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Centerline 11.1 cam

7K views 23 replies 10 participants last post by  alfaparticle 
#1 · (Edited)
On our Fall tour, my long-serving (30k miles w/ two different Alfas) ported head developed a catastrophic crack, the resulting failure of which prompted a engine rebuild. We did the work at my old friend Bob Fernald's little shop in Austin. It took awhile but was a memorable experience for me to again work with someone with his skills. When I told Bob this was just like old times, he told me there was a big difference: he can't easily get off the floor and I can't easily kneel down on the floor . . .

So, anyway. I bought a good replacement head from my friend Howard but, when it came to cams, we had in a dilemma. Our solution led us to a very satisfying result. Please read on. My previous head used a Delta A474 12mm intake cam which necessitates cutting notches the cam follower bores. Since this head was to be a temporary replacement while I prepared a new ported head, I decided to fit the Centerline 11.1 cam I'd used as an exhaust cam on the intake side of this replacement head. Mainly as an expedient let's-use-what-we-have-here solution we decided to use a stock 2.0 fuel injection cam on the exhaust side of our head. So: we had the Centerline 11.1 x 254 duration (I think that's right) coupled with a stock FI cam. Basically, all I was hoping for was a decent running motor which I could use until i got the replacement ported head done.

Taking my Super out for a short drive, I immediately noticed an instantaneous throttle response combined with bags of torque and a smooth delivery of power all across the rev range. Well, I thought, this is a satisfying surprise. On my drive back to San Antonio from Austin I took some back roads so I could do some break in miles. Frankly, I couldn't be more impressed with this dumb luck choice of camshafts. With 10.1 Motronics, 40mm Webers w/33mm chokes (restored by Gordon Raymond), balanced bottom end, headers, ignition, and light flywheel my new engine has plenty of torque and a very satisfying increase is unsable power. If you are interested in building a performance street 2 liter, this accidental combination might not have occurred to you but I can strongly recommend using the Centerline 11.1 cam combined with a stock 2 liter fuel injection cam.
 
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#3 ·
Jim I'm so glad you're pleased with the cam.

The practice of running an asymmetrical cam set-up is a tried and true way to get a very nicely balanced street motor. We often sell our 11.1mm cam for the intake paired with a 10.5mm cam for the exhaust. It sounds like you got very similar results with a stock cam on the exhaust side.
 
#4 ·
on a garden-variety street motor, with head not cut (or if so, only skimmed), can the 11.1 cam be dropped in without head modifications? ie no relief of follower pocket/ etc

I realize that the piston to valve clearance will need to be checked

Looking for some cam improvements without head work over and above 10548 euro cam for a SPICA injected (Wes modified) motor
 
#5 · (Edited)
on a garden-variety street motor, with head not cut (or if so, only skimmed), can the 11.1 cam be dropped in without head modifications? ie no relief of follower pocket/ etc
The head we used had some port work done on the intake side only and used stock intake and exhaust valves. Only the port runners had been modified while the valve-throat pocket---a critically important area to work on when doing port work---was left alone. The opened up port runners most likely contribute some extra hp to the engine's performance, although I think the ported intake manifold, 40DCOE carbs with 33mm chokes, the raised compression and cams are more significant. I think you would find this camshaft combination well suited for use on an otherwise stock engine. The 11.1 cam can be used (we set both at 102 degree lobe centers) without modifying the cam-follower bores which is something you'd need to do with, say, the Delta A474 12mm cam that was in my failed head.

I would think this combination would also work well with a Wes Ingram modified motor. I should add that the Centerline cam gives a smooth 700 rpm idle, coms on strong at about 3k rpm and makes good power throughout the rev range. Judging from the position of my gas gage's needle, I also think I'm getting a lot better mileage than the 18-20 mpg I was getting with the previous camshaft combination. With stock pistons or Motronics I don't think you'll run into clearance probolems with the Centerline cam. Keep in mind that I was running a 12mm cam with 10.1 Motronics and didn't encounter clearance problems.
 
#6 · (Edited)
I realize that the piston to valve clearance will need to be checked
Piston valve clearance puts a limit on cam timing but it is unlikely to limit performance with these cams. Use RJ's method of slipping a couple of cable ties between the piston and the valve and feel for it being pinched as you rotate the motor thought TDC. Exhaust valve timing has less effect on the power curve than intake timing. If you read posts about engine setup for motors that dyno'd big numbers you will find that about 98 intake and 108 exhaust give the best results but some piston/cam combo's will not allow you to set the intake below about 101. I recently did back to back dyno runs with two different performance exhaust cams at the same lobe center and the results were quite similar.
The attached chart shows the effect of moving the intake cam LC from 104 to 98.
 

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#11 ·
Exhaust cams

Just FYI...
The exhaust cams in all the Spica, Weber and FI engines are the same lobe design as the intake in those motors. The exhaust cams in them are not good designs for that purpose.
In engines built for the Motronic FI system with the large diameter BC intake that exhaust cam is a much better exhaust lobe design and the one I suggest using with the likes of the 10548 cam, and mild aftermarket cams on the intake.
 
#15 ·
Slowcreek, I think that you could pick up maybe 5 HP with a change of LC's. I would advance the intake one hole to about 99 and verify that you have at least .050" piston-valve clearance then retard the exhaust two holes to about 108 and check that you have at least .100" clearance. Then take it back to the dyno.
 
#16 ·
In engines built for the Motronic FI system with the large diameter BC intake that exhaust cam is a much better exhaust lobe design and the one I suggest using with the likes of the 10548 cam, and mild aftermarket cams on the intake.
This is good to know. Something I always like about these discussions is that they generally produce additional useful information. And the more good information we can have the better. The Alfabb is a genuinely unique resource in that regard. I've never encountered anything comparable to it.

I posted my comments because our cam choice was an expedient, the result of me deciding that I didn't want to take the time to notch the cam follower bores so I could run my 12mm Delta cam. The results were so surprisingly good---much better than I was expecting---that I thought I would add a factoid on cam choice to the BB's knowledge base. Using asymmetrical cams remains something of a black art and so I think it's fun to accidentally stumble across something that works. Is this the best combination? Nope. And I don't think it makes the hp of the Delta A474 12mm cam/Centerline 11.1mm combination which will go on the new head I intend to build. That said, I posted my comments because the combination works real good. If you have a stock Spica cam to use, the Centerline 11.1mm cam sells for $229US. That's a cheap entry fee for the kind of performance improvement you'll get.
 
#20 ·
Great to know. Thanks for posting. AlfaParticle who are the big power guys running 98-99 degree intake lobe center and what cams are they doing it with? At least in a near full or full race application it's hard for me to imagine advancing the intake that far not having a detrimental effect.
 
#21 ·
Hi Curtis,
Jim Steck's motors are typically 98/108. Msiert's black spider road car made 167 HP at the wheels on pump gas. Steve Schwitters built the motor and it was about 98/108. My street motor made 155 HP at the wheels with RJ575/457 cams at 98/108.
 
#22 ·
Interesting Ed, The 2L must be more different than my 1600 than I thought. The dyno has never suggested I advance a 1300 or 1600 intake past 102 and they usually seem happiest around 104. This includes my current engine with Steve's intake and RJs exhaust. If I ever build a 2000 I better ask around I guess!!
 
#23 · (Edited)
Cam timing

I have never used "EFFECTIVE CAM CENTERS" that far advanced as it "would & should" bias the power band to lower RPM ranges (Which you might want for a street car)

Given: Jim`s head mods and intake designs and piston shapes are VERY different.
Most racers using my "race cams" typically find good results using my base line LCs of 104/104 or 104/106. Both of the engines in my two race cars are set at 103/106 now. A 104-105 LSA seems appropriate for the typical Alfa intake length. BUT, I`m using a shorter intake track length with very large raised ports (short custom manifold, 1" air horns in the cold air box) and 50mm DCO carbs. Hayes Flynn`s 230hp/215 hp (different RjR cams in same engine) and Ed`s use only a modified factory airbox (rounded 52mm openings to the 45 DCOE carbs I modified internally).
All these intake track differences have to be considered when choosing LCs of any cam, and the dyno adjustments are pretty much required to optimize the power band.

Key points of making real power are closing the intake valve "early" enough to limit the amount of reversion, and delaying the opening of the exhaust (and still get it closed before P to V issues) to lengthen the power stroke.

My newest Race intakes have total "off the seat duration (at .010" "lash" settings of 298* int. and 276* exh. Key points are durations at .050 are 265* int and 246* exhaust which is where "flow" really starts, and very high durations from there upward 125* int and 110* exh at 450 lift. (Total lifts are .525 int. and .495 exh)
 
#24 ·
Jim first advised me to advance the intake to below 100 was when I first met him at Watkins glen in 2015. The very fast 1500 Giulietta that he was supporting was running about 98/108 and he thought that my motor would benefit from similar timing. I was unable to advance the 575 that much with the Venolia pistons but road testing indicated that 101 was better than 104. My sessions on Al's dyno showed that 101 was better than 104 and 98 was best of all. The dyno charts show that the improvement was from 3000 rpm to 6200 and they were the same above 6200.
 

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