best 66x90mm combo? + 3.0 questions

JYRI ERAMAA · 05-06-2009, 08:20 AM

hello, i have:

66mm S-crank, rods,
machined 90mm carrera pistons and cylinders 10.0 cr
1968 S-block
heads with 46mm intake valve and was it 38 exh (intake port 34mm)
weber 40 mm / k&n filters
vertex mag with 901/02 curve & 911 S-dizzy (yellow tag)

but what would you use for cams?
or would you use bigger PMO carbs?
header size?

i would like a oldschool looking screamer, with attitude, autobahn stormer :-)

also im interested of the possibility to put bigger cylinders on a 3.0 block.
the idea would be to use 3.0 block - 3.6 crank & rods - bigger cylinders with high compression...and some hot cams and maybe something like 40mm - 50mm carbs... (any suggestions?)...

i have also questions in the 912 are about brakes, if someone can help on that too...

thanks for your time and for any help...

Jyri / http://volkswanker.blogspot.com

bob barnes · 05-06-2009, 10:40 AM

Yes,

I already built the 76.4 crank/ 98mm Cosworth Pistons/Race Cams/50PMO Carbs.

Sold the carbs but You can buy the Engine built on a 3.0L Case.

PM me if you are interested.

Bob

JYRI ERAMAA · 05-06-2009, 12:25 PM

How big is it? Is the 98 mm bore the biggest that can be used?
Jyri

bob barnes · 01:56 PM

The biggest Piston 100MM but with this stroke, 98MM safe! 3458CC

Bob

JYRI ERAMAA · 07-16-2009, 05:22 AM

BTW would the Jerry Woods GE80 cams be good in a hot rod 2,5 liter screamer or better in a bigger 3,4 liter setup? or do you have better suggestions?

Raceboy · Raceboy's Garage

Hi Jüri! Oled sa Eestist pärit? Nime järgi tundub küll nii?

JYRI ERAMAA · 07-16-2009, 05:31 AM

en ole kuin tästä naapuri maasta ;-)

Raceboy · Raceboy's Garage

Oko

kenikh · 07-16-2009, 07:14 AM

For a 2.5 screamer, I'd go with a custom cam, maybe a GE60 with the lobe center tightened up a few degrees. Or and RSR sprint cam with a little less overlap and a dash more lift.

jpnovak · 07-16-2009, 07:29 AM

Be careful to not overcam the car with those small intake dimensions. Too much lift will exceed the flow capacity of the heads. Better to stick with lower lift, longer duration cams with a slightly faster ramp speed. This means a custom grind as Kenik described. I also agree to slightly reduce the lobe center (less overlap) this will help broaden the torque curve and have a little more pep at low(er) rpms.

Otherwise, port the heads, do the correct oil mods to keep the crank happy and fit some cams that will be happy at 8500.

I have a similar spec build I am starting to collect parts for. My SWTarga will thank me.

kenikh · 07-16-2009, 09:22 AM

Bottom line is to talk to camgrinder. I should have caveated my cam selection to include port work. A high comp 2.5 can take a lot of cam. OEM Sprint cam in a 2.8SS is a joy, so scaling that back a bit for the loss of displacement is what i was after.

Steve@Rennsport · 07-16-2009, 09:53 AM

Quote:

Originally Posted by kenikh

............I should have caveated my cam selection to include port work.

Excellent suggestion,......

JYRI ERAMAA · 07-16-2009, 12:14 PM

Be careful to not overcam the car with those small intake dimensions.

Ok, what if the ports would be 38mm then? We experimented long time ago that a small head of the smaller engine has too small intake port, 34mm, when modified to use a 46mm intake valve... So if the ports would be ported, and modified to 38mm size, what would you use then?

bob barnes · 07-16-2009, 04:16 PM

Sprint cams make very little low-end Torque. GE-80 not the right cam for a 2.5L Race Motor. I had both of these cams in some Race Engines. A starting point is buy the book 911 Story and check out what was the starting point 30yrs ago. Send your heads to a well known head porter and then Cam the engine.

Bob

JYRI ERAMAA · 12-19-2009, 09:09 AM

ok, the 3.0 is under dismantling, so far looks pretty nice inside.
so i have the 76.4 mm crank, with correct rods, and now i have a 100 mm cylinders,
...what i would like to have is a set of 100 mm je high comp pistons, some nice cams (any suggestions), and 50 pmo´s... but is it going to be a time bomb?

i would like to use the 3.0 heads, but what do you guys think...do they need porting, or are they good allready?...how much do they flow anyway? a 300 hp street engine "with evil temper" & fast response, in a SWB 912 body would be great. ;-)

or am i going to the wrong way?

thanks for any hint...

Jyri / Helsinki

volkswanker