Dyno day, the good and the bad....

No,

Head studs are a completely different deal.. as long as the bores are honed with the studs and a honing plate, there should be no issue.

The Main bearing housings are much more critical for size and out of round.

JW

 

Well, last night after draining the water and oil, I removed the intake, heads and oil pan. Here are the observations so far....

Intake: The first thing I found was two lifters with rough edges, #8 int. and #1 exh. I have not removed them from their bore's yet. I also saw a few specks of copper on some of the cam lobes.

Heads: The cylinders look decent, I can see some mild vertical marks in the bores, nothing bad I think, feels smooth.

Oil Pan: The #7 rod shows signs of heat, the cap has blued. I have not removed any main or rod caps yet, but externally the others look o.k..

I did not measure the torque to turn the engine after removing the heads but it is definately easier. It does not take much to keep it rotating but it does take more than it should, I think, to initiate rotation (tends to grab).

What order are things oiled in the BBB?

Suggestions going forward o No:
Thanks.

 

Oiled front to back. Lifter gallery first, with passages dropping down to feed main saddles. Mains feed rods. #7 rod gets oil from #4 main.

 

Easiest is the front, but rear is better to see how the last bearings to get oil are doing. Some check pressure at both ends.

Devon

 

Currently, stock location, front passenger side.

 

Could you provide more detail?

Is there one feed from the pump or does it branch off in multiple directions? I thought one or the main feed runs from the pump diaginally up to the bottom of the the front cam bearing o No:

Time for rod caps and main caps to come off tonight.

 

This should help, but ignore the rocker arm oiling as it's a '67-'69 only-thing.



Devon

 

I ran by the house at lunch, here's what I found:

Two lifters worn, looks like they wore on the outside edge mostly. Holding it to the light you can clearly see a raised circle in the center of the lifter diameter.

I was told these were Johnson lifters. Here is a good article on Flat Tappet Cam Tech - Righting the Wrongs from the Hotrod site: http://www.hotrod.com/techarticles/engine/flat_tappet_cam_tech/cam_construction.html

I broke the cam in with the outer springs only...but for only 10 minutes, verying the rpm from 2200 to 4500 (dyno program). I did not use EOS but did use Brad Penn 30W break-in oil.

#7 rod bearing spun, it is worn on the outside edges to the copper, in maybe .1" in from each edge. I think clearances were just too tight. The inside of the cap was dark/black in the center area. The crank also shows some damage. with copper residue but it's not too bad, I can't catch my fingernail on it. I may be able to have it polished out. The crank measures about .0005 smaller in diameter than the adjacent #8 journal that looks pretty good.

One other rod bearing I checked #4 looks fair. No copper showing but with only the center area containing the silver bearing coating that was there when installed/new.

Cylinders look good.

The mains I looked at (#3) looked o.k. with no copper but more ware than I would expect for ~30 minutes of dyno time.

More details tonight....

 

Take a look at this lifter!

Third picture shows two of the lifters, one good along with the worst one (top), both against a straight edge. These are advertised to be hardened?

Here's the #7 rod bearing. Key or tab was sheered off due to being spun. Cap is black.

I have yet to pull the cam, don't know if it is re-usable yet but have my doubts.

 

Wow what an unusual wear pattern on the lifter. Normally when a lobe/lifter fails it gets concave, not convex. That lifter was spinning normally judging from the even/symmetric wear. Also the rough edges indicate that it was riding on the edge of the lobe somehow. Lifters are crowned ever so slightly, to enhance rotation, but it's like a thou or 2, as your good lifter shows.

 

Yes, this was the dyno operators program. The idea is to vary the rpm under very low or no load operation.

 

Yeah, first time I've seen it like that. There is one other lifter that way but is not as noticable.

I found another spun rod bearing, #2. Not as bad as #7 above however.

 

+1

 

I measured the rod journals last night. As mentioned above, #7 rod bearing spun resulting in obvious heat marks on the rod cap, I also found #2 had spun, cap was only mildly brown. Here are the dimensions I got:

First picture: #8 = 2.2299", #7 = 2.2302"
Second: #6 = 2.2298", #5 = 2.2298"
Third: #4 = 2.2298, #3 = 2.2299"
Last picture: #2 = 2.2303", #1 = 2.2301

The journals were measured by first turning the crank so the journal was in the 12 o'clock position (with engine up side down), I then measured the journals in the horizontal plane (paralell with the floor). I know ideally you would measure in more places (or different places), but this is for comparison only.

The larger journals were the one's that had the spun bearings, I wonder how much of the measured diameter is due to the rod bearing material vs just a slightly larger journal....which would result in less clearance, heat and/or lack of oil.

Rod clearances......
Let's see if I've got this right; if the rod bearing journal of the stock crank is 2.250" and the journals have been turned down by 0.020" then my journal diameter should be 2.230". This will give the same clearance as before, and if you want more clearance (or more then you had before) you would have more material removed from the journal. The rods on the other hand will be machined concentric to the same size as they were before with the thicker bearings. In other works the clearance is determined by the machining of the crank not the rod. Same philosiphy for the mains I'd guess.

Am I on the right track here?

Looks like I'll need a couple of rods, anybody have spares to spare? Thanks.

 

to the best of my undrstanding u r bang on 4 the clearances

 

Craig,

Get 2 new rods, have the bolts installed and the rods resized. Then put the new .030 under bearings (yes, you will have to grind that crank another .010 on the rods, but no biggie..) and then torque the rod up with the bearing in it, measure the vertical clearance (in line with the rod beam) and subtract .0025. This will be the size to have the rod journals of the crank machined to.

Then you will be good.. you have fixed the symptom.. but keep looking for the problem, because I don't beleive you have found it yet.

Look carefully at the main bearing housings.. I beleive your problem lies there, as I have mentioned in the past.

Also, I should note that the crank is going to wear first in line with the rod.. or aproximately 90* from where you have the arrows in that picture. Run your finger across the journal on the area that is between the counterweights, and I bet you can feel the wear on those spun journals.

JW

 

What I will do differently this time (before the dyno) for this street/strip motor:

1. Make sure each main stud is inserted the same way/direction in the block.
2. Make sure ARP rod bolt nut flange clears cap contour (mine were o.k.)
3. Reduce torque to the mains from previous 130 ft-lbs (30W), w/moly about 60 to 75 ft-lbs (less friction with moly is good), w/30W oil 80 to 95 ft-lbs, strongly consider measuring bolt or stud stretch.
4. Ask for main clearances of 0.027 +/- 0.0002 (#1-#4) and 0.0028 +/- 0.0002 #5
5. Ask for rod clearances of .0023 +/-0.0002
6. Ask for rod side clearance of 0.013 to 0.018.
6. Measure all parts for fitment before assembly (with an accurate tool): the big end of the rod torque without bearings, the rod journals, and the rod side clearance.
7. Use Delphi GM lifters
8. Use something better than jumper cables to connect the starter the battery at the dyno
9. Install flange and short 3" exhaust pipe to header for a better fit to route exhaust out of dyno room...goal, to reduce exhaust noise to hear engine better during dyno pulls.
10. During cam break-in hold the motor within the range of 1800 to 2500 rpms for a full 20 minutes, with outer springs removed.
11. At the first notice of power falling off on the dyno, take the oil filter off and cut it open to inspect
12. Take two oil filters to the dyno.

I'm sure I'll find more to add....

Rods are on the way...thanks Chris! Thanks to everyone for your advice!

Who knows once I get this thing right with less drag, I may make a little more than the 509 HP!

Crank and cam come out tomorrow.

 

I pulled the crank today and took lots of measurments. The mains bearings look pretty good considering two rod bearings spun (#2 & #7). From left to right you can see 1, 2, 3, 4 & 5 mains. The final picture is the main caps, also in order but with #5 left, then 4, 3, 2 and #1 on right. The main journals on the crank look about the same as when it went in (better then the bearings).

The cam is out, but I still need to inspect it along with the cam bearings.

I also took measurements of the rods torqued with the old bearings (straight up and down, 45 deg left, 45 deg. right ..... and close to parting line left and right) but I need clarification to calculate rod clearances. What orientation do you take the measurment from for both odd and even piston rods positions?

One more:
How thick are 0.020 over rod bearings when new? My old ones are ~.0700" to .0705"

Thanks!

 

0.0619" plus 1/2 of 0.020" should be 0.0719"

 

Scott, using 0.0719 thickness I've calculated my rod clearances in the attached spreadsheet. I still need to check the rods (2 & 7) that had the spun bearings, but I know they will be off. The attached also contains a diagram to show where each measurment was taken.

How much additional clearance is acceptable within .050" from the parting line of the rod/cap?