TheSamba.com :: View topic - Opinions on mileage-performance cams

Sat Jul 20, 2013 6:09 am

I'm interested in a mild cam for a 1776 build with a single carb. From the descriptions from some of the cam manufactures, a running duration of 227 or over is not going to provide a smooth idle ;which is what I want. No lope but it does not have to be as smooth as stock. I came a cross Eagle Fuel Efficient Series (Performance Group 1) cams and would like to hear about any experiences anyone has had with them.

Thanks! [/url]http://www.cbperformance.com/searchresults.asp?cat=185[url]

Sat Jul 20, 2013 7:04 am

Howdy
Tell us all more about the Carb, Cylinder Heads.

Sat Jul 20, 2013 7:34 am

Stock and stock. I might go for a dual barrel single carb for it if I can find it used.The vw specs don't make any sense to me. If this was a muscle car , I would put a 266 advertised duration in it or 210 running. I would like it's rpm range to start at 1200-1500.

Sat Jul 20, 2013 9:54 am

CB 2228. One of the best off the shelf fuel eficcient cams on the market.
Expect to have to play a little with the vacum advance.

28 mm venturi in the stock carb is recommended.

T

Sat Jul 20, 2013 11:50 am

theKbStockpiler wrote: Stock and stock. I might go for a dual barrel single carb for it if I can find it used.The vw specs don't make any sense to me. If this was a muscle car , I would put a 266 advertised duration in it or 210 running. I would like it's rpm range to start at 1200-1500.

The stock cam IS 210/215 at .050, but it is not very aggressive.
I haven't tried the #28 CB cam, but that's probably a good choice for a very mild performance cam if Torben says so

1200 rpm is a good idle speed IMO :lol:

Sat Jul 20, 2013 1:24 pm

Let's use 'idle speed' as a axiom for cam selection and I want a normal idle speed of lets say 650 to 800 max. What durations are going to support this idle speed range in a vw type 1? Can someone please explain why vw aircooled cams are so different then a domestic v8 cam? Why is a rv cam for a ford 5.0 210 @ .050 and a stock vw cam is higher than this? :?

Sat Jul 20, 2013 1:50 pm

um, 210=210 ? I don't see how it is different. looks the same to me.
A much larger engine with more cylinders can idle slower, right? 600 rpm idle is possible, sure, Several engines of mine CAN idle that slow but I don't set it that low, it just doesn't really matter. I stay away from the traffic jams.

A mild cam for a V-8 and a VW are very much the same, but not split cams like most V-8s, and the rocker ratio is 1.1 not 1.5, and the valve/to throat ratio is very differetn, so that must be taken into account also, and the I/E ratio is the opposite, and all things considered a mild cam is very much the same. What is mild? well mild is 230 @ .050 IMO an RV cam is not a mild cam it is just a stock cam with more aggressive ramps and higher lift.
There is little demand for "RV cams" as you cannot cruise at low rpms anyhow at any reasonable speed(due to being small CC and aircooled), and very few have automatics or power steering or that junk. If the engine is below 2500 rpm you downshift :wink:
The only times that I find below 2000 rpm useful are parking lots, driveways, and parades, but if you do not have to drive with modern traffic then i suppose it could be useful to make a low powered low rpm engine???? for some strange purpose

Now, what about these 250+ at .050 cams? It is mainly due to the use of IR carbs, which allow the intake to be opened VERY early with no side effects from it.
A high compression v-8 with webers will like a similar cam also

Sat Jul 20, 2013 2:03 pm

Forget everything you know about V-8 engines. Your going to have to relearn everything about VW engines.

The idle speed needs to be 750 or higher to get the oil flow and the airflow from the cooling fan to the heads to help cool them.

Dual carbs will get better MPG then any single carb.

Sat Jul 20, 2013 2:06 pm

With a domestic v8 , you can only go with an advertised duration of 268 before you kill the bottom end and have to ,gear it lower ,run a high stall converter and the idle goes from rough to loping. So you can only use a 266 or 268 before it is no longer a daily driver. I had a comp cam in a jeep which was pretty decent. Quote: Exhaust Valve Lift (in.)0.433Intake Valve Lift (in.)0.433RPM Range1000-7000Exh. Duration @ .050 in. (Deg)206Int. Duration @ .050 in. (Deg)206Exh. Duration Advertised (Deg)252Int. Duration Advertised (Deg)252Engine Make/SizeAMC 199-258Lifter TypeHydraulic Flat TappetUsageStreet/Performance It was however as hard as a marshmellow. It had overall good power and turned on a bit at higher rpms and idled almost perfectly. What would the vw numbers look like to get the same personality out of a vw cam? :D

Sat Jul 20, 2013 2:16 pm

the CB 2280. 222 @ .050

Automatic transmissions are not usually the best for MPG. Why not use a manual trans if that is your goal?

Sat Jul 20, 2013 2:29 pm

I'm just making comparisons. For a daily driver I don't think it is practical to use over a 268 advertised duration cam. After a 268 it's time to go turbo in my opinion and it's no longer territory to keep upping the cam. A turbo starts to look practical at that point.

Here is the page for comp cams.

http://www.compperformancegroupstores.com/store/me...ry_Code=VW[/quote]

Click onto the "learn more" link, OMG!

Sat Jul 20, 2013 2:43 pm

Glen , I'm curious to know what your idle speed is with your daily driver? This engine is going to back up a type IV engine and also get it around while I restore the car. I only want to deal with one involved project at a time. The body/type 1 engine first, the type IV build-install later. :shock:

edit:
Where did your slow lane post go? 'Beetle beetle' does not have to be that fast for my needs anyways.

Sat Jul 20, 2013 2:52 pm

The secret is the IR carbs. One time I had dual weber 36 idfs on a stock 1600. It would idle strong and stable at 400 rpm. I got second place in the slow-drag competition with it :lol: Got beat by an automatic, which is really cheating anyway.

The rough idle of a more radical cam is due to exhaust reversion and due to valve overlap.
The exhaust reversion is pulled in by manifold vacuum, so the intake system is the #1 factor in what you can get away with. The VW stock intake has longer skinner runners vs the average american iron, and of course only four cylinders, so I'd say you can use 10 degrees more for the same idle behavior. Keep the overlap at .050 less than 10 degrees and it will idle just fine.

With the dual webers it handles 40 degrees of overlap just fine. The idle speed is about 800 cold and 1200 hot, it can be set lower, but that's personal taste.

Sat Jul 20, 2013 4:57 pm

What if I have a choice of compromising lob separation angle or duration as in the cam at the top of this selection? http://www.cbperformance.com/searchresults.asp?cat=185

Sat Jul 20, 2013 6:29 pm

Of course if you do something stupid and pollute the set up you wohnt make it idle very nice. But both the 2280 and the sister cam 2228 will idle rock steady at 850 rpm., just like a stock engine. I´m sure it can idle at about 750 if you want it to, but not strong, and I do not see the need. At that rpm the lubrication and cooling is also limited. So really, no idea in that.

I could easily recommendyou a cam with more duration that would idle about as well as the above, but the things that need to be done also is not for beginners (no offense, but it really is´nt) As always, and especially with limited carburetion one thing affects the other.

T

Sun Jul 21, 2013 6:34 am

I have had two decent mild or what they used to call (rv) cams in a carburetored 5.0 and a jeep with a 4.0 renix fuel injected system. The otherwise stock jeep idled fine ,had more power through out and a little more peak with no consequences that I could tell besides for gas mileage. I know from tuning 1850s that you can't tune a mechanical secondary so multi-carbs or mechanical secondaries are not practical in a daily driver in my opinion. Having your foot to the floor at standstill or having it to the floor at 55mph are not the same but the carb reacts the same way.You have to choose where it is acceptable to run rich which is a longevity concern. I don't have the peak power desires that a single plenum won't support but otherwise I do think that IRs on a fuel injected system would be interesting for people with those needs.

Will IRs make better power at lower rpms than the duration is designed for or just bring the idle speed down? To clarify myself , I want the power band to be between 1200-1500 but have the type 1 idle at the factory designed rpm. :D

Sun Jul 21, 2013 9:50 am

Do you mean that you want the power band to start at 12-1500 rpm ? Then my recommendation still holds.

T

Sun Jul 21, 2013 10:04 am

for low apps I would also recomend a 30 mm oil pump or more.