My new cam is 262/272 dur@50, 714/714 lift with a 112 LOB, old cam
was 252/262 dur@50, 651/651 lift with a 112 LOB. How much difference
if any is my new cam over old one. I was told very little due to not much
difference in dur #. I thought it would be a fair amount due to size
increase in lift. Not a motor guy so just asking. Motor is a BBC 540 ci

Another question: I talked to Shafiroff (Mike) since they build the motor
(540 Ultra Str) and he said I do not need a girdle. Told him it is weekend
driven and he still said no but I talked to other people and they say yes
due to 700 lift on street. I know Mike built motor and should know better
than anyone but still would like opinions on this matter. Why asking is I
will need to change brake booster from current 11" due to tall covers
needed if girdle is used. I know people say safe than sorry but car is used
weekends only and have heard why 700 lift on street but done is done
and just want other opinions on girdle.

So in ending, is new cam much more performance than old and is a
girdle needed. Thanks for all replies!

No girdle needed, thats more for high rpm use.

I know people say safe than sorry but car is used
weekends only and have heard why 700 lift on street but done is done
and just want other opinions on girdle.

So in ending, is new cam much more performance than old and is a
girdle needed. Thanks for all replies!

Why .700 lift on the street refer them to 540 ci.Takes alot of air to feed that many ci.You should see a boost in hp but I don't think it will be a huge increase.I would install a girdle,good insurance IMO.

what kind of cam is it? just wondering because im building a 496 and want a cam like the one your talking about

what kind of cam is it? just wondering because im building a 496 and want a cam like the one your talking about

Comp Cam. Mike at Shafiroff sent them the specs to make. I wanted to
go as much as I could for my 10.5 comp motor and Mike said that any
thing bigger would be basically unless due to compression

Bob,10 degrees at.50 is a BIG change! So is the lift increase.In my BBC I had a Comp that was 270/278 .714 /.714 on a 108 to a Comp 272/280 .748/.710 on a 110 with much more aggresive ramps and picked up over a tenth,and this is in not very good air. As far as the girdle, believe your engine builder,you trusted him to build it! I run mine to 7200-7400 thru the traps with no valve train problems, and no girdle. Sounds like you have a nice engine.

Bob:

I also believe a 10 degree increase in duration is significant and you should see some gain. How much you see will depend on other items too like exhaust system (hope you have 3 inch), carb tuning and other items. Are your heads ported or as cast? Big gains here to be had but lot more work than just changing cams.

Are you planning to run comp roller lifters or are you going to something more expensive like Isky Red Zones? Who spec'd the valve springs - very important item.

Tom

Bob:

I also believe a 10 degree increase in duration is significant and you should see some gain. How much you see will depend on other items too like exhaust system (hope you have 3 inch), carb tuning and other items. Are your heads ported or as cast? Big gains here to be had but lot more work than just changing cams.

Are you planning to run comp roller lifters or are you going to something more expensive like Isky Red Zones? Who spec'd the valve springs - very important item.

Tom
The alum. heads are mildly ported according to previuos owner. Yes, I
am running comp roller lifters. Also have 3" exhaust with Dynamax
Bullets. Thanks for info!

Bob,10 degrees at.50 is a BIG change! So is the lift increase.In my BBC I had a Comp that was 270/278 .714 /.714 on a 108 to a Comp 272/280 .748/.710 on a 110 with much more aggresive ramps and picked up over a tenth,and this is in not very good air. As far as the girdle, believe your engine builder,you trusted him to build it! I run mine to 7200-7400 thru the traps with no valve train problems, and no girdle. Sounds like you have a nice engine.

Concerning your girdle answer. Is your car just a drag car. As I said, I
drive mine on str on weekends. Not a lot of starting, stopping but still
on street thats why I'm asking about girdle. Lot more constant running
of motor with big lift and no girdle. Thanks for your response(s)!!

Bob, I think Rolling- Robert is correct, girdles help keep things stable at upper rpms. I am not sure they help much at lower rpms. I would be more concerned about roller lifter wear- make sure you have good quality ones and keep an eye on them and your lash.

Bob, I think Rolling- Robert is correct, girdles help keep things stable at upper rpms. I am not sure they help much at lower rpms. I would be more concerned about roller lifter wear- make sure you have good quality ones and keep an eye on them and your lash.

I will be installing new lifters, springs, etc with cam. Do have 1 other
question. Was told to use longest possible exhaust stud i can use for
my heads since not using girdle. Using 714 lift cam, should use biggest
stud head can accomadate? Has anyone else done this, I'm sure it can't
hurt and only help? Thanks!

Bob, I'm just lurking to get advice. But now you've done it! I've got that burning feeling we hotrodders get when we want new parts. A new roller is sure to be installed this winter. Problem: How to race without a roll bar? (My car is less than 4/10's away)

Seems like I remember using the longer ARP studs, I think on both in. and ex. IMO the pro series are worth the money. Ask around, but I like Manley NexTek springs.I also run Comp roller lifters without a problem, but some guys do not like them. If you can afford them ,you might look into Crowers or Iskys.

It really depends on how well your combo is sorted out and how well it is matched. Adding 10 degrees of duration without loosening up the converter could kill some 60 foot.

Seems like I remember using the longer ARP studs, I think on both in. and ex. IMO the pro series are worth the money. Ask around, but I like Manley NexTek springs.I also run Comp roller lifters without a problem, but some guys do not like them. If you can afford them ,you might look into Crowers or Iskys.

As a matter of fact, my new springs are the Manley Nex Tex and the
lifters are the Crowers Hippos.

It really depends on how well your combo is sorted out and how well it is matched. Adding 10 degrees of duration without loosening up the converter could kill some 60 foot.

I am new (learning) to the performance part of anything. What do you
mean loosening up the converter? Glad I'm getting input on this matter.
I originally posted this senario awhile back and the few replies said that
not much change if any will be noticed. Was replied that the lift went up
a good bit but the duration at 10 degrees more won't make any difference
but this current post the replies are saying just the opposite unless I am
thinking to much into it the wrong way. As always, I appreciate all your
replies as I am learning by it. Thank You! Bob

Bob, a more powerful camshaft almost always has to move that power band UP in the RPM range. That means less power at the low end. That's why most trucks have mild cams to pull heavy loads. The loads have to be started from a standstill so mild engines are needed.
Most racers use automatic transmissions. Ask them why. Stick shifts and clutches break and are hard to consistently race successfully. So most use an automatic and the fastest ones use a torque converter with a high (loose) stall speed. That's the speed the engine is allowed to reach on the starting line while braking the car before the green light. The higher the speed the faster the car to the finish line. That's because the engine can put out more power at higher speed sooner. My car came alive when I changed converters from the original to a loose TCI.

Bob, a more powerful camshaft almost always has to move that power band UP in the RPM range. That means less power at the low end. That's why most trucks have mild cams to pull heavy loads. The loads have to be started from a standstill so mild engines are needed.
Most racers use automatic transmissions. Ask them why. Stick shifts and clutches break and are hard to consistently race successfully. So most use an automatic and the fastest ones use a torque converter with a high (loose) stall speed. That's the speed the engine is allowed to reach on the starting line while braking the car before the green light. The higher the speed the faster the car to the finish line. That's because the engine can put out more power at higher speed sooner. My car came alive when I changed converters from the original to a loose TCI.

I have a TCI trans and 10" torque converter with 3500 stahl. From what
I gather from your reply, higher the stahl, faster you can go. But can you
go to big a stahl and would that be a negative in racing. Thanks for your
response(s).

I have a TCI trans and 10" torque converter with 3500 stahl. From what
I gather from your reply, higher the stahl, faster you can go. But can you
go to big a stahl and would that be a negative in racing. Thanks for your
response(s).
I'm not sure. I think stall is RPM based. They have to work with each other.

3500 stall isn't nearly enough flash stall for that camshaft. Of course, you have not stated your goals for this car, such as maximum performance on the dragstrip.

I'm running a 269/276 @ .050 .738/.738 on a 108 LSA in my 468 and my converter flashes 5700 RPM in good air. Check out my vids below and you'll notice that my converter keeps the engine in the sweet on launch and on gear changes.

Bob:

I would also suggest you post your question on Chevelle forum - lots more BBC guys hanging out over there.

Tom

Bob:

I would also suggest you post your question on Chevelle forum - lots more BBC guys hanging out over there.

Tom

I have it posted there also. Not much response (3) yet. Thanks for
suggesting it.

Bob, for your converter,get all ,I mean ALL of your info on your engine, car weight,gear,ect. and call the tech guys at the companies and get their ideas on whats best for you. Most of the bigger ones can be found in the man. listing in National Dragster. Sounds like the guys are right-you need another converter,or maybe TCI can redo the one you have.

I assume the cam change will be be better with stall I have but could be even be
more with stall change. Seems that's what your saying, correct.

I would also add that there are a number of local transmission conmpanies through out the country that have been around for decades. For the price of an off the rack converter you could have one custom made to your car's weight and suspension and motor's chracteristics for about the same price. A custom converter will pull a lot harder than one that is generic (the money you pay buys a converter and not advertising).

Larger Dave

I would also add that there are a number of local transmission conmpanies through out the country that have been around for decades. For the price of an off the rack converter you could have one custom made to your car's weight and suspension and motor's chracteristics for about the same price. A custom converter will pull a lot harder than one that is generic (the money you pay buys a converter and not advertising).

Larger Dave

The previous owner told me the 10" converter in it now is a custom
piece he had done for the car. That's why I am asking if the one in
now will be OK for the new cam. I'm really set on leaving it in since
it was made for current car set-up even though I want to upgrade
cam. Is this new cam that much difference in performance that the
converter needs changed. Thanks!

Whenever you increase the duration you increase the overlap which kills the bottom and midrange torque requiring you to shift your stall speed up to compensate. Yes a cam change necessitates a converter adjustment (rebuild) or replacement.

Larger Dave

Sorry but 3500 isn't even in the ballpark, not even for your current combo. Give Charles Plott a call at ATI. www.atiperformanceproducts.com.

My 468 runs better than average and I don't think it was all an accident.

Sorry but 3500 isn't even in the ballpark, not even for your current combo. Give Charles Plott a call at ATI. www.atiperformanceproducts.com (http://www.atiperformanceproducts.com).

My 468 runs better than average and I don't think it was all an accident.

WOW! No other responses said that, not even for current as you said.
What do you think I may need for the current set-up let alone for new
cam?

Bob:

Not knowing your goals and other details, it is tough for group to provide solid recommendations. I'm going to suggest something against the grain - try your existing converter with new cam and see what happens. With 540 cubic inches on hand, you have a lot more torque than a smaller BBC. A looser converter might be a better choice but unless you are running slicks will likely overpower the tires anyway. Changing cam is at the other end from transmission, why not try cam change first and follow up with converter if needed.

Tom

WOW! No other responses said that, not even for current as you said.
What do you think I may need for the current set-up let alone for new
cam?

A quick rule of thumb, you want your flash speed to be no less than 1500 under your shift point.

A quick rule of thumb, you want your flash speed to be no less than 1500 under your shift point.

What do you mean by flash speed? New to this stuff but learning.

Bob, the way I check to see what I really have for a converter is to measure it`s "flash" rpm. I put the trans in high gear and let the engine almost idle,like 5-10 mph roll, then mat the throttle and watch the tach. The engine will rpm up,almost free rev, to a certain rpm and then the car will accelerate. For instance, my converter flashes to 5600 rpm on average. This is the best way, I think, to measure a converter performence. Guys help me on this, someone else might explain it better!

Bob, the way I check to see what I really have for a converter is to measure it`s "flash" rpm. I put the trans in high gear and let the engine almost idle,like 5-10 mph roll, then mat the throttle and watch the tach. The engine will rpm up,almost free rev, to a certain rpm and then the car will accelerate. For instance, my converter flashes to 5600 rpm on average. This is the best way, I think, to measure a converter performence. Guys help me on this, someone else might explain it better!

Still unsure here. What does the flashes tell you. Need more or less
converter? Does a certain rpm mean good, bad. Still confused but I
appreciate your reply.

Same thing in your daily driver if it's an auto, press the break and the gas down at the same time, the engine WILL NOT rev past a certain rpm until the tires begin to break free... 1,800-2,200 for most stock vehicles. But your definition worked well for me, then again I have also researched the same thing. Bob, read up on this on wikipedia or something, they have pages and pages explaining this, you can hear it in a nutshell form here but you will really understand it better to read up on it for 30 min or so if you have the time...

Your converter needs to be decided on your entire drive line, engine rpm band, trans ratios, rear end gears.
High rpm motor, stock stall, highway gears= no bueno.
It would be like driving a manual, on high rpm engines with crappy rear end gears, you simply can't just let out the clutch, you have to feed the motor some rpm to get things going, a stall does the rpm-ing for you??? If that makes sense.

Bob,I do not use my transbreak when I leave the line, I leave at about 1200-1500 rpm. When I release the footbreak and mat the gas,my engine rpms up to near my converter flash before the car leaves the line. Since my engine runs best between say 5500 -7000, it leaves very well at 5500, not so well at 4500, even worse at 3500. My cam simply does'nt make effective power at anything below about 5000rpm. A converter that flashes to where the engine is most happy makes or breaks the performance of an automatic trans car. Keep in mind, with everything right, including the carb, this flash I'm talking about is nearly instantaneous. As a matter of fact with everthing else the same,say an A stock BB Camaro,same engine combo, the automatic car usually out 60 foots,out 330 foots and out 1/8 miles the same car with a stick. The back half is usually a different story, however! Hope this helps.

Thanks guys, understanding this a little better.