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Speco-Thomas 357 cam - any more information ?
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Author:  74snail [ Sun Feb 28, 2010 8:17 pm ]
Post subject:  Speco-Thomas 357 cam - any more information ?
Speco-Thomas 357 cam , I recently found a reference to the cam as a high rev small bore cam ,apparently it comes on about 2000rpm and gives a high top end, very little information regarding its use other than its more suited to a 998 ( or hot 850 ) , or maybe a Formula Junior

Speco-Thomas 357 cam

Valve Overlap- 71
Cam Lift- 0.280 Valve Lift- 0.356
Inlet Open- 33 Inlet Close- 72
Exhaust Open- 67 Exhaust Close- 38
Inlet Period- 285 Exhaust Period- 285
Valve Clearance- 0.12

Apart from the cam lift and valve lift its quite similar to a BMC 544

BMC C-AEA544

Valve Overlap-73
Cam Lift- 0.306 Valve Lift- 0.388
Inlet Open- 34 Inlet Close- 74
Exhaust Open-69 Exhaust Close- 39
Inlet Period- 288 Exhaust Period- 288
valve Clearance- 0.015


anyone have some first hand experience using the Speco-Thomas 357 cam in a small bore ?
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Author:  mini7boy [ Tue Mar 02, 2010 1:08 am ]
Post subject: 
Camshaft design is a complex subject and the comparison of two cams is a lot more interesting than simply comparing lift and timing specs. But don't take my word for it. A chap named John Fowler said it beautifully in this piece he wrote: Lumpy Torque Or How To Choose A Cam

available at: http://reality.sgiweb.org/mg/ahsdc/goblins/tech/cams.htm

Fowler said:

"Different cams have different rates at which the inlet and exhaust valves open and close. The "ramp" of the cam lobe may gradually and evenly open the valve, open the valve very suddenly, start to open gradually and then finish opening quickly (or vica-versa), or any combination in between. The same number of possibilities exist for the closing ramp (and it may not be the same profile as the opening ramp). This rate of opening and closing of both inlet and exhaust valves has a lot to do with the harshness or smoothness of the operation of many cams and also the expected life of the valve train. Thus, 2 cams can have exactly the same timing and lift specifications, but they can operate as totally different cams."
Author:  74snail [ Tue Mar 02, 2010 6:53 pm ]
Post subject: 
Thanks for that M7B , I read that article quite a while ago , its an interesting read , I,m not doing a cam comparison , I only put the details of the 544 cam as a reference.

I,m sure there must be someone who has some information on the use of a Speco-Thomas 357 cam in a small bore
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Author:  mini7boy [ Tue Mar 02, 2010 9:51 pm ]
Post subject: 
I guess I misunderstood this remark by you:

"Apart from the cam lift and valve lift its quite similar to a BMC 544"
Author:  74snail [ Tue Mar 02, 2010 11:08 pm ]
Post subject: 
Hi I,m Zoomer and I like Prozac wrote:
I guess I,m misunderstanding this remark by you:

"this not a cam comparison, I am asking about the use of a Speco-Thomas 357 in a small bore"


Well Mr Zoomer that is correct , this is not a cam comparison , I am asking about the use of a Speco-Thomas 357 in a small bore
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Author:  drmini in aust [ Wed Mar 03, 2010 1:55 pm ]
Post subject: 
Just bolt it in Dean, you know you want to..:mrgreen:
Author:  74snail [ Wed Mar 03, 2010 8:14 pm ]
Post subject: 
drmini in aust wrote:
Just bolt it in Dean, you know you want to..:mrgreen:


Mr G are you saying that you have heard of it before ?

Bolt it into the "Snail" ?

Its not for me Mr G, I,m not sure how it would be on an 1100, if its supposed to be a high rev cam you could limit the top end putting it in a 1100 but if you were to run 9.9:1 compression with heavier double valve springs and a light flywheel it could work OK and the extra torque would widen the midrange , a 997 Cooper would be right on the money for a test bed but :roll: $

So it seems that information regarding the use of the Speco-Thomas 357 cam in a small bore is a little thin on the ground :?
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Author:  sgc [ Wed Mar 03, 2010 8:19 pm ]
Post subject: 
74snail wrote:
So it seems that information regarding the use of the Speco-Thomas 357 cam in a small bore is a little thin on the ground :?
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Here's an idea.....

Chuck it into a smallbore and thicken up the info a little ;) :D
Author:  BALLISTIC [ Wed Mar 03, 2010 8:36 pm ]
Post subject: 
Specs seem a little smaller than the one I like to use in a "nice" small bore :wink: . . . .
Stop talking Dean, coz talk is cheap :!: Just fit it in the "snail" and use it, REALLY use it . . . or Im sure I know someone that would know how to use it in a small bore engine :wink: :lol:
Author:  drmini in aust [ Wed Mar 03, 2010 8:42 pm ]
Post subject: 
Way back in the 60s I ran a 544 in a 1098 bored to 1220, was a real 544 cam, twin Amal 1-3/16" Monoblocs (then twin HS4s) and a Sonic LCB. Head was an 1100S.
It hauled ass all the way to 8500. Until it broke a circlip...
Anyway my point is, the 544 wasn't too bad on the road. it did lose a bit of torque down low though. :lol:
Go on... fit that sucker... :P
Author:  74snail [ Wed Mar 03, 2010 9:15 pm ]
Post subject: 
:lol: Hell I,m copping flak now !

you guys are evil , I,m just getting used to the brutal power of a bog standard 1100 that's been given more fuel and air and reliable spark , when the "Snail" gets an engine refresh I was planning on using a Waggott 509 , nice strong torque and a slight lump on idle, but if Scott says the Speco-Thomas 357 is a milder version of what he likes in a small bore then it must be good :roll: ( read - safe enough for Nun's, French train drivers and people with cramps )

No , the only motor here that will be getting a new cam soon will be the 1275 auto, its getting a Wade 240

I,ll tell you what though guys, I,ll have a chat to Clive and if he gives it the thumbs up for an 1100 I,ll build a motor with the Speco-Thomas 357, when the time is right , and get stickers for the car , 357 Magnum :D
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