The Cal-look Lounge

Hi everyone

When I had my 1776 built, I had asked for different cam but it turns out the original builder put a Scat C35 cam in unbeknownst to me.  Only discovered this recently when someone else did some repairs for me (along with a multitude of other sins).  

(http://i2.photobucket.com/albums/y23/stait9/60%20Green%20Ragtop/IMG_4761.jpg)

Have been doing some research into the cam as we're about to do some tuning after a shake down.  Currently the engine doesn't seem to really come alive, and feels a little flat as the revs go up.  I was looking for a mild/hot street engine which can act as daily driver and yet be fun off the mark.

According to the speil from Scat, the cam is:  BUG MASTER = 1776 - 2027CC HOTTEST ALL-AROUND POWER FOR STREET OR OFF-ROAD (1500 - 5500)

I was wondering if anyone had any thoughts.

The rest of the engine details are:

- 1776 with AS41 case
- Twin 40 dells
- 1:1.25 rockers
- CB performance Los Panchito heads - ported and matched
- Full flow
- 009 Dizzy with electronic Petronix points

The exhaust is the 42 mm CSP Python - but have a selection of restrictors to test.

Any thoughts would be much appreciated as don't want to really split case at the moment.

Cheers

Stuart

Used to fit these quite often back in the 1970s to engines we built at Autocavan. A good all-round cam that performed well in 1700 and 1835 engines with dual carbs.

If it feels flat, I'd check the cam timing first...

Hi Keith

Sorry for being thick, what do you mean by cam timing?  Am on a bit of a backward learning curve here, would that mean the cam was positioned wrong during build?  If it is out, would the engine still run?

Cheers

Stuart

Stuart!

Hate to say it, but your specs are far to vague for anyone to make a decent diagnosis as to your problem.
However, the first thing I would check is the ignition timing ... assuming (dangerous as it is) everything else is PERFECT. LOL

Let us know as much as you can tell us ...

TxT

I built a 1776 last year with a Scat C35 cam and it ran great! I had Steve Tims 40 x 35.5 heads (no extra porting just blended the seats) 69 counter weighted crank, lightened flywheel, scat lifters, scat rockers 1:1, scat pushrods, etc. I ran Kadrons with a vacuum advance dist with pertronix module (both set up by Low Budget). 1 1/2 merge header. The motor pulled great and sounded great at idle up through the rpm range. It had a nice idle to it, had several comments how nice the motor sounded. I thought long and hard about what cam to go with but was very happy with the choice.
Larry

Check your timing, your valves, sync the carbs. Still sluggish? Do a compression test. Keith suggested checking the cam timing to see if the cam is going flat... You can also check the lift at the valve to answer the same question.

Thanks for the comments everyone, here some more info.  Still got bits to confirm such as jets in Dells:

AS21 Case full flowed
26 mm oil pump with Berg Cover Plate
1776 cc Mahle B&Ps
Scat C35 cam - Lift: .419 (w/1.1 rockers), Duration 285
Heads - CB Performance CB1676 Los Ponchito 92 Bore, 40 x 35 Valves, Dual Spring
Bosch 009 with Petronix Electronic Points - plugs unknown
69 mm counter weight flywheel
12lb flywheel - 8 dowel
Dell 40s - jetting TBC
Rockers - 1:1.25 Scat Pro Street
Deep sump

Also still to confirm, con rods, push rods and lifters.

Compression ratio info will help?

Plus:

CB Unitech Con Rods
Manton Chrome Oly Push Rods cut to length for correct geometery

Compression approx 1: 8.6 (after fly cut).

As I mention, the C35 wasn't may choice originally and want to check it was a good choice based on the rest other components.

The C35 is a fine choice for a 1776. The exhaust is a little on the large side, but overall that is a good combo. Should run well to 6,000+.

Cheers for your thoughts Zach

No Zach – when I suggested checking the cam timing, I was hinting at whether the cam has been fitted 'straight up' (a meaningless expression really, but implying simply bolting the cam wheel on with zero-offset washers) or whether it was dialled in according to the cam spec card.

I was doing some reading at it would seem the 1:1.25 rockers are not necessarily a good choice with the C35, would the stock rockers be a better choice?

Stuart!
What is the ignition timing setting or what have you tried?
And, yes the 1.25 are certainly not necessary, but I don't believe could cause the poor running you're experiencing.

I can't imagine the engine would run at all if the cam had been installed on the gear incorrectly ... as in 120* out or other ... ?

I would think that combo would be very responsive with all things considered.
TxT

Hey Tom
Not sure at the mo but I'm getting into the garage next week hopefully.  Was trying to collect thoughts together beforehand - time in the garage at a premium at the mo.
From everyone's feedback on here and other conversations it seems like the right pieces, they just need to work better together.  Have collected the parts we need to be able to tweet carbs, timing and dizzy.
Thanks for the input :)
Cheers
Stuart

Ahh, good point. The cam gears may have been installed off a tooth, too. Seen it...

That cam is just Scat's version of the Engle W-110, one of the most popular, all-around cams going. That's a great cam for that combo (peak torque at 3,500 or so and peak power at 5,500). Unless lobes have gone flat I wouldn't say that the cam is your problem. I'd even recommend a cam with those specs for your engine. Your builder may have done you a favor.

That big exhaust is carving a huge hole out of your low-speed throttle response and torque. It's not killing things but it wouldn't be my first choice for that displacement and cam.

Tom asked and I'll ask again. What's your ignition timing? Base timing is sort of irrelevant; what's important is timing at full advance and at what speed the advance is all in. And again, what's your jetting? Venturi diameter?

Hello.
The lift data on the 35 is slightly off. Real life is 0,410" w. stock rockers. (I even think it says so on their web site)
The CR is on the low side for a cam like that. There is a significant difference from 8,6 to just 9-1.
That cam normally works well with 1,25 rockers. In this case I think it would be beneficial to reduce lift to 0,410" on the exhaust side due to the oversized header. I do not like the cone solution. It usually results in elevated head temperatures. Controlling the flow at the exhaust valve is better when things are not 100% a match.
The Panchito´s are very good heads, and should perform well in general. They - are - on the large side for the combo. Keep in mind that we can pull 150+ hp easy withém in a good set up)
The power pattern is more "flat" compared to a W110, slightly less peak torque and power. With the 1,25 rockers it should equal or even superceed the W110.
But of course other parameters, which are already menthioned, need to be OK.

T

Woops  :-[

Thanks everyone, lots of variables to consider  ??? :) but feel a lot more confident about the cam for the engine I was after.
Will have the last bits of info when I get into garage next week and have had a chance to check.  Then we can start to make changes and see impact.

One point: agree about exhaust - it was already on the consideration list but was waiting to see what happens when we had a look at with tuning carbs and timing before going to the expense of new smaller diameter.

Really interesting point about the cones Torben, thanks.

Actually really excited about figuring this out, so thanks again all for your inputs.  Will let you know.

Cheers

Stuart

Had an 1835 on the dyno on Monday with a c35 and 1.25 rockers. It had 40x35 heads and port and chamber work, 9:1 squeeze and cheap 1 3/8 header. Made 126 hp at 5800rpm and 175nm at 4200rpm. A pair of 40 Dells with 34 vents also

You got used to the power, and now you want more. Turbo is the solution!  ;D

Sorry for stealing an old thread but what about scat for stock 2,0 type 4 turbo?
budget is really tight and scat cam + lifters would be around 300€ but webcam  would be twice more.
Ive heard awful stories about ultimate little life of scat cams :S

Web has "real" turbo cams. Scat dont. Go figure.

T