| [ Total Views: 827 | Total Replies: 11 | Thread Id: 88334 ] |
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 sander288
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| posted on January 25th, 2011 at 03:52 PM |
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Camshaft Question
I have been looking at this cam (see below) from CB performance for my 1300 Motor. would link to it but their site is down.
"Offroad Special"
Adv Duration: 296 deg
Adv Duration @ 50: 256 deg
Lift @ Cam: .420"
Lift @ rocker 1.1:1=.462"
The motor specs are (current)
Internals: Stock 1300 VW Stock C/R
Heads and Valvetrain: Stock VW
Oil: Stock VW with addition of Pobjoy anti surge sump.
Induction: Stock Solex 30 pict
Ignition: 009, compufire module, W8AC plugs, stock leads and coils.
Exhaust: 1 3/8 Extractor, (VVDS Mild steel one)
When the cam i'm thinking of goes in it will look like the following.
Internals: C/W Crank, lightened flywheel Stock C/R
Heads and valvetrain: 1300 Twin port heads Formula Vee porting job; straight cuts; "offroad special camshaft" and stock elsewhere
Induction: 34 Pict 3 modifed for Vee racing; CB Perf high flow PICT manifold
Ignition: 009, compufire module, W8AC plugs, stock leads and coils.
Exhaust: 1 3/8 Extractor.
So the motor won't change a great deal but will run alot better; what are peoples thoughts on the potential of this cam?
The use of the car would be tarmac rallies; road touring events; regualrity trials; odd hillclimbs and supersprints where able.
Cheers
Shaun
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sander288
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| posted on January 25th, 2011 at 03:55 PM |
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Before people ask why so conservative on the motor; it is being built for the standard class regs under Tarmac Rally rules as the Targa Tasmania is my
end goal with the car. And with this set-up it can easily run under historic rules be used on the road and be a blast to drive flat-out all the time!
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 matberry
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| posted on January 25th, 2011 at 11:14 PM |
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Not sure how it will perform, but I'd recommend hd valve springs, solid rocker shaft kit and swivel foot valve adjusters as a minimum to cope with
the quicker acceleration rate.
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE
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clinker42
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| posted on January 26th, 2011 at 08:46 AM |
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More info required. What RPM range do you intend to us.
Do you want high HP for fast speeds down the straight, or do you want it to pull out of the corners. A cam profile that will give you great top end
will sacrifice corner exits. But the cam that gives you great corner exits will sacrifce top end. You can solve some of those issues with higher
gearing to keep your rpm up, but that can hurt engines.
This tarmac stuff you do, will the engine be above say 3500 all the time.
256 @ 50 is a reasonably big cam, maybe too big for stock comp and only 1300 cubes, more duration must have more cubes and more comp to work, if you
dont give them that you will have less hp and poor torque. If you go too big in duration you will have to keep the revs high and the torque curve
will be too high. If you have flow figures from the heads, exact C/R and required rpm range I could feed that into works computer and come up with a
grind. I would suggest looking for something with a bit more lift and a bit less duration, say around the 248-250 @ 50 and around 425 -428 lift. If
the heads ports are good, you can use less duration and make more power Bigger duration can fix poor ports but it comes at a cost, more rpm. Also,
ask guys like Matt about high lift rockers, I think I read here some guys use them. Smaller cam, high lift rockers and good ports will mean leass
revs, better HP and a much better torque curve
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cnfabo
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| posted on January 26th, 2011 at 01:25 PM |
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would you need a C/W crank......stan told me you can rev a non counterweighted crank @6000 all day as long as you use a stock weight flywheel... just
saving you money thats all.....
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sander288
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| posted on January 26th, 2011 at 02:40 PM |
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Cheers for the feedback on the cam; i'm not an engine builder so only go off what I read on websites and stores about the cams; it read alright in
the catalog.
I figured a C/W crank would be right as I know stan built a 1200 motor for hsitorics that had a C/W crank in it that took out most of the races in
it's class.
Clinker
I wouldn't be able to give you flow figures on the heads but the C/R would as it is now 7.3:1 and rpm range of 2500-6000 but ultimately i'll rev to
what it will go too; as at present from what I worked out with tyre size and speed in 3rd gear the stock motor goes to about 5500rpm so I would hope
more than 6 was possible.
Maybe an email to Tighe Cams with the specs would offer a better grind.
Cheers
Shaun
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66brm
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| posted on January 27th, 2011 at 04:10 PM |
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I would probably bump the compression up a bit also if the class rules allow, that'll give it a bit more poke too, I've never seen 1300 dp heads
here in Aust but are you going to p&p the intakes and exhaust? match port the end castings to try take advantage of the cams rpm band. Can you run
ratio rockers?
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Craig Torrens
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| posted on January 27th, 2011 at 07:02 PM |
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| Quote: | Originally
posted by sander288.
I figured a C/W crank would be right as I know stan built a 1200 motor for hsitorics that had a C/W crank in it that took out most of the races in
it's class.
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Yeah but that was designed to rev at 7500rpm all day long, thats why it had a CW crank. 
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70AutoStik
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| posted on January 29th, 2011 at 12:06 PM |
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Not sure what "1300 Twin port heads Formula Vee porting job" are, but knowing the strict limitations on modifications in the Targa and Formula Vee,
I imagine they are going to be the limiting point for your engine - the small ports of the 1300 are going to stop you going much past 6000rpm.
It would be wisest to talk to your head guy before choosing a cam - while longer duration in the cam may still make a little more power, your power
band may be too small to be useful. I doubt a close ratio box will fit within the rules and going beyond 4 gears in a VW gets expensive anyway.
1.25 rockers should be allowed if you use the "genuine VW" type.
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sander288
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| posted on January 30th, 2011 at 08:10 AM |
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Ratio rockers are allowed as is any change of cam unfortunately it does say no c/r change the twin port heads will all be matched to the manifold and
end castings as well as p&p.
I plan to get some second hand heads off Boris who said he has some lying around.
If people are curious of the rules then look on the targa websites and grab their supp regs or look at aasa website the rules are close to cams Tarmac
classic ones though (class c1) I think
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sander288
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| posted on January 30th, 2011 at 08:17 AM |
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http://targahighcountry.com.au/download/2010THC-Sup%20Regs-V3-181010.pdf
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sander288
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| posted on January 30th, 2011 at 08:19 AM |
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Refer to classic (ss) standard specification
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