad smaller, IME.

So, if you really want to do this correctly, you will buy a set of gears, try them out, and see how they fit, without committing to use them unless they fit correctly.
I keep a couple different sets of cam gears on-hand to test fits and verify not only what cam gear size the case actually wants, but how it relates to the particular set of gears to be installed.

But, I'm some kind of nut-bar.

Just do what everyone else does:
Stab them in, pay no mind to the fit, wonder what that clack-clack noise is, and either not notice it, or convince yourself that it's cool...
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mcmscott · Posted: Sat May 30, 2015 7:49 am Post subject:

raul arrese · Posted: Sat May 30, 2015 8:01 am Post subject:

I see both sides , I have used both with good and bad results , make sure you check the back lash real close on the straight cuts ... I have had some that were so loose they would clack there ass off ... helical will work fine also ... but really for the cost of a straight cut gear its no big deal .. they are cheap .. either way until you get real serious with springs.
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jfats808 · Posted: Sat May 30, 2015 8:43 am Post subject:

Imo, I feel that your proposed combo needs straight cuts. The helical gear in short order will start to develop thrust wear into your cam bearings. I've seen it happen to an engine with helical gear, single spring on stock heads and w125. I would err on the side of caution.
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Dan Ruddock · Posted: Sat May 30, 2015 10:02 am Post subject:

I have run stock gears with a web 86c for 40k miles with berg dual springs and the thrusts were like new when it cam apart. If they go away sooner than that with less cam something was done wrong. Polish the thrusts on the cam and use the right size gear and it will last.

Am I correct that the old Type 4 copper face thrust bearing are NLA? I have a few of those stashed away.

The only sounds I like to hear are intake and exhaust sounds which are music to me but mechanical noises (including a whine) make me cringe and would feel embarresed to call myself an engine builder.

I use OG mag gears as I can get the size I need and they hold up well. Sometime junk yard stuff is not junk.

Dan

Dan Ruddock · Posted: Sat May 30, 2015 10:19 am Post subject:

Oh look what I found. Money well spent on these and are cheaper than straight cuts.

http://www.thesamba.com/vw/classifieds/detail.php?id=1762566

earthquake · Posted: Sat May 30, 2015 11:56 am Post subject:

How come some body hasn't made a set of Dual Overhead Cam heads driven by belts that are shim over bucket so we can get rid of the valve train all together?
They could even be 4 valves per a cylinder! They did it on Air Cooled motorcycles for years.

Casey
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