Cam shaft question/3.1 buildup

[Doubt_Incarnate]

why would you do this to a porsche?

[Froggx]

why would you do this to a porsche?

Make it cheap to maintain/reliable?
Never specified if it was a current porsche or something ancient.

My vote is for the 260 unless you plan on spinning it up over 6000 rpm most of the time, in which case the 272's better top end makes more sense.

[geoffinbc]

Its a 3.1L bottom with a 3100 heads and a 3400 mani/plenum. All going into a Porsche.

Thanks.

So then yes 260 cam with stock Gen III valve springs from the 3100 heads.

Should be sweet.

Suggestion. Get roller rockers

[Froggx]

Does the Gen 3 top end not come with roller rockers? Or am I crossing gen 2 and 3 again, I tend to do that?

[614streets]

i didn't think big cams were good for boost, how is it you forced induction guys are using them? or are these not overly agressive, agressive cams?

id stick with the 260 cam if you dont plan on getting out of the first 2 gears. more torque than stock, and the 272 cam in the bottom end. first to 2nd seems to drop quite few rpms on my car, so id want a broad torque curve to cover that. as far as springs, i think the ones crane has for us are sbc springs, i dunno if ls1 springs are stiffer, if you dont plan on reving higher than stock, don't bother.

Well for me I choose the 272 Because I was on a budget (building two engines at once and the 355 budget was bigger) , although I really want a solid roller cam in it. The 272 Duration 216 ° ~228 ° helps scavange my exhaust since Im not using a turbo but Supercharger and Nitrous.
I never really considered the 272 a big cam , but when I did some wot runs after intial break in the truck would carry way past 6500. Plus I ran a 4:10 gear out back , which btw is a ton of gear on the street.

But For an NA motor the 112 lsa is lil lil conservative if u ask me. Youd be better off with a 108 or 106 lsa if you can stand a choppier idle. And a solid cam is going to make more power. The lash wear for a true daily driver , you know the one you drive to work, would be a factor with it though.

12370 on a n/a hot rod motor would really scream , but w/o tuning it wouldnt work with a stock ecm.

http://www.schneidercams.com/cams/35.htm

For the money the 260 is a looks like a good buy.

[Stevesr]

why would you do this to a porsche?

Make it cheap to maintain/reliable?
Never specified if it was a current porsche or something ancient.

My vote is for the 260 unless you plan on spinning it up over 6000 rpm most of the time, in which case the 272's better top end makes more sense.

Let me clear this up for people who don't what is going on here,The Porsche is a 1971 914 NOT a real Porsche is some peoples eyes,second it is not a concourse car or trailer queen by any stretch of the imagination.nor is it a rust bucket. I just wanted cheap reliable power and the 60*V6 in my opinion was the perfect choice. Alot of guys put V8's in this car but I think that is overkill,this motor weighs 85lbs more than the stock flat four cylinder. but a lot smaller than a V8. Any one that hasn't done so check out my thread in the swap area. V6/ Porsche 914 project.

SteveSr

[Doubt_Incarnate]

ok, not much of a porsche i agree.

i know the 260-272 cams arent really "big" cams, but they do sem to be the bigest readily available. i think the 272 moves the power out to far, im more for quick streetability, the 260 seems to add power without pushing it up to or beyond 6000rpm, i hardley ever get there. usually just up to 5-5.5K or so, on a sporty day. i think it should give a good fast feel off the line, instead of waiting for power to come in.

im finally going to get my godforsaken car together soon, cant wait(first car+sentimental fool=me). im just a lazy goodfor nothing, so its been apart for like 2 years. good thing i have an ls1 to beat around.

[geoffinbc]

Does the Gen 3 top end not come with roller rockers? Or am I crossing gen 2 and 3 again, I tend to do that?

Sadly not until the 1995 model year. Even at that only some engines had it. In 1996 all engines had roller rockers.

[Stevesr]

Ok,so it sounds like I want the 260 cam because of the low end HP,and we hashed this all out in another thread,3100 pistons,260 cam/3400 topend, headers,after market throttlebody and an ECM tune. Are the roller tip rockers readly available from parts stores,dealer? Or are used ones ok?

SteveSr

[geoffinbc]

You can buy roller tip. But I would be looking for a machined full roller rocker. Either Comp or Crane can offer them and a few other companies.

If you going racing you will want a heavy duty, light valvetrain.

[Doubt_Incarnate]

im not 100% sure, but i dont think cranes work with the new heads, the new heads you actually torque the rockers down, lash/pre-load is built in. i dont know if the cranes can just bolt on, or if you need to machine the pedestals down and screw in some studs.

[Doubt_Incarnate]

im not 100% sure, but i dont think cranes work with the new heads, the new heads you actually torque the rockers down, lash/pre-load is built in. i dont know if the cranes can just bolt on, or if you need to machine the pedestals down and screw in some studs.

[Stevesr]

So then yes 260 cam with stock Gen III valve springs from the 3100 heads.

Should be sweet.

Suggestion. Get roller rockers [/quote]

Ok,I jumped over to "Jegs" web site and looked at full roller rockers,you can get Comp Cam's best for$300+,they have about 8 or 10 other options which were cheaper. What will it take to get these on my heads?
I have read on other threads about grinding clearance.

SteveSr

[Doubt_Incarnate]

i have those on my gen 2 heads, there are no clearance issues i can see, but my motors still on the stand, sorry for the double post, i dunno what happened

[Stevesr]

Ok,so what do you order from places like Jegs or Summit,I have a hard time finding anything for our v6's at these places. Do the ones for small block Chevy fit. Who has a part number?

SteveSr