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Fri Dec 18, 2009 3:22 pm

I can not decide between these 2 cams

Webcam (86,5 + 10) 280deg .432/.366" lift

Webcam (86a) 290 deg .435/.369" lift

I would like peak hp at no more than 6500 rpm's

Engine spec:
74x90,5 (stock porsche crank, vw t1 modified cylinders)
9.5:1
1.5/8 4-1 custom exhaust
Ported stock heads 38x34 (Edit: proffessional 3 angle valve job)
Weber 40 IDF's 34mm venturis
Stock distributor
98 octane (europe) fuel
Stock 5 spd 912 tranny

I like the low end grunt of a stock engine, but would like a bit more pull above 5.5k than stock.

Any advice welcome:)

Sat Dec 19, 2009 12:32 pm

Id say the 86a would do well. Be nice to know what your flow numbers are on your heads.
If your heads dont flow much, id suggest the smaller cam again depending on what the heads flow. Exhaust may be a bit much also. 1.5 pipe would be better.
Keep us posted on what you end up with, and dont be afraid to call web cam and ask what they would recommend for your setup. They are awesome in that reguard.
later dave

Mon Dec 21, 2009 12:40 pm

The heads have not yet been ported yet, so i do not have the flow #.
They will just get a clean up and a 3 angle valve job (after talking to my machinist he recommends 3 angle instead of 5 to keep the seating width wide enough)

I will probably go with the 290 deg cam. Since displacement iswill be 1904cc i would still get more or the same low down torque as a stocker?

Are there aney flow numbers around for 356SC/912 heads?
I have not found any yet.

Mon Dec 21, 2009 9:51 pm

See wilhoit auto restoration website for some flow numbers. I built a 1904 but used the flattop vw pistons and had about 7:1 c.r. It wasn't any faster than a 1720. What did you use for pistons?
David

Tue Dec 22, 2009 1:59 am

David Seeland wrote: See wilhoit auto restoration website for some flow numbers. I built a 1904 but used the flattop vw pistons and had about 7:1 c.r. It wasn't any faster than a 1720. What did you use for pistons?
David

I will use flat top, but they will be machined to hava a small dome.
It should be possible to get compression up to 9.5:1

Even with flat top 90.5s compression will be 8.2:1 with a 0.047" deck height and stock 58.5cc chambers.

Tue Dec 29, 2009 4:05 pm

Went for the 86A.
Have to wait until spring time to see how it performs :)

Tue Dec 29, 2009 5:21 pm

Nice, my mind is failing me, as its been years since i had my 356s. but cant you flycut the heads down a bit just like a VW so you can reduce the size of the chamber and increase compression? cause mid 9s will be perfect.

Tue Dec 29, 2009 10:38 pm

You would have to flycut so far that you would be well in to the angled exhaust seats before you reduced the chamber cc's enough to raise the compression to the mid 8's. Plus about 20 other problems.

Tue Dec 29, 2009 10:54 pm

Just took down what i posted, i took a look at some pics and i remember. You have to weld up the side of the chamber opposite the spark plug. Make a heart shaped chamber, then you can get compression where you want it. Its a better chamber for burning unleaded anyways. You can get down to 50 cc that way which is where you need to be for mid 9s on his setup. It takes some wizardry but its been done. Special pistons doesnt hurt either. :)

Wed Dec 30, 2009 4:46 pm

bcrazy wrote: David Seeland wrote: See wilhoit auto restoration website for some flow numbers. I built a 1904 but used the flattop vw pistons and had about 7:1 c.r. It wasn't any faster than a 1720. What did you use for pistons?
David

I will use flat top, but they will be machined to hava a small dome.
It should be possible to get compression up to 9.5:1

Even with flat top 90.5s compression will be 8.2:1 with a 0.047" deck height and stock 58.5cc chambers.

I will use 0.040" deck heigh and even flat tops will get 8.3:1 minus valve pocket for exhaust.

You can mill the head about 1 mm beforeyou hit the exhaust valve seat. This should reduce the chamber around 5 cc, giving 8.9:1

I will use domed pistons so mid 9s "should" be easy

Thu Feb 18, 2010 12:08 am

some problems with my machinst guy that modified the vw piston's. He basically destroied them.. So now i will go for the 86 mm slip in's since i do not have the time or money to start over again.

This leaves me with 1720cc, and i already have the 86a cam.
So now I am a bit worried about the low down torque of the 1720 with this cam.

Should i advance it a degree or two???