351c 2v Cam advice

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ianpala

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Yet another cam thread.... 

351c 2v 

Edlebrock 2750 performer Intake 

Quick-fuel Slayer 600cfm vs 

Dual exhaust with stock manifolds...  might get headers later but in no rush

Screw in studs and guide plates with comp cam roller rockers 1.73 ratio.  

Sealed power HT900 lifters, with 2 days of driving on them, will replace.

So I just did all the work listed above when I put on some rebuilt heads.  Drove it for about a day and some serious noise started coming from my passenger side valve cover.  Popped it off and one cylinder 1 rocker was completely off the spring with a bent pushrod, and the other rocker was bottomed out on the stud and loose, also scored on the bottom from where its scraping the pedestal. A shop recently replaced my lifters and I'm thinking the new lifters ground down some already unhealthy cam lobes.  Long story short new cam is the diagnosis,  will check to see the health of the lifters after I take off the intake. 

I want a good power upgrade, about as much as I can get without replace my springs or pushrods (at least immediately). I don't know my spring rate, I'm guessing its close to stock, which is? Heads are on, engine is in the car. I wan't a nice power upgrade from stock that I'll noticeably feel but is also good for city driving and road trips.  This is my daily driver. Right now I have 3.00 rear gears. I plan on getting the radical punch later with an AOD trans and 3.50-3.72 rear gears. 

Here's what I'm thinking: (edited)

1st Choice (If I can get away with not changing my springs, at least right away): Comp Cams Xtreme Energy with Duration 262/270 (218/224 @.050" lift) , Lift .513/.520, 110 lobe separation. $143

2nd Choice Summit's SUM-5200 cam with specs Duration 282/292 (201/214 @.050" lift) , Lift .486/.512, 112 lobe separation. Great reviews and only $73. Also said it works with the stock springs.

3rd Choice Comp Cam High energy 32-22-13 with Duration 268/268 (218 @.050" lift) , Lift .494/.494, 110 lobe Separation. $140

Any thoughts?  Good cam? Better ideas?

Thanks in advance.  I've learned everything I know on this car with much help from you guys. 



upload image

 




 
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ianpala

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What is your static  compression ratio?  Might be worth measuring everything while you have the heads off to install screw in rocker studs.
I'm not sure. I'd imagine the ratio is stock for a 1971 2v.  Also the heads are back on. Hopefully don't have to remove them again, fingers crossed and they do have screw in studs.

 
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Got any pictures of your valvetrain setup?

You have guideplates under your studs correct?

The Summit cam you picked out seems pretty mild, low ramp rate, not a ton of lift, seems reasonable. I don’t think I would consider using a new cam with anything other than new lifters.

 
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That should work well for you.

Never use old lifters on a new camshaft. The old lifters have developed wear patterns that won't match the surface of the new cam.

Whether or not you can reuse your pushrods depends on several factors. You said one is already bent, you'll need to check all of them for straightness. Easiest way is to roll them back and forth on window glass, see if you feel any bumping. You'll also need to verify that the length of them is compatible with your new cam, and you have the correct contact pattern between the rocker tip and the valve stem. You may need to get a pushrod length checker.

 

Mister 4x4

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I went for a little more oomph and got a CompCams K32-421-8 kit.  Came with hydraulic lifters, lifter 'keeper,' and a timing chain/sprocket set-up, and I added some CompCams 7825-16 Hi-Energy push rods to go with the 17045-16 Hi-Energy die cast aluminum 1.73 roller rockers.  The lifter 'keeper' is necessary for the hydraulic roller lifters to maintain their alignment, and will require drilling and tapping the block in the valley.  

The cam is pretty 'middle of the road,' as in better than stock and not getting into the racing cams range.  After doing some fuzzy math using the CompCams CamQuest utility (plugging in all the other engine mods I did, including headers, intake, carb, etc.), I figure I'm in the 400-ish hp range, and the car runs great! It's backed up by an AOD and 3.00 rear gears - and has no issues with burn-outs or just putt-putting down the road.

Hope that helps!

 

ianpala

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I went for a little more oomph and got a CompCams K32-421-8 kit.  Came with hydraulic lifters, lifter 'keeper,' and a timing chain/sprocket set-up, and I added some CompCams 7825-16 Hi-Energy push rods to go with the 17045-16 Hi-Energy die cast aluminum 1.73 roller rockers.  The lifter 'keeper' is necessary for the hydraulic roller lifters to maintain their alignment, and will require drilling and tapping the block in the valley.  

The cam is pretty 'middle of the road,' as in better than stock and not getting into the racing cams range.  After doing some fuzzy math using the CompCams CamQuest utility (plugging in all the other engine mods I did, including headers, intake, carb, etc.), I figure I'm in the 400-ish hp range, and the car runs great!  It's backed up by an AOD and 3.00 rear gears - and has no issues with burn-outs or just putt-putting down the road.

Hope that helps!
Thats a little more lift than I want I think.  What do you think of the Comp Cams Xtreme 32-242-4 Duration 262/270 (218/224 @.050" lift) , Lift .513/.520, 110 lobe separation as a step under? Still trying to figure out if ill need to change springs right away.

 

ianpala

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Sorry if I missed it but did you install new hardened pushrods when you had the head work done or did you re-use the stock pushrods?
I did not.  I need to.

 

Mister 4x4

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I went for a little more oomph and got a CompCams K32-421-8 kit.  Came with hydraulic lifters, lifter 'keeper,' and a timing chain/sprocket set-up, and I added some CompCams 7825-16 Hi-Energy push rods to go with the 17045-16 Hi-Energy die cast aluminum 1.73 roller rockers.  The lifter 'keeper' is necessary for the hydraulic roller lifters to maintain their alignment, and will require drilling and tapping the block in the valley.  

The cam is pretty 'middle of the road,' as in better than stock and not getting into the racing cams range.  After doing some fuzzy math using the CompCams CamQuest utility (plugging in all the other engine mods I did, including headers, intake, carb, etc.), I figure I'm in the 400-ish hp range, and the car runs great!  It's backed up by an AOD and 3.00 rear gears - and has no issues with burn-outs or just putt-putting down the road.

Hope that helps!
Thats a little more lift than I want I think.  What do you think of the Comp Cams Xtreme 32-242-4 Duration 262/270 (218/224 @.050" lift) , Lift .513/.520, 110 lobe separation as a step under? Still trying to figure out if ill need to change springs right away.
To be honest, I have no idea what to think - I didn't know much at all about cams until another member was working out which one he wanted for his car.  I pretty much went the same direction as he did, since his car was a lot like I wanted mine to be, and his videos were all I needed to see (0 to 100 in 6 or 7 seconds, with an automatic and 3.00 rear gears was pretty impressive to me).

I don't know the difference between a symmetrical vs. asymmetrical cam, or the benefits of each.  What I do know is that mine is 274/274 @ .566" (works out to 218/218 @ .050"), and has a very slight chop to the idle.  The throttle response is incredible, and the engine doesn't seem to break a sweat no matter what I do or how I drive it.

http://www.mister4x4.net/cars/Mach_1/Frankenstang_20180928.mp4?_=1

 

ianpala

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I went for a little more oomph and got a CompCams K32-421-8 kit.  Came with hydraulic lifters, lifter 'keeper,' and a timing chain/sprocket set-up, and I added some CompCams 7825-16 Hi-Energy push rods to go with the 17045-16 Hi-Energy die cast aluminum 1.73 roller rockers.  The lifter 'keeper' is necessary for the hydraulic roller lifters to maintain their alignment, and will require drilling and tapping the block in the valley.  

The cam is pretty 'middle of the road,' as in better than stock and not getting into the racing cams range.  After doing some fuzzy math using the CompCams CamQuest utility (plugging in all the other engine mods I did, including headers, intake, carb, etc.), I figure I'm in the 400-ish hp range, and the car runs great!  It's backed up by an AOD and 3.00 rear gears - and has no issues with burn-outs or just putt-putting down the road.

Hope that helps!
Thats a little more lift than I want I think.  What do you think of the Comp Cams Xtreme 32-242-4 Duration 262/270 (218/224 @.050" lift) , Lift .513/.520, 110 lobe separation as a step under? Still trying to figure out if ill need to change springs right away.
To be honest, I have no idea what to think - I didn't know much at all about cams until another member was working out which one he wanted for his car.  I pretty much went the same direction as he did, since his car was a lot like I wanted mine to be, and his videos were all I needed to see (0 to 100 in 6 or 7 seconds, with an automatic and 3.00 rear gears was pretty impressive to me).

I don't know the difference between a symmetrical vs. asymmetrical cam, or the benefits of each.  What I do know is that mine is 274/274 @ .566" (works out to 218/218 @ .050"), and has a very slight chop to the idle.  The throttle response is incredible, and the engine doesn't seem to break a sweat no matter what I do or how I drive it.

http://www.mister4x4.net/cars/Mach_1/Frankenstang_20180928.mp4?_=1
Turns out the rebuilt heads I bought have some performance springs on them.  They are dual coil and also have a dampener coil.  Can't find a spring rating under 320lbs on summit with these features. This being said I think I should be good to go with more cam than I originally thought. I will just have to upgrade to some hardened push rods.  Hoping not to have to change the length.

 
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If you are replacing cam and lifters, why not look at a roller cam. Will cost a little more, but you don’t have to break it in like a flat tappet lifter.

 
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The 351C 2V heads are very different from the 351C 4V heads. The stock 2V intake port stops gaining flow at about .450 lift where the stock 4V increases in flow until about .600+ lift. The Intake to exhaust flow ratios are very different. The 2V and 4V should be treated as two different engines. The rest of the drive train also needs to be considered when picking a cam, gear ratio, stall speed, exhaust, intended use, desired idle quality, etc.. Given what you said about dual valve springs you need thick wall hardened pushrods, something .080 as a minimum. There is a reason the pushrod bent. You also should research how to obtain proper valve train geometry/pushrod length. When they replaced the lifters did they use a proper break in oil and procedure? The zinc and phosphorous content in current "modern" oils are not sufficient to support the use of flat tappet cams. I suggest you contact someone like Brent Lykins at Lykins Motorsports or Mike Jones Cams for a cam recommendation that will fit the overall build. The extra cost is worth it to obtain the results desired. I hope all goes well with the new cam. Chuck

 

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ALRIGHT! Whew what a crazy couple of weeks, sorry for the radio silence, but I was tending to it all . Aside from all the mishaps along the way, I crashed my motorcycle and broke my foot. But got her all put back together now. Thanks for the advice everyone, might need a little more.

For the Cam I went with:

COMP CAMS Xtreme energy with a 32-242-4 with a lift of .513/520 duration 218/224 @.05

Headed everyones advice and fought the urge to go much hotter.

Also got:

Matching lifters

Comp cams 221 double roller timing set

Comp Cams magnum pushrods 7502

Break in additive.

I didn't get new springs because the rebuilt heads I bought definitely had some Comp Cam performance springs, retainers and keepers.

Didn't realize I'd have to drop the oil pan in order to do the timing... that was a pleasant experience. Will say its definitely doable by disconnecting the engine mounts and jacking up the engine. ALSO went through the god forsaken Cam break-in tip of removing the inner spring in all my dual spring valve springs, broke in the cam, and then put them back in. Did a rough timing adjustment on the dizzy with a vacuum gauge.

SO. She seems to running good, a lot more power, HOWEVER not idling too great and seems to be at a loss of power. When she's cold, the idle goes up and down (Surges?) between 1000 and 500 RPM making for a real uneven lopsided idle. After she warms up, this seems to go away or at least get a lot better and stay steady around 750 RPM. Also I'm only pulling about 15 pounds of manifold vacuum at idle. I've checked for vacuum leaks from the hoses and manifold, and non found. Going to look some more. I have new taylor plug wires, my spark plugs are in good shape. Adjusted my brand new quick fuel carb with a vacuum gauge (about 1.5 turns out on each screw) floats are about half way up the glass. Any suggestions of what else to check? Could an old coil cause this ? Maybe my new carb is faulty?

 
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Hemikiller

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15" vacuum seems almost right for that cam. Hard to say what is causing the surging, other than an engine with a larger cam is going to be cranky when cold. Adjust your choke so it'll fire and run at around 1200 rpms. You'll also want to set the hot idle mixture with your vacuum gage.

Once you've got that sorted, you'll need to figure out the best static and total timing for the engine. I usually start at 10* and work my way up until the engine labors against the starter when hot. Back off 2 degrees from there and go back to step one to reset your idle speed and mixture. After that, you'll need to get your total timing and the timing curve dialed in. IIRC, the open chambers like 34 total all in by 2500.

 

ianpala

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15" vacuum seems almost right for that cam. Hard to say what is causing the surging, other than an engine with a larger cam is going to be cranky when cold. Adjust your choke so it'll fire and run at around 1200 rpms. You'll also want to set the hot idle mixture with your vacuum gage.

Once you've got that sorted, you'll need to figure out the best static and total timing for the engine. I usually start at 10* and work my way up until the engine labors against the starter when hot. Back off 2 degrees from there and go back to step one to reset your idle speed and mixture. After that,  you'll need to get your total timing and the timing curve dialed in. IIRC, the open chambers like 34 total all in by 2500.
Thanks that will be helpful! Glad you think the vacuum sounds normal (between 14&15) I thought I should be closer to 20. Re-did the choke and mixture screws when it was hot. Didn’t change much. Will have to dial in the timing precisely when I get back into town. From fiddling with it before, I couldn’t get that surge to go away and 300-500 rpm seemed excessive, even when it’s not fully warm. Maybe I do just need to get used to a hotter cam and it’s fuss. This my first :)

 
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