TheSamba.com :: View topic - Cam/springs engine break-in question

Fri Dec 13, 2019 5:59 pm

Hello Samba community!

I came across an interesting point brought up by ACN's engine break-in guide and it sparked a question for my current build parts list, particularly the cam shaft/lifter and rocker arm assembly.

I plan to use an Engle w100 with SCAT 1.25" rockers & pushrods, Engle light weight lifters, and MOFOCO 042 heads. ACN strongly recommends having dual springs with 1.25 rocker arms with use of either Engle w100 or w110 cams. They don't make the same warning for C20 or C25 SCAT cams (the only reason I am passing on those is the power band is lower than I would like--4000rpm. Engle revs up to 5400 & higher with w110).

ACN recommends during break in period to use single HD springs, as using dual runs a risk of damaging the cam lobes before the metal has been heat tempered, so my question is this-- What do you all think? Can I "get by" through break-in period with dual springs?

If curious, the other major components will be a 74mm cw crank, 90.5mm pistons, and 40mm dual weber IDF.

Thanks!

Quote: Quoted from ACN break-in article:
"They get enough oil for running, but not break-in itself. In addition, you also run the risk (the higher valve spring pressures you run, the higher the risk) of one or more of the cam lobes getting scored and even going flat. Some engine builders (myself included) will run the engine on one set of valve springs for break in, and change to the competition springs (really heavy) after the cam and lifters are broken in. The cam and lifters must work together under a moderate load (valve springs), to allow the metal to work harden before extreme loads are placed on them. This oiling quirk is also the reason for cranking the engine for oil pressure with no valve spring pressure on the camshaft (no push rods, remember?). With really heavy valve springs, just this cranking alone can damage the cam if racing spring pressure is present!"

Fri Dec 13, 2019 7:00 pm

Did you post this to Facebook? Looks awful similar to someone I just helped...

You can use some single springs. They are not all alike, and that page hasn't been updated in awhile.

Since you haven't purchased anything yet, here's my recommendation: there are a few ways to combat your situation: use more spring pressure, use higher quality single springs, or lighten your valvetrain so a regular single can rebound without so much weight on-top of it.

If you want to try the latter, ditch the Engle lifter idea. They're not light - actually the heaviest I've ever come across. Buy either CB Ultra Lightweight lifters in the smaller diameter with your 100 and 1.25s OR order the cam directly from Engle on the "SC-1 blank". Then you can use SCAT's lesser-priced 20008WIN 71 gram lifters. You'll know it's an SC-1 because A: it's stamped right on the shaft amd B: it comes with as-cast notches to clear long stroke crankshafts. If you go with the SCAT option you'll save around 30-40 bucks.

Next use aluminum pushrods. Stock will flex. Use CB's straight-walls that are cut-to-length so you can figure the length yourself. That alone is good enough to just run a $20 CB set of springs.

An easier solution might just be to buy good springs. You can use the CB650 outer spring, or Oteva90s from CSP or JPM. If you need any help, I sell valvetrain parts and do valvetrain machining.

Fri Dec 13, 2019 7:25 pm

bugguy1967 wrote: Did you post this to Facebook? Looks awful similar to someone I just helped...

Haha nah, but I appreciate your helping the both of us!

Would the single HD springs in the MOFOCO heads do for this application? How would I know I have enough spring pressure? What are the consequences of not having enough spring pressure? Valve failure? Just curious.

CB lifters are compatible with Engle cams?? Thanks for the tip!

I forgot to mention, I will use ACN's aluminum pushrods precut for scat 1.25's.

Fri Dec 13, 2019 7:45 pm

There's really no way to "cut for 1.25s", but hopefully it gets you close. If you want reliability, then proper rocker geometry is of paramount importance.

If you do the things I suggested, whatever Mofoco uses will be fine.

With the regular EP-12 round blank typically used on the W-series cams, you can use: Riosulence Brazilian, IAP Mexican, Engle, Tool Steel, CB lightweight, and old stock Wizemann. There are probably a few others. CB, Engle, Clay Smith, SLR, and Gene Berg uses the EP-12 blank, so they're all compatible with each other.

The SC-1 blank is SCAT's proprietary blank. It can be used with their lifters or tool steel. The blanks are harder than the EP-12 (Engine Power Corp - #12, which is the Type 1 designation). EP93 is the Type 4 designation.

Fri Dec 13, 2019 7:56 pm

What type of scat 1.25 rockers are you talking about? I don’t recommend the stock style rockers. The webcam 163 is a better choice for 1.25/1.3 rockers. The problem with HD singles is poor control of harmonics which ends up being a short life spring. Here is the train parts I sell in the link below. ACN does sell my spring kits. Dan

https://www.thesamba.com/vw/classifieds/manage.php?type=all

Fri Dec 13, 2019 8:23 pm

Dan Ruddock wrote: What type of scat 1.25 rockers are you talking about?

https://www2.cip1.com/ProductDetails.asp?ProductCode=C15%2D20188S

Fri Dec 13, 2019 8:26 pm

Dan Ruddock wrote: The problem with HD singles is poor control of harmonics which ends up being a short life spring.

so, are dual HD springs safe for the break-in period of all new components? That's my main anxiety with running those. Thanks for your input!

Fri Dec 13, 2019 8:26 pm

Single springs will be fine for your application as long as you use the lighter parts suggested. That's not a high revving or lifting cam so theres no point revving it till the valves float. I beat on HD singles on a 110 cam and 1.25 rockers for years and had no issues with valve control.

I never pull inner springs to break in a cam in any engine whether it's a VW or a BB Ford. I've broken in cams with CB650 springs and CB Racemasters which are within a few pounds of K800s cams and lifters broke in just fine and looked and measured out like new on teardown.

brad

Sat Dec 14, 2019 9:58 am

Relyt610 wrote: Dan Ruddock wrote: The problem with HD singles is poor control of harmonics which ends up being a short life spring.

so, are dual HD springs safe for the break-in period of all new components? That's my main anxiety with running those. Thanks for your input!

Break-in is mostly about oil. You need plenty of it on the cam and it needs to be high zinc oil like Valvoline VR1 or brad penn GT1. I like to overfill the crankcase up to the point of when it starts drain out of the rocker boxes with the car level. The cam becomes submerged in oil. Obviously drain the excess when break-in is done. Never had a failure when I did it this way.

You want this type of rocker. They actually measure 1.3 ratio not 1.25 as advertised. The geometry and pushrod tube clearance is not ideal on the stock style rockers. I never use stock style or stock rockers for anything more than .430" lift even though many builders do. The problem is the pivot point is too close to the valve for high lifts. VW designed it for only .340" lift and it works just fine for that.

https://www2.cip1.com/ProductDetails.asp?ProductCode=C15%2D20196

I have a set of new 1.3 in stock for $120 but they are not scats.

As I said the web 163 cam is a better match for a 1.3 rocker and the combo will be easier for the springs to control over a 100 or 110 but the 100 or 110 are a better match for stock 1.1 rockers.

Another very durable option is to run 1.4 rocker and the web 86a, will be about the same performance as the others but is a combo that is very easy on the valve train.

Dan