I do have the pushrod checker,i know how to do it,my point was that wouldnt the lift be the same even if the shaft of the cam is smaller,600 lift is still got to be 600 lift on both cams ,right?
Second ,the only thing thats different is the bottom of the lobes on the cam,being that the shaft is smaller,right?

 

Anybody know? i would like to understand this before i do the cam change.

 

Yes the diameter of the cam is smaller and yes the lift is going to be the same. The roller is just down in the hole as said above. The base circle is just smaller than a stock cam.

 

So the shorter base circle of the cam is the measurement that the pushrod will have to be lengthened?

 

Also if i am right,then why doesnt the top of the cam lobes hit the crank?

 

Because the top of the cam lobe is also shorter on a small bas e circle cam. Say the SB cam is .900 diameter and the lobe lift is .300. You have a peak of 1.200. On a normal base circle cam say it is 1.100 diameter and you have a lobe lift of .300 you have a peak of 1.400. That gives you .200 more clearance on the small base circle cam and you still have the same exact lift. You would need a pushrod of .200 inch longer.

 

Got it thank you,thanks for the lesson sometimes i am a little slow

 

Before you spend alot of time on this, i'd suggest posting the particulars on both cams, i.e. lift and duration & .050 on both intake and exhaust on both cams. I can tell you what the change will do, one way or the other.

 

And most importantly, lobe separation.

 

The Chevy small block is about 50 years old. Do you think that maybe some thought was put into making cankshafts with throws small enough in diameter to not hit cam lobes?

 

I thought it was the base circle that was smaller,i wasnt comprehending that the lobe was smaller to and you must take up the added distance with a pushrod.I dont know anything about small base circle cams,thats why i am trying to find out I think i got it now

 

Both cams are the same, one is retrofit and the other is a small base circle cam.same profile.

 

Okay, this is getting to be a troublesome exercise. You want cam help? You can get it, but the specs need to be SPECIFIC.

I assume this is the 'retro' version : http://www.compcams.com/Cam_Specs/Ca...?csid=162&sb=1

And I assume this is the cam you run now:

#2201 Edelbrock

ENGINE: CHEVY 283-400 V8 (1957-1986)
RPM RANGE: 1500-6500

Duration at 0.006" Lift: Intake: 296° Exhaust: 300°
Duration at 0.050" Lift: Intake: 234° Exhaust: 238°
Lift at Cam: Intake: 0.359" Exhaust: 0.365"
Lift at Valve: Intake: 0.539" Exhaust: 0.548"
Timing at 0.050" lift: Open Close
Intake: 10° BTDC 44° ABDC
Exhaust: 56° BBDC 2° ATDC
Centerlines: Lobe Separation - 112° Intake Centerline - 107°

I'm not exactly sure what you're trying to do, but comp has a very very limited selection for anything intended for forced induction or nitrous (and overall decent grinds). Sure, they have a flashy name and good advertising, but the truth hurts.

Just going off your pictures of your car, you 'may' be able to improve some performance with this:

http://www.compcams.com/Cam_Specs/Ca...?csid=172&sb=1

The one you have picked will 'sound' like it has more power, but you'll most likely be slower than your old cam as soon as you wack the loud pedal.

I'd bet money on it.

 

This is what the comp cam tech said,theres no difference.

Bill the two cams are the exact same thing. The duration actually falls in
the middle of those two different sets of numbers, so when we wrote out the
grind numbers for the cam we rounded up where as when the computer made a
custom spec card for your cam it rounded down.

Aaron Mick
COMP Cams Technical Consultant
amick@compcams.com


Subject: Bill Baker - COMP Cams Product/Technical Support

From: brfab@verizon.net , Bill Baker --- Message: Hello,i just bought one of
your cams,i wanted 12-443-8 extreme energy cam for a older chevy block and a
383 stoker kit.This cam that i bought is small base circle for older blocks
but on the spec sheet its a little different then the regular retrofit cam
spec sheet,the duration is a little off buy one degree,mine reads,293/299
and the retro cam is 294/300,why is this different?plus the retro cams are
made to work in older chevy blocks,these two cams should be the same.The
serial number on my cam is S2916-10,why is this cam different then the
retrofit cam 12-443-8 ?

 

If it is a shelf cam, I'd send it back. You're going the wrong way with the lobe separation angle....112 to 110. You need to be going the other way, more like 114 or 115, with a center of 110 or 111 (which is 4 degrees advance (max) machined into the cam). Also, you need at least 10, but preferably 12-14 more degrees duration on your exhaust.

I slapped together a 383 with vortec heads (with 1.94 intake valves) several years ago when nobody used vortecs, with a 238i248e 114 lobe separation net lift .497 cam w/a victor junior and 750 holley and it ran 10.50's in a camaro. (not a light camaro either).

They've come a long ways with heads since then, just not cam techs when you call in.

 

Joebob,i know about blower cams and their lobe seperations,but this is an experiment i doing because blower drive service has come out and said that a 110 LS runs best for blowers that run gasoline,i know it goes against what i have been told but these people know what they are talking about,i would think,they are one of the biggest blower sales and service companys out there.So thats why im going to try it,plus this cam was tested on a dyno in a 383 and NA engine put out over 500 hp and when added a 150 shot of nos it produced a whopping 700+ hp,not too shabby,

 

I run Comp Cams small base circle solid roller lifters part #891-16 if that helps any

 

Wayne you know why im doing it

 

Okay, it's your motor, do with it what you will. You asked a simple question about cams that you didnt know the answer to. Now you say you know about blower cams. Okay, im with you.

Now, back in the real world, which the guy at bds doesnt apparently understand, is the fact that there is no such thing as 'blower cams and nitrous cams', there is only cams that work best under certain conditions.

I can tell you that i had a car several years ago that i ran an old style procharger on, a blow through set up at that....which is the one that took many years for people to figure out....and that gas fed non-intercooled BB ran low 8's, and at the time there was only one car in the ball park of my set-up in the country. Now folks like steve morris racing engines are cashing in. I was there before those guys and i had to custom make some of my own stuff, because there simply wasnt stuff on the self to get the fuel delivery right. Much like BDS, the procharger folks could build a product, but they couldnt tell you what to put with it to make it work. I've been there and done that. You do what you want to do, but if you put that cam in with a 671 (im guessing that's a 671 from the pics although its hard to see) and you give it a hundred fifty or so shot you'll most likely knock main registers out of your block and that sob will be trash. You'll only get one chance. That valve timing is not optimal for that kind of setup by no means and ignition timing will be critical.

I personally know someone who did THE EXACT SAME THING you are talking about doing. With a BDS 671 i may add and he knocked the mains right out of it.

If BDS told you that, they are full of it.

I once took a junk 350 out of a van, ringed and bearinged it, slapped some 1978 305 light weight casting heads (which i put in 1.94 valves in place of the 1.60 or 70 something valves and did a little port job) on it, popped in a crane 222/234 @ 114 hydralic flat and managed to squeak out some 12.20's with that poor boy build. The cam was the most expensive item. Not to shabby for a few hundred dollar build that had 15 inches of vacuum at idle and no noticeable lope.

I suggest you get some second opinions. But this is america, do whatever you want.

 

Joebob,i know everything that you are saying,i have a built 383 victor jr heads custon 144 weiand blower with 100 shot of nos that i dont use,dont need it,too much for the street.I think you are totally misunderstanding everything ,i had another post about what im doing earlier on,i do know 114 ls cams work best.I was just wanting to know about small base cams,never put one in an engine before and i just wanted to know about them.If you go to blowerdriveservice.com they have a article about what cams worked best on alcohol ,gas ,race fuel etc,they said a 110 ls with max lift and duration ran better in gasoline engine running a blower.Im just going to give it a try ,if i dont like it ,i will change back.The other part of the story is that i saw a dyno test of four mitrous cams and one na cam to see how they ran in a 383 and this na cam ran the best by a long shot,nitrous cams are comparable to blower cams,and this cam extreme energy comp cam 12-443-8 ran very very good for some reason,and its a 110 ls ,like what blower drive service was talking about,so i am going to experiment with this cam to see what happens,thats all this whole thing is about. I appreciate your help though.