straight cut vs helical cam drive gears

[Northof49]

I am planning to run a W120 cam with 1.25 rockers, dual valve springs and double thrust cam bearings. Can I get away with oem helical gears like they sell in the set at CIP with the crank slinger, spacers and keys? I don't want the added expense of straight cut gears, nor do I want to run the gauntlet of poor quality parts.
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1958 Karmann Ghia owner

[bugguy1967]

I'm interested to know after what amount of lift, duration, or RPM are they considered necessary. Or is it the steepness of the ramps?
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"A petrol engine can start readily, run smoothly and give every appearance of being in good order, without necessarily being in good tune." - Colin Campbell, "The Sportscar Engine"

[kadub]

I think mostly spring pressure and valve lift determine weather or not straight cuts are a "good idea" or not. Trick is to setup your double thrust cam bearings just right, without too much clearance, so the thrust surface has a chance of keeping a good oil film protecting it. Most double thrust bearing sets I've installed in recent years seem to be just a little too tight out of the package. Be careful to not remove too much material off the thrust surfaces before installing and measuring. Also, POLISH the cam bearing journals and thrust faces before trying to remove any material from the bearings.

I think general rule of thumb is if you're running dual valve springs, best to go with straight cuts. I ran a very mild cam (almost a W100) with dual springs (turbo motor) and helical gears and my cam thrust was warn WAY past spec in about 6,000 mi. Should have no more than .003" end play on the cam thrust.

I switched to a set of straight cuts and REALLY HATE the noise they make. The more rigidly your engine/trans is mounted, the more those noise makers are going to piss you off while trying to enjoy a cruise, in my opinion.
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Karl

aka Turbobaja

[Art.b]

They are noisy...but I like it!
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THE MOTOR CITY

[GTV]

The problem with helical gears today is they are not offered in all of the +/-sizes that VW built engines with back in the day (far as I'm aware). Nowadays it's a one size fits all sorta deal.

I used to dig straight cuts also, now I dig quiet.
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EMPI Power Rules!

[Dan Ruddock]

I don't know if they are still avalible but the copper faced thrust bearing held up much better. Dan

[vwracerdave]

You don't need them with VW sized dual springs. When you run larger K800 or CB 650 springs then you need straight cut gears. The helical cut gears are just like anything else. You have cheap junk and good quality. I personally would use the Bugpack "Made In USA" helical gears.

My 2165 has the Bugpack gear with a FK-8 cam turning 6800 RPM and no problems.

The noise level of straight cut gears is dictated by the case machining of the relationship between the crankshaft centerline and the cam centerline.
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2017 Street Comp Champion - Thunder Valley Raceway Park - Noble, OK
2010 Sportsman ET Champion - Mid-America Dragway - Arkansas City, KS
1997 Sportsman ET Champion - Thunder Valley Raceway Park - Noble ,OK

[Quokka42]

True you don't need them on most street engines, certainly not on your combo - the guy who wore out his thrust in 6000 miles with a W100 obviously did something else wrong. I find the noise quite intrusive on anything but a loud strip or dirt engine - it is loud enough to mask other noises you might want to hear if something goes wrong. The noise is due to the necessary "slap" between the gears and while you can get a little noise from the stock style, the combination of aluminium and the helical cut makes it a lot quiter.
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There has only ever been one man who was perfect, and they nailed Him to a cross.

[vugbug68]

I'm actually disappointed in the lack of whine that my straight cuts have, I have a set of the CB pro series gears and a set of their normal straight cuts. Both engines have a very slight whine at idle but I was expecting them to be a bit louder. CB even told me that the pro series gears were noisy, I said good!
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71 Super - Backroad Thrasher
66 Corvair - Weekend Cruiser
90 4 Runner - Muddin

[kadub]

[mark tucker]

rememner the crank is also thrusted back&forth from those heli gears...it's not just the cam. I gopher straight cuts.

[deadkombi]

I have exactly that combo and they sound great. I'm using CB 044 heads with their standard dual springs. Won't hurt the engine anyway, but can be noisy. I would be more concerned about the 1.25 rockers. I tried scat, empi and now CB. The others gave 1.33 and 1.37 respectively. CB rockers with adjustment at the valve side gave exactly 1.25. I was told not to go over 500 lift at the valve. Make sure you check lift at the valve.

[64 ragtop volks]

If you want a loud whine use steel on steel straight cut gears.if you want it quiter use the aluminium cam gear .i like the steel on steel setup,makes it sound very nasty!

[Quokka42]

Ay, if noise is all you want get a rice burner and put one of those oversized ground scraping "silencers" on it.
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There has only ever been one man who was perfect, and they nailed Him to a cross.

[Northof49]

Well now that I've decided to order it, CIP is out of the spacers and won't shp it. Not much sense buying less than the whole kit.
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1958 Karmann Ghia owner

[mark tucker]

everything I ever got from cip was junk, was not what I ordered, it was subsituted crap at full price. and no refund on shipping thier crap back.they tried to pass off a crap crank for a 4340 crank,pure junk H beam rods that had the rod bolts so loose it was like putting 5/16 bolt in a 11/32 threaded hole. and bolts were rough like they were sand balsted with corse sand. I think the only thing I got that was what it was supposed to be was the engle FK 8 cam. the wild thing about all this crap is 95% of the people getting this crap dosent know it isant the real stuff.( oh we buy in bulk and package it our self so we can give you better prices!!!)NOT!!!there lots of counterfit parts out there.if you cant tell the dif how do you know???

[Northof49]

We are at a disadvantage in Canada for sources of parts. Shpping is a real killer from the States now. I am not ordering everything from cip, but they are convenient. The crank gear kit they sell is supposed to be Oem vw. I might just order the crank gear itself so I can at least go ahead with clearancing the camshaft.
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1958 Karmann Ghia owner

[Greezy Joe]

My straight cuts are not real noisy, Alum. I have pulled motors apart that the thrust, single thrust, was gone with Helical gears on a stock motor. The straight cuts do not push against the thrust bearing as hard. If you don't want the whine get the Alum cam gear, mine are from DRD.
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Current:74 Ghia Coupe w/ 2276
71 Ghia Vert w/ 1835
07 GMC Truck
12 Jeep Wrangler
73 Harley FLH 93 cid
89 Harley 883 Sportster (1200)


Owned before: 58, 69 Ghia Coupes, 64 Canvas Sunroof, 68, 72, 73, & 74 Bugs, 63 Single Cab, 65 Bus, 66 & 70 Camper
" Duct tape can't fix stupid, but it'll muffle the sound".

[jfats808]

I just pulled apart a 1776 with single springs this past saturday. It had a w125 and helical cam gear. The cam thrust bearing had between .030 and a .040 gouge in the inner face. End play was .0035. Missing the 1/2 side center bearing dowel, pieces of spring washer in the sump, oily metal sludge, etc. Un c/w crank 8 dowel w/ 8 dowel 15lb flywheel. I shook my head at the combo. My minimum cam like profile I do straight cuts with are w120. I may do a w110 dependant on the rest of the combo. I forgot to check the thrust mainly because of my shock to the thrust face. I did spin the cam like I usually do and it stopped after one rotation. Never know what you're going to find till u split it.....
In the end, better safe than sorry.
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