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Tue Feb 21, 2023 9:11 am

Hey Guys:

I need some advice regarding this T4 I'm building. Here's the background: it's an '80 Vanagon air cooled 2.0. My buddy has spent numerous dollars and hours trying to make it run right and came to the conclusion it had too much cam for the stock FI system. Upon teardown he found what appears to be a Scat C25 cam which may be incompatible with the FI, this is where I became involved. We're now going together with it spending much more attention to cam timing to be sure everything is correct on assembly. (Especially with the cam timing thread!) Anyway, it's going together with a new stock cam from a reputable source, but they did not (and so far have not) supplied us with a cam card/tag. Following are the readings we're getting on the cam, we only did #1 and #2 cylinders so far (which covers all 4 cam lobes).

All measurements are taken at .050"

#1 intake opens at 8° ATDC and closes 20° ABDC, 192° duration, .208" lift at cam
#1 exhaust opens at 30° BBDC and closes 14° BTDC, 195° duration, .190" lift at cam

#2 is almost the same:

Intake opens at 7° BTDC and closes 20° ABDC with .206" lift at the cam.
Exhaust opens 30° BBDC and closes 15° BTDC with .190" lift.

Notes:

-Case is mocked up dry, endplay set, cam gear backlash is zero but does not walk out of the case when the crank is turned.
-Cam gear is aftermarket but looks identical when laid upon a stock T4 gear.
-A new lifter is used on the cam with a used lifter inverted on top of the new lifter. This gives a nice surface to dial off of with very repeatable results. Everything is lubed well and operates smoothly with no hangups.
-I have several dial indicators but the old nasty one was the smoothest with a magnetic base stuck to a giant 2x4x6 block of solid steel. There is no flex in the DI mount.
-We didn't have the fan and timing marks handy so I determined TDC using a depth mike on the crank journal using the cylinder opening for a base. This could be a degree or two off at the most.
-Lifter does rotate as the cam spins.
-There is a super small glitch in the #1 intake lobe- the DI jumps .001" for a degree or two about 10° before the intake ramp starts. Could this be an imperfection in the break-in coating? It's barely perceptible when you rub your finger on it.

These numbers are nowhere near the cam tags I do have from previous CB and Engle cams, I'm especially concerned about how late the intake opens. If you eliminate the .050" baseline we get 301/305° duration.

Unrelated question; Why does VW post rod bearing clearances at .0001/.0002"? Two tenths? All four plastigaged at .002" so I'm going with it.

Any comments are welcome.

Tue Feb 21, 2023 10:32 am

Interesting...

You might double-check your TDC marking.
Most cams should have split overlap when straight up.

Web doesn't list stock type 4 numbers,
But here's type 1, which should be similar.
http://www.webcamshafts.com/pages_vehicles/automobile/volkswagen/670.html

Their 107i is a pretty much stock hydro grind.
https://vwparts.aircooled.net/Web-Cam-Type-4-Camshaft-107i-Grind-00-612-p/00-612.htm

300 advertised seems way too much duration.
You're converting to solid lifters?

Tue Feb 21, 2023 10:33 am

Stock cams are measured @ 0,040".
A stock hydraulic grind measured at 0,050" is close to your measured numbers: Intake -12-24
Exh. 25,5/24
Advertised duration 223/229 degrees
That said, the one you got there sounds really off because the lift should be very close to 0,252 on intake and 0,240 on the exhaust.
If y´the numbers you get are accurate I would send that cam back and ask for a proper one, or find another source.
The 80 F.I is normally not so picky with cam duration, but everything at its place of course. My bet is that it, once again, is partly due to an inaccurate cam that he could not make it run right. Another thing could be insufficient static CR. Third thing, fuel pressure not corrected for the new cam. Scat cams are sadly terrible these days. - Back when these vehicles were more a part of the daily picture we installed more/better cams in these engines every now and then. Back then we typically used 270 degree FAT cams which were 234 @ 0,050 if memory serves. We could typically release another 20 hp or so from the engine without any major changes apart from a decent valve job and correcting the CR and of course adjusting the F.i.
BUT, it can also be an issue with the F.i. It - is - after all a 30+ year old system now. Even wires dont last forever.

Wed Feb 22, 2023 8:13 am

Any way to check a new cam outside the engine, without a gear?
I have a new "shit" c-25 TYPE 4 cam.Looks good(?), I've measured the journals (they are good), and measured lift. All lobes consistent , with 1-3 ex maybe .010 less lift.
How about duration? Would readings be double crankshaft degrees? Anyway to index to TDC?
I bought this cam a year ago thinking it was the right choice for me,from recommendations from this forum. Now everyone says these cams are "scat"
I'd like to see if it's close enough to use before splitting the case.
Thanks

Wed Feb 22, 2023 11:48 am

Looks like the numbers say its 5deg advanced from straight up. You can use the 4deg washers to correct most of that.
The lift you say is .200"? That seems way off. Should be more like .250-300".

Lastly, you have your events incorrect. There intake opens before the exhaust closes (overlap). Either way, it's just semantics.
It's very possible the stock cam is ground 5deg advanced... Would give more vacuum.

Wed Feb 22, 2023 11:52 am

VW rod journal clearance is targeted at .0019".
The .0001"-.0002" is the allowed variation at any point (taper, oval, dipped). Rods must be round.

Wed Feb 22, 2023 1:40 pm

Ohio Tom wrote:
Lastly, you have your events incorrect. There intake opens before the exhaust closes (overlap). Either way, it's just semantics.
It's very possible the stock cam is ground 5deg advanced... Would give more vacuum.
No. A stock cam actually has negative overlap.

That said, I looked a little more into the numbers given. Assuming they are correct, that cam is WAAY off.
It is on 101 LC and 3 degrees retarded.
Intake 191 @ 0,050"
Exh 224 @ 0,050, as you also wrote initially. I just did not pay enough attention to it.
And the lift is off too.

I can only say send it back and get a proper stock cam, - or a mild performance cam instead.

Wed Feb 22, 2023 3:13 pm

I don't know if it is any help here but I will post the cam card specs that came with my type 4 Web cam.

That is very close to the specs Alstrup quoted except for the valve lift.

Sat Feb 25, 2023 12:05 pm

OK Guys:

I appreciate all of your input. We mocked up a piston, rod, and cylinder to confirm TDC yesterday using the piston stop method and degreed 3 camshafts. The numbers vary only slightly from before showing that my TDC using a depth mike was very close to correct. We only checked cyls #1 and 2 on all cams (all 4 lobes). For shits and grins I also set up a Matco dial indicator to double check my readings which agreed with the Standard dial indicator (made in NY) readings. The Standard DI was super smooth with no glitches, almost antique quality probably made in the '50s. Each was set up on a separate magnetic mount on the heavy steel block, all readings were consistent and easily repeatable.

Comments:

-Can you help identify the cam which appears to be marked "C25"- is this a Scat C25? Look closely at the grind marks on the lobes also, it does not appear to be a precision ground camshaft.

- The base circles on the 2 stock cams were very stable when rotating the cams, with the minor exception of the brand new cam from Jorge at European which had a .001" glitch or booger on it for a few degrees on one intake lobe. This might be a blob of what appears to be break-in coating and I'm not worried about it.

-The base circle on the "C25" cam was all over the map- the dial indicator would float up and down in a .005" range for no rhyme or reason. This makes degreeing the cam really hard as I didn't know what's "float" and what's lobe. I shot a video of it if you're interested. Also, if the base circle is floating around .005" is this opening the valve enough to piss off how the engine runs? The lift and duration was also not consistent between the two intake lobes and two exhaust lobes tested. The intake open variation was 4° , the exhaust open variation was 2° , the intake lift variation was .007" and the exhaust lift variation was .011". To say this is a poor quality cam is being really polite.

- The diameter of the base circles was also unusual: I measured all of them before installing the cam and got odd variations: The best was the new cam from Jorge at European, all lobes were 1.214" base circle. The C25 base circles varied from 1.156 to 1.165". The OEG cam was surprising, the base circles measured 1.185, 1.202, 1.202, and 1.210", a variation of .025"! WTF, is this normal?

-Alstrup was right about "negative overlap" which I'd call "no overlap" on a stock cam. I didn't know a stocker has no overlap and only a performance cam does. I'm learning a lot by degreeing these cams. I'll probably include this on everything I build now, especially seeing the poor quality of the unknown cam. Clatter was right about split overlap, but in this case it was only on the stock cam.

-Tom, I haven't talked to you for a while and hope you're doing well. I loved the high quality work you've done for me in the past and appreciate your input. The Vanagon Bentley isn't arranged like the older Bentleys, it doesn't have a "spec chart" in the back of each section like I'm used to. It has the specs scattered around accompanying each section and photo. The book does mention rod big end distortion but then shows "rod bearing clearance" at .0001-.0002" in the water cooled section of the book. It completely skips over this in the air cooled section. I guess it's a typo. See the picture.

At this point I'm pretty confident that the cam from Jorge is a decent grind stock cam and I'm ready to assemble the case. I'm feeling more confident that the "C25" cam grind was probably the root of the drivability issue my buddy experienced.

Any and all comments are welcome.

Sat Feb 25, 2023 12:57 pm

my head is spinning. What cam DO YOU PLAN on running in this engine, and why are you choosing that camshaft? How will the engine be used?

To determine TDC, follow my thread below. Use a engraver or a tiny punch to make a mark at the top case line and label it TDC. You can now refer to that line for any other thing like when you put the scale on or measure the cam with a degree wheel.

SGKent wrote: Bus type 4 motors are different than type 1 motors in that we rely on a bolt on timing scale. Often the timing scale is broken or bent. If that scale is wrong, your timing will be too and the results of setting the timing wrong on a bus type 4 engine can be disasterous because we carry weight and wind resistance that other VW's don't encounter. Additionally we are geared different and the overall affect is to create greater heat on a bus engine than any other VW. You need to know where TDC is on a bus type 4 engine, especially when you have just spent a ton of money rebuilding it as compared to what a stock Bug, Split or T1 bus owner might spend.

This thread is for anyone wondering how to find exactly where TDC is on a bay bus type 4 engine when assembling it or when the heads are off. You can then compare your TDC mark to the bolt on scale because if the timing scale is off by just a few degrees, your engine timing will be too.

Bolt the flywheel on. Bolt the cylinders down firmly so they can't move. Set your dial indicator up in some fashion where it is secure. Run the #1 piston to as close to TDC as you can and zero the indicator.

Turn the crankshaft until the indicator reads .020" of fall. You can use .050" if you prefer. I use .020".

Lightly mark the flywheel with a fine line at the case split. I use a sharpie and a scribe.

Run the flywheel in the oppisite direction until it reads .020" fall (or whatever number you used in the last step. Scribe a line.

Measure between the two and divide by 2. Make a mark at that distance. It will be TDC. I usually then run it up to .050" and make a second set of marks. They should appear equal distance from the TDC line you drew. When the engine is assembled, you can place the flywheel on this line and compare it to the bolt on scale.

I might add, if you measure the circumference of the flywheel accurately and divide by 360 it will give you the measurement per degree. You can then multiple the per degree number X 7.5 and that will give you a distance to 7.5 degrees where you can draw a second mark to static time it while you are assembling the motor. These lines will not be visible once the engine is in the car, and they are for reference only when assembling the engine.

Sat Feb 25, 2023 1:23 pm

SGKent wrote: my head is spinning. What cam DO YOU PLAN on running in this engine, and why are you choosing that camshaft? How will the engine be used?

It's a stock 2.0 engine running stock FI going in an '80 Vanagon. We want a stock cam that runs correctly with the factory FI. Rumor has it that performance cams don't work well with VW FI.

I don't need to know how to find TDC, it's very simple with the "piston stop method". Find a way to stop the piston, rotate the engine in each direction and make a mark, and the halfway point is your exact TDC. With an assembled engine you use a hollowed out spark plug with a bolt in it, but this engine is not assembled. We put a rod, jug, and piston on it, bolted a strap across the top of the jug, and put a widget on top of the piston to stop it from rotating. Spin till it stops, spin the other way, mark the halfway point. It's simple and dead accurate.

Sat Feb 25, 2023 1:47 pm

Bruce Amacker wrote:
It's a stock 2.0 engine running stock FI going in an '80 Vanagon. We want a stock cam that runs correctly with the factory FI. Rumor has it that performance cams don't work well with VW FI.

That is not true. The Vanagon L jet will handle quite a bit more than stock cam, but not a POS cam like that C25, which by the way looks moire like a C35 though not quite that either.

That said, the Vanagon engine is a b*tch. It is so down graded everywhere that it cant make power. I have converted a couple to 2165 which makes a tremendeous positive difference, - still with the (slighgtly modified) stock L jet. That gave us an engine that pulled about 100 hp still peaking below 4500 and with about 160 Nm already at 2000, which is what these vehicles need.

Sat Feb 25, 2023 2:20 pm

Bruce Amacker wrote:

Unrelated question; Why does VW post rod bearing clearances at .0001/.0002"? Two tenths? All four plastigaged at .002" so I'm going with it.

Your manual has the decimal place in the wrong spot, fix the manual.
.002" is good IMO.
Whatever bearing you use will have their own specs, look it up in the bearing catalog when in doubt.

Sat Feb 25, 2023 4:22 pm

Clatter wrote: Web doesn't list stock type 4 numbers

They do but the Type 4 cam Web Camshafts calls 'stock' is a stock 914 2.0l cam.

Also to Altrup's comment, this cam below (Web 00-142) works very well with stock L-jet, and you could go a bit bigger and it would work fine also. Key is having decent heads and exhaust and enough compression ratio.

Sat Feb 25, 2023 5:05 pm

From gallery

Sat Feb 25, 2023 5:50 pm

the webcam 142 plays really well with FI. It is the 100 HP 2L European GA motor cam used in the European 914-4 and 912e. It has a little lope to it at idle if you have a keen ear, barely noticeable but it does well at all RPM's you will drive a bus. Good luck finding one, last I heard Webcam was on back order months due to a shortage of cam billet blanks.

It also passes smog. Below is the test on my 1977 bus from yesterday. By the way, the screw a plug in method doesn't work on a Type 4 engine like it does on a Type 1 engine. The plug angle is way off for that on a Type 4 head.

People who have run a Scat 25 with FI in their FI buses complain that there is not enough vacuum at idle to make them work right. Even the Webcam 142 vacuum is lower than a stock BUS cam.

T4 Plug angle

Sun Feb 26, 2023 6:35 am

SGKent wrote: the webcam 142 plays really well with FI. It is the 100 HP 2L European GA motor cam used in the European 914-4 and 912e. It has a little lope to it at idle if you have a keen ear, barely noticeable but it does well at all RPM's you will drive a bus. If the 142 gives you a slight lope at idle, one or 2 of your adjustments are not trimmed correct. The 142 can run perfect with even the D jet (which it actually does in both the W, AP and GE) My guess is that it is either running lean or rich at idle, -OR that you did not correct the static compression from bus to GE specs,- or at least close.

Wrt the ability of the L jet to work with more cam duration. I have run Web 86 cams with L jet in 2,2 l. engines. No problem. you have to correct the idle timing of course, but that is minor. You can even keep the idle stability control. With that much duration the idle will be a tad lopey. If you cant handle that you can increase the volume of the center plenum to double or 3 times, sort of like the 914. this will cure the lopey idle and at the same time release more torque.
But again, if you use a POS cam like the above you will not succeed.

Sun Feb 26, 2023 10:00 am

Look at the smog numbers. The engine is PERFECLY tuned. It is getting 15% CO2 and has less than 1% O2 left. That is a perfect burn. Timing is at 7% (actually 7.5 at idle and 32 BTDC full in. The lope takes a keen ear, in fact if you do research you will find that VW went to a milder cam because an occasional person with a keen ear complained. I spent enough years winning trophies at the race track to know what a lope is. If you put a fine tach on a 142 to read idle RPMs, it will hunt about 50 - 75 RPM at idle. It is not rock solid like the milder stock cams for a T4 that will sit on an RPM and not move at all.

Sun Feb 26, 2023 12:02 pm

I didnt even look at the emission sheet, until now. But the lopey idle issue is staring you in the face ;-) One little change and it will almost vanish.

Mon Feb 27, 2023 8:05 am

Can anyone identify the stampings on the "C25" cam? Do you think they're Scat's, or is another cam grinder using a similar number ID? It does not match Scat's C25 cam specs at all.

Do you see anything in the new cam profile you don't like? It does not match the cam tag that was finally provided by the seller. It is close enough to the stock profile that I feel fine using it.

Thanks, guys!