BBM block question

[BattlestarGalactic]

Ok, since mine is back apart getting the sludge cleaned out from the head/water leakage issue, it has come to light there is wear on the cam bearings.  #2 and 4 have a groove worn in them, maybe .003-.005.  Enough to hang a nail on. Seems the oil groove in the camshaft is leaving a mark in the bearing(high spot) as the rest of the bearing is getting worn on the bottom half.

This was common on my old 428 block after 4-5 yrs of running, I would replace the bearings.  I have just maybe 40 passes and it's already noticeable.  Seems the BBM block only takes one style bearing and no other option for improvement. Yes, I still run a flat tappet cam.  I was discussing options today trying to come up with a game plan to improve this situation.

What is everyone else doing??

I also found out today that TF heads have raised rocker stands.  Going to mill that down to run my original Dove set up.   I see they did this to get more material for the stud, but doesn't that really limit your choices for rockers?  The shop I use has gone both ways, cutting or using new rocker set ups.  Again, what is everyone else doing for this?

[blykins]

No cam bearing issues.  I use the Durabond FP-01 with a regular F-33 front bearing.

As for the TFS heads, we have been speaking on this for about a year and a half.

The valves are about .050” taller and the stands are .300” taller.

I mill the stands down by .200” to get the geometry right and then fine tune from there.  I have yet to find a rocker setup that works out of the box. I’ve tried HS, Comp, T&D, and factory.  They all need cut.

[AlanCasida]

I am by no means an FE expert so I may have just gotten lucky or did something wrong but the Dove HD rocker assemblies cam out ok on my TFS heads with no milling. I am using .027" head gaskets though. I am running a .640" lift solid roller cam. Here are a couple of pictures.

[CaptCobrajet]

The grooves in the cam on #2 and #4 are the root of your bearing problem.  If you run your finger over the journal, you will probably feel a very sharp edge.  We always chuck the cam in the lathe and chamfer that edge slightly with a file, and then hit it with a little 600 paper.  It helps keep the cam from "digging" a hole in the bearing.  Iron cam cores are not as wide as billets, so don't get carried away and take too much of the load bearing surface away.  With iron core cams, I like to use the Durabond F-33 or Clevite SH-781S if not coating the bearings.  The harder non-performance bearing will live better on an iron cam core.  The FP bearings are softer.  For the BBM, the FP is all that is available, so chamfering the edges of the groove, coating the bearings, and verifying that you have .0015 to .002 clearance after coating, will all help you.  It is easy to polish the needed clearance into the cam journals, and then chamfer the grooves before you really slick the journals up.  I believe that the cam thrust clearance allows the cam to wiggle just enough to chew on #2 and #4 if the edge of the groove is sharp.  Over the years, I have seen improvement when they come back for a freshen up, by using the above methods.  I chamfer that edge on any cam that has the grooves.

[blykins]

I also check cam bearing clearances just like the rods and mains.  They need clearance just the same. As Blair said, you can easily polish the clearance in and hit the sharp edges too.

Alan, I’m wondering if your stands had been worked on before.  If you think about it, how would a rocker arm that’s designed to fit a standard head work perfect on a head where the stands have about a net +.250” stand height?  We do shim rocker stands up quite often with factory heads, but most rocker systems are designed for standard LR/MR heads.  Yours are closer than most but still need to be whacked a little.

[BattlestarGalactic]

Brent, that is the part number we used on mine.  Since I'm not well versed in cams, what cams are you running?  Rollers?  Do they have the oil groove in #2,4?  Have you pulled any motor down yet to see any wear?  I would not have see this if I didn't have water leakage in my old heads.  It would have been another 4-5 yrs before I would have even thought to tear into this again.

What I was told was the FP bearings are a softer material and they don't offer a coated version to help with wear.  Maybe it won't be a serious issue, maybe my old block had issues right off, but once it wore in slightly it didn't get worse and I never knew because it stayed together for years.  I typically put 100 passes/yr.

I had thoughts of converting to roller cam bearings.  Pricey, but a fix I would never have to worry about.  The shop has always pushed roller cams, but again, pricey and I'm too old school to make the jump.  The DLC lifters I bought worked perfect on my cast core flat tappet cam.  They looked as new as I put them in, and that was a concern for many people.  I got the lifters off Ebay for $100.

Alan,  we will get it figured out once the valves are fit and mock it up.  I'm reusing my Ebok valves because I just bought eight new 2.25 intakes and springs and didn't want to throw it all away.  Yes, we'll have to open the guides to make them work, but so what.  They had to take .05 off the intake side of the heads to get the intake to fit.  Now we'll have to take .05 off the intake ends to get some room for silicone.  It has about .025 clearance now and I think that is a bit tight.

After running those heads for 24 yrs, I was on the verge of having to buy shorter push rods.   When we skimmed the heads early in the season when I was chasing water issue(turned out to be a cracked cylinder), I had to put another .04 shim under the rockers to get enough adjustment for lash.  The new BBM block made things fit okay since the deck had not been cut a few times over the decades of use.  Those old heads had been skimmed a few times also, all adding up to shortening the height too much for the push rod length.

Blair,  The new cam cores do have a more narrow oil groove compared to earlier cams with more then 1/8" wide groove.  New ones are just over 1/16" or so which does help with surface area.  I wish you could get a core without oiling and let it oil around the back of the cam bearing.  That would eliminate many issues.

What are you coating the bearing with?  I have a local buddy that does coatings and he wanted me use it on this build anyway, I might look into it.

[blykins]

I run both roller and flat tappet, mainly with grooves..  I don’t see bearing wear like you’re seeing, but I also check cam clearances like I do with main/rod bearings.  As spring pressure goes up, it’s critical to have sufficient oil wedge.

You can’t run roller cam bearings with a cast iron cam.  You also can’t use DLC coated tool steel lifters with a cast iron cam. 

You would have been a lot better off just buying the TFS heads bare with valves.  They are designed for 2.190”/1.625” valves so it’s hard to say what they will do with the valves opened up that far.  You’re taking the guides out to 3/8”??  Valves are cheap....

[AlanCasida]

Alan, I’m wondering if your stands had been worked on before.  If you think about it, how would a rocker arm that’s designed to fit a standard head work perfect on a head where the stands have about a net +.250” stand height?  We do shim rocker stands up quite often with factory heads, but most rocker systems are designed for standard LR/MR heads.  Yours are closer than most but still need to be whacked a little.

That's a possibility.  They were originally on my MR heads. I got the rocker assemblies through Gessford Machine and they mocked everything up when they did the machine work on my 427 and to get the right pushrod lengths so they could have done some work on them. I don't think the bottoms have been touched but next time I have them off I'll double check them to see if they have been milled.

[BattlestarGalactic]

 

You also can’t use DLC coated tool steel lifters with a cast iron cam. 

I do many things that aren't suppose to work according to the rules.  We talked to Comp about it when ordering the cam.  They micro polished the journals and it seems to be working well together so far.

You would have been a lot better off just buying the TFS heads bare with valves.  They are designed for 2.190”/1.625” valves so it’s hard to say what they will do with the valves opened up that far.  You’re taking the guides out to 3/8”??  Valves are cheap....

Point well taken.  Time will tell.  Likely put them on the flow bench and just see what happens?

[Barry_R]

Don't know if things have changed, but Durabond used to use only one babbitt formulation on their bearings - a lead based babbitt back then IIRC.  Probably tin now with environmentals.  On their performance bearings they used to plate them thicker and then run a roller around the I.D. to increase the density.  The coating used to be a spray apply - something along the lines of a DuPont D10 like used on piston skirts.  Good for dry wear reduction and lubricity - - kinda like plating lead with lead - but will not add any appreciable strength.

Blair is likely on to it with the sharp cam groove edges - we see the same thing with distributor gears on cams

[blykins]

I've never tried because my Comp and Trend reps have always told me explicitly not to do that....LOL

They micropolished the journals or the lobes?

[BattlestarGalactic]

Sorry, they polished the lobes.  (forgot to engage brain before typing)

[fekbmax]

Not meant to hijack but just a quick question.  How do the later runs of the old Geniuses iron block compare to the BBM iron block strength wise ?

[BattlestarGalactic]

Keith, sorry I have no input on your question.

I do have some update:
After discussing the situation with the shop, I'm going to buy new valves for the TF heads(not reuse my 3/8" stem stuff).  It's only money, right?

Secondly, camshaft will likely get changed to full roller set up.  Again, it's only money.  This leads to the possibility of putting roller cam bearings in it eliminating any wear issues on those soft cam bearings.  Again, WTH, it's only money.

My next big concern is my old Dove HD(wide) rockers.  Going to a "big" roller cam will increase spring pressure.   How will the vintage(1995) Dove rockers hold up?  That brings in the thought of T/D, Jesel, etc rockers?  Cha-ching.

I'm spending it like it's falling out of the sky!!!  But I don't want to have to deal with any issues.

[cjshaker]

Not meant to hijack but just a quick question.  How do the later runs of the old Geniuses iron block compare to the BBM iron block strength wise ?

Keith, I don't believe there's any strength difference between the 2 blocks. Yes, the BBM block seems to be cast with a little better quality control, but they both have the same features of thicker crank support webbing, siamesed cylinders that extend to the outer front/rear portions of the block, thicker decks and thicker bores. About the only difference that I've noticed from the BBM and my late Genesis block (from a strength point of view) is that the main caps are a machined fit on the entire length of the sides of the BBM, where the Genesis is more like the factory design with it being open from the crossbolt to the main webbing. I suppose that may give the BBM an advantage on cap walk issues, but I know there are quite a few Genesis blocks making big power without that issue. Blair didn't seem to think there would be any issue at the 700-800 hp level with the Genesis block design. Hope that helps.