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Who will grind me a cam to MY specs for a decent price?
I would suggest Bullet Racing Cams. I ordered my cam from them. They guy who answered the phone was the guy who machined my cam. Whenever I have any questions I can call or email those guys and they're very helpful. I'm thinking they'd be happy to use whatever specs you want.
 

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I am no cam
Guru but I know some馃榿
For a street car, I first ask how rough an idle I can tolerate. Then guess at that idle vacuum number. Then you look at the corresponding overlap number that gives you that vacuum at idle. Your longer exhaust duration increases overlap. Personally for my uses the extra exhaust duration is not worth it on a street car.
Vizard has a good article you can find online that covers the effects of Overlap.
 

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It's fun to learn about all the black magic that goes into a cam. To be real, if you talk to a good cam grinder, they have many decades of experience as to what works in the real world and what doesn't. You can't learn all that from Internet research.
Agreed, why reinvent the wheel?
 

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jdub,
This may be a bit lengthy , but I hope enlightening.
Let's first look at the physics of what we are dealing with and why we need ( most of the time) , dual pattern cams. On the intake side we are dealing with vacuum created by piston motion. PLUS we are dealing with air AND fuel mixed with the aid of a carburetor. I'll talk about EFI when I get to LSA. Maximum or mean piston speed is dictated by stroke and is a FIXED number for the specific stroke regardless of engine type. piston speed before and after mean piston speed can be changed by altering rod length longer or shorter. This can be very important based on cylinder head "quality". Intake duration ( and lift) can be adjusted for small , stock, unported heads and for larger fully ported heads too. The stock head favors "late" opening to allow more lift at a later point before the valve starts closing. The long rod combinations help slow the piston off of TDC until the valve lift is higher and the piston is closer to mean piston speed. Now switch gears to a 320cfm head or a Boss 302 head and you would want to look at a very fast opening cam AND potentially a lower rod to stroke ratio so that faster piston speed off of TDC would pull more vacuum right away and get the big port flowing. Next post Exhaust.
 

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So now we look at exhaust. We change "mediums" to HOT , still burning air , PUSHED out around the valve into the exhaust port and into the header which has vacuum in it because of the "pulses" created by other cylinders firing. Here we tend to want longer durations to allow more chance to get it all out. "Lift"is not as critical here as the valve is way off of the seat as the piston begins pushing the exhaust out and that is why. There are "some" cylinder heads where the exhaust port/flow is TOO good and the extra duration is NOT needed. This is the case in many of the "modern" 4 valve heads out now.
Next is LSA/ICL. LSA varies because of induction ( carb or EFI) , cubic inches., cylinder heads , anticipated rpm range , and a few other factors. As mentioned earlier a carburetor depends on vacuum to "pull" the fuel out . EFI squirts the fuel based on the air flow and measured A/F ratio. Because of this the "overlap" , commonly used to help carburetted engine performance isn't needed so the LSA goes wider . "tuning is done by cam advance or retard ( ICL changes). LSA is ground into the cam ( on single cam engines) and CANNOT change unless the cam is reground. Cam "timing" (ICL ) CAN be changed as I mentioned to enhance performance. "In general" but not ALWAYS , "advancing" the cam improves bottom end performance and curbs top end performance BUT if the duration is long enough , high RPM performance isn't hurt. On the other hand , retarding the cam (ICL) "can" improve upper RPM performance and indicate the cam "could be too small".
To sum it up , SBF "caburetted" engines like 106-108 LSA and don't mind an ICL change to fine tune. Duration @ .050 numbers for a 306 should be in the 240s for a flat tappet and 230s for a roller and ideally have lift numbers .030-.050 ABOVE maximum airflow/lift of the head. This is not always possible and a rocker ratio change might be needed to get there. The exhaust duration should be about 8*s more than the intake and .050 LESS lift than the intake.
These are based on my 54 years of building/racing 289-351 engines and a lengthy employment at Sig Erson cams in the '70s. I am well recognized on the Boss 302 forum as a go to guy for camshaft information.
I welcome comments/opinions/questions.
Randy
 

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I welcome comments/opinions/questions.
Randy
Ok, Try and dumb this down for me.
2 cams same lift and dur. LSA 108 or 112 which is described as having a broader range and why? its almost like its written backwards to me.
 

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In the recent Engine Masters LSA episode they did a 440 that revved to 6500 or so. The tightest LSA was best. The takeaway that I got is that in a street car a tighter LSA is going to give more low end torque across the board and and the engine runs out of steam before the a wider LSA would pay off.

Looking at the 289 LeMans cam, I believe it has a 114 LSA. But it was meant to operate at high RPM in a road racing scenario.

That's all good info GT350HR. And it's definitely inline with the other information I have found. The .030-.050 above max lift is interesting. Here's what my heads flow:
764304


It's interesting that you say the exhaust lift should be less than the intake because that's not what we see in the aftermarket, but it does seem to pop up in custom cams. What lifts would you recommend for these heads?

Also interesting that pretty much every aftermarket SBF cam is 110 or 112 LSA when many knowledgeable guys are saying 106-108 is best. Weird. I guess it's just to keep the idles OK for people who aren't carb experts but want to say they have a big cam.
 

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2 cams can have the same LSA and very different timing events. LSA doesn鈥檛 matter, as its a number derived from timing events and is meant to provide basic information for the average catalog surfer. Don鈥檛 make your choice based off an advertised LSA number.
 

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Jdub, your takeaway isn't quite right. The narrow LDA is not always best for low rpm power in a street car. The LDA will be what it will be because of the other events. But all of the 'tests' I have seen are widening or narrowing the LDA and splitting the difference. This means that the most influential event, the intake closing is also moved. If you really want to play at this, get a narrower version of the cam you already have, and then a 9 key timing chain. Keep the same intake center line and see what you get. For most street drivers, I prefer the short overlap, wide LDA cams. Then, with a 9 key timing chain, I can advance or retard the whole deal and see what the engine likes best. Most of the street engines like it advanced 2~6 degrees. But every engine is a little different. Camshafts are fun and interesting, but some guys don't know much about them. We had one customer complain about the 'off brand' cam we chose for him, it was from Elgin. He liked how it ran, but he didn't know who that was ! LSG
 

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Generalizing on different LSA numbers is dangerous. Different engines/cylinder heads have VERY different "optimum LSA s ". A "wedge" head 302 has a different LSA requirement than a Boss302 head ESPECIALLY as the cams get bigger. I laugh when guys like Vizard ( who I met 44 years ago) have "new revelations" because they found something on the dyno that "others" have been doing for DECADES but don't write books for a living.
The reason for the "broader range" is because the wider LSA has a smoother idle because of lower overlap and ( in some cases) a smoother torque curve. Notice I didn't say more powerful torque curve. A "stock cam" could be considered a "broad power" cam , but is certainly not the most powerful as we know.
 

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Thanks for the information. Why is it that they say factory Ford EEC EFI systems require a wider 114 LSA ? Is that just a peculiarity to that system, or also common to aftermarket EFI systems ?
 

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What is MOST important is to HONESTLY figure out what you want or how you are going to use it. The LeMans cam was tested with LSAs from 104 to 114 by ford before it was eventually released to the public. There were at least twenty different experimental versions. The Ford version ( yes others sell the same cam under different part numbers) was released as C7FE 6250 A and was on a 109* LSA. "For it's time" , it was powerful and durable. There were "better" race cams but Ford's goal was WFO for 24+ hours , not maximum HP. Interestingly , your TW heads have flow numbers similar to the heads used in '66-67 at LeMans where that cam was used with Weber carburetion.
The reason "most" cam companies with split duration cams have more exhaust lift is because they use the next higher duration lobe which "usually " has more lift in general. I call it laziness.
There is no advantage in having the valve higher off of the seat when piston speed id very slow.
As sportsroof69 has noted , it is REALLY important to have the valve "in the right place at the right time" to make serious power. This type of design if a bit more complex than picking one "out of a catalog" and can end up not following ''conventional wisdom" when it comes to the numbers "most" look at. It IS the difference in power on many race applications..
The "flow balance" on your head is such that I might use a single pattern cam depending on use.
 

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Wide LSAs are common on EFI because of the lack of "signal" ( vacuum) needed to make the carburetor function.
 

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Just for reference for guys looking at it. This was the cam spec鈥檇 for me by Chris Straub for my 408. 10.21:1, with TW heads and a Vic jr intake, and it was meant for small amounts of nitrous (200ish shot). With the long stroke of the 408 it had great street manner and made power everywhere. It was also matched up to a good Neal Chance converter. It went [email protected] on motor and [email protected] on the bottle and was driven everywhere. Even on a small nitrous motor, he kept the LSA narrow.
64868327-2ED3-4353-B405-700DBAC19518.jpeg
 

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The reason for the "broader range" is because the wider LSA has a smoother idle because of lower overlap and ( in some cases) a smoother torque curve. Notice I didn't say more powerful torque curve. A "stock cam" could be considered a "broad power" cam , but is certainly not the most powerful as we know.
2 cams same lift and dur. LSA 108 or 112 which is described as having a broader range and why? its almost like its written backwards to me.
I wrote this poorly, it was meant as more of a which is which confirmation question, not that the 112 had a broader range than the 108. Howards has two identical except the LSA&CL I consider mildly big:) 496/512 225/231 @50. The 112/107 usage band says 2500-6200 the 108/104 says 2000-6400rpm. vroom vroom.

Im won't be trying for max HP, decent power will be just the by-product of a broad range and potential high winding screamer.
 

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The guys over at the speed-talk Engine forum are super knowledgeable (many here are also) and several are professionals including custom cam grinders who will answer questions in a very helpful manner.
 

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There are so many variables when it comes to designing a cam to fit an engine. Look at these numbers for an LS7 hydraulic roller split cam and look at the separation angle. Then consider the engine makes over 500 HP @ 6300 and usable power to the 7K redline. The car idles so smooth that i can lug it in traffic in 1st or 2nd at 5-7 MPH which is a great thing because otherwise if it bucked the car would be a real pain to drive in traffic. The induction system on this engine flows nearly 300 cfm stock so it definitely can breathe. I'm sure there was a lot of research that went into designing this cam to meet power requirements while still providing great driveability and meeting emissions standards...interesting.

Camshaft Part Number12638426
Duration @ .050 in. (int./exh.)210掳/230掳
Valve Lift0.593 in./0.589 in
Lobe Separation120掳
 

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I wrote this poorly, it was meant as more of a which is which confirmation question, not that the 112 had a broader range than the 108. Howards has two identical except the LSA&CL I consider mildly big:) 496/512 225/231 @50. The 112/107 usage band says 2500-6200 the 108/104 says 2000-6400rpm. vroom vroom.

Im won't be trying for max HP, decent power will be just the by-product of a broad range and potential high winding screamer.
Yes that is contradicting for sure. "I" would list the 108 as "carburetted use" and 112 for EFI use.Both should run the same upper RPM range. BTW , "MY" experience is the 108/104 WOULD run POORLY in an EFI application compared to the 112/107. I have done this and "tuning" was difficult. Switching back to a 112 LSA ( from a 108) made a big difference , EFI only.
 
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