TheSamba.com :: View topic - Any Way to Tell What Cam You Have Without Splitting the Case

Tue Feb 23, 2016 10:59 am

Ok, so I know this might be a dumb question coming from someone who has built an engine before as well as currently doing so now and I probably already know the answer..... But, I was wondering if there was any way or tricks unknown to myself that would enable me to determine what cam an engine might have (even cylinder size for that matter) without tearing it COMPLETELY down.

You see, my dad, brother and I have just bought into a large collection of buggy/vw parts. Included in this deal are three complete mildly modified engines (all AE or B cases). Two have Dual carbs (one with 34 ICTS and the other with 34 PDSIT). It would seem to me that someone along the way put at least a little thought into their build, but with offroading, Lord knows what someone has done over the years to an engine. Oddly enough, the previous owner has no idea what he really had in parts, inside or out because someone else built them :roll: . The reason I'm asking is, if one of these motors is in good shape and has the components I'm wanting out of my current build (i.e. 87 cylinders and W110 cam) then why not just put that build aside (or do a different one) in place of the "newer" motor.

Any revelations would be good. Thanks.

Tue Feb 23, 2016 11:02 am

most aftermarket cams have the grind # stamped on the drive flange of the camshaft. You can see this if you remove the oil pump.

Many reground cams are NOT stamped.

But this is what you should do, hopefully it will be right there.

Tue Feb 23, 2016 3:43 pm

You can measure bore and stroke by removing a head, measuring the cylinder diameter, and then rotating the crank and measuring how far the piston moves from TDC to BDC.
Slide one cylinder out enough to see if your crank has counterweights.
Follow John's advice on figuring which cam you have, or you can get some idea from measuring valve lift without taking a head off.
Taking the heads off will also give you an idea of the condition of at least top end parts.
You can do all this without splitting the case.
Also, if you pull your clutch off the engine, you can see if you have an 8 dowel crank

Tue Feb 23, 2016 5:31 pm

The only way to really know what any cam, is to degree it. This is just as easy to do in the engine as out, but it is hard to do in the car with a VW.

Wed Feb 24, 2016 8:17 am

This is some good info fellas. I appriciate it. It'll be another week or two before I will have time to mess with that but your information has been helpful. John, I'm not very familiar with the PDSIT carbs, but with what very little I do know I would imagine that they are fairly stock, so depending on what venturi is inside, I may be making a larger venturi and jet purchase from you guys in the near future.

Wed Apr 01, 2020 1:08 pm

Hello,
I know this is an old thread but I am in a similar situation. Recently purchased a used running 2276cc engine. The PO does not know what cam was used and I do not want to split the case.

I purchased the VW oil pump puller tool, however realized this won't work as the engine is fitted with an full flow filter oil pump. The body of oil pump only has a cavity on one side. The T section of the oil puller tool cannot grab on to anything on the other side.

I thought trying to tap the oil pump body out of the case but am a bit concerned I may damage the case in the process.

A previous poster, thechief86, mentioned about measuring valve lift as a rough estimate to determine the cam. Does anyone know how to do this? I'm guessing with the shortblock assembled and valve gaps set, I measure the distance between the valve and the rocker, like setting the valve timing. The difference between TDC and BDC, a full stroke. Is this how the valve lift is measured?

Thu Apr 02, 2020 7:21 am

Oil pump puller tool: Grind off one tab short enough so that you can insert it into the pump.

If the pump has bolts (not studs with nuts), you can remove the bolts, and then spin the pump a few degrees by tapping sideways on a corner (using a wood block). This will make the ears of the pump hang over the case so you can pry on it evenly with 2 large screw drivers an pull it out.

Stamping on the end of the cam is the best way to find out what it is...

Thu Apr 02, 2020 9:24 am

You can also free up the oil pump by backing off the two transverse case stud nuts one above and one below the pump.

I can then get my CB Maxi 3 pump out hooked on one end of the T piece on the pump puller.

Thu Apr 02, 2020 11:41 am

Tom & Mike, that's great advise, thank you! I will loosen the bolts above and below. Then try the oil puller with one side shortened. If that does not work I will rotate the pump by tapping a corner (it uses bolts) and try tapping it out.

Sun Apr 12, 2020 9:32 pm

Update: I did all of the above plus welded the T section the tool thicker and welded an extra brace to it but it still wouldn't budge. Maybe I need to knock it harder to turn it clockwise but I'm paranoid about damaging the case. Original builder must have used some super strong sealer.

So I decided to measure the cam. It appears to be a CB 2248 (slightly more aggressive than a W140):-
Dur at 0.050" 276 degrees
Lift at cam 0.426"

This is a drag racing cam, used with 1.1:1 rockers, making its torque high in the RPM range. My problem is I want to use this engine (without splitting the case) in a daily driver. Ideally I would like to keep the max engine RPM's around 6,000 (so it lasts longer) and have the engine make most torque around 3,000 to 5,000 RPMs.

This maybe a dumb question but is there anything I can do to the engine to make the effect of the cam less aggressive and bring down the RPM range at which the engine makes it power at (without splitting the case)?

Currently the engine has a 1.1:1 rocker which gives the following:
Dur at 0.050" at rocker arms 279 degrees approx
Lift at rocker arms 0.470"

I was thinking of changing to a 1.0:1 rocker to bring down the numbers. Has anyone tried this? I read lift for 42mm valves should be atleast 0.413" so they would still be above this at 0.426". Duration would be still a bit high at 276 degrees.

Engine specs:
AS21 case
94 x 82 (2276)
9.5:1 static compression
CB 044 G04 42x37.5 heads, 58cc, dual springs, 33mm round intakes (planning to port these to 34mm)
11.06" chromoly pushrods
1.1:1 rockers
DRLA 48 with 36 venturis (may change these to 38 venturis or use HPMX 40 with 36 venturis)
Connecting rods unknown
Transmission: early 5 speed 901 porsche
Car weight 2,200 lbs

Mon Apr 13, 2020 3:02 am

Whats your valve lash on your intake that your checking?
Are you assuming the duration based upon a cam that matches your lift findings?

Hows your oil pump passage look after wrenching on it with the puller?

You need to loosen the 13mm case bolts above and below the oil pump before trying to pull it out. Did you do that already?

I wouldnt assume that cam is what your guessing it is just yet.

Mon Apr 13, 2020 8:06 am

1:1 rockers will help to reduce lift.

Advancing the cam 4deg will bring the powerband down.
However, that duration is going to be all wrong for a daily that doesn't see above 6,000rpm.
You will have a very narrow power band at the very top only.
Mid range will suck.

The cam is all wrong for your intended use.
You will be "under the cam" for 90% of driving. It will feel soggy and lack power.

Mon Apr 13, 2020 11:11 am

I did loosen the 13 bolts. Oil passage has a slight indent on the corner now shouldn't effect it.

I don't know what the valve lash was. I measured the cam with the head removed. I measured the distance from the lifter. Triple checked the measurements then compared it to camshaft specs on the list of all VW camshafts on the internet. The CB 2248 was a match for lift and duration (I know the original builder purchased most of the parts from CB). I know it might not be this cam, lobe could be different for example.

I agree its the wrong cam. Duration is too big. Right now I just want to use the engine without stripping it down. I haven't rebuilt an engine before so rebuilding will take me a while. Think I will change the rocker from 1.1:1 to 1.0:1 and run it in the car and see how it performs first.

Mon Apr 13, 2020 1:45 pm

tappets and tappets diameter alter the readings of duration but not the lift
a 276 deg at cam could be 290 reading
so your cam could be a less aggressive 262 (plus or mine)

Mon Apr 13, 2020 3:44 pm

lelef, when you say 'tapets', do you mean what they call in the USA 'lifters' (that go between the cam lobe and the pushrod, located inside the crankcase)?

Mon Apr 13, 2020 4:05 pm

If I understand this correctly, measuring the duration at the pushrod seat on the lifter (tapet) may produce a different measurement compared to the duration of the actual cam (the duration number listed by cam manufacturers).

If this is correct then does measuring duration with the lifter included always give the same or higher duration number? For example cam 262, cam + lifter 262 or higher? Or can it be the opposite also, for example cam 262, cam+ lifter 262 or less.

Sorry for the questions. I'm just trying to understand what effects the lifters can have on the cam duration.

Mon Apr 13, 2020 4:47 pm

ottobevis wrote: lelef, when you say 'tapets', do you mean what they call in the USA 'lifters' (that go between the cam lobe and the pushrod, located inside the crankcase)?

Yes in UK English those are tappets, in USA English they are lifters or cam followers. :D

Tue Apr 14, 2020 12:17 am

yes,sorry, lifters
when you neasure the cam durtion on the cam lobe you use a single point

But with lifters the contact point is different

the larger is the lifter foot the wider is the resulting cam duration (2x larger than the ramp end radius has no more effect)

For a lot of engines you can't change the lifters geometry or if you use roller lifters you have to use the maching cam and the constructor gives you all the specs
in this engine you can use different fooot diameter lifters and also but rarely hemisferical foot lifters
so the specs are at cam measuring because the resulting duration depends on the lifters you are using.

With lifters the duration is allwais more than measured at cam
How much? it depends to a complex geometry !
very roughly it could be a 5% difference

for example :same cam different lifters

Tue Apr 14, 2020 1:52 am

Lelef, great examples!

Tue Apr 14, 2020 12:39 pm

Lelef, thank you so much for posting this. I was visualizing yesterday how the lifters could effect the duration and was thinking the same thing. Diameter and the slight dome on the lifter (if they are not flat) and how it would effect the point of contact of the cam lobe. I searched the internet but could not find anything about this but your picture, the middle example, shows this perfectly.

I also read that the standard 0.050" duration measurement (I believe 1mm is used in France) is to measure with the lifter, at the pushrod seat. But I can imagine some cam manufacturers measure this at the cam (due to the different lifters available). I understand now that the lifter diameter, whether the lifter face is flat or domed, and the curve of the lobe can add a small amount of duration to the duration measurement.

Basically my duration measurement maybe overstated (I may not have a cam I thought I had).

By the way I should have known what a tappet is - I lived in England for 24 years!

Do you have a 13b rotary engine in your buggy? I have a 13b S5 streetport that was in a dune buggy, saving that for a future project.