[callmewaylon]

Looking to upgrade the failing flat tappet in my 408 SBC to a roller cam. The engine has about ~20-25k miles on it and has been a great engine until the intake gaskets started to delaminate last summer and it started to burn oil. In the ensuing teardown to diagnose I found that the lifters were starting to wear. Not a total failure, but all the lifter faces were concave so I'm thinking only a matter of time.

About the engine: Stock cast crank turned .020, 10.5:1 comp, Eagle 5.7 SIR I beam rods, speed pro hypereutectic pistons, balanced rotating assembly, Performer RPM 60899 64cc heads(the newer 195cc version) and regular Performer RPM intake Lunati Voodoo p/n 10120704 dur @.050" is 233/241 and lift is .505/.526 comp roller tip rockers poly locks, and magnum chrome moly pushrods.

Looking to replace the Voodoo with one of the following Howards cams:
110265-10 233 241 @.050 .530 .545 110 106 or (similar numbers to my current cam)
110275-10 241 247 @.050 .545 .565 110 106 basically one step up from my current cam

Leaning towards going with the bigger cam to spice things up a bit. I'd like to upgrade the heads at some point, but the budget for this winter doesn't include that at this point. Howards says the 110275 makes power to 6400, but I'm thinking that's referring to a 350 so the 408 should make power closer to 6000.

 

[callmewaylon]

I am pretty sure they are supposed to be concave, so the lifter rotates in the bore and wears even on the lobe

No, they need to be convex so they spin as the camshaft turns.

 

[callmewaylon]

you will need to go through the entire engine and clean it. Freshen rings n bearings as requires. Your heads probably need a split.
Post the flow numbers?You did not say if you are using an 850 CFM carb?

Yes will be going through everything shortly as the rest of the engine comes apart.
Head Flow numbers from Edelbrock are below. Mine are 60899.
Not the best flow numbers, but with the old cam, 3:73:1 gears, 2500 converter in 700R4 my 3800lb Malibu(with me in it, I'm a big guy) would run 12.70's @ 107mph. I was eyeing up either AFR or Profiler 210's for this engine, but another project is sucking up the funds.

 

[callmewaylon]

They are supposed to be Convex, not Concave.
The lifter pictured is well on it's way to failure....cam lobe nose will be similarly worn.

Waylon, I think your assessment of power peak for the #110275-10 is going to be about right, might be as high as 6200 rpm since you've got decent heads
[/QUOTE
I can live with 6200 as that's still pretty reasonable. The only thing I'm worried about is my power brakes with the @.050 duration well over 240. My power brakes are fine now except when the engine idles really low like at start up.

 

[callmewaylon]

Yes. Convex.

Considering just the engine combination, in my opinion, the smaller off the 2 cams seems like a better fit for the combination right now.

What do you have for a transmission/converter and rear end/gearing?

700R4 with a 2500rpm stall converter. Seriously considering going to a 3000-3200 rpm converter while the engine is out. 3:73:1 rear end gears. You're probably right about the first cam being better for the combo right now. I street drive the car a lot too an the first cam would for sure be fine with my power brakes and such. I drive the car ~20 miles each way to work in the summer when the weather is good.

 

[callmewaylon]

those cars usually go 12.0s with what you have?
Lets say your combo is 300 lbs over weight thats still 12.3s?
Lets figure out your issues,,,

I'm more worried about picking a good cam right now. Won't be back to the track for 4 or 5 months anyway due to winter. My 'meh' 1/4 mile times are a product of not enough converter(supposed to be 2500rpm stall, but is a 12" unit), mediocre heads, 1 5/8' headers.

 

[callmewaylon]

just looked at your head flow numbers. The int/ex ratio is terrible. Its like an FE? You need 10º extra on the exhaust side. I would use split ratios and a moderate cam profile. If you like 106º icl I think 110-112º ecl with 8-10º extra on the exhaust side. If you buy AFRs or profilers later this camshaft will suck

Yeah, the exhaust is weak on the Edelbrocks. I originally picked them up several years ago for a 350 used in a pickup truck before I got back into working on engines. I've been soaking up as much knowledge as I cam about head porting and did some mild porting and valve destrouding on a set of 882 heads that went on a 327 for practice. Thinking about cleaning these Edelbrocks up some while I have the time. My calculated compression ratio is 10.7:1.

 

[callmewaylon]

I know the 882s are boat anchors. The point of doing the work on them was to get experience doing. Nothing I did was radical or would hurt flow.

For the current combo, I'm just trying to get the most out of what I have while keeping it streetable. For the fun per dollar ratio, I'd go right back with the same Voodoo flat tappet if I knew it would be reliable long term.

 

[callmewaylon]

What is the valve train? High lift cams need a better that average supporting cast that includes for flat tappet cams the use of hard face lifters, sturdy pushrods, 7/16th studs with for aluminum head’s must have a 3/4 inch long bottom thread to grab as much of the head threads as possible when they project into the port the length is correct, probably even 7/16th studs need a girdle. Getting into these high lift flat tappet cams with fast lobes using a roller can thrust bumper is a damn good idea it greatly relieves the lifter interface from having to also manage the thrust moments that high lifts and high spring pressures engender. This thrust problem is also enhanced by running roller or gear driven timing sets. These remove a flex absorption point that a link belt style timing chain provides at the cost of a short life but the crankshaft has its vibratory modes as does the cam unlike a turbine which at least in theory has a smooth rotation the piston engine is introducing discontinuous rotation moments on the crankshaft and does a similar thing on the camshaft albeit for differing reasons but the result is a shaky motion on both shafts that meet at the timing set. If the timing set pretty rigid as dictated by the need to keep the timing in a tight circle of error probability but the downside is a whole lot of shaking goin-on between these shafts. This tends to tear up lifters and lobes pretty fast. This might grab you where you’re not expecting it but street driving is much more severe than racing in this regard because at lower RPM the forces are present over longer time periods. But transferring this to high levels of competition builds over the years you see top top end competition builders try to deal with this by the use of thrust buttons on flat tappet cams often using silent link chain drives with frequent replacement or belt drives and the really radical flat tappet guys go to Chrysler (.904) or Ford larger (.875) diameter lifters which wear better than the Chevy .842 and a matching contour cam lobe. Another thing is keeping track of the lifter bore diameter and clearance. The lifter bore wears in an egg shape and clearance between lifter and bore should be .0015 to .0021 inch. The question here is how many guys actually measure these things? The lifter’s motion is much more complicated that just up and down abs round and round in its bore, there are substantial lateral loads that push the lifter pretty hard against its bore wall in a motion that would like to bind it across to bore diameter.

So the message I’m trying to put through is on the Chevy and GM engines in particular that use the .842 dia lifter are subject to motions that want to restrict vertical motion, that the lifter has a lot to do in order to maintain lateral thrust control of the vibrating and rotating cam. The Chevrolet in particular snd GM in general is one of few if not the only company that doesn’t use a thrust plate on flat tappet engines. And Chevrolet SBC’s in particular suffer abnormal cam and lifter wear some of that can be directed at the smallish root diameter of the cam as well, but that rather than an excuse is another reason to beef up the thrust control efforts on these engines even with flat tappets. Now there’s a thought for the aftermarket to make a flat tappet cam for Gen1 roller blocks using the thrust plate and the OEM roller cam timing set. This would be pretty simple mod to standard flat tappet blanks by just machining the thrust step on the nose and drilling the roller timing set bolt holes.

Bogie

The roller cam thrust button on a flat tappet is something I haven't heard of before. It certainly couldn't hurt. Also, I've heard talk of "hard faced" flat tappet lifters but never seen any specified as such. I've wondered if the lifters I've seen with a different material around the foot of lifter were "hard faced". If I knew they would make a difference and which ones to buy, I might just stay with the flat tappet for simplicity and to not sink more into this particular engine. I've been using the Lunati "micro trol" lifters because they had the snap ring retaining the plunger and I've had issues with the cheap wire ring style lifters coming apart. The remainder of the current valve train on the engine consists of the the valves and springs, etc that came with the Performer RPM heads. Rocker arm studs are the stock 3/8" ers that Edelbrock installed along with the Edelbrock guide plates. Comp Magnum pushrods and Comp roller tip cast rockers(I know, not ideal).

I realize a bunch of that will have to change for the roller. I planned on the appropriate springs(I have the tool to check installed height now) along with Scorpian roller rockers and the appropriate length pushrods, cam button, better timing cover, etc.

 

[callmewaylon]

great info Bogie but maybe a bit complicated? Because you are good at explaining maybe explain to Waylon how long duration on the exhaust side can while helping improve hp especially as a crutch to bad exhaust ports can also cause a loss of bottom end torque. (should not be as big a deal on his 408)
Thanks for a great post Bogie

I understand that these Edelbrocks need more crutch on the exhaust side than even other SBC heads do. The cams I'm looking and my current cam at all have split duration and lift. This engine was built 5 yrs ago and I've learned a lot since then. The 383 I built for my Dad's El Camino last year got 195cc AFR's. I upgraded the rocker studs to 7/16" and it got a Howards hydraulic roller single pattern cam since the AFR's have a good intake to exhaust ratio. 237 @ .050 duration and .560 lift with 110 LSA and 106 ICL. That engine pulls extremely hard. I really don't have any complaints about my current combo on the 408 either. If it hadn't started sucking oil through the intake gasket I never would have known the cam was on its way to failure so I guess I lucked out?

 

[callmewaylon]

@BogiesAnnex1 Great info. Less is more with home porting. Have been doing my research and know not to go too far, but a guy's got to dig in and try some of this stuff to get good at it. I might wind up having a valve job done, will decide when I'm done.

Any specific cam buttons you'd recommend or at least what to look for?

Which hydraulic flat tappet hard faced lifters have you had luck with?
The GM Performance look like they have the hard face, but have the chintzy wire retainer instead of a circlip:

CHEVROLET Chevrolet Performance 12371044 Chevrolet Performance Hydraulic Flat Tappet Lifters | Summit Racing

Free Shipping - Chevrolet Performance Hydraulic Flat Tappet Lifters with qualifying orders of $99. Shop Lifters at Summit Racing.

www.summitracing.com

The Comp Magnums claim made in USA, seem to have the hardened face and have a circlip retaining the plunger:

CHEVROLET COMP Cams 858-16 COMP Cams Pro Magnum Hydraulic Lifters | Summit Racing

Free Shipping - COMP Cams Pro Magnum Hydraulic Lifters with qualifying orders of $99. Shop Lifters at Summit Racing.

www.summitracing.com

 

[callmewaylon]

Cam was broken in properly with plenty of the prescribed Lunait cam lube and break in oil. Edelbrock says the springs are good to .575 max lift and I'm using 1.5 rockers. If you look at the first pic I posted, you can see that the lifters are showing mild wear after 25k hard miles. The only place where I could have done things differently would be to use lighter springs for break in. The springs I'm using only have a damper and are not double springs so I just used them. Maybe it accelerated wear? I'm wondering if the wear is more due to the VooDoo cams 43 degrees of hydraulic intensity and just won't ever live a really long life. If trying to get by with a flat tappet and trying to get a lot of miles out if it I should probably pic a cam with lazier ramps, but that's no fun!

 

[callmewaylon]

Did anyone else see that his build is using 5.7 rods in a 400 sbc. I would be very concerned about cam lobe to rod bolt interference. The factory SBC 400 rods are shorter and use shorter rod bolts for block rail and cam lobe clearance. using 5.7 rods is a concern. Even in stock 400 shortblock with cam upgrade a small base circle cam is frequently used to clear the rod bolt interference.

Yep, rod to cam clearance was checked! The Eagle SIR rods I used don't have the best rod clearance, there are better out there but they work. Scat makes some nice stroker rods with lots of clearance.

 

[callmewaylon]

Hey, how is the car and engine going? The scat stroker rod is a good rod. i would go 6". Try a Mike Jones Cam Designs hydraulic roller. Pick a cam one smaller size than you think you need and you are on your way. Try one of their EHR designs and use their roller lifters. Careful here, you may think you can get away with another lifter. You can't. You must use their roller lifter with the high lift design and engineering and metallurgy that they use. These cams are the best street hyd. roller i have ever seen or heard of for a SBC.

I wound up freshening the engine up, new bearings and rings. Changed things up and went with the new version of the Dart SHP 200cc heads with 72cc chambers for 9.5:1 so I can run it on 87 octane since I drive the car a lot. Those 5.7 rods are still doing fine. I would go with something different if I did it again, but they work in this combo. I chose a Howards retro roller cam, 233 in and 241 ex @.050 roller cam on a 110. Runs really strong. Best pass in a 3900lb car last summer was 12.01 @ 113 with consistent 12.10's.....on 87 octane.