I finally got my car back from having the body work done and was able to check out my cam and sure enough it has a couple of flat lobes. My question is I did everything they told me to do to break the cam in and still had this problem. For people who have sent a cam back after it has went bad do the just say sorry it is not the cams fault or do they try and make it right?

Corey

What cam?
What valve springs?
Solid, hyd.?

How many lobes are gone? Did you check clearences? coil bind? You sure you didn't barely overtighten any?

I have no experience with messing up cams but i have a buddy that went through SEVERAL!
mostly his fault, barely overtightening will kill'em, he had some noisy roller rockers and thought it was the cam so he kept tightening.

Internal Duration @.050" 258
External Duration @.050" 268
Internal Lift 560 @ 1.5
Exhaust Lift 580 @ 1.5
Lobe Separator 106
Advance Internal Duration 296
Advance Exhaust Duration 306
Valve Lash .018-.020

Solid Cam

k-motion valve springs.

Recommended Camshaft Style Flat tappet solid
Installed Height (in) 1.700
Seat Pressure at Installed Height (lbs) 130
Open Height (in) 1.150
Open Pressure (lbs) 395

1.6 full roller rockers

2.02 - 1.6 valves

Well there's your problem right there. The valve springs bound up on you. If you installed them at their correct 1.70" installed height then they only have .550" of travel before they hit their recommended maximum lift (1.70 - 1.15 = .550"). You might have squeaked by with standard 1.5 rockers and about .020" of valve lash MAYBE. But with the 1.6s I'll almost guarantee you bound up the springs or cam close enough to put some serious stress on the rest of the valvetrain- expecially on the higher-lift exhaust side. Any bent pushrods?

Also, that open pressure looks a little extreme for break-in. 395 lbs over the nose of a flat tappet cam is a LOT. 300, 325, MAYBE 350 but 395 is just too high for break-in.

You need a set of springs that will take at least .600" lift to be safe with that cam and 1.6 rockers. That almost certainly means a set of dual-coil springs with probably about 1.45-1.55" diameter, ~130 seat pressure, about 350 at max lift of .600. Most springs of that general description will have a recommended installed height around 1.80". When you replace the cam and get the right valve springs (and retainers AND make sure your installed height is correct) you'll probably want to yank out the inner spring to reduce valve spring pressure during break-in only.

The SMALLEST spring I could see you getting away with would be a Comp 987 spring and you better be SURE the actual installed height is at least 1.80" or even slightly more. I'd also check for retainer-to-guide clearance with that much lift. Aftermarket heads and duel-spring retainers can usually be counted on for at least .550 lift, but you're going beyond that.

You just don't have the valve springs and such you're going to need with a radical cam like that and 1.6 rockers.


[This message has been edited by Damon (edited March 25, 2005).]

Whoever selected those springs for a flat tappet cam should have their head examined. 320 maximum at full cam lift is all you need for all but the extreme RPM application, more will shorten (or eliminate) cam life. Be sure to pull the pan and clean it well, maybe check some bearings, and throw those springs in the bush.

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Custom Auto, your source for quality machine work, cores and new parts at competetive pricing right here in British Columbia 1-888-563-4050
A Canadian, EH? (with a 10 second street car)

<font face="Arial,Verdana" size="2">Originally posted by Damon:
Well there's your problem right there. The valve springs bound up on you. If you installed them at their correct 1.70" installed height then they only have .550" of travel before they hit their recommended maximum lift (1.70 - 1.15 = .550"). You might have squeaked by with standard 1.5 rockers and about .020" of valve lash MAYBE. But with the 1.6s I'll almost guarantee you bound up the springs or cam close enough to put some serious stress on the rest of the valvetrain- expecially on the higher-lift exhaust side. Any bent pushrods?

Also, that open pressure looks a little extreme for break-in. 395 lbs over the nose of a flat tappet cam is a LOT. 300, 325, MAYBE 350 but 395 is just too high for break-in.

You need a set of springs that will take at least .600" lift to be safe with that cam and 1.6 rockers. That almost certainly means a set of dual-coil springs with probably about 1.55" diameter, ~130 seat pressure, about 350 at max lift of .600. Most springs of that general description will have a recommended installed height around 1.80". When you replace the cam and get the right valve springs (and retainers AND make sure your installed height is correct) you'll probably want to yank out the inner spring to reduce valve spring pressure during break-in only.

You just don't have the valve springs and such you're going to need with a radical cam like that and 1.6 rockers.</font>


I may have put the wrong info down on the springs! I will check the box when I get home. But the engine builder checked out the springs and also put a shim in the spring to get a little more installed height.

Ok can you all give me you opinions on a good cam for this. I would like to have around .600 of lift with the 1.6 rocker arms. My old cam came in around .596 of lift on the exhaust and the car ran great.

It is in a 406 flat top pistons, cast heads that have been ported, 2.02 and 1.6 valves the rockers are full roller. Victor Jr. intake. Holley 750 carb. Cast crank.

With the old cam the car ran 7.69 in the 1/8th with no port work. I would like to get this just as close if not better. I will try and get on this weekend and post the old cam specs.

I'm going to say that you get more power out of duration then you do with lift by a bunch! So why go through all this b/c a lower lift cam can probably make as much if not a bit more power than the high lift one if your whole combination is better matched!

You mention the first motor had ported heads whereas the second, present motor didn't. Why not use a lower lift cam along with the best heads you can afford and go??

I finally figured this out b/c I never could figure out why all of the 6, 7 to 8 motors that the mag's tested at a time that were built almost identically to each other EXCEPT they were diferent makes, (Olds, Chevy, Ford, with E-brock heads and CC's Extreme 274 hy-cams, etc...)...

And ALL of them have diferent max. valve lifts with about the same cam!! AND hp was always pretty close between ALL of them except for differences that I figure were b/c of the inherent differences in all the motor's physical designs...

Therefore I finally figured out that lift is NOT where it is at UNLESS you are out to get the absolute max. out of your motor AND THEN I would start with the best intake and exhaust systems money could buy and match the cam to it!!

And playing around with D2K verify's this except as everybody know's, it's just a sim. program BUT darn good on creating "trends" to compare!!

Please think about this for a bit........

pdq67

PS., And fwiw, Elgin makes a supposed stock diameter and type, .600" lift at 1.800" installed height Z-28 SB spring that MAY be just the thing for you AND they are cheap!!

I got a set from Midwest Motorsports for some over $50 or so, (with retainers).....

shimming doesn't give more installed height does it? I think thats to get the correct installed height or more seat pressure?

I have friends with 400's & flattops running 7.4 / 7.3 with 3.42 / 3.08 gears and camel hump heads with performer RPM cam.

If you are looking for a good double spring that will take the lift and not get stupid with the open numbers the Comp 986-16 and 987-16 are good choices. I'm using the 987's in my combo with 1.6's and they work well. Picking a cam that will hit .600" lift with 1.6's is going to have a ton of duration, requiring good components and lots of stall to get it to work. Look for a cam in the area of 250 max intake duration, maybe 256 exhaust, let the lift fall where it may, and prepare for a crapload of torque from 3500 RPM and up. Your shift point should be 6000. Since you are running a cast crank I'm going to assume it's externally balanced, you don't want to spin it much past 6000 as it will eat main bearings. (been there, done that) I would also specify a lobe separation between 106 and 108 degrees if you have a decent stall and drag racing ET's are your goal. (lower that is http://www.nastyz28.com/ubb/wink.gif )

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Custom Auto, your source for quality machine work, cores and new parts at competetive pricing right here in British Columbia 1-888-563-4050
A Canadian, EH? (with a 10 second street car)

<font face="Arial,Verdana" size="2">Originally posted by rustbucket79:
If you are looking for...good torque from 3500 RPM and up...I would also specify a lobe separation between 106 and 108 degrees if you have a decent stall and drag racing ET's are your goal. (lower that is http://www.nastyz28.com/ubb/wink.gif )

</font>

Yep, agreed!

Corey, I emailed you tonight on this-though you won't get it until you go to work. http://www.nastyz28.com/ubb/smile.gif Anyway, after reading these posts you might see how going a little smaller with the cam will most likely lead to equal numbers, and with a more stable valvetrain. I suggested a cam for you, and I can call Crane and have them grind a cam with a wider ls if you want. I'll be over Saturday anyway so I'll talk to you about it then. I know MWM builds a lot of motors but sometimes the details get lost in translation. I'll see ya. -Jabin

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Gmachinz Sales and Performance
"...updating the level of performance..."

<font face="Arial,Verdana" size="2">Originally posted by rustbucket79:
I'm using the 987's in my combo with 1.6's and they work well.
</font>

I too am using the Comp 987's with a 306S Magnum solid and 1.5 Crane roller rockers. I am quite pleased with these springs, and, as Rust pointed out earlier, whoever recommended a 395 lb over the nose spring for that solid cam needs his frigging head examined. When my cam was broekn-in, we pulled the inner springs and just used the outers to give the cam a chance to live during break-in.

Cam break-in with a big solid cam and stiff dual springs should entail pulling the inners . Otherwise, you stand a pretty good to excellent chance of wiping a cam lobe.

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'Silver Bullet' 1977 Z-28 413" SB
11.73 @ 115.10 on drag radials
Old Vortec combo:
12.15 @ 110.52

After I dealt with Comp Cams concerning my cam which lost a lobe, they told me this is how they recommend break-in(assuming you have the correct springs, pressures, and height with no binding)-

Take then inner spring out (with double springs) and run it for 30 minutes, then re-install the inners and run it for 20 min. They also say if your car sits for 4 or 5 months without running (like we do in the winter states) you should pre-oil (prime) the motor before startup.

Thought I would pass on what they told me over the phone.

<font face="Arial,Verdana" size="2">Originally posted by Mwilson:
shimming doesn't give more installed height does it? I think thats to get the correct installed height or more seat pressure?

I have friends with 400's & flattops running 7.4 / 7.3 with 3.42 / 3.08 gears and camel hump heads with performer RPM cam.</font>

Shimming DECREASES the installed height and adds seat pressure, yes.

I'll call you tonight but in case you don't answer: go with the 114691 cam you mentioned. It will put you at .571/.590 gross lift with them 1.6's which is pretty damn close to your original cam from the first build. After working your heads as much as I did, this will serve to wake that cam up-before those castings were holding you back some. I think you'll get to your 6,000 shift point quicker now. -Jabin

Ok, I finally got the engine out and started pulling it down last night. The lifters were just killed. They look like they were dished lifters not a little bit of a dome.

Anyways I was showing a guy at work one of the lifters and he seems to think that anytime you have a cam an lifters go bad it also takes out the rings. I was looking and the block (don't have pistons out yet) but the cylinder walls still look good. Why would he think it would take out the rings. I could understand if I had alot of miles on the car but the only time it has been running is to put it on and take it off a trailer.

Thanks,
Corey

Id say the cam is gone too

With that much metal floating around I'd take it apart and clean everything. The only time I ever wiped a lobe was due to a rocker arm failure. So I flushed the oil and two passes later I spun a bearing. Just MHO. Pat.

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73 RS Black w/Silver stripes going to the dark side with a 468. 96 GTS Viper Blue w/white stripes (wifes).

Speaking from experience, you really need to tear the motor down and check everything for damage from all the metal that has been pumped through your oil system. The metal that used to be on those flattened cam lobes had to go somewhere, it didn't just disappear. Check your oil pump internals, your bearings (main, cam and rod), your heads, basically anywhere that oil flows.

just my $.02 worth

Just so everyone knows I did tear this motor completely down to clean everything very well. I am replacing the following- Rod bearings, Main Bearings, Cam Bearings, Cam, Lifters, Oil Pump. I pulled the pistons out to check the rings and they look good as well as the cylinder walls. If I remember correctly when I put in the old crank I had to use 40 under bearings so this motor is also getting a new standar/standard Scat 9000 crank.

New cam specs. etc. What do you think.

Internal Duration @.050" 250
External Duration @.050" 260
Internal Lift 532
Exhaust Lift 555
Lobe Separator 106
Advance Internal Duration 285
Advance Exhaust Duration 295
Valve Lash .026-.028
Solid Cam

k-motion valve springs.

Recommended Camshaft Style Flat tappet solid
Installed Height (in) 1.700
Seat Pressure at Installed Height (lbs) 130
Open Height (in) 1.150
Open Pressure (lbs) 395

1.6 full roller rockers

2.02 - 1.6 valves

I am going to check for pushrod length as soon as I get the crank back from being balanced, But I am thinking this will just take a stock length pushrod.


[This message has been edited by SUPERSONICBLUE70 (edited April 08, 2005).]

you cant always have a high lift cam on
your motor (as should every1 know)..
i was was running 510 lift cam on my 383 srtoker engine with 1.7 full roller rockers and trick flow aluminm heads. when i first got that bad boy running it ran like champ..
i had had it on my 74 chevy p/u.. can you imagine a p/u smokin cobras? well i can cause it was me.. but anyways it turns out that w/ my 1.7 roller rockers and stock pushrods the lift goes up about 30 to 40 degrees..(thats alot) so i was runnin like a 550 lift cam.. I ran it for about 5000 miles till i started to feel the difference. but after the first iol change u start noticeing metal in your oil,,then your oil pump takes a shit,then your whole block takes a shit...sucks!

<font face="Arial,Verdana" size="2">Originally posted by silverz28bullet:
you cant always have a high lift cam on
your motor (as should every1 know)..
i was was running 510 lift cam on my 383 srtoker engine with 1.7 full roller rockers and trick flow aluminm heads. when i first got that bad boy running it ran like champ..
i had had it on my 74 chevy p/u.. can you imagine a p/u smokin cobras? well i can cause it was me.. but anyways it turns out that w/ my 1.7 roller rockers and stock pushrods the lift goes up about 30 to 40 degrees..(thats alot) so i was runnin like a 550 lift cam.. I ran it for about 5000 miles till i started to feel the difference. but after the first iol change u start noticeing metal in your oil,,then your oil pump takes a shit,then your whole block takes a shit...sucks!</font>

What brand rockers have 1.7 ratio? I've seen them but forgot the maker.

sounds good!

crane, comp cam, and scorpion roller rockers make 1.7 ratio. and even summit makes them.

i had the crane gold race 1.7