So Joe could have been faster with the 190cc ported stockers instead of the 200cc ported stockers?

What was ya thinking Joe?

 

You are somewhat right that flow number alone are not the measure of a head BUT at the same time we have ported stock castings available to us that do flow 290cfm and have proven time and time again to make wonderful power, guys have swapped them in after trying aftermarket stuff and gone faster. Plus your paperwork says a 4.155 bore which will inflate numbers somewhat. If you were looking at numbers that peak by .500 I bet you were looking at gen 1 stuff not LT1. A well done LT1 casting keeps gaining past .500.

Looking at your pictures the guides are not even fully shaped, looks like a pretty basic quick job, sorry the guy sold it to you as something more.

The 114LSA you like is also the reason you want to change the cam, that is part of the reason it wants to keep pulling.

You are rather determined to defend what you have even as you want to make changes, that is going to get in the way of making meaningful change.

The 112 LSA of the typical shelf cam is already really wide when you consider most of the fast NA cars use more like a 108LSA.

A 114 for NA could be done out of ignorance by someone who thinks the computer needs a wide LSA, it can be done for emissions, or it can be done to broaden the rpms range which also brings down peak numbers. So right now you have a cam that trades peak numbers for a broader rpm range and because of that broadening goes higher than you are willing too, but you still want to stick with that because of the smooth idle???????????

I would go a little shorter on the duration and go with no more than 112 LSA. If your heads are actually any good the 503 is still going to want 64-6500, from your pictures though I think those heads will hold it back to a little lower rpm though so it would be a safe shelf cam choice for you at this point long as you get it on a 112 LSA.

 

Not at all, I just don't want the thread getting derailed by people who really don't know about head porting and just look at a cfm number, which would be most of the guys here. Not saying that's you but there are people who are under that impression.

I never once defended the cam that I have. I was simply saying that I liked the smooth idle, and I was told that the 114 is why it idles smoothly. When I asked "How will this cam help me reach my goal over the current cam" I am trying to get educated. If you take that as defending what I have then by all means you do not have to reply to the thread. I have tried reading online about this stuff and I just can't grasp an understanding.

I am just asking somebody if they can explain to me what the difference is.

When I see numbers that look close to what I have, I am going to think it's similar. If it is different, how will it be different? Not defending - I am legitimately curious and trying to figure it out.

If a 112 LSA is better then I would love that and would leave the 114 in the garage, I do not care.

Cam stuff is very confusing and I would venture to say that 99% of the people on this forum do not know much about it, even if they have cams like myself, they go by what knowledgeable people tell them.

 

You cant just look at .050" numbers and say the cams are similar. You really need to look at the entire curve of the lobe which that information is rarely ever given. From advertised duration to .200, .300, etc... Cant tell what the cam does over the nose and how it sets the valve down if you just look at .050" numbers This is where a good cam designer comes in handy.

Wide lsa minimizes overlap which helps create the smoother idle. Nothing wrong with it but these cars do like tighter lsa's. If you dont wanna pull rpm, you need smaller duration cam.

 

3.73 with a 3600 stall

Take your time picking a cam and try to get what best suits your needs/wants. I spent so many hours researching before I bought the XFI280 and was very happy with it. I even had people try to talk me out of it. Now, that I'm building a stroker motor I've turned to a custom built one.

 

Yes higher velocity and swirl head can produce more power than a head with higher flow numbers. U can't find many that understand that here on this forum. For over 20 years now there are adapters to a flow bench to measure just the swirl and i have seen pix of them. I can't explain why this is so painful to learn here on this forum. BTW i like your heads and would like to know where i can find that kind of head work. Not having any luck here in So Cal for LT1 head work - all the shops here want to treat the LT1 head like a GEN I head. My opinion is it's more of an vortec head (actually the LT1 can first so the vortec is more of an LT1 head).

As for a cam I can't tell what your full duration numbers are now so can't figure your amount of overlap. But FYI as you reduce the full duration numbers u reduce the amount of overlap and can reduce the LSA to "tighten" the cam and produce more mid to upper range torque for the same idle/vacuum characteristics. Once u get to 109 (108 may be even better) u are close to optimum/max torque LSA for the GEN II sbc.
To make this easier take 109 times 2 = 218. Using 50 max overlap for street added to 218 gets you 268* full duration for a single pattern cam. But for an extra 6* exh duration on a dual pattern cam use 265* intake and 271 exh full duration. Hmm, very close to a comp 264HR-12 but just call comp and have it ground on 109* (108) LSA (i suspect it would be a264HR-109 or 108). Now your talk'n a short cam with lots of punch/torque and less than 6,000rpm.

Hope this helps,
cardo

 

While many don't understand heads need swirl and proper velocity and will buy on flow numbers. Some of us do understand there are heads available that give us flow/swirl and velocity.
Some folks feel the need to pretend they can reengineer the wheel and just need someone to help them build it.

There are a lot of successful LT1 builds out there and a LOT more mediocre to poor ones. All any of us has to do it figure out which one we like and copy it.

I really don't understand pretending barely ported heads with what look like as cast guides yet are some revolutionary product.

If the "vortec" style is what you think is best then the IRON LT1 heads are where to start since the IRON LT1 heads that came out in 94 are what the Vortec heads that came out in 96 are based upon.

 

You have contributed no help in choosing a cam and have only given your opinion based one a single picture of a head in how they flow. Please just move along.

 

Because a quality port job on a stock casting LT1 head looks like this:


same angle as your pic

 

Hardly top of the line here. EASY to see they aren't

 

This is what a real quality portjob looks like.

 

I have a pic like that also.


What are the major differences?

 

raroz28, you are biting the hand the feeds. 96capricemgr has offered up plenty of good information, most of which I completely agree with. I see no reason to repeat what he has explained. However you're rejecting that good information and insinuating that others don't understand; basically pushing away the few people on this board who are able and willing to help you.

I asked for basic information to try and assist in cam selection, regardless of the mediocre heads you had, and I still haven't got it.

This shows me you're not serious about figuring this out and I'm wasting my time trying.

-Dustin-

 

This is clearly not the head YOU showed a picture of, saying it is YOUR(top of the line) head. If you cannot see the difference between the 2 different heads that YOU have shown we CANNOT help you. I showed you a picture of my 200cc Advanced Induction ported stock castings, RamAir did as well, I believe. We are just trying to let you see what the difference is between a good port job and the pictures that you showed of your head. This pic you just showed ain't the same head as the first pic of your's.

 

Just from a pic alone its hard to judge performance of a head...but we know the data the AI heads have and they work very well so I would consider them one of the best. I have not see the velocity profile of those heads nor have data on the cross sectional area of the port but it seems to be well done by the performance of cars running those heads.

Shaping the guides is one of the first and most basic things head porters do to improve head performance and flow. Sounds/looks like the OP heads have had some casting flaws cleaned up, maybe port matched to a gasket size and possible seat blending but thats about it. Just a basic clean up for a step above stock head performance.

Some stock classes demand stock heads and those good porters can do some magic to the port without increasing the size of the port to fit stock rules, yet they perform completely differently! Undercover porting that passes tech inspection...Hard to see with the eye too unless you really know what you are doing and know what to look for.