Right now I am in the process of buying parts for a stroked 305. I was wondering if on the camshaft I should go with a lower Lobe Center Angle(say 110) and a higher than normal exhaust valve opening. I have decided that the duration should be in the high teens to high 20s. Keep in mind I will use moderate leakdown lifters also to help give it better idle and low rpm ability. Thanks alot

 

you are about to get 50 people coming in here to tell you...... theres no such thing as stroking a camshaft.

 

If you stroke your 305 and run a cam like you're suggesting, I don't think there's a need for fast bleed lifters.

 

If you are not well versed in camshaft design your best starting point would be to call a couple of cam manufacturer help lines and get some ideas. After you get their recomendations you can look at the profiles and see what trends the experts follow.

Bob
http://www.turbotime.us/gallery/bigtime01

 

What induction are you using?
What are the flow numbers from your heads?
What is your gearing & transmission/stall?

 

World Torquer S/R cylinder heads flowing 171cc on the intake runners and 58cc on the chambers. L98 TPI from a corvette 350 with the stock injectors. Rebuilt 5 spd with stock gears.
I meant that I wanted your opinion, what kind of camshaft to put in the stroked engine. I already know about camshafts, I just wanted other people's opinions. T'he Moderate leakdown lifters will help out with some of the lost low rpm torque since it will be a daily driver. Thanks again.

 

he asked those questions because believe it or not, your tranny, convertor, gears and induction play an important role in what cam you choose and thus our opinions on what will work best.

That said, I wouldn't go too big at all with the cam considering you're using the stock TPI system. I like the LPE 211/219 cam. Excellent low end and it works well with the LTR's. It's a fairly mild cam for a 350, but in a 305 I think it will be sufficient.

 

HEH?

 

flowing 171cc's huh?
Well I'd say you better stick with a short duration cam like the LPE part mentioned above. That should work just fine.

 

NastyL98_T/A where can I learn more about the camshaft that you mentioned? With the 1.6 rockers, how much valve lift do you think that I could run @.050? Thanks.

 

I just listed one on ebay!


http://cgi.ebay.com/ebaymotors/ws/eB...tem=2444869966

 

Tibo,

Let's clear up a few things for you..we know you're trying, but...

171cc on you heads is referring to the intake port size, not the flow.

The chambers are not rated in flow, but volume...58cc is the volume of the chamber.

Lift at .050, is exactly that, .050inches...what you want to know is the duration of the camshaft at .050inches.

Even a stroked 305 with S/R heads, probably would be a mismatch with enuogh cam to require/need fast bleed lifters...the heads are just not "enough" to use a large enough cam.

I'd suggest you do some more invesitgating and knowledge building before you start buying parts...not meant as a flame, just advice before you spend your money on anything.

 

Thanks 8mike9, I guess that I had said that wrong. I was trying to figure out how much valve lift I could run with the Worlds. I found it to be at 600. I will keep researching I buy the major parts, which will still not be for a few months. Thanks alot.

 

Most people who would stroke a 305 wouldn't know the difference anyway.

Anyway, to answer your question, I'd get something with a lot of duration, because lift won't help much with the massive amount of valve shrouding you're going to have.

 

Jim,
How much would enough be considering the flow rates of a TPI system and the TPI computer, while still having adequate low RPM ability? Also someone else had mentioned that I stay with a shorter duration(?).

 

Allot of duration will kill low end power and move the powerband away from the TPI rpm range. Keep the duration low and pick up your cylinder filling from lift. TPI's long runners like this combo.

 

yeah, duration may kill low end power, but the valve shrouding is going to make lift less effective. If you keep a wide LSA, you should be able to get away with extra duration without too much overlap, so unless you get stupid with way too much cam, you shouldn't find too much of a low rpm loss.

 

Lift or duration is not going to change valve shrouding. Anything more than 211 @.050 duration will need at least a 2500 converter even if its ground on 114.

 

I realize that it's not going to "change' the shrouding, but the shrouding will limit flow, so opening the valve farther won't be effective, but keeping it open longer will.

If you do the good old air to water comparison, it goes like this:

You can't change the diameter of the hose (lift), so you've got to keep it on longer to fill the glass of water.

Obviously more duration his its own host of drawbacks, but regardless, this debate is quickly turning more and more useless. Without better heads and a way to unshroud the valves, the cam is going to need to be very mild anyway, so a lot of this crap is a non-issue.

 

If you're trying to make the most low-end possible for a fun daily driver, then why in hell are you considering stroking a 305 when you could build a 350 for less money that will make more power and torque through the powerband?

I know people hate the 'why build a 305' argument, but only because there is no reason to do so besides 'wanting to be different'. But when your goal is to build a torquey daily driver, you get more for your money with a 4" bore

 

Well, if my thinking is right, I'd have to agree with bigtime on camshaft choice because I am going to keep the L98 TPI set-up, which supposedly falls flat on it's face at 4500-5000 RPM. So, I would need a camshaft with a lesser amount of duration. (Even though Jim, you would still be right about the valve shrouding issue.) I would need a camshaft that would put my shift point at about 4500-5000 RPM, and extending the duration might change the power curve of the camshaft, placing it higher in the RPMs. Stop me if I am wrong of course. Thanks again.

 

I agree with the last paragraph. Not the first

 

Chris,
Seeing that you have stroked your 305, what camshaft profile did you go with?

 

This is posted on his site:

Comp Cams hyd. roller cam (.480/.480 Lift, 264/274 adv duration, .210/.220 @.050,112 LSA)


I'd say it's a good choice.

 

Yep its a Comp Cams "computer controlled" camshaft. I had one of their catalogs, it took me along time to decide on which cam to go with...but I finally chose that one. It is recommended for 1200-5200rpm.

The car is a daily driver back and forth to school, so I didn't want anything too radical...plus I'm still running stock heads and intake. But this cam still allows for a better intake and heads when the time comes.

Supposedly its a good cam for a daily driven 305 or 350 TPI, and it seems to work good on mine. The torque peak is at 3000rpm, and horsepower is really fat and flat and peaks around 4600rpm.

 

The duration on that Comp cam is very close to what the LPE 74211 uses. Looks like it would be a good choice if you are leaving the heads stock.

The LPE 74211 does have considerably more lift however, and is a good choice if you're willing to modifying the heads and EPROM.

 

Would the higher valve lift (.530/.560) be TPI computer friendly or would I have to do some ECM changes? I have heard in other posts that the optimal valve lift for TPI is in the low .500s.

 

It might run without ECM mods, but it will be a long way from optimal.

Never heard abt the optimal TPI vavle lift being restricted to the low .500's. I think that would depend on what heads were used and how stock they were.

LPE has done a ton of R&D with TPI, so I tend to believe what they recommend.