Cam Degreeing.

kwplot34

kwplot34

Heart Attack
Joined
Mar 24, 2008
Messages
2,373
Location
Liberty,Mo
Ok guy's educate me on this. First my story :D My motor realy comes into it's power around 2700rpm,which is great the car takes off like a rocket and winds to 7000rpm in the blink of an eye :cool: The down side is the in town driving it's just wearing me out,below 2000rpm the car bucks like crazy in time with the cam (if that makes since) and i'm constantly riding the clutch.
My thinking was,if i could get the power band a little lower it might help with the in town driving,although i might give up some higher rpm grunt,but thats ok,i have the rev limiter set at 5500rpm right now anyway.
So if i advance the cam will this help?? do you need a degree wheel to do this? or can you use the marks on the cam gear and do this right?

Plus,if anybody has some good reading on this could you pass it on,the books i have only touch on the procedure very little.
 
hard to say without knowing the specs on your cam and engine....

Over-camming a engine seems to be #1 mistake made when building an engine. Everybody likes the rough idle sound but nobody wants a unstreetable engine.... one of the cam manufacturers just came out with a cam that makes your engine sound great but is mild enough to drive it on the street.... Lunati/Holley ???

Advancing the cam is what ? +/- 4 degrees ??
 
Yes, you can advance it using an offset keyway or multi key sprocket, however make sure no advance is already ground it. it's pretty common to have that.
A heavier flywheel will also help you a little.
 
I dunno Kev, over the decades I have constantly heard about guys with too large a cam, and that sort of complaint.....seems that everyone over cams their engine, or wants to....I sort of like to stay on the + side of one hp/cu inch and leave it alone, getting into 2 hp/cu inch is a bit much for me.....

:D my accounts are:crutches: so it's gotta be cheeeeeeeeeep over the long run.....

:harhar:
 
I am by no means even close to you guys on engine tech, but I'll throw this out anyways.

Since you need to lug that fuel to Kal, I'm guessing that your at 11+ compression ratio.

Based on your RPM range described above, I'm guessing that your intake advance at .050 is greater than 230. Your base RPM operating range starts at greater than 2300RPMs. And it's a pain to ride the clutch.

Your driving habit tells you that you want to have an RPM range between 1500 and 5500(rev limiter info).

So why not just get a cam designed for that range with a little more overlap to bleed some CR and get onto strait pump gas? Maybe also thicker head gaskets.

I don't know how much degreeing the cam is going to help, but I know the procedure is in my rebuilding BBC book. I would guess that the procedure is also in the rebuilding SBC book. You can search for it on Amazon.com.

OK guys, fire away...is my ignorance showing:hunter:
 
SmokinBBC said:
I am by no means even close to you guys on engine tech, but I'll throw this out anyways.

Since you need to lug that fuel to Kal, I'm guessing that your at 11+ compression ratio.

Based on your RPM range described above, I'm guessing that your intake advance at .050 is greater than 230. Your base RPM operating range starts at greater than 2300RPMs. And it's a pain to ride the clutch.

Your driving habit tells you that you want to have an RPM range between 1500 and 5500(rev limiter info).

So why not just get a cam designed for that range with a little more overlap to bleed some CR and get onto strait pump gas? Maybe also thicker head gaskets.

I don't know how much degreeing the cam is going to help, but I know the procedure is in my rebuilding BBC book. I would guess that the procedure is also in the rebuilding SBC book. You can search for it on Amazon.com.

OK guys, fire away...is my ignorance showing:hunter:
Click to expand...

When i had the motor built i wanted one that could handle high rpm's and wind up fast,well it does that but i did not think that the low rpm driving would be such a pain:suicide: I like having a motor that revs fast and high it's alot of fun,so i guess i'm going to have to decide which i want more low end or high end :crap:.
My cam spec's are 230 in/ex @.50 and .540 in/ex @.50 and a 108 lobe center,and 1.6 rockers. Brodix IK 200 heads,all roller. 11.5:1 cr.
i don't think that cam is all that big,i could have gone bigger :lol:
Who was it that said alum flywheels are better because they are lighter,might have to swap back to cast,maybe.
I did find some good reading on degreeing a cam and i'm pretty much screwed there,i can't find my cam card :crap::crap:
 
That cam isn't all that "hot", it should be very streetable. I run a 230-236 with .510" lift and 112 LS and it runs just fine at 1700rpm in OD.... ok, mine is a 383, the addtl. stroke might be the reason why it runs better at low rpm...
 
MYBAD79 said:
That cam isn't all that "hot", it should be very streetable. I run a 230-236 with .510" lift and 112 LS and it runs just fine at 1700rpm in OD.... ok, mine is a 383, the addtl. stroke might be the reason why it runs better at low rpm...
Click to expand...

Mine is a 388. Maybe i have something going on with the tune,either the andvance in the dizzy (msd pro billet no vacume can) or with the carb (road demon 725 vs).
Now that i think about it,i had a dizzy once that the mechanicle weights had to lite of springs on it and it realy fouled things up,Hmm its worth a look and change the springs.
 
In a 383/388 you can run as much as 242/248 and still cruise at 2000rpm.... something else is wrong.... your engine should run smooth from idle.

Are you sure you're bleeding off enough compression? 11.5 is kinda high.... thicker head gasket will not lower it a lot, maybe 11.2:1, still very high...

Do you have a standard dizzy that you can install to see if it runs any better ? I bought one of those $60 distributors off Ebay and it runs just fine.
 
MYBAD79 said:
In a 383/388 you can run as much as 242/248 and still cruise at 2000rpm.... something else is wrong.... your engine should run smooth from idle.

Are you sure you're bleeding off enough compression? 11.5 is kinda high.... thicker head gasket will not lower it a lot, maybe 11.2:1, still very high...

Do you have a standard dizzy that you can install to see if it runs any better ? I bought one of those $60 distributors off Ebay and it runs just fine.
Click to expand...

I'm not sure of the compression bleed off,not even sure how to check it :noob:. I think my problem lays within the dizzy,or the timming,now that i have had time to think about and talk to you guy's. I'm going to recheck my timming,and if thats good i will change the springs in the dizzy or maybe just one to heavier one and see what that does,and also make sure the weights are not sticking. The motor runs great no problems there,but i still think it should be making more power at lower rpm's,once it hits that 2500-2700 mark it just flat gets out of town.
I have messed with springs in the vac/secondary on the carb to a one step lighter than what it came with,that helped some,tried 2 steps lighter and that went the wrong way.Maybe i need a speed demon 750 mechanicle carb????

Or maybe the timming is comming in to fast :banghead::banghead:
 
Just my opinion but I don't see a need for that fancy MSD dizzy... sell it on Ebay andbuy a regular good ole dizzy for $60 - mine ran fine right out the box but you should verify clearance at the drive gear...
 
If you have a 388 with that cam you shouldn't have any problems. My guess is that you either have a to small lca (108) causing a lot of blow back into the intake at low rpm compromising the mixture in that amount that it leans out and gets difficult to ride.
If you want a high rpm cam that still stays streetable you absolutly have to go towards 112-114° lca.

I would also check you ignition advance.
 
MYBAD79 said:
That cam isn't all that "hot", it should be very streetable. I run a 230-236 with .510" lift and 112 LS and it runs just fine at 1700rpm in OD.... ok, mine is a 383, the addtl. stroke might be the reason why it runs better at low rpm...
Click to expand...

I snatched this from DC. I know it is only a reference to operating ranges vs duration.

rpmrange.gif


It puts him right on the edge of the low RPM range.
 
kwplot34 said:
When i had the motor built i wanted one that could handle high rpm's and wind up fast,well it does that but i did not think that the low rpm driving would be such a pain:suicide: I like having a motor that revs fast and high it's alot of fun,so i guess i'm going to have to decide which i want more low end or high end :crap:.
My cam spec's are 230 in/ex @.50 and .540 in/ex @.50 and a 108 lobe center,and 1.6 rockers. Brodix IK 200 heads,all roller. 11.5:1 cr.
i don't think that cam is all that big,i could have gone bigger :lol:
Who was it that said alum flywheels are better because they are lighter,might have to swap back to cast,maybe.
I did find some good reading on degreeing a cam and i'm pretty much screwed there,i can't find my cam card :crap::crap:
Click to expand...

I decided on 224/234 with .569/.569 with 10.7.1 CR, 108ICL and 111LSA on my BB. I wanted to make sure to keep the low end and run pump gas(93). I have a ton of low end with and it packs a punch and revs nice up till 5200(haven't had it higher).

I'm interpretng .540 to be your gross lift(not at .5).
 
SmokinBBC said:
kwplot34 said:
When i had the motor built i wanted one that could handle high rpm's and wind up fast,well it does that but i did not think that the low rpm driving would be such a pain:suicide: I like having a motor that revs fast and high it's alot of fun,so i guess i'm going to have to decide which i want more low end or high end :crap:.
My cam spec's are 230 in/ex @.50 and .540 in/ex @.50 and a 108 lobe center,and 1.6 rockers. Brodix IK 200 heads,all roller. 11.5:1 cr.
i don't think that cam is all that big,i could have gone bigger :lol:
Who was it that said alum flywheels are better because they are lighter,might have to swap back to cast,maybe.
I did find some good reading on degreeing a cam and i'm pretty much screwed there,i can't find my cam card :crap::crap:
Click to expand...

I decided on 224/234 with .569/.569 with 10.7.1 CR, 108ICL and 111LSA on my BB. I wanted to make sure to keep the low end and run pump gas(93). I have a ton of low end with and it packs a punch and revs nice up till 5200(haven't had it higher).

I'm interpretng .540 to be your gross lift(not at .5).
Click to expand...

Yes my bad on the .540 that is not at .5 sorry about that.According to the graph i am about right on with the power band for the low end,will having the 1.6 rockers move that up any? I am still going to re-check my timming and my advance to make sure it's right on. And it looks like if i want more low end i will either have to change cams or rear end gears (i have 3.70 right now and a 4 speed) but i sure hate to give up all that power on the top end,man is it a blast when it comes in :devil:
The MSD dizzy i like them they are simple,all they do is distribute the spark,the ign box takes care of the rest plus it has the rev limiter in it.
 
I have an HEI here now I am recurving/shimming. We can shove that in when you get here, and we will see what we will see.;)
 
big2bird said:
I have an HEI here now I am recurving/shimming. We can shove that in when you get here, and we will see what we will see.;)
Click to expand...

Sounds like a good idea,maybe there is nothing wrong and this is just how my motor run's,i will wait and get a second opinion from you when i get out there to CA. May just be that i'm getting use to the motor and i find myself wanting more,other people that have rode in my car or have seen it run say i'm crazy :quote: and that it does not need any more ponies.
 
kwplot34 said:
big2bird said:
I have an HEI here now I am recurving/shimming. We can shove that in when you get here, and we will see what we will see.;)
Click to expand...

Sounds like a good idea,maybe there is nothing wrong and this is just how my motor run's,i will wait and get a second opinion from you when i get out there to CA. May just be that i'm getting use to the motor and i find myself wanting more,other people that have rode in my car or have seen it run say i'm crazy :quote: and that it does not need any more ponies.
Click to expand...

The fact that your crazy and that you need more ponies are 2 seperate issues.:devil:
 
kwplot34 said:
Yes my bad on the .540 that is not at .5 sorry about that.
Click to expand...

I would think that you mean that your valve lift with 1.6 ratio rockers is .540" ????

With stock 1.5 ratio rockers the valve lift would be .506" (.540/1.6X1.5=.506)

Again: a stroker SB with that cam and 11:1CR should have a lot of power off idle... just for shitz and grins I'd put a stock HEI dizzy with vacuum advance on there, check and adjust timing and see how it runs.
 
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kwplot34 said:
big2bird said:
I have an HEI here now I am recurving/shimming. We can shove that in when you get here, and we will see what we will see.;)
Click to expand...

Sounds like a good idea,maybe there is nothing wrong and this is just how my motor run's,i will wait and get a second opinion from you when i get out there to CA. May just be that i'm getting use to the motor and i find myself wanting more,other people that have rode in my car or have seen it run say i'm crazy :quote: and that it does not need any more ponies.
Click to expand...

Hopefully it is your dist and the Bird fixes your problem...but it sure does sound like your engine runs as designed. :devil:
 
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