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RuffXf

Unknown cam performance

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Gday all I’ve had a mate give me a cam for a crossflow I’m planning to build. Only problem is it is a reground factory cam so I have no idea how much I need to do to run it. I haven’t a huge amount of knowledge in engine building and this is my first build

 

Valve lift is about .500 and duration seems to be left standard. What will this do for my torque and power and will solid lifters and roller rockers get the job done?

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Gday all I’ve had a mate give me a cam for a crossflow I’m planning to build. Only problem is it is a reground factory cam so I have no idea how much I need to do to run it. I haven’t a huge amount of knowledge in engine building and this is my first build
 
Valve lift is about .500 and duration seems to be left standard. What will this do for my torque and power and will solid lifters and roller rockers get the job done?
You can never hurt anything but your wallet with roller rockers, but stock rockers aren't a deal-breaker at 0.500" lift. You will need valve springs at a minimum, seeing as they are very ordinary even with a standard cam. Having a more aggressive ramp on the lobe will amplify any lack of spring pressure.

You may run into issues with pushrod length with the base circle taken off, by how much I dunno but to compensate, I guess you could either run valve lash caps or take a bit off the rocker pedestals. If you choose to go with 7/16” stud adjustable roller rockers, that will let you take up this clearance, but that will need machining of the head. All this is extra expense just to run a cam that will have questionable benefit to power. False economy if you ask me. Unless there's an absolute must-do reason why you have to run it, I would pass on it.

It would ultimately be cheaper, and result in more power and torque, to go with a mild aftermarket cam that's compatible with stock valvetrain components. So, still around 0.500" lift like the one you have, but longer duration and overlap. Build for midrange to capitalise on where the crossy's going to be happy. Something like a 214/214 @0.050", with a nice overlap aiming for a 110 LSA but no more than 0.500" lift to keep your springs and rockers happy.

Roller rockers aren't a power-adder like the manufacturer's always harp on about. This has been proven many times on a dyno. They're insurance against premature wear or breakage when you start going bigger with everything else (springs, valves, cam lift, pushrods), so if you don't need them, don't get them. They'll offer a very poor hp-per-dollar return on your project.

For a first engine, keep things conservative and focus on proper assembly, maximising what stock parts you have, and aim for 15-20% power increase maximum. Balance rods and pistons, shave flywheel, bump up compression a tad. Crossys are pretty lazy in the rpm department so make them work where they're happy; between 2000-4500. The only internal component besides cam that I would change is valvesprings.

Cam: look at crow's catalogue as a guide and look down the column at hydraulic grinds at around the 0.500" lift, then from there choose your duration. I think a stock speedway cam is a good warm streeter with not too much lift but lopey idle and midrange punch.

Springs: stock ones barely test at 80 pounds on the seat. The next step up would be around 110 which would be more than adequate for a warm street engine.

Your mate giving you that cam might be a nice gesture but you'll spend big dollars getting it to work for little gain over stock.

Sent from my CPH1920 using Tapatalk

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7 minutes ago, gerg said:

Your mate giving you that cam might be a nice gesture but you'll spend big dollars getting it to work for little gain over stock.

 

i agree with this.
i bought a cam for $50 that i spent more money setting up for it, only to find out it wasn't as big as i needed.. 

i'd have been better off getting the biggest cam that worked with stock components(other than valve springs) 

choose a cam that runs in the rev range you are happy with(ones that rev high won't like tall diff gears.. if you aren't changing the diff(assuming 2.92 or 2.77),  you'll need to go for an EFI grind cam in My opinion) 

if you go for a larger cam, you'd really need a higher compression ratio.. so you start mods there and money goes down the rabbit hole. 

 

i like the rule.. if it aint broken, don't fix it.

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Gerg, deankdx, you’ve both bought up my main concern. I was worried I’d spend more than I’d saved to run that cam

 

After a quick bit browsing and bit of adding up it looks like I’d only be saving a few hundred on the valve train and still have a lot of unknowns. Much safer to buy aftermarket

 

What’s everyone’s opinion on Camtech? I reckon I’ve found a cam that suits what I want. 208/208 @ .050” with 110LSA and .477” lift. I’m running a 5 speed with a 3.23 diff so id be cruising right in the middle if it’s rev range

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9 hours ago, gerg said:

Springs: stock ones barely test at 80 pounds on the seat. The next step up would be around 110 which would be more than adequate for a warm street engine.

I’m looking at a set of 120lb springs with dampeners. I’m assuming a standard valve train can handle that?

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15 minutes ago, RuffXf said:

What’s everyone’s opinion on Camtech? I reckon I’ve found a cam that suits what I want. 208/208 @ .050” with 110LSA and .477” lift

 

i am no expert at all on cams, but comparing it to crows list (page 12 here https://www.crowcams.com.au/Portals/0/Crow2020/CrowCams2020.pdf?ver=2019-12-18-095023-240 )

it looks kind of small still to Me. 

if @ando76 has time he's one of the best crossflow experts (you could read his posts if you have time)

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it looks kind of small still to Me. 


Yeah i agree on that Dean. The next one up from there in the Camtech range is 218/218 on 110 lobe sep and 0.510" lift. The Crow equivalent is 215/215 but 112 lobe sep, same lift as the CT though.


What’s everyone’s opinion on Camtech? I reckon I’ve found a cam that suits what I want. 208/208 @ .050” with 110LSA and .477” lift. I’m running a 5 speed with a 3.23 diff so id be cruising right in the middle if it’s rev range


I think that would have nice midrange but it is a pretty mild cam. Provided you give it a better manifold and tweak the carby (or go up to a 4 barrel), you could potentially be making 100kW at the wheels with this combo, nothing to sneeze at. That Camtech is basically the same grind as what's in my 302C except I put mine in 4 deg advanced. I like the low-to-midrange it gives.... A lot, but it does drop off sharply after 5000 (according to the dyno) and in a 250 installed at 0 deg, it would behave similarly.

I’m looking at a set of 120lb springs with dampeners. I’m assuming a standard valve train can handle that?


Yeah that's again what I ran in my 302, measured a little more when new but they tend to soften a bit over a short time according to the cyl head guy I used. If going with that Camtech you referred to, the nose pressure shouldn't be too silly with such modest lift (it's best kept below 300lbs on stock rockers and pushrods). Make sure you get retainers while you're at it.

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Unknown camshaft equals troubles really.  By the time you send it to get a cam doctor sheet for dial in the cost is already close to a new cam. 

 

Have a look on the end of the r-grind cam for any identifiers. Might save time. As others have said, nut out exactly what you want from the engine and then build a combo to suit. COMBINATION being the emphasis. Not all of us want a 280-300rwhp crossy.  Whilst they are fun and manageable on the street, they are not cheap. 

 

Gerg is spot on with his recommendations,  on lift, duration and lobe sep. in my opinion a good fun street engine hits bloody hard off the bottom, has enough vacuum for decent brakes and has a mid range hit that gets you very excited. Many years ago I did a small 2 barrel engine for a bloke well past his 50’s who lives in Brissy. 240@.050 and .510 lift solid Tighe cam. It does everything very nicely. Runs 3.45 gears as he runs it at Willowbank on club days. Drives it everywhere and smiles every time.  Made 198rwhp on Zox performance dyno.  

Ultraflow 2 barrel, 500 Holley a set of rockers, extractors etc. - all second hand to keep it budget friendly. 

 

Follow the cam grinders guidllines on comp and gearing and you can’t go too far wrong as they are an excellent base. Enjoy 

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This is a bit old now, but I run that Camtech cam in a turbo'ed 250 and ran it NA for a while. It is a perfect HWY cam with 2.92 or 2.77 gears and can be used with an auto and stock converter. It suits an otherwise stock setup. Std springs are even ok. I recon Camtech's cam below this one should have been std. Both are perfect for how Ford planned for a 250 to be driven and are nice for cruising around.

 

With a 5 speed and 3.23 gears I probably would go bigger (depending on what the car is used for) than the 208 cam, but no more than the 218 deg cam if it is a regular driver. The 14892 Crow used to be the go to cam.

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12 hours ago, matt_lamb_160 said:

This is a bit old now, but I run that Camtech cam in a turbo'ed 250 and ran it NA for a while. It is a perfect HWY cam with 2.92 or 2.77 gears and can be used with an auto and stock converter. It suits an otherwise stock setup. Std springs are even ok. I recon Camtech's cam below this one should have been std. Both are perfect for how Ford planned for a 250 to be driven and are nice for cruising around.

 

With a 5 speed and 3.23 gears I probably would go bigger (depending on what the car is used for) than the 208 cam, but no more than the 218 deg cam if it is a regular driver. The 14892 Crow used to be the go to cam.

The cars probably going to end up as a daily to take some Ks off the other car so easily drivable and not an absolute fuel guzzler was what I had in mind. It’s not intended as a performance build, it’s replacing the flogged out current engine. so I’m not to worried if I should’ve gone .500+

 

I ended up sticking with the camtech .477 208deg cam. Haven’t finished the build yet but I’m happy with what I’ve decided on. My brothers bought a 14892 so it’ll be interesting to compare the two when we’re done.

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