Roller or Flat Tappet? Mild 440 build prep

[Road Grabber]

Is it plausible to break in the flat tappet cam with weaker springs since you will do the break in period at only 2000 rpm? That might put in a good starting position.

That’s in the event you decide to use a flat tappet cam. I believe I saw someone comment on this before.

I’ve been watching Salter Racing on YouTube. Unbelievable expertise. He mentioned using a dial indicator to compare before and after lift after start up to determine if a lobe(s) has begun to wear out. He also recommends using a micrometer to measure to lobes front and back after getting a new cam to make sure you have at least a .002 difference. A new cam could be ground faulty.
Just some intel…

 

[Thunderdan]

The OP wanted cam information. I have had cam and lifter issues with my last three big block builds. Crower in one, Racer Brown in one and Mancini in one. Used Valvoline motorcycle oil and zinc additive. The metal grit wiped out oil pumps, bearings, seals, and of course the cam and lifters.
Going roller is more expensive than a flat tappet up front but, how many roller cam failures do you read about?

Thanks, Wedgie, for addressing the topic I raised with this thread. The fact that you experienced failures with all three reputable cam manufacturers in B block builds - and I suspect all three were flat tappet- speaks directly to my concern about running on a mild build with low pressure springs and blueprint approach to cleanliness and accuracy when I assemble mine. Save for finding a NOS cam to use with refaced or original NOS lifters and running all of the ZDDP oil and additives I can throw at it during and after break-in, I'm not convinced that a roller isn't a more reliable approach from the outset.

Conservative estimates to freshen up a recently built engine that eats a cam is at least $850, with a gasket kit ($250), new FT cam and lifters ($350+), rod and main bearings ($150), and all the time involved (that just if one does it themselves), and can easily tally up to thousands more if pistons are scored, oil pump is trashed, and crank journals are scored. And that's just to replace it with another potential failure point (Flat tappet) to do the whole gamble again.

Stack that against the ~$2.5K to move the whole works to a hydraulic roller and the roller -with it's better lobe profile to boot -looks more favorable each time. Very few of us are made of money, and deciding where to invest it for peace of mind in a build we are passionate about and, further, don't have the luxury in time and money to redo it when we have a chance to head off the problem at the outset with some forethought seems like the choice gets easier with each consideration.

 

[Thunderdan]

For a basic 446 build that will put the power at over 500tq/450-ish hp-

Flat tops near zero deck
Stealth heads with the most basic of bowl blending
Rpm intake/750 carb
Headers
Comp XR274HR cam(or something equivalent)(224/230-110)

That's what I've been thinking too, @PRHeads. Nothing crazy, but a bump in compression, some better head flow, intake, and headers and you're there with careful assembly and tuning. I can see you've had considerable experience with builds in lots of threads so your input carries weight too. I ran a Comp 274 in a 400 Pontiac in a '69 GTO I once had with Edelbrock heads, RPM intake, Doug's 1-7/8 headers, scat rods, and Speed-pro forged pistons and it ran very well for the time I had it. Broke it in and ran it with Brad Penn oil too.



Even when that 400 was built back in '07 the machine shop (a very reputable one in Austin, TX) said it was a 50/50 chance the cam/lifters wouldn't get wiped out in the first 1K miles as they were already seeing that happening.

I do like the mild but effective lifts/ramps of the 274 on a pontiac 400 and there were lots of build that went with that cam or similar ones back then so if there's a similar one, but ground with a lobe more tailored to a .904 mopar lifter that wouldn't go flat I'd be all over it.

 

[PRHeads]

I’m not personally a fan of fast rate Hyd cams.
The Hyd portion of the lifters often seem to have issues dealing with that.
You end up at the mercy of the lifter hydraulics(well, you kind of always are, but more so when the opening rates are high).
That being said, both Howards and Comp have fast rate .904 lobes if you care to venture down that path.

The build in the post you quoted was referencing a build that used a HR cam.

 

[furious70]

@wedgie you used wet clutch motorcycle oil? If so, how come?

 

[Thunderdan]

I’m not personally a fan of fast rate Hyd cams.
The Hyd portion of the lifters often seem to have issues dealing with that.
You end up at the mercy of the lifter hydraulics(well, you kind of always are, but more so when the opening rates are high).
That being said, both Howards and Comp have fast rate .904 lobes if you care to venture down that path.

The build in the post you quoted was referencing a build that used a HR cam.

Thanks for the correction - I overlooked the "HR" in the cam details in your post, but having now looked up the specs, it's pretty impressive and highlights why rollers have so many advantages. The only downside is that my gearing is 2.71 with a 28.7" tall tire so I suspect I may need something even milder.

 

[ckessel]

I'm looking at HR units too now. The HFT stick I had ordered from Howards in November is n/a due to no cores. Then I got to thinking if I do go HFT and it goes flat, there went a bunch of money on a fresh build. Waiting to hear back from them about a similar HR unit to the one spec'd out. Build/car/tire/gearing wise we are similar.

 

[wedgie]

I don't know if the overwhelming number of flat tappet cam failures is because of the iron quality, the machining or the oil. $ure is expen$ive to experiment though.

 

[BSB67]

I don't know if the overwhelming number of flat tappet cam failures is because of the iron quality, the machining or the oil. $ure is expen$ive to experiment though.

All of the above

 

[PRHeads]

The only downside is that my gearing is 2.71 with a 28.7" tall tire so I suspect I may need something even milder.

Getting something even smaller isn’t a problem……. It’ll just make less power.