ShopTalk Forums | Aircooled VW Tech & Restoration Help

I'm building a VW trike, out of a 1973 Super Beetle 1600cc, dual port engine, and I'm trying to decide on a cam.

Can anyone please tell me the valve timing of a stock VW engine of that same year?

Thank you very much.

Check out this page as it gives the stock cam info. -> http://www.1800vw.bizhosting.com/caml=Lift_dur.htm
Don't get carred away with the cam, as what you need is low end torque.

No, unfortunately, that page doesn't help. It simply says the duration is 225 and 285 - 300 lift, but it doesn't tell whether this is "advertised" duration or "duratioin @ .050", and it doesn't tell whether this is "lift at the cam" or "rocker lift".

But thank you very much anyway.

And yes, I'll be careful about the cam.

Many years ago, in the old flat-head Ford days, I built and raced modified stocks at Medley Speedway, in Miami, and was top money winner for 1951-1952, plus I built racing engines professionally.

But none of that does me a whole lot of good today with a VW engine.

Thank you very much.

Gene Neill wrote:...But none of that does me a whole lot of good today with a VW engine...

It means you know how to tend to the details, and that helps a whole lot.
Cam timing on a VW engine is a bit radical compared to a "conventional" engine and all the experience in the world with the latter isn't going to help you much in selecting a cam for your project. Tell us the gearing, tire size and gross weight, and whether you're more interested in low-end tractibility or sparkling top-end and you'll be sure to get some suggestions. Will you be bumping up the compression or do you want to stay with 87 octane fuel? What are the carbs again? Only a handful of "performance" grinds will work with stock valvesprings and pushrods, and many extend the upper RPM range well past where a stock crankshaft can be used without damaging the case - there are several good stock-rocker cams that will work well in the critical 2000-5000 RPM range with a stock valvetrain. Have you considered increasing the displacement? The expense of going to 1775cc is trivial and wouldn't necessitate changing any other components.
A stock cam has about .214°@.050" and .334" valve lift w/1.1:1 rockers...
"advertised" duration would be ~250°
By way of comparison a Scat C25 (which I think should be one on your short list) is "275°" 235°/.385". Bugpack's 4061, Engle's W-100, & Web-Cam's 86 are likely prospects too (the latter two accept 1.25:1 rockers readily if desired). You're right on the cusp between shimmed-up stock springs and some light "HD singles", the added mass of non-stock adjusting screws or steel pushrods will push you over. If you need stronger pushrods but want to keep a quiet valvetrain there are some good HD aluminum p'rods: http://aircooled.net/new-bin/viewproduc ... 10&cartid=

Thank you, Marc - Master Of All Things VW!

Yes, I am spastic over details.

And yes, I know my professional flat-head engine building of yore is worth very little to me today with the VW.

In answer to your questions, I don't know the gearing yet - haven't opened the transaxle to count teeth yet, but I'll be using stock gearing; don't have exact tire sizes yet, but they'll be 27" in diameter, 10" wide and low profile tires; gross weight = normal VW trike gross weight; more interested in "low-end tractability.

I'm going to run twin 36 or 40 Solex carbs, new 044 heads, stock 1.1:1 rockers, light flywheel, centrifugal distributor, premium Amaco white gasoline on 7.5:1 CR - and all I want is a mild street cam, 3/4 at most.

I can't get Bugpack's 4061 specs online; can't get Web-Cam's 86 specs online, and the Scat 25 specs you gave me and the Engle 100 specs both seem a little more radical than what I would call a "mild 3/4 street cam".

Anyway, thank you very much for your help.

I've heard the term 3/4 cam before but for the life of me can't remember details of how one should 'feel', guess I'm too young. But what Marc said is dead on, those cams he listed are likely the most mild non-stock cams you can get without doing custom grinds. Running dual 1bbls carbs lets you get away with bigger cams w/o sacrificing drivability. Dual 2bbls carbs lets you do some crazy stuff that the small block world would never consider. For example, the cam specs for my daily driver (70 miles/day) are 300 advertised, 260 at .050" and .560" at the valve. It's a Webcam 86B, probably shares the spot of 'most popular cam' along with the engle FK-8. Pulls from idle to about 7500rpm.
The rest of the engine is what helps to support this cam choice, but you probably get the idea that this is quite a different world from the V-8 guys. Engine building experience is universal, it's all about details, so you have that much going for you. Now you just need to adjust to a different set of details. --Ryan

Thanks Ryan - but never mind. Someone sent me the stock VW cam timing, and that was all I was asking for. Remember? I know all the rest.

And yes, you're right. You are a trifle "too young." Smile, Ryan!

You don't "feel", Ryan, a 3/4 cam. You study and learn and experiment for thirty or forty years, professionally on race tracks and as a fan on the streets, and you still can't "feel" a 3/4.

You recommend the Engle F -K8 for my pitiful little neighborhood 1600 VW trike, but Engle says this grind is "PERFECT FOR LARGE DISPLACEMENT, STREET AND STRIP COMPETITION. IT OFFERS 298 DEGREES OF DURATION AND .382" LIFT AT THE CAM. DESIGNED FOR USE WITH 1.4:1 ROCKERS, BUT YOU CAN USE LARGER."

If you were older, you would perhaps have read Engle's recommendations.

Or you would have known from experience that a 298/382 is WHOLLY inappropriate for a "mild 3/4 street cam."

And your recommendation for a Webcam 86-b is even far less appropriate. But - like you say - you're still young.

Joel Mohr did the 11.55 1/4 mile @ 114 mph; 723 in the 1/8 in his 84x94 2332. He was running Bugpack flanged with Chevy journals and type 4 center main. Scat H beams 5.6, Berg pushrods, Mahle lifters, Pauter 1.5s. His heads were 041s with 45.5x35.5 Tivalves with Berillium copper seats; THIRTEEN POINT TWO CR; EMPI MANIFOLDS with P&P; 46mm butterflies, carbs bored to 44mm; a 21mm Shadek oil pump . . . .

Oh Yes. I almost forgot. Must be getting old. . . .

HE WAS RUNNING YOUR WEBCAM 86-B!

Give me a break, kid.

And stay out of print as long as you can.

Guess you didn't read to closely, I believe my exact words were, 'for example'. As in I gave an example of a cam that you apparently think is too big based soley on numbers, very short sighted on your part. As you said experience here is the key. Do you have experience with that cam? My engine isn't even stroked, it's just a 1915. Point was simple, it's a cam that has bigger numbers than you are used to, however in this arena it is not considered a big cam. It is by all means a street cam.
I'm young yes (26), but I obviously have more experience in this field than you do. The age comment was made because I don't know the details of what a 3/4 cam is, it was before my time and not even in my field of interest, V-8s. I do however know the details of the cams that you just shoved off.
The idea I was trying to get across to you is that the cams suggested by Marc are mild cams, probably along the lines of what you are looking for. I was actually supporting his suggestion and trying to make you understand that they are NOT 'big' cams. And by numbers alone, even bigger cams still are not that big. --Ryan

You know I just went back and re-read your post even closer. Time for point-counter point.
As for how a 3/4 cam should 'feel'. Plain and simple, what's it's powerband. What does one expect from it. If it takes you 30-40 years to learn what one cam feels like, you're in the wrong hobby.

Not only did I read all the info on Engle's website, I use it quite often for comparisons. I've corresponded with Mark Engle on a few occaisions via email in the past and know the specs of most of the VW cams by heart.

A Webcam 86B is very much like a K-8 (that's slang for FK-8 for the newbies who don't get it). It lifts 1 thou higher and has 2 more degrees advertised and at .050". My numbers are different than spec because if you ever bothered to measure actual valve lift, you'd find that damn near all ratio rocker arms in the VW aftermarket have higher ratios than advertised. My 1.4s measured out to 1.46.

As for Johl Mohr, who cares what the specs of his race engine are unless they are trying to either compete with him in the kadron class, be a name dropper, or act like they think knowing those specs makes them special. Or, big OR here, you copied those specs off AJs (www.lowbugget.com) site, DOH, word for word even. You should really cite your references, that's plagiarism.

My suggestion to you would be that just because you're old doesn't make you smarter than me, it does seem to make you come across as an pompous jerk though. Next time someone offers advice regarding something you know nothing about, don't attack them without pooling your resources first. --Ryan

Gene Neill wrote:Give me a break, kid....

Tell us, Doc, what did Ryan say to deserve this? If you think an Engle 100 cam is "radical", you have a bit more learning to do. For starters, I would suggest Gene Berg's book of technical articles...

Gene Neill wrote:Thanks Ryan - but never mind.

Oh Yes. I almost forgot. Must be getting old. . . .

HE WAS RUNNING YOUR WEBCAM 86-B!

Give me a break, kid.

And stay out of print as long as you can.

wow....Gene, you'd think since you know more than anyone here you wouldn't bother trying to ask a question here...you are apparently new to the vw engine building...the people here have experience you don't...at least be open minded enough to add it to the "research further" list....3/4 grind cam is v-8 talk, you may not find too many here that understand that...if you really want to communicate here don't expect everyone to learn your "lingo", try to pick up the lingo used in the vw field..."When in Rome......"

LOL I come from a small block world too. When I started looking at cams and saw a duration of 240* in the Engle book I was shocked that they called this a street cam. In the V8 world this would put you smack in the 3500RPM to 7000RPM range. But in a bug apearetally it will purr like a kitten at idle.

But when people, no matter how old, who have built a few motors I have never delt with... Well I am inclined to listen to their advice.

what the heck! dude Ryan you're pretty cool in the face of that trippy cat..I don't know either how the heck you deserved that reply..dang, age got nuttin to do with it!

3/4 cam ? I've heard that alot too back in my V8 days..something to do with three quarters..or in cam talk 270 degs or somewhere around that.

VW Grommet wrote: 3/4 cam ? I've heard that alot too back in my V8 days..something to do with three quarters..or in cam talk 270 degs or somewhere around that.

Naaah, strictly a subjective term that allowed cam grinders to keep their numbers secret. "Full-race" was for a car that spent 100% of its time on the track, "half-race" for a street/strip car, etc.
3/4 race was the most popular, even when 1/2 might have been the better choice.

Gene, after the wholly unjustifiable way you lit into rcb78 I'm disinclined to offer you any more assistance - but there may be someone else following this thread who'd be interested.
Here's a compendium of cam specs: http://www.phnet.fi/public/hefor1/vwinfoca.htm
Always cross-check the info (links are included to many grinders' websites) and watch out for the fact that some are spec'ed at the cam, others at the valve with various rocker ratios.
The tires gear you up about 6% (coincidentally, the spread between the three available stock ring & pinion ratios of 4.375, 4.125, and 3.875). You don't want to even think about opening up the trans to count teeth, you'll be way over your head in there (it ain't some frickin' top-loader that'll still work with parts left over). Generally speaking, the trans codeletter is all you need to reveal the gearing - but when in doubt you can always count turns.
I know of no "normal" weight for a VW trike. I've seen some with hundreds of pounds of ballast added at the front legs in an effort to keep the nose down in first & second. Safe to say that it'll weigh between half and 3/4 of a bug's weight with passenger(s) I suppose. I stand by the cam choices I mentioned above, something in the low- to mid-270 advertised duration range. Hardly racy for a VW, honest.
You'll be wasting money on fuel, 89 (R+M)/2 is the most that engine will need - in fact it'll probably run better on it, with lower exhaust temperatures (if you haven't heard, burning/breaking exhaust valves is the primary cause of death for a properly-assembled bug engine).