Cam/rocker questions - help please!

[Lee.C]

Hey guys I have a quick question about cam/rockers - The guy I am building the 68 for has just aked me to fit a set of Scat 1.25:1 rockers to his 1915cc type1 motor

Now this Motor already puts out 124bhp at the wheels - pretty good I think,

Now the main question is - It runs an Engle120 BUT he doesn't know what the rockers are (he thinks they are 1.1:1)
So what SHOULD a engle120 cam run with and if its NOT with 1.25 rockers then How do you think this will "Effect" the motor

Let me know what you think guys 

[Lee.C]

Anyone 

[John Maher]

Engle 120 will work with 1.1 or 1.25 rockers.
Only way you can be sure what you have right now is to measure lift at the valve - but it goes without saying you were going to do that anyway, weren't you? 

Some Scat '1.25' rockers actually measure out closer to 1.4:1 
Don't trust the label on the packet or the catalogue description.
Once you've set geoemetry/shimmed the rockers/got pushrod length right, measure ACTUAL lift at the valve.
it's not recommended you run 1.4s on E120 - you could get yourself into big trouble very quickly.

E120 w/1.25 rockers (true 1.25) works nice with the right head and carb combination.

[Lee.C]

Thankyou very much John - Perfect info as always    here's the project: http://cal-look.no/lounge/index.php/topic,7573.0.html

I did not build the motor (the owner did with some help ) and up until now we were just gonna keep "as-is" but now it looks like I'll be making a few changes,

I am kinda happy I am now looking into the motor a little more as there are a few "issues" I have never been happy with but I will go into them later, Today I stripped the heads and here's what I found:

1 - it has 280mm 3/8 ALUMINUIM pushrods
2 - it has DUAL Valve springs
3 - it has what looks like ALUMINUIM retainers (anodized blue)
4 - 5.5mm of spacers/shims under the Rocker sharfts  (my guess is they did this so they didn't have to shorten the pushrods )

Any more thoughts 

[Udo]

I would use the 1,25 rockers that fit on the  original shafts (hope they are hd with screws at the end) and chrome molly pushrods .

Udo

[Rasser]

last set 1.25 rockers i used, measured out at 1.34:1 

I would use 1.1:1 rockers, they will let the valvetrain/springs live much longer.

[Lee.C]

Ok guys here's a few more spec's:

- 69x94 (1915cc)
- counterweighted crank
- unknown rods
- CR = 9.2:1 (unknown deckheight/chamber cc)
- Engle 120 Cam
- Normal cam gears
- 40x35.5 valve heads (vw/gex/mexico ) whith HEAVY port/polish,
- Stainless Valve,
- 3 angle valve job
- Suspected Aliuminuim retainers
- Dual Valve springs (Waterboxer Inner & Remell Outer - unknown spring rates)
- "Bolt up" rocker sharfts (with 5.5mm of shims under them!)
- 280mm 3/8th ALUMINUIM pushrods 
- 1.1:1 Rockers
- Swivel feet adjusters
- And all this runs on a pair of 44idf's (32 vents, unknown jets) and a 1 3/" stainless header system

Any further thoughts guys 

[Zach Gomulka]

Give it 36 vents, should run like a champ

[Lee.C]

Give it 36 vents, should run like a champ

I was thinkin it could use a little more Airflow  I have always felt the engine was "soft" even with 124bhp AT THE WHEELS, The 1 3/4" header is VERY long with 2 (two) very large mufflers all hidden away That might also be having an effect

Also checkout the "restrictive" German look Airbox setup - a VERY well made piece of kit from GWD but not to my taste 

[Rob DVKK]

I ran the old style scat 1:25's in my 1914 with both a 120 and 125 engle cam. Think they measured out at about 1:38.  The heads were 42 x 37.5 with a port job.  Never had any problems. Ran bugpack doubles. All steal 54 sunroof and a stock gear box ran consistant 14.0-'s with that combo.

Also drove from Vancouver to Seattle a couple times a year with that combo.

[Lee.C]

I ran the old style scat 1:25's in my 1914 with both a 120 and 125 engle cam. Think they measured out at about 1:38.  The heads were 42 x 37.5 with a port job.  Never had any problems. Ran bugpack doubles. All steal 54 sunroof and a stock gear box ran consistant 14.0-'s with that combo.

Also drove from Vancouver to Seattle a couple times a year with that combo.

Hmmmmm what pushrods did you run 

[Diederick/DVK]

sounds like a good engine. but judging from the thick washer under the rocker shaft i don't think the valve geometry is correct. with swivel feet adjusters, stock rockers on a w120 you shouldn't have to shim it that high.

and like what has been said, 1.25 rockers are often more like 1.3/1.35. i'd have a look at the valve geometry as is unless you can find good rockers. and perhaps up the venturi size like zach mentioned.

that airbox looks expensive, but unless there's some scoops in the decklid where is it supposed to suck in the air

[JS]

I do love that spark plug wire "separator"... 

[Lee.C]

I do love that spark plug wire "separator"... 

Oi don't be mean  But you are Right 

[Rob DVKK]

I ran the old style scat 1:25's in my 1914 with both a 120 and 125 engle cam. Think they measured out at about 1:38.  The heads were 42 x 37.5 with a port job.  Never had any problems. Ran bugpack doubles. All steal 54 sunroof and a stock gear box ran consistant 14.0-'s with that combo.

Also drove from Vancouver to Seattle a couple times a year with that combo.

Hmmmmm what pushrods did you run 

Pretty sure they were bugpack as well - chromoly with hardened tips.

Still using the same rockers in the 2275 I'm running right now. Switched the cam out to an 86b though - do miss the on/off of the 125 with those rockers. Ran nice and calm until you ran it up over 4500. Then it was a different story - really worked with my heads once the revs got up there.