I was just wondering, and couldnt find anything on the net about it.... Thanks, Tommy
How does a dual grind cam work?
- Thread starter hasa68mustang
- Start date
A dual pattern cam compensates for design shortcomings in a motor.
If flow in or out is restricted by port design, exhaust or intake manifolding etc, it opens the cam at a different point and to a different height/duration in order to optimise intake, and then allow that amount of fuel inlet, to be exhausted fully when burnt.
A single pattern cam assumes that the intake and exhaust capabilities are equal to each other and suit the motor build.
If flow in or out is restricted by port design, exhaust or intake manifolding etc, it opens the cam at a different point and to a different height/duration in order to optimise intake, and then allow that amount of fuel inlet, to be exhausted fully when burnt.
A single pattern cam assumes that the intake and exhaust capabilities are equal to each other and suit the motor build.
Mikes site states "This dual pattern camshaft profile was designed primarily for use with the increased induction that is achieved when using an OZ250-2V or Argie head, or with multiple carb setups such as with the Offy 3-1V manifolds or custom log heads." and I was just wondering if my car would classify for one of these cams. He recommended the 264 110* installed 4* in advance, not going against him in any way or trying to even get someone elses opinion but if I were to go with a FI setup (nothing radical) which would be a better choice?
Thanks, Tommy (Addo you never fail) oh or a different suggestion...
Thanks, Tommy (Addo you never fail) oh or a different suggestion...
Mikes suggestion is right on the money.
If you have the C4 trans with a stock stall speed converter you might go with the 112 degree centerline, if its a stick or with a looser converter the 110 -264 4 degrees advanced is right on.
Better yet, if you have flat top pistons with over 10-1 compression & a stick shift I would go with the 274 degree cam with 108 lobe center & advance it 4 degrees. William
If you have the C4 trans with a stock stall speed converter you might go with the 112 degree centerline, if its a stick or with a looser converter the 110 -264 4 degrees advanced is right on.
Better yet, if you have flat top pistons with over 10-1 compression & a stick shift I would go with the 274 degree cam with 108 lobe center & advance it 4 degrees. William
one more thing.. springs, will the stock springs be able to keep up with that cam? I havent really read anything about springs... Thanks, Tommy
8) some good information from ron iskanderian regarding dual pattern cams;
Tech Tip - 2003
Longer Exhaust Duration: Is this really necessary?
Most stock camshafts from American production V8, V6 and 4 cylinder engines manufactured today are ground with the longer exhaust lobe duration. Or, another way of looking at this is that they are ground with shorter intake durations! The former embraces the viewpoint that either the Exhaust Ports or Exhaust Pipe system is somewhat restrictive, and is in need of an assist. The latter suggests that the intake system is rather efficient and cam timing can be trimmed back a bit with out much sacrifice in power, in order to maximize throttle response and cruising efficiency.
Take your pick here. There is no absolutely correct viewpoint - because both are probably true! In a stock engine running at conservative RPM levels, for the sake of overall efficiency, fuel economy and a quiet smooth running engine, this staggering of intake and exhaust duration is quite common and appropriate.
However, High Performance is another thing entirely. Change one factor, let's say in this case, the exhaust system (installing headers and larger pipes) and you have just negated in most cases, the need for that longer exhaust lobe. Now couple this change with a different intake system and camshaft and you have really scrambled the equation. But, wait just a moment. Why is it that so many people (racers & cam grinders alike) insist on running a cam with longer exhaust duration regardless of what equipment is employed? The answer is "habit". Most of them have been somewhat successful in doing it their way and will probably never change unless virtually forced by circumstances to do so.
Before we go any further however let's review what it actually is we are trying to do with an engine when we attempt to make more power. Our best result comes when we are cognizant of the fact that an engine is basically an air pump. We pump it in and out (although in a different form) and we have problems when one side or the other is restricted. Balance or the equilibrium or flow should be our objective, unless of course we are not trying to make more horsepower!
Example #1 (Oval track racing) Here, I have often observed that the most experienced drivers are those who are most likely to run a single pattern (equal on intake and exhaust duration) cam. Why? Because such cams always, I repeat always make more torque! These veterans have a more educated foot and greater experience in feathering the throttle in the corners. They can therefore, utilize the benefit of added torque, in the lower to mid RPM range, to their advantage.
Their counterparts, the younger drivers on the circuit, generally are not as experienced and may at times actually get "crossed up" in the corners especially with a lighter car or when they are learning the ropes. In their case, a longer exhaust duration is often the more appropriate choice. It will often help them to drive better, more "flat footed" if you will, without consequence. But please for the sake of accuracy, let us be truthful. The benefit comes from an actual bleeding off of low to mid range torque, which is always what happens when Exh. Duration is lengthened, not from any improvement. The improvement, (if any) would come because of an improvement in scavenging at the extreme upper end of the power curve and would usually be marginal at best. Yet the so-called "extra power" potential of a longer Exh. Duration cam is most often why they are touted - power most people are backing away from at the end of the strait away!
Example #2 (Drag Racing) At the drag strip it's a little different and I feel more honest. Here, racers have long enjoyed longer exhaust and longer durations across the board (If I may add specifically for the purpose of "killing" low-end torque) to keep the tires from too easily breaking lose. This has been successful and sometimes actually results in a slight increase in top end power - something you can actually use in drag racing since it is a full throttle endeavor through the lights. Keep in mind here though, it's quite possible that a longer duration cam overall would have done just as well or better. In other words if you needed that longer exhaust for top end, perhaps the intake could have benefited from such a lengthening as well.
One of my favorite expressions is how "The Drag Racing mentality has infiltrated the ranks of Oval Track". Many have crossed over and made the switch in the past 10-15 years and some have brought their preconceived notions about how to cam an engine with them. A few may actually read these concepts and if they do so will at least come away with a better understanding of what they are doing. On the other hand they also could find that this information might actually help their cars to run just a bit faster!
Note: Readers may find Camfather Ed Iskenderian's Top Tuners Tip #33 "Can an Exhaust System Over-Scavenge the Combustion Chambers" to be a relevant precursor.
Tech Tip - 2003
Longer Exhaust Duration: Is this really necessary?
Most stock camshafts from American production V8, V6 and 4 cylinder engines manufactured today are ground with the longer exhaust lobe duration. Or, another way of looking at this is that they are ground with shorter intake durations! The former embraces the viewpoint that either the Exhaust Ports or Exhaust Pipe system is somewhat restrictive, and is in need of an assist. The latter suggests that the intake system is rather efficient and cam timing can be trimmed back a bit with out much sacrifice in power, in order to maximize throttle response and cruising efficiency.
Take your pick here. There is no absolutely correct viewpoint - because both are probably true! In a stock engine running at conservative RPM levels, for the sake of overall efficiency, fuel economy and a quiet smooth running engine, this staggering of intake and exhaust duration is quite common and appropriate.
However, High Performance is another thing entirely. Change one factor, let's say in this case, the exhaust system (installing headers and larger pipes) and you have just negated in most cases, the need for that longer exhaust lobe. Now couple this change with a different intake system and camshaft and you have really scrambled the equation. But, wait just a moment. Why is it that so many people (racers & cam grinders alike) insist on running a cam with longer exhaust duration regardless of what equipment is employed? The answer is "habit". Most of them have been somewhat successful in doing it their way and will probably never change unless virtually forced by circumstances to do so.
Before we go any further however let's review what it actually is we are trying to do with an engine when we attempt to make more power. Our best result comes when we are cognizant of the fact that an engine is basically an air pump. We pump it in and out (although in a different form) and we have problems when one side or the other is restricted. Balance or the equilibrium or flow should be our objective, unless of course we are not trying to make more horsepower!
Example #1 (Oval track racing) Here, I have often observed that the most experienced drivers are those who are most likely to run a single pattern (equal on intake and exhaust duration) cam. Why? Because such cams always, I repeat always make more torque! These veterans have a more educated foot and greater experience in feathering the throttle in the corners. They can therefore, utilize the benefit of added torque, in the lower to mid RPM range, to their advantage.
Their counterparts, the younger drivers on the circuit, generally are not as experienced and may at times actually get "crossed up" in the corners especially with a lighter car or when they are learning the ropes. In their case, a longer exhaust duration is often the more appropriate choice. It will often help them to drive better, more "flat footed" if you will, without consequence. But please for the sake of accuracy, let us be truthful. The benefit comes from an actual bleeding off of low to mid range torque, which is always what happens when Exh. Duration is lengthened, not from any improvement. The improvement, (if any) would come because of an improvement in scavenging at the extreme upper end of the power curve and would usually be marginal at best. Yet the so-called "extra power" potential of a longer Exh. Duration cam is most often why they are touted - power most people are backing away from at the end of the strait away!
Example #2 (Drag Racing) At the drag strip it's a little different and I feel more honest. Here, racers have long enjoyed longer exhaust and longer durations across the board (If I may add specifically for the purpose of "killing" low-end torque) to keep the tires from too easily breaking lose. This has been successful and sometimes actually results in a slight increase in top end power - something you can actually use in drag racing since it is a full throttle endeavor through the lights. Keep in mind here though, it's quite possible that a longer duration cam overall would have done just as well or better. In other words if you needed that longer exhaust for top end, perhaps the intake could have benefited from such a lengthening as well.
One of my favorite expressions is how "The Drag Racing mentality has infiltrated the ranks of Oval Track". Many have crossed over and made the switch in the past 10-15 years and some have brought their preconceived notions about how to cam an engine with them. A few may actually read these concepts and if they do so will at least come away with a better understanding of what they are doing. On the other hand they also could find that this information might actually help their cars to run just a bit faster!
Note: Readers may find Camfather Ed Iskenderian's Top Tuners Tip #33 "Can an Exhaust System Over-Scavenge the Combustion Chambers" to be a relevant precursor.
Interesting writing. Scans like the fellow is thinking in French and translating to English as he goes.
It doesn't really disagree with the summary I posted, but offers some ideas for other competitive situations.
Tommy: Regarding EFI, I personally believe "we" are short on reliable, effective ignition controls for that to work best. Once somebody manages to cross that bridge, it'll be well worth doing.
It doesn't really disagree with the summary I posted, but offers some ideas for other competitive situations.
Tommy: Regarding EFI, I personally believe "we" are short on reliable, effective ignition controls for that to work best. Once somebody manages to cross that bridge, it'll be well worth doing.
Thanks guys, you made me feel like an idiot.... I read last night under the cam section about what it is, now it makes sense and if I would have read that I would not have asked this, it is a very simple subject, which I believe for my application (headers to glass packs 18" behind them) I dont really think I have a restriction problem... if anything wouldnt we need the opposite with the dreaded log? addo, ummm when did I ask about EFI? now about the spings? anyone? Im still looking, Thanks, Tommy
Titleist16
Well-known member
I just had my engine rebuilt last week and I used the FSPP 264 110* cam. The rebuilder said that stock springs wouldn't be sufficient for that cam so he used some V8 springs. If you have the Falcon Performance Handbook it lists a few different springs from Ford V8's that you can use.
Inline6Merc
Well-known member
can you use '73-'78 302ci. exhaust springs for the intakes on the log head as well as for the exhausts?
later,
curtis
later,
curtis
Titleist16
Well-known member
According to the handbook you can use them for the intake and exhaust.
I ahd never thought about that... can someone please confirm the 70 exhaust valves? I read a post about mustangaroo buying them and they werent the right ones? heres a link: http://fordsix.com/forum/viewtopic.php?t=20253&highlight=cam+springs+73
Im going to goto Mikes site and look that up... oh and I am now superenthusiastic about doing some more stuff cause I got my butt whooped by my friends 3000gt and he rubbed it in and now I want to be able to at least sorta keep up and no I didnt race him up to like 90.. it was 55 in a 45 so it wsnt that bad... and there was no one on the roads and it was a highway... and yes I also know the cam isnt going to add 100 hp.... thanks for all your guyses help! oh and the 3000 is also supposed to be overrated and are suppsed to have like 160 hp and tq... Tommy
Im going to goto Mikes site and look that up... oh and I am now superenthusiastic about doing some more stuff cause I got my butt whooped by my friends 3000gt and he rubbed it in and now I want to be able to at least sorta keep up and no I didnt race him up to like 90.. it was 55 in a 45 so it wsnt that bad... and there was no one on the roads and it was a highway... and yes I also know the cam isnt going to add 100 hp.... thanks for all your guyses help! oh and the 3000 is also supposed to be overrated and are suppsed to have like 160 hp and tq... Tommy
A
Anonymous
Guest
hasa68mustang":flfieho0 said:
No matter how much you spend to make your car faster,
there will always be someone faster than you.
Build what you can and have fun with it for what it is.
Linc's 200":1qb54dw5 said:
VERY true, but he is one of my friends and his mommy bought his car... but for the 7 grand they paid for it I would have bought something different... but he does have to pay her back so he is too poor to do anything to it... he is a HUGE talker.... when he first started looking for a car he wasnt allowed to get anythign fast and he wanted a truck, and s-10 or something, then he wanted an srt-4, then his mom said something to me about it.Llater that day he said their crap and just overpriced neons..lol, and he went back to wanting an s10, and how he as going to supercharge it, then his uncle came into the story and he was going to buy him a car and he then rewanted an srt-4 and he was going to do all this work because his uncle was going to pay for it, then he wanted a 240sx because drifting became popular and he was going to build a drift car, and then he didnt want one because he didnt want to do a motor swap because he said he was lazy (I believe his mom told him he couldnt do it, either way he doesnt even know how to change his oil so I wouldnt trust the car) and then he wanted the srt-4, and then wanted a rotory motored rx-7, then he spent quite a bit of time looking at 240's again, and FINALLY he bought the 3000gt because he thought it was rear wheel drive, and later on he found out when he went to do a bunout and couldnt and then tried doing a donut and it wouldnt.... then he was going to convert it to a vr-4 and then he was goign to just supercharge it, and then he didnt want it... and he started looking at 240's AGAIN, and then stopped and started looking into hybrids because of him goign to be goign to college soon. BUT he stopped and started back int the rotarys and the srt-4s.. then one day him and his dad painted his hood scoops with spray paint, and his mom went ballistic! because the car wasnt paid for...but wait? he said he bought it... oh I guess he lied... and according to him he does 130-150 mph daily... ok so not every day but weekly, he'll be like I was hauling coming over I did 130 past a cop but he didnt pull me over... but its amazing how when your with him he doesnt drive over speed limits because hes already gotten a ticket for doing 37! in a 30...wow... I think its pretty funny myself... oh and my dad recommended him to change his timing belt because his car has close to 90k miles and though it will cost alot, it will cost more when your internals scatter.... but its his car, and hes not worrying because he put belt dressing on it...
, I so hope he breaks sometihng, his trannys already going, and his dome light broke and is hanging by wires, and the carpet on the bottom of the doors is held on by string... hes trying to sell it to someone for 6500... if you look them up you can buy a nice low mileage one for that... oh and its a 93... I am sure most of you guys know people like this... man thats a long story of me sorta hijacking my own thread... just getting a little off topic.... oh and now in his profile he put a message that he is going to take money out of his bank acount to buy a 240.... oh forgot one of my favorite storys... well a month or so ago he "went to test drive a srt-4 (you know the overpriced neon)" and he said it was fast and it was a 5 speed and he was going to buy it, and one days his dad let him drive his 70 something nova with 700 horsepower the first time he told me but now its only 450, and he knows how to drive a standard but when he needed to drive his friend hoe after gettting drunk he wasnt sure of his standard driving skills.. but didnt he test drive that srt-4 the week before? and yes HE sad he drove it... hes funny...
Jackfish, you are right on about valve springs. If you are using the 264 fspp camshaft you need at least 90# on the seat with a valve spring with a damper.
Stock ford valve springs are just a single spring with no damper qualities.
With a performance cam they are not recommended.
With the poor breathing of the log manifold, I don't know if even a dual pattern camshaft would help?? William
Stock ford valve springs are just a single spring with no damper qualities.
With a performance cam they are not recommended.
With the poor breathing of the log manifold, I don't know if even a dual pattern camshaft would help?? William
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