TheSamba.com :: View topic - 2007cc Engine build in progress Cam opinions, other thoughts

Fri Dec 07, 2007 7:25 am

Several months ago I stumbled across a good looking complete 76 FI bug motor for a good price and picked it up, supposedly never been rebuilt. I tore the FI stuff off, got a carb off e bay and ran it couple weeks ago, fired up on 1st crank. It had 50 psi oil pressure at idle with 10w-30 and seemed to run good however 1 cylinder had low compression (120, 110, 120, 85). I ran it a few more minutes hoping to loosen something up and no change so it became the basis for a winter project motor.

My sunny day driver is a 250 hp 2276 turbo so I wasn't looking to break the world record for HP and wanted something bulletproof that wouldn't break the bank. I have scrounged good quality/deal parts for about a month, here is what it is shaping up to be (all parts are new unless otherwise indicated)

Used "AJ" 76 case, never line bored ( had Orig Germ brngs)
78mm Forged/counterweighted Chromoly 4340 (Chinese)
5.4" forged I beam rods 4340 with 180 ksi bolts (not ARP) made by AA
Mahle 90.5 B pistons and cylinders, targeting 8.5:1 compression
Scat C35 cam (Engle 110 copy) 285 adv dur, 246 dur @ .050
Forged Bugpack 1.25 ratio rockers (Swiss) will give .476 lift at valve
28mm lightweight lube a lobe lifters
Bugpack Street Pro II heads 40x35.5 dual springs chromoly retainers, supposedly are cast with big ports. No plans to port/polish yet
Schadek 26mm oil pump, will use steel cover and full flow
Forged Brazilian 12.5 lb 8 dowel flywheel with chromoly gland nut/washer
Dual Dellorto 40s (Alfa1750) with CB perf offset manifolds/linkage
Used VW doghouse fan/cooler setup from 76 motor

I have deliberated at length on the cam choice, I picked the cam up from a local guy along with the flywheel for a good price. After studying the Scat C35 and Engle 110 cam specs I concluded I am splitting hairs on setting it aside for an Engle 120 since the 120 only has 7 degrees more duration (at .050) and .020 more lift (with 1.25 rockers). I didn't want this motor to be a "spinner" and was targeting the power band tapering off around 6,000 rpm. I have read all the posts on C35 vs 110 vs 120 and haven't seen anything yet that would convince me to spend the money to get a 120. Considering that along with the Scat Street Pro II heads which are cast with larger ports (but not manually ported) I thought the cam/rocker/heads were a good balanced match. Ideally I would prefer to run single HD springs with the cam to minimize valvetrain wear but the heads already came with duals so.... Piled through a year 2000 hot VWs the other day and saw a build they did of a Scat engine kit that was virtually identical except they used a cast 78.4mm crank (nets a 2017 vs 2007), 5.6 in rods (vs my 5.4s), and Scat Mini D port heads everything else was virtually identical (cam, 1.25 rockers, carbs, etc...) they used 8:1 compression and got 125 hp on the engine dyno but stopped at 5500 rpm due to the cast crank. The HP number sounded a little high but I think the Scat mini D ports probably flow better than the Bugpack head I will use

Thoughts/opinions on the build list and cam selection? Opinions on single vs dual springs and the 28mm lube a lobe lifters (I won't mention the 4 letter word company that made the crank/lifters). Thanks in advance, now I just need to find a car/bus to put it into!

Sat Dec 08, 2007 1:01 am

If you plan to turn 6000 on a regular basis with close to 1/2" lift you really should go consider going with dual springs just to be on the safe side. just check to make sure that you don't have any coil bind. Remember that valve springs tend to lose some tension over time and your heads probably don't have the strongest available dual springs. I suspect that with the 110 type cam and unported heads your power will start to fall off closer to 5500 than 6000. Since you already have the dual spring heads and the C35 cam I'd go ahead and use them as is. The C35 cam might actually work better with your unported heads than a 120 would. The 26mmoil pump should be fine but I suggest that you use a welded/balanced doghouse fan.

Sat Dec 08, 2007 6:46 am

Ditto what Gerico said. With that cam, it's not gonna want to spin higher than 6K or so anyway and all you'll be doing is making noise and floating valves. I have no experience with the SCAT cam, butu I have ran the 110/120...bot with 1.1 and 1.25 rockers.
The small-ish ports and that cam will make TQ. Don't go crazy on the exhaust. I'd keep it 1.5".

Sat Dec 08, 2007 2:45 pm

I've had good luck with the engle 130. not too lopey, pulls good & very driveable. The 40 X 35.5 heads you have will work good & when you port them later you won't need to upgrade the cam. Just throw a set of 1.25's on it. Had one in a 78.4 X 90.5 motor. Drove it 7 hrs 1 way to nor. cal all the time. I never had a problem. I ran 9.5 comp. in it & it never ran hot eather. I had a pair of 44 webbers on it too.