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Thread: Roller Rockers 1.6 vs. 1.7? Which is better, and why? Cam selection, HELP?

  1. #1

    Default Roller Rockers 1.6 vs. 1.7? Which is better, and why? Cam selection, HELP?

    Haven't picked a cam yet, but beforehand I need to full understand whether I need to go with 1.6 or 1.7 roller rockers on my aftermarket heads.

    Heads are the AFR 165cc Renegade heads.

    I'll be using a GT40 intake that's been ported and polished with a 65mm throttle body that's been polished.

    I've got 3.27 rear gears.
    How much cam is too much with the "stock size" 1.6 rockers, whereas what would be too much for the higher lift 1.7 rockers.
    Not revving to the moon as I'll be stock bottom end this go around. So I'll be wanting a non-stock HO firing order cam, but don't know what to pick here.

    Basically, what's going to make my car pull hard across the usable RPM range, I understand the heads may be overkill, but the price point says I have to get them.

  2. #2
    Road Warrior Kodachrome Wolf's Avatar
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    I know the 1.7s are good for ~.028" more lift on a stock HO cam compared to the 1.6s. I've got a set of the 1.7s on my car currently, however as it goes, I don't think the gains were really anything serious with my setup. Obviously they might have more impact on a more aggressive cam.

    Regarding your cam pick, you're wanting something that pulls hard across the RPM range, but you're not wanting to rev it way high. Are your primary plans more cruising levels where low end would be preferable?

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    P31 Pursuit Car Brown_Muscle's Avatar
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    Generally you match it with what cam you pick, depending on your goals. Lift will be determined also by your valve springs, I imagine the AFRs are good to .600 lift, I doubt you’ll reach that with your goals. Some aftermarket cams advertise that they should be used with 1.7's, however if you generally want more aggressive lift, get a more aggressive cam and stick with 1.6 rockers. I don't think the AFR's are overkill at all, they're pretty well sized for a modest 302 build. If you want to get the most out of your build I would suggest a custom cam. If you want to save about $100 and get an off the shelf cam, my buddy and I have had great luck in multiple engines with similar builds with comp cams XE270HR, it has a very nice broad power band, and wont leave you wanting at any RPM. If you're partial to another brand many offer similar grinds to that cam. In general with fuel injection, and wanting a broad power band, I recommend a wider lobe separation. 112-114 is a pretty nice range, the bigger the number the broader the curve
    Last edited by Brown_Muscle; 02-23-2021 at 11:20 AM.
    -Phil



    +1982 Ford LTD-S Police Car. 351w, GT40 Heads, Edelbrock 1906 Carb, Full exhaust headers to tails. 3.27 Trac-Lok Rear. Aluminum Police Driveshaft. Speedway Springs+Bilstein Shocks, Intermediate Brakes, Baumann Shift kit.

    +2003 Acura CL Type S 6-speed

  4. #4

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    Quote Originally Posted by Kodachrome Wolf View Post
    I know the 1.7s are good for ~.028" more lift on a stock HO cam compared to the 1.6s. I've got a set of the 1.7s on my car currently, however as it goes, I don't think the gains were really anything serious with my setup. Obviously they might have more impact on a more aggressive cam.

    Regarding your cam pick, you're wanting something that pulls hard across the RPM range, but you're not wanting to rev it way high. Are your primary plans more cruising levels where low end would be preferable?
    Yeah, cruising so like 60-100mph pulls on the highway, and redlight to redlight fun. Mostly the latter. Keeps me from losing my license. And it is a daily driver, and I intend for it to remain a daily driver.

    I've got a 318 that's going back in a '77 Plymouth Volare station wagon that is my long term build for high revs and sheer ignorance. This car allows me that luxury.

    Quote Originally Posted by Brown_Muscle View Post
    Generally you match it with what cam you pick, depending on your goals. Some aftermarket cams advertise that they should be used with 1.7's, however if you generally want more aggressive lift, get a more aggressive cam and stick with 1.6 rockers. I don't think the AFR's are overkill at all, they're pretty well sized for a modest 302 build. If you want to get the most out of your build I would suggest a custom cam. If you want to save about $100 and get an off the shelf cam, my buddy and I have had great luck in multiple engines with similar builds with comp cams XE270HR, it has a very nice broad power band, and wont leave you wanting at any RPM. If you're partial to another brand many offer similar grinds to that cam. In general with fuel injection, and wanting a broad power band, I recommend a wider lobe separation. 112-114 is a pretty nice range, the bigger the number the broader the curve
    Heard that, so if I go with a cam around that range I should be good with the 1.6 rockers? The heads are already assembled and came off a running motor, guy just wants something bigger for his purposes. So I can get them and they'd be ready to bolt on to my 87 whenever I can/get around to it. Also getting some BBK shorty headers he pulled off these heads when he took them out of his Foxbody, went with longtubes instead. So, one stop shop. Noted on the lobe separation, cam stuff really still confuses me because there's so much differing info about it, and how it works with the rest of the setup is something I'm trying to wrap my pea brain around still.

  5. #5
    Told ya everything I know when I said hello P72Ford's Avatar
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    With that intake and 165s, you would be fine with a factory HO cam. Excellent drivability and a significant power improvement. Rocket arm ratio is usually spec'd to a specific cam, like Phil said. A 1.7 ratio arm just means valve lift is 1.7X the lobe lift. So whatever, your lobe lift is, you will get another .1X at the valve (for a 1.7 ratio vs a 1.6 ratio); but only if you properly set the geometry, which very few people actually do. If you slap them on and expect to feel a difference, you will be disappointed.

    If you choose an OTS grind that is more aggressive it would behoove you to check PTV clearance. There are definitely advantages to a wider LSA if you are running fuel injection and want to have properly functioning power brakes.

    A better converter and some more gear would also optimize a build like this. The HO cam has a bit of a "light switch" effect around 2500 rpm in a heavier car; much less noticeable with supporting drivetrain modifications.

    Always have used heads checked at a machine shop.
    **2012 Ford Mustang Boss 302: 5.0/ 6 spd/ 3.73s, 17K Cruiser
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  6. #6

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    Quote Originally Posted by P72Ford View Post
    With that intake and 165s, you would be fine with a factory HO cam. Excellent drivability and a significant power improvement. Rocket arm ratio is usually spec'd to a specific cam, like Phil said. A 1.7 ratio arm just means valve lift is 1.7X the lobe lift. So whatever, your lobe lift is, you will get another .1X at the valve (for a 1.7 ratio vs a 1.6 ratio); but only if you properly set the geometry, which very few people actually do. If you slap them on and expect to feel a difference, you will be disappointed.

    If you choose an OTS grind that is more aggressive it would behoove you to check PTV clearance. There are definitely advantages to a wider LSA if you are running fuel injection and want to have properly functioning power brakes.

    A better converter and some more gear would also optimize a build like this. The HO cam has a bit of a "light switch" effect around 2500 rpm in a heavier car; much less noticeable with supporting drivetrain modifications.

    Always have used heads checked at a machine shop.
    Definitely don't want my valves to kiss my pistons. That tends to break things. I'll likely ask my cousin who has built several Foxbody 5.0 engines what cam he'd put in it. Maybe some family bonding time could be good. Heck, he may be able to solve my ECU dilemma too.

    I forgot until now that he does more than just Coyote engines...

    I don't mind a different converter in the future. I really like the interstate cruising RPMs with the 3.27 gears though.

  7. #7
    I'm an air-conditioned gypsy gadget73's Avatar
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    Its not really valves hitting the pistons. Thats a function of duration, the extra smidgen of lift will not affect that. What you need is proper lifter preload, and the rocker has to contact the valve stem correctly. Too far off center and it will side load the valve enough to wear out the guides. If the height isn't right the contact patch ends up too wide, and that actually side loads the valve in two directions to oval out the guide. What you want is a contact patch that is narrow and centered, while having correct lifter preload. Its a juggling act with pushrod length and rocker height.

    The cam in my car is supposed to be used with a 1.6 rocker. I had a set of 1.7's on hand and what were on the car were fucked so I put it together. Possibly not ideal but the preload and contact patch is good so I'm using them.

    Thing about asking Mustang guys for advice is they are dealing with half a ton less car and quite often have a 5 speed. The cams they usually go with are gutless wonders down low and in a nearly 2 ton car with an auto thats the last thing you want.

    86 Lincoln Town Car (Galactica).
    5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

    91 Lincoln Mark VII LSC SE, triple black (Timewarp) - poly front bushings, KYB struts and shocks, Holley SystemMax1 lower intake, SilverFox AOD valve body,

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    Quote Originally Posted by phayzer5 View Post
    I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

  8. #8

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    Quote Originally Posted by gadget73 View Post
    Its not really valves hitting the pistons. Thats a function of duration, the extra smidgen of lift will not affect that. What you need is proper lifter preload, and the rocker has to contact the valve stem correctly. Too far off center and it will side load the valve enough to wear out the guides. If the height isn't right the contact patch ends up too wide, and that actually side loads the valve in two directions to oval out the guide. What you want is a contact patch that is narrow and centered, while having correct lifter preload. Its a juggling act with pushrod length and rocker height.

    The cam in my car is supposed to be used with a 1.6 rocker. I had a set of 1.7's on hand and what were on the car were fucked so I put it together. Possibly not ideal but the preload and contact patch is good so I'm using them.

    Thing about asking Mustang guys for advice is they are dealing with half a ton less car and quite often have a 5 speed. The cams they usually go with are gutless wonders down low and in a nearly 2 ton car with an auto thats the last thing you want.
    That's true, he also mostly deals with boosted applications these days. And mostly Coyote stuff. He does run a powerglide behind the Coyote his dedicated drag car. But that car is literally only a street car in legality/class these days and a full blown racecar in actuality.

    With the Scorpion 1.6 roller rockers that are on the AFR heads I just picked up, would you say your cam would be a good choice for our cars?

    Also, does it have a noticeable idle?

  9. #9

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    Side note, I spoke with a tech at Lunati and he said this would be a good choice based on the rest of my parts.

    https://www.lunatipower.com/efi-comp...o-276-284.html

    The guy I bought the heads from said he'd likely run the F303 cam like he's got in one of his Mustangs. Has a good one with 1 hour of break in time on it that he'd let go for $200.

  10. #10
    P31 Pursuit Car Brown_Muscle's Avatar
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    That Lunati looks like a nice cam.

    Please stay away from the letter cams, this isn’t 1991 anymore. For slightly more money you can get the lunati which is a MUCH better cam
    -Phil



    +1982 Ford LTD-S Police Car. 351w, GT40 Heads, Edelbrock 1906 Carb, Full exhaust headers to tails. 3.27 Trac-Lok Rear. Aluminum Police Driveshaft. Speedway Springs+Bilstein Shocks, Intermediate Brakes, Baumann Shift kit.

    +2003 Acura CL Type S 6-speed

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    https://www.summitracing.com/parts/c...14-3/make/ford

    I have this cam with 1.7's in a 310ci, D0OE heads, with basic hand porting, and just about 10:1. Lumps pretty good, but kinda also sounds like a chris-craft with thru hull exhaust. Lol. Really haven't found a way to measure the power since that car isn't going to pass tech on the drag strip, and I'm definitely not paying for dyno time. I'll borrow my buddy's accelerometer gtech thingy when I get it back together and the snow is gone.

  12. #12

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    Quote Originally Posted by Brown_Muscle View Post
    That Lunati looks like a nice cam.

    Please stay away from the letter cams, this isn’t 1991 anymore. For slightly more money you can get the lunati which is a MUCH better cam
    I've heard this, hence the reason I didn't snag a known good cam and timing set while I was there.
    I know you suggested possibly the XE270HR, and the specs seem similar.

    Quote Originally Posted by JeffBoudah View Post
    https://www.summitracing.com/parts/c...14-3/make/ford

    I have this cam with 1.7's in a 310ci, D0OE heads, with basic hand porting, and just about 10:1. Lumps pretty good, but kinda also sounds like a chris-craft with thru hull exhaust. Lol. Really haven't found a way to measure the power since that car isn't going to pass tech on the drag strip, and I'm definitely not paying for dyno time. I'll borrow my buddy's accelerometer gtech thingy when I get it back together and the snow is gone.
    Heard that, auto trans in a Box or? I'm sorta locked in with the 1.6 rockers now. Since I own them at this point.

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    Aod with a baumman shift kit.

  14. #14
    I'm an air-conditioned gypsy gadget73's Avatar
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    I'm pretty happy with my XE-258, but I don't have a lot of basis for comparison. I have run a lopo, an HO, and an Explorer cam in the same car but not with precisely the same mix of other parts. The HO cam was also a tooth off and the cylinders were oval so the compression was for shit. I have a couple of other healthy stock HO cars with similar weight to a Vic though so I know what they feel like. Under about 2800 there is nobody home with an HO cam. A better intake got some bottom end gains on my black Mark VII but its still not a stop light terror. A looser converter would help, lower rear gears help a ton. Better heads may help too, but a bone stock HO with 3.27 gears and an AOD in a 3900 lb car just ain't impressive.

    The Explorer cam runs like a truck. Lots of bottom end, engine is done by 4500. Think of it like a lopo cam with another 60 hp. If you don't want to change the tall rear gears, this is probably a good cam to use but my car with the 3.55 it just ran out of power before it shifted. I manually held it in gear to 5500 once and it just made a lot of noise without actually pulling.

    The XE-258 just makes power from idle to WOT shift around 5200. It might be able to wind out a little more, but I don't really know what the valve springs will deal with so I don't want to push my luck too much. Its not lumpy but there is a bit of rumble at idle in the exhaust. Don't feel anything in the car though. Other cams will probably make more power but I honestly think the power band and performance of this one is fine if you want a stock+ sort of feel. I didn't want lumpy shaky nonsense that was going to be unhappy with life in a 2 ton boat with a stock AOD converter and I wasn't going for ultimate performance either.

    86 Lincoln Town Car (Galactica).
    5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

    91 Lincoln Mark VII LSC SE, triple black (Timewarp) - poly front bushings, KYB struts and shocks, Holley SystemMax1 lower intake, SilverFox AOD valve body,

    1984 Lincoln Continental TurboDiesel - rolls coal

    Quote Originally Posted by phayzer5 View Post
    I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

  15. #15

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    Quote Originally Posted by JeffBoudah View Post
    Aod with a baumman shift kit.
    Noted, I'll likely end up with some transmission upgrades after I do the engine things. Which may result in a different cam selection once I get into that. How's your power off the line? Any videos, maybe?

    Quote Originally Posted by gadget73 View Post
    I'm pretty happy with my XE-258, but I don't have a lot of basis for comparison. I have run a lopo, an HO, and an Explorer cam in the same car but not with precisely the same mix of other parts. The HO cam was also a tooth off and the cylinders were oval so the compression was for shit. I have a couple of other healthy stock HO cars with similar weight to a Vic though so I know what they feel like. Under about 2800 there is nobody home with an HO cam. A better intake got some bottom end gains on my black Mark VII but its still not a stop light terror. A looser converter would help, lower rear gears help a ton. Better heads may help too, but a bone stock HO with 3.27 gears and an AOD in a 3900 lb car just ain't impressive.

    The Explorer cam runs like a truck. Lots of bottom end, engine is done by 4500. Think of it like a lopo cam with another 60 hp. If you don't want to change the tall rear gears, this is probably a good cam to use but my car with the 3.55 it just ran out of power before it shifted. I manually held it in gear to 5500 once and it just made a lot of noise without actually pulling.

    The XE-258 just makes power from idle to WOT shift around 5200. It might be able to wind out a little more, but I don't really know what the valve springs will deal with so I don't want to push my luck too much. Its not lumpy but there is a bit of rumble at idle in the exhaust. Don't feel anything in the car though. Other cams will probably make more power but I honestly think the power band and performance of this one is fine if you want a stock+ sort of feel. I didn't want lumpy shaky nonsense that was going to be unhappy with life in a 2 ton boat with a stock AOD converter and I wasn't going for ultimate performance either.
    I don't mind lumpy and shaky, but driving overcammed cars really isn't a thing I like. Sounds cool because of valve overlap, but won't get out of it's own way from a stop. Do you have a video demonstrating the idle sound/performance of it?

    I can live with some not ideal circumstance until I can justify transmission upgrades, but, I'd prefer to change the shift governor out and probably do a fluid/filter change.
    Any better ideas?

    I need more info on what works well with our transmissions. Automatic transmission are witchcraft to me. Plus, I hate dropping them and being paranoid that I got a torque converter lined back up right.
    Part of the reason I want to try and keep the 3.27 gears is the fact that I can run 110 without the engine screaming. No idea what RPM that is, but the Lopo doesn't sound mad yet. Loud, however, yes.

    Which forum do you post pictures and can I keep up an overall build in? I send updates to my group chat because my friends are excited about it. But if I can memorialize it all online, that'd be even better.

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    Told ya everything I know when I said hello P72Ford's Avatar
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    Automatic transmissions aren't my bag, but the AOD in my white coupe was pretty decent. It was a basic rebuild with upgraded clutches and an A+ servo, Silverfox SPT-R (OD lockout), B&M deep pan, stacked plate cooler, and a Dirty Dog 3600-ish stall NLU converter. Rest of the build was a .020 over GT40P headed 302 with an HO cam (straight up), Crane 1.7s, Holley 600 DP, 2.5" exhaust and 3.73s. The car was a nice time and would blast the tires off from a stop; excellent throttle response. Decent around town drivability, and no HO cam light switch nonsense with that converter. I would highly recommend those drivetrain mods to support your engine build.
    **2012 Ford Mustang Boss 302: 5.0/ 6 spd/ 3.73s, 17K Cruiser
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    I'm an air-conditioned gypsy gadget73's Avatar
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    Quote Originally Posted by AngryMcMuffin View Post

    I don't mind lumpy and shaky, but driving overcammed cars really isn't a thing I like. Sounds cool because of valve overlap, but won't get out of it's own way from a stop. Do you have a video demonstrating the idle sound/performance of it?
    first one has a lot of rambling but there is a start and idle bit at the end there. Also get to see a big part of what prompted the cam swap, though I honestly did not know that damage was there beforehand. i just know the engine was getting noisy and the performance was lacking. once it came apart it was fairly obvious why. The rocker arms also got replaced, went from Crane Cobra 1.7 to the Scorpion. no better reason than because I already owned them and they fit under the valve covers. Honestly they seem better made anyway.



    86 Lincoln Town Car (Galactica).
    5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

    91 Lincoln Mark VII LSC SE, triple black (Timewarp) - poly front bushings, KYB struts and shocks, Holley SystemMax1 lower intake, SilverFox AOD valve body,

    1984 Lincoln Continental TurboDiesel - rolls coal

    Quote Originally Posted by phayzer5 View Post
    I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

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