"BIG" HEAD, SMALL CAM ........ THEORIES?
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Depends on the cam and the usage, 205's on a 358 with a big cam and set up for drag racing and steep gears arent too big.
My theory is its better to get a custom ground cam to your combo and usage, match the cyl head flow,compression,weight of the car,gear ratio,intake,carb etc.....
Even though depending on the cam bigger heads will make a difference, but say putting 205's on a 351w with say a cam with 220 @0.50 specs will only kill bottom end and wont take advantage of higher rpm's that the cam wont hit. A smaller head like the 185 or twisted wedge would make more overall power, the only exception I could think of is in a extremely light car where the loss in bottom end would allow more traction.
theres and article on enginemasters where they built a 393 stroker, with a custom cam similar to the xe274hr, out of the box canfield heads, 9.5.1 compression that idles like a stocker,good vacuum,excellent BFSC (economy), makes 400ft lbs right off idle and peaks at about 505 hp and the same torque all below 6000 rpm.
got to this link and read wicked windsor in a box pt 1 and 2
www.popularhotrodding.com/enginemasters/articles/ford/smallblock/
My theory is its better to get a custom ground cam to your combo and usage, match the cyl head flow,compression,weight of the car,gear ratio,intake,carb etc.....
Even though depending on the cam bigger heads will make a difference, but say putting 205's on a 351w with say a cam with 220 @0.50 specs will only kill bottom end and wont take advantage of higher rpm's that the cam wont hit. A smaller head like the 185 or twisted wedge would make more overall power, the only exception I could think of is in a extremely light car where the loss in bottom end would allow more traction.
theres and article on enginemasters where they built a 393 stroker, with a custom cam similar to the xe274hr, out of the box canfield heads, 9.5.1 compression that idles like a stocker,good vacuum,excellent BFSC (economy), makes 400ft lbs right off idle and peaks at about 505 hp and the same torque all below 6000 rpm.
got to this link and read wicked windsor in a box pt 1 and 2
www.popularhotrodding.com/enginemasters/articles/ford/smallblock/
Everyone is saying that to get 300rwhp from a small cross section head is going to take more duration, where a large cross section head will need less duration. Of course this is assuming that you're comparing 300rwhp for both (you said 300hp for large) I'll guess that the lower duration cam larger cross section will be more streetable.
And Erik you know if that you, or Buddy, or myself are doing the cam it would be ok. The problem is saying "Too Big" is that it just depends. No, I say again, No I am not advocating a 305cc Victor or a 260cc Yates head on a 306. But an AFR 205, Perf RPM and the right cam would be a friggin blast to drive on a 306 and as Erik has said, it gives the customer an option for more later. I said this in another thread as well.racer7088 said:
No to the guy asking about is a 205AFR qualifies as a Big Head on a little engine, that depends. If it is a very small stroke and a larger bore, it *could*. A 3.3 stroke and a 4.155 bore yields 358 cid. This is getting close. But if it is 4.03 bore and 3.5 stroke, no it is not.
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I have yet to see a 205 headed 302/306. Who's got one and what's he doing with it?
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i might be.......
just trying to find out if im going to have a turd down low.......... if it has nothing untill 3500, and the 145cc setup is going to have alot more down low, well then i must go with the small port setup.
and the heads im looking at are not afr 205's...... but they are 200+ cc intake ports.
just trying to find out if im going to have a turd down low.......... if it has nothing untill 3500, and the 145cc setup is going to have alot more down low, well then i must go with the small port setup.
and the heads im looking at are not afr 205's...... but they are 200+ cc intake ports.
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THEN.........
c'mon mat..........you know your heads wont be 165cc's when neil is done with em.......and if they were box stock 165's, they would certainly be small for a 364" combo........ now, will vic jr's be too big for my 302 ?
that is the question!
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"Okay, Buddy and Jay, going backwards then, for your average 3200lb stock-shortblock (cam included) stick car with 3.73s, what is the optimum intake runner volume for peak power at about 5800 rpm? That would be beneficial info for everyone, and also what intake runner length would work best with these? Thanks for your inputs...."
this is too convoluted of a way to look at performance. You are taking an existing camshaft and bottom end geometry and working out the intake and exhaust specifics to match it. the problem is, that thought process assumes/implies at some point the stock camshaft is the most optimized camshaft for a given set-up(period). That wont be the case.
It takes a pretty decent inlet cross-section, definitely among the bigger style heads available, and the exhaust will have to be equally flow capable. On the stock cam thread I threw out an example, the same one as Jay did above. A 5.0 liter with a head similar to an AFR 205, with its high E/I ratio, in the lower lifts, a very flow capable intake (not even being afraid of a racing manifold) and some large headers and exhaust system. On the order of 1 7/8 and 3 1/2" system is going to start really utilizing the cam and its lobe separation well. It will need to be installed on down around a 110 intake CL, though. Bumping compression and adding some higher ratio rockers will work wonders for it. It will purr like a kitten and run very well. a definite sleeper. But is it the true optimum for the camshaft? possibly. Is it the true optimum for the motor, with all those really nice parts? not even close. It all depends on which side of the fence you are on. I dont think many people are going to spring for that sort of upper end capability and run a stock cam, unless there is some sort of class limitation. going smaller on the exhaust is going to force the exhaust needs earlier and greater, and will drop cylinder pressure. Going smaller on the inlet will end up having too early of exhaust events.
The fix, it seems, would be to drop the flow capability down on the inlet and exhaust. but thats not a fix. Then you get into the problem of not having enough lobe or correctly positioned exhaust events.
Buddy Rawls
this is too convoluted of a way to look at performance. You are taking an existing camshaft and bottom end geometry and working out the intake and exhaust specifics to match it. the problem is, that thought process assumes/implies at some point the stock camshaft is the most optimized camshaft for a given set-up(period). That wont be the case.
It takes a pretty decent inlet cross-section, definitely among the bigger style heads available, and the exhaust will have to be equally flow capable. On the stock cam thread I threw out an example, the same one as Jay did above. A 5.0 liter with a head similar to an AFR 205, with its high E/I ratio, in the lower lifts, a very flow capable intake (not even being afraid of a racing manifold) and some large headers and exhaust system. On the order of 1 7/8 and 3 1/2" system is going to start really utilizing the cam and its lobe separation well. It will need to be installed on down around a 110 intake CL, though. Bumping compression and adding some higher ratio rockers will work wonders for it. It will purr like a kitten and run very well. a definite sleeper. But is it the true optimum for the camshaft? possibly. Is it the true optimum for the motor, with all those really nice parts? not even close. It all depends on which side of the fence you are on. I dont think many people are going to spring for that sort of upper end capability and run a stock cam, unless there is some sort of class limitation. going smaller on the exhaust is going to force the exhaust needs earlier and greater, and will drop cylinder pressure. Going smaller on the inlet will end up having too early of exhaust events.
The fix, it seems, would be to drop the flow capability down on the inlet and exhaust. but thats not a fix. Then you get into the problem of not having enough lobe or correctly positioned exhaust events.
Buddy Rawls
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the totally stock cams are so small that I did not think that they even fall into the realm of consideration for compatibility with any of the performance heads.
even with the knowledge that the bigger head can use a smaller cam,
the seat to seat and "at .050" numbers are so small that I dont think that they help the low lift flow rates.....at least with the idea that the larger head does not need as much low lift duration to give a total net cylinder fill advantage.
for some "small" is pretty small
for some "SMALL" is pretty "BIG"....
the advantages of larger total lifts cannot be overlooked, especially in the area of more top R.P.M.
even with the knowledge that the bigger head can use a smaller cam,
the seat to seat and "at .050" numbers are so small that I dont think that they help the low lift flow rates.....at least with the idea that the larger head does not need as much low lift duration to give a total net cylinder fill advantage.
for some "small" is pretty small
for some "SMALL" is pretty "BIG"....
the advantages of larger total lifts cannot be overlooked, especially in the area of more top R.P.M.
Jay Allen said:
have either of you guy's heard of TRW solid rollers? Im building a 408 for a friend of mine and he has a TRW solid roller cam, SBF,
TRW TP 215
288/288 106/114 .566/.566 overlap 68
@.050
intake opens TDC: 17.5
closes ABDC: 49.5
Ehaust opens: BBDC: 57.5
Closes: BTDC: 9.5
can you tell me the duration @.050? thats all the info I had, and I dont know how to translate that into duration numbers @.050 I can understand...lol
sorry but this is really bugging me, thanks!
2wld4u
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seems like alotta work to make the stock cam "optimal".......
BUT, TO BE THE BROKEN RECORD........
whats the *best* way to get there?????
do i just call ed and get the cookie cutter 165 setup? (not likely, im too cheap, and dont like to do everything like everyone else)........
do i go "big" and have you (buddy) hook me up with another cam???
we did this once before, but i did not go into it this much. the cam you ground me was "tiny" if compared even the milder alphabet cams. i did not get to run the thing, as the car was stolen, then i sold the motor. but, on E.A. it looked quite good. i had one problem, the exhuast was really the killer......... 1 5/8" short tube headers, with a 300cfm capable intake port.......
this time i would like to do it right, but i still want enough cylinder head to keep me happy, and not have to send them out for someone to "fix" their shortcomings, or have to sell them, and buy a new set later......... this is why the vic's are looking nice to me.. plus, how can ya argue with the sub 1300 price tag? would the intake valve be too shrouded by the small 4" bore? if so, why do people run these with good results on a 408 with a ~ 4" bore?
ok, now IM getting off topic!
ohh great........... ill never get my question answered
once again, thanks for the imput thus far
BUT, TO BE THE BROKEN RECORD........
whats the *best* way to get there?????
do i just call ed and get the cookie cutter 165 setup? (not likely, im too cheap, and dont like to do everything like everyone else)........
do i go "big" and have you (buddy) hook me up with another cam???
we did this once before, but i did not go into it this much. the cam you ground me was "tiny" if compared even the milder alphabet cams. i did not get to run the thing, as the car was stolen, then i sold the motor. but, on E.A. it looked quite good. i had one problem, the exhuast was really the killer......... 1 5/8" short tube headers, with a 300cfm capable intake port.......
this time i would like to do it right, but i still want enough cylinder head to keep me happy, and not have to send them out for someone to "fix" their shortcomings, or have to sell them, and buy a new set later......... this is why the vic's are looking nice to me.. plus, how can ya argue with the sub 1300 price tag? would the intake valve be too shrouded by the small 4" bore? if so, why do people run these with good results on a 408 with a ~ 4" bore?
ok, now IM getting off topic!
ohh great........... ill never get my question answered
once again, thanks for the imput thus far
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duration at .050" is "paper" calculated by adding the @.050" opening number + 180 + the closing @.050" number....
the other way is to use a degree wheel, and count the degrees of total timing.
the other way is to use a degree wheel, and count the degrees of total timing.
Thanks Kato, thats the info I was looking for! 288/ 247 @.050
Im having the small head big motor problems, 200CC roush cast iron (as cast) heads and 408 cubic inches.. and he will not change heads or have any portwork, and he wants 500hp, (flywheel) and it will be 10.5:1 with dish piston and 64cc heads.. is this possible for one, keeping the RPM At or below 6500 rpm shift points, and two is this perticular motor going to benifit from a custom cam?
not meaning to hi-jack, I feel others may benifit, from my perticular situation...
2wld4u
Im having the small head big motor problems, 200CC roush cast iron (as cast) heads and 408 cubic inches.. and he will not change heads or have any portwork, and he wants 500hp, (flywheel) and it will be 10.5:1 with dish piston and 64cc heads.. is this possible for one, keeping the RPM At or below 6500 rpm shift points, and two is this perticular motor going to benifit from a custom cam?
not meaning to hi-jack, I feel others may benifit, from my perticular situation...
2wld4u
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6,106 Posts
Sorry Matt...
But I don't sell "theories" on customer combinations. Especially when it's "their" money being spent. I will only provide packages that meet the customer's requirements. No sense in selling something for "future" needs that may never occur. If you wish to call these packages "cookie cutter" combinations, you are not properly informed and you are completely mistaken. These packages range from the mildest of stock shortblock 5.0 engines to stroker LS1 Corvettes.
I guess the real issue is the success of these FTI customers. It always seems to come into question by others that are now delving into this business. Maybe it's because, unlike all the theorists, these combinations are real world and they perform as advertised. Sorry if they can't provide you the same type of proof. Their loss.
Like I stated above, these custom designed combinations work and work well. That in itself should speak volumes of what is practical versus what is theoretical. If you want to chase a theory, better have a fat wallet and a lot of time to test a ton of "theoretical" pieces. Since you state you are on a budget, I doubt you have the time and resources to prove out any of these theorists.
Good luck with your search for the Holy Grail of big heads and tiny camshafts. So far, the only successful ones exist on internet forums and not in the real world.
Ed
But I don't sell "theories" on customer combinations. Especially when it's "their" money being spent. I will only provide packages that meet the customer's requirements. No sense in selling something for "future" needs that may never occur. If you wish to call these packages "cookie cutter" combinations, you are not properly informed and you are completely mistaken. These packages range from the mildest of stock shortblock 5.0 engines to stroker LS1 Corvettes.
I guess the real issue is the success of these FTI customers. It always seems to come into question by others that are now delving into this business. Maybe it's because, unlike all the theorists, these combinations are real world and they perform as advertised. Sorry if they can't provide you the same type of proof. Their loss.
Like I stated above, these custom designed combinations work and work well. That in itself should speak volumes of what is practical versus what is theoretical. If you want to chase a theory, better have a fat wallet and a lot of time to test a ton of "theoretical" pieces. Since you state you are on a budget, I doubt you have the time and resources to prove out any of these theorists.
Good luck with your search for the Holy Grail of big heads and tiny camshafts. So far, the only successful ones exist on internet forums and not in the real world.
Ed
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ED,
thanks for the reply. actually kind of suprised, you usually will not get much into theory.....which i fully understand, it is your bread and butter, and took some time for you to learn no doubt!
as for the cookie cutter statement.....well, maybe you just make it look so easy, that one might think it is "easy"...........
your also correct about the big wallet statement, hence the reason i want to do as much research, and learn from those who have done many things, many ways.....collective experience is more than one person is ever going to get....if your a formula one fan, you know what i mean with the bridgestone vs. michelin war right now..
hopefully we wont make this into a jay vs. ed thread...............again. not needed. i want my next combo well planned out, i do not want to spend money on things over, and over.................. like the last 5 combos i built for the same car...lol.
trying to learn from my mistakes....and sorry, the will not be an afr 165/fti cam/pref rpm setup. it will have to be different. i might not get as good a result.....but, maybe i will?
anyhoo, good thread.
thanks for the reply. actually kind of suprised, you usually will not get much into theory.....which i fully understand, it is your bread and butter, and took some time for you to learn no doubt!
as for the cookie cutter statement.....well, maybe you just make it look so easy, that one might think it is "easy"...........
your also correct about the big wallet statement, hence the reason i want to do as much research, and learn from those who have done many things, many ways.....collective experience is more than one person is ever going to get....if your a formula one fan, you know what i mean with the bridgestone vs. michelin war right now..
hopefully we wont make this into a jay vs. ed thread...............again. not needed. i want my next combo well planned out, i do not want to spend money on things over, and over.................. like the last 5 combos i built for the same car...lol.
trying to learn from my mistakes....and sorry, the will not be an afr 165/fti cam/pref rpm setup. it will have to be different. i might not get as good a result.....but, maybe i will?
anyhoo, good thread.
Matt, my car started off as a daily driver so it's roots are a very mild combo. Stupid me bought pedistal mount 165 heads which to this date limits me to pretty small camshafts.
I raced the AOD with a stock motor for two years prior to getting H/C/I and one thing is found was the AOD cars love anything that boosts mid range torque (locking timing at 32° or Longtube headers). Armed with that theory and a 2800 stall converter, I thought it best to stay with smaller 165 heads.
My main area expertise is only why my combo works, so the question I have is with big 200+ cc heads, how can a 302 generate enought velocity to make any good low/mid range power? If you look at the short side radiaus as an airplane wing, it seams like the big slow moving column of air would actually stall out on the turn into the chamber and hurt low/mid speed cylinder filling.
The objective of my combo is to keep velocity up and to get it moving early int the RPM band. On the dyno my 306 makes 300+ RWTQ from 2800-5100 and peaks at 346 RWTQ with the converter locked through an AOD. HP drops off after 5500. Last winter with a 5600 pill in the shift light the car ran a 11.41 @ 116 on motor.
When I daily drove the car, it would get lugged at 1200 RPM in 3rd or 4th gear and never buck. I figure most OST cams are designed for 5 speed cars that can lauch off the rev limiter or be manually held in a lower gear to keep the revs up if need be. Which is why I went with one of Ed's cams.
So with that being said, I think a big head small cam combo is the wrong way to go on a automatic unless you have a huge stall.
Since ROG30Y is local to me, I'll put my mid sized head and mid sized cam against his Big head small combo at the race track once he gets the bugs worked out.
FWIW my cam is 220/225 and 535/545 with a 109 LSA, box stock AFR 165 heads
I raced the AOD with a stock motor for two years prior to getting H/C/I and one thing is found was the AOD cars love anything that boosts mid range torque (locking timing at 32° or Longtube headers). Armed with that theory and a 2800 stall converter, I thought it best to stay with smaller 165 heads.
My main area expertise is only why my combo works, so the question I have is with big 200+ cc heads, how can a 302 generate enought velocity to make any good low/mid range power? If you look at the short side radiaus as an airplane wing, it seams like the big slow moving column of air would actually stall out on the turn into the chamber and hurt low/mid speed cylinder filling.
The objective of my combo is to keep velocity up and to get it moving early int the RPM band. On the dyno my 306 makes 300+ RWTQ from 2800-5100 and peaks at 346 RWTQ with the converter locked through an AOD. HP drops off after 5500. Last winter with a 5600 pill in the shift light the car ran a 11.41 @ 116 on motor.
When I daily drove the car, it would get lugged at 1200 RPM in 3rd or 4th gear and never buck. I figure most OST cams are designed for 5 speed cars that can lauch off the rev limiter or be manually held in a lower gear to keep the revs up if need be. Which is why I went with one of Ed's cams.
So with that being said, I think a big head small cam combo is the wrong way to go on a automatic unless you have a huge stall.
Since ROG30Y is local to me, I'll put my mid sized head and mid sized cam against his Big head small combo at the race track once he gets the bugs worked out.
FWIW my cam is 220/225 and 535/545 with a 109 LSA, box stock AFR 165 heads
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