Some thoughts on cams

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IMPI
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Re: Some thoughts on cams

Post by IMPI » Thu Aug 05, 2010 8:19 pm

It is on the ragged edge of streetability in a 1600 (your mother will hate it) but will be good in a 1915. Using a cam to try getting hp out of an engine and doing nothing else is a total waste of time.
SAC 2 liter Polos came with a 276 degree cam


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IMPI
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Re: Some thoughts on cams

Post by IMPI » Fri Nov 30, 2012 10:50 am

Lately a lot more questions came up regarding cams.
I have rarely had to replace a type one cam when doing standard rebuilds there being only three reasons to do so
First the lobes are completely gone or the bearing surfaces are worn.
the cam is brinelling That is there are pitts starting to apear in the surfaces and it looks like the lobe is shedding skin.
the gear to cam attachment is worn and the rivits or gear is loose causing a tapping noise which is impossible to trace.

When the type one cam is reground to another profile (nothing wrong with that either and fairly cheap) hve the same crowd do the lifters as well. The thing to remember is that the grinder ads another std or custom profile within the metal that already exists this makes it difficult to grind more lift into the cam as well as more duration. It also follows that the base circle (the part that doesnt create lift) must become smaller to accomodate the new profile. now grinding to restore wear doesnt remove significant ammounts of metal but as soon as radical profiles are ground this becomes a problem. in simple terms you need a longer pushrod to restore valvetrain geometry if all else stays equal. but also the lifter can now move closer to the cam so much that its oil feed may be cut off again something to watch.

Grinding a stock cam to w100 spec is probably the most you would get reliably but a new cam is probably the best choise if your budget allows.
Armand
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jazz1002richard
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Re: Some thoughts on cams

Post by jazz1002richard » Mon Aug 31, 2015 7:03 pm

hey guys new bloke on the block , i am building a 2.6 lt vw based flat 4 , type 1 origins , i am looking for some help with a cam selection please , basically it operates at 4300 rpm and has 1,5 pauter rockers , i am looking at an approx duration of around 240 degrees and lobe centres around 108 degrees , i am after around 12,5 to 13mm lift , scat C20 or C25 cams appear to be suitable and would really appreciate knowing if anyone has one of these cams available to sell or for me to try
many thanks guys
rich

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