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Old 26 Apr 2010, 19:19 (Ref:2680112)   #31
phoenix
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Originally Posted by Robyn Slater View Post
Also interested in the calcs to determine cam profile. Any suggestions where i can find info for further study?

Robyn
Hi Robyn

I have my own and very crude method of evaluating the duration required, based on cylinder capacity and revs required, which I have devised myself. Nominal lift I determine from valve diameter and the calculated gas speed through the curtain area. These are both very, very crude and I would never spec my own cam as I am certain I haven't mastered the finer details of cam design - I would always talk to an expert and get their advice.

If you are seriously developing an engine and they know you are going to give it the dyno time and all the other effort involved, there are cam manufacturers who will do their best to arrive at the correct cam profile even if it takes a couple of attempts. If you want to know who I would suggest you talk to, drop me a PM.

Bye the way, I thought you were a twincam man?
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Old 26 Apr 2010, 20:27 (Ref:2680165)   #32
tony griffiths
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SCC specs

Capacity 1097cc Bore : 83.5mm Stroke : 1,970"

Gross HP : 130bhp minimum @ 8,500

Cams : F1

Inlet valve : 1.53"
Ex " : 1 .30

Slipper pistons

Lucas Opus ign !

Carbs 40 IDF

Rev limit 9,500

SCB -- no spec -- marked as development purposes only
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Old 28 Apr 2010, 06:15 (Ref:2680913)   #33
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Originally Posted by phoenix View Post
Do you have a spec sheet for the SCC also? I found a reference on the web that these produced 135 BHP from 1099.6 cc (83.5 mm bore and 50.20 mm stroke) but with the same size inlet valve - so I'd like to find confirmation of that. Also Rob mentioned that some SCCs had 1.55" inlet valves.
Actually, it was the SCD 1500cc engine that was listed as having a 1.55" intake valve. I don't know if they ever built one or not.

Robyn, the small shaft in the nose of the crank is what drives the crank gear. The crank gear floats on the end of the crank on a bronze bushing and the two pins limit its rotational travel. I am assuming this was all done to damp out torsional vibration and prevent it from being transmitted to the cam drive gear train.
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Old 28 Apr 2010, 06:28 (Ref:2680919)   #34
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Originally Posted by phoenix View Post
Rob

Are you planning to use and 83.5 mm bore for your SCB? If you are free to do so you could find a 6% improvement on torque output from the 1593.5cc that would result in (same capacity as the FVA I believe) and more bore clearance for your 1.6" inlet valve.
Martin,
I was originally planning on using an 83.5mm bore for the exact reasons you stated. I will have to make a decision here very quickly. I have both 81mm and 83.5mm blocks, so I could go either way.

Regards,

Rob
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Old 28 Apr 2010, 17:51 (Ref:2681270)   #35
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Cosworth did not build a SCD and FVA was 1598cc
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Old 28 Apr 2010, 20:43 (Ref:2681351)   #36
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Robyn, the small shaft in the nose of the crank is what drives the crank gear. The crank gear floats on the end of the crank on a bronze bushing and the two pins limit its rotational travel. I am assuming this was all done to damp out torsional vibration and prevent it from being transmitted to the cam drive gear train.
I think i'm getting this now
The Quill (dumb bell) actually drives the gear and acts as a torsional damper,limited by the pins in the nose of the crank.
Sorry but i can now see thats exactly what you said.

When i read the Cosworth book a while back i remember it said the Duckworth used "Quills" to cure torsional vibration problems in the DFV engine.
Up till now i didn't understand what they meant but now i have a better understanding


Pheonix,Where did you get the impression that i'm a Twink man?
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Old 29 Apr 2010, 06:15 (Ref:2681468)   #37
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Gentlemen,

Below is a shot of the SCA cam carrier, cam, tappet, and bearing inserts. Interesting that the cam carrier and caps are cast iron, I assume to provide a good bearing surface for the tappets. It appears that the cam bearing inserts are same as Twincam, but the tappets are different, actually a little larger in diameter. Too bad, as I had assumed I would be able to use off the shelf tappets. Now it looks like I will be spending some money with Arrow for custom tappets, as I only have one set of tappets between the four engines.

Tony, thanks for the info on the SCC engine, as I had not been able to find anything. How did you come accross all the Cosworth data sheets?

Regards,

Rob
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Old 29 Apr 2010, 15:35 (Ref:2681730)   #38
tony griffiths
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Rob,

Used to work for Cosworths in the late 70's and was given spec sheets on the majority of the engines !
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Old 2 May 2010, 17:09 (Ref:2683294)   #39
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Gentlemen,

Here are a few more photos of some things I find interesting about the SCA/C. The shot of the timing gears shows (I believe) an early and a late compound gear which mounts to the front of the cylinder head and actually drives the cam gear. The early one on the left has bolts holding the two gears together, but the later one on the right uses 4 spring pins. I am thinking that the spring pins might be able to give just a little bit and help with the torsional vibration damping in the cam drive geartrain. Or possibly it was just a cheaper, quicker way to join the gears. I have never rebuilt a DFV, but I am told that the torsional vibration damping in that engine is accomplished within the compound gear at the branch of the "Y" in the geartrain.

The third photo shows the Lucas Opus ignition box and distributor; there was also a normal looking ignition coil as part of the system. I have never seen this setup except on F2 cars from this period. I have run several F1 cars from that period and they seem to run a larger box that includes the ignition coil inside it.

Regards,

Rob
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Old 3 Jul 2010, 23:42 (Ref:2721609)   #40
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chassis number and history of SCB powered cars

Since I have more than a passing interest in the SCB engine, I started looking into just how many were built. I found a post from Bob Ilich in Oz stating that three were built, including the one in his car. I looked into the F2 register for '67 and found two cars:

Brabham BT-16 F2-23-65 Driver Brian Redman Entrant David Bridges
Cooper T83 F3-1-66 Drivers David Darby/Brian Myers Entrants same

I then found a Palliser/SCB driven by Hugh Dibley in a Formula Libre race in '67, which makes 3 engines.

Bob Ilich took delivery of Brabham BT-21B-16 with an SCB, I assume in '68, and took it to Australia where it remains today, still with the SCB.

There is mention of another BT-21B with an SCB used by Louis Parsons in Formual Libre racing in '69-70.

I figure the engines from the BT-21s could have come from earlier cars, so there still might be only 3 engines.

Can anyone shed any additional light on this?

Regards, Rob
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Old 10 Jul 2010, 23:12 (Ref:2724596)   #41
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Originally Posted by rkshanahan View Post
Gentlemen,

Below is a shot of the SCA cam carrier, cam, tappet, and bearing inserts. Interesting that the cam carrier and caps are cast iron, I assume to provide a good bearing surface for the tappets. It appears that the cam bearing inserts are same as Twincam, but the tappets are different, actually a little larger in diameter. Too bad, as I had assumed I would be able to use off the shelf tappets. Now it looks like I will be spending some money with Arrow for custom tappets, as I only have one set of tappets between the four engines.

Tony, thanks for the info on the SCC engine, as I had not been able to find anything. How did you come accross all the Cosworth data sheets?

Regards,

Rob
The cam carrier design looks to me very much like it could have been copied from a Coventry Climax FWA/FWE/FWB, maybe the buckets are the same size if that is the case. Climax buckets are 1.398 inches as best I can measure with them in the head. Not sure of the length or internal step height, but a check with a Climax stockist - Dave Bean, Bill Hutton etc would soon tell you.

The SCA SCB are to me a real jewel of a motor ...

Photo is of a rare 5 bearing version of the Climax carrier in an FWA from a Lotus Eleven that has been apart now for over 30 years.

Ed
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Last edited by edholly; 10 Jul 2010 at 23:25. Reason: add photo
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Old 17 Sep 2010, 05:02 (Ref:2760704)   #42
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Update and new flow data

Gentlemen,

It has been a while since I updated this thread, but progress has been slower than I hoped. Since my last post I have gotten my pistons made, sleeved my block down to 81mm, made a crankshaft, recieved my new cam blanks and new cam followers, and finished up my flow work on the cylinder head. I have now selected a cam profile based on the flow data, so the cam grinder can get to work finishing up the camshaft. I needed to replace some missing or damaged timing gears, and those gears are now cut but need heat treating to be complete. I am hoping I can start on assembling the engine as soon as the gears are finished.

The flow data on the cylinder head was disappointing. The stock intake port flowed 150 cfm @ 28" vac. which was less than I was expecting. We were able to get the one "large valve" head I have up to 185 cfm @ 28", but I am told that even a mildly ported Twincam head would be over 200 cfm. The low lift flow was really down compared to a Twincam. The good news is that the flow numbers were the same with the intake manifolds and carbs bolted on, so at least I don't have any restriction there. I was able to pick up 7 cfm by stepping up the venturi size in the carbs by 2 mm.

Please let me know if there are parts you would like photos of or additional detail I can provide. I will be busy the next couple of weeks, but after that I plan to get the first engine together and on the dyno pretty quickly.

Rob
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Old 7 Jan 2011, 05:02 (Ref:2812265)   #43
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SCC engine update

I am assembling the one SCC 1100cc engine I got in my parts package. The SCB project is on hold until I can sort out some gear backlash issues. The head has been decked in the past, which of course means the backlash between the gear attached to the head and the gear attached to the block is now zero. I am getting a thicker head gasket made to take care of the issue.

I only just recieved the folder with the paperwork that came with my engines. It included a copy of the Cosworth "manual" for the SCC. It is 6 typewritten pages, and includes the specs and assmebly instructions. There was also a drawing of the crankshaft snout and crank gear included, which was really helpful, and a drawing of the standard SCC pistons. It was pretty interesting pressing the crankshaft gear and its drive quill into the nose of the crankshaft, but I now have the hang of it. Requires some pretty precise grinding of the quill in order to get the press fit just right.

I have also made some pretty significant headway on gathering the parts to make one of the engines fuel injected. I have managed to buy an original SCA Lucas metering unit mount, which was going to be a real pain to fabricate. I also now have a proper 6mm metering unit, a mechanical pump, injectors, and most of an intake manifold with slide throttles.

I have had a couple of people ask me how they can build up an SCA out of bits. I think you could buy or make most of it, but the cylinder head would be the problem. You can't just make one from scratch, and I don't know where you can buy any spare.

Regards,

Rob
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Old 5 May 2015, 08:36 (Ref:3534247)   #44
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Hi all, <br />
I have found your forum fascinating and very informative, helping me with something which may be of interest to someone here.<br />
I have found an SCA engine, totally complete and assembled with F2 exhaust and engine mounts and pumps alternator etc. with Lucas slide throttle injection, sadly static in a barn for the last 35 years, athough covered with blankets. Any interest?? The owner wishes to sell, it is located near Le Mans France.
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Old 5 May 2015, 08:42 (Ref:3534248)   #45
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I forgot to say, you can reply here, or email me on steve.peel@hotmail.co.uk Thanks, Steve.
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