[TnVTX]

The shop is wanting to set my rod clearances ~.025", and the mains ~.030" for this kit.
Does this sound about right?

[DPlum]

Sorry to hear that but that has been my exper. for years helping others . Mic the housings should be on the high mid or low of tolerance your bearing manuf. gives those sizes be sure they all match crank on the mid all others should be . Then install bearings in housings and torque measure crank and housing diff. is actual clearance NO PLASTIGAGE .0025 -.0028 on rods and .003 -.0035 on mains be sure crank is consistant from pin to pin If not have turned by competent shop [Crankshaft specialties Fairfax Va.] Gary Facmire

[rolling money pits]

Originally Posted by DPlum

Sorry to hear that but that has been my exper. for years helping others . Mic the housings should be on the high mid or low of tolerance your bearing manuf. gives those sizes be sure they all match crank on the mid all others should be . Then install bearings in housings and torque measure crank and housing diff. is actual clearance NO PLASTIGAGE .0025 -.0028 on rods and .003 -.0035 on mains be sure crank is consistant from pin to pin If not have turned by competent shop [Crankshaft specialties Fairfax Va.] Gary Facmire

where in FFX are they located, and do they work with kenson?

[scott70]

I was having a 455 freshened up,its was an uncut,stock crank,they ordered stock bearing size and when checked,it had only .0017 clearance on the rods.Good thing it was checked!A different brand high per. bearing gave the needed clearance wihout cutting the crank.

[uneasyrider]

Originally Posted by uneasyrider

The oil clearance spec's people are talking about above appear to be stock RAIV spec's:

1970 RAIV

Rod: 0.0015-0.0031
Main (1-4): 0.0012-0.0028
Main (5): 0.007-0.0022

Is that what we need to run, RAIV clearanses?

P.S. Just a side note, I was talking to my boss who used to drag race Pontiac's many years ago and he said that the oil clearances was more than likely ont the problem in my case because he ran his engines on the tight side and never had a problem spinning his destroked 400's to 8,000rpms BUT he drag raced NOT road raced. From what he could tell my issue was because of oil starvation from braking and cornering.

P.S. Why would they want less clearance on the rear main?

[Half-Inch Stud]

After having heard "lifters collapsing in the thurns, I feel it wise to comment:
divide .025" and .030" by 10

[DPlum]

Yes at kenson Gary rents space there you can get his home # on 411 and deal direct with him.

[hurryinhoosier62]

There is such a thing as having too much oil pressure and/or too much oil
volume. Both can "wash" the babbitt right off of a bearing. It's rare,but it
does happen. As for clearances, I've always used .002 on both mains and rods
per Ken Crocie. My guess... does the crank have babbitt embedded in the
journals? If so, the RA(roughness average) is too high. It should be around 10-15 using a profilometer. I learned another way to check from an old
machinist. Take a penny(preferrably one that is all copper,not just copper-plated). Rub it on the journals. If copper is left, the journals are too rough
and need to be machined. You could have gotten some bad bearing,also.
Good luck on the rebuild!!

[Will]

A good rule of thumb to use for bearing clearances for a high performance/high RPM application is .001" clearance for each 1" of journal diameter.

Thus, for a 400 with 2.25" rod journals a .00225 or .0025" clearance would be fine on the rods and with the 3" main, a .003" main clearance would also be fine. This is a little on the loose side, but from what I've seen loose is a little safer than tight, or more forgiving overall.

I might try a tight clearance engine if I could trust that all the machine work was 100% spot-on and if I had a clean room to assemble the engine in so that no chance of any contamination getting into the bearings during assembly.

[uneasyrider]

Originally Posted by pontiac jack

Olds & Caddy - 1949
Chevy & Pontiac - 1955

Ooops, my bad... I had it in my head Pontiac came out with the Olds and Caddy. ANYWAY, I still have heard over the years Pontiac didn't have the "best" oiling system. I haven't built dozens of Chevy's and Pontiac's to compere each but some "old timers" have told me that. Considering the above I wonder... There are plenty of people on here that have built and raced plenty of Poncho engines. I tend to believe the biggest issue with my engine is oil control under hard brakeing and cornering and I think the road race pan and accumulator will fix that.

[PONTIAC DUDE]

Having the oil system run down the lifter bores first doesn't help.

[PONTIAC DUDE]

Originally Posted by scott70

I was told by some well known pontiac guys(I know you guys are well known too) that .0024 -.0025 is too tight for an engine thats going to be raced from the get go and.What do you think?

I run that.

[scott70]

Originally Posted by PONTIAC DUDE

I run that.

My last engine refresh was .0025 on the rods and .003 on the mains and raced it for 4 seasons and the bearings still looked great.Ive heard any where from .0025 to .003 on the rods from different people,but the reason i wrote that is i'm putting h beams in my engine right now and new bearings and asked the butler camp what they would run on a race engine,they said .003 rods and mains and said they thought .0024 was too tight for a engine thats going to be raced from the get go.Thats why i asked what other people thought.I just told my engine guys to shoot for .0028 rods and .003 on the mains.

[PONTIAC DUDE]

Originally Posted by scott70

My last engine refresh was .0025 on the rods and .003 on the mains and raced it for 4 seasons and the bearings still looked great.Ive heard any where from .0025 to .003 on the rods from different people,but the reason i wrote that is i'm putting h beams in my engine right now and new bearings and asked the butler camp what they would run on a race engine,they said .003 rods and mains and said they thought .0024 was too tight for a engine thats going to be raced from the get go.Thats why i asked what other people thought.I just told my engine guys to shoot for .0028 rods and .003 on the mains.

Better to be on the loose side with customers. when ya don't know what they know or how they drive. LOL.

I also use synthetic oil.

[uneasyrider]

Originally Posted by PONTIAC DUDE

Having the oil system run down the lifter bores first doesn't help.

Isn't that the way a Ford FE block oils? Isn't that why they built the Side Oiler 427's? From what I understande they were having problems with the bottom end so they put oil to it first in the Side Oilers.

[hurryinhoosier62]

Ken,
AMEN!! For a little insight, I used to crew a P-51D Mustang with an Unlimited
Class engine: 2,500hp@120 inches of manifold pressure. Our builder specified
.003 rod journal clearance and .0035-.004 main journal clearance. Guys, we're talking 1,650 cubic inches here. In otherwords, BIG!!

[Will]

hurryinhoosier62 - was that a P-51D Mustang?

[hurryinhoosier62]

Will,
You bettya! If I remember the USAAF# correctly it was 414064 Tail #N3751L
It was painted to recreate "Pete" Peterson's "Hurry Home Honey". She was
a Cavalier conversion(aft fuel tank removed/seat added, step in flap) that some yo-yo flew to Tahiti back in the '60s. It did have some corrosion issues
but we got them all repaired. One sweet bird. There's nothing like the sound
of a Merlin in high-speed supercharger at low(250 agl)altitude!! It just makes
the hair on the back of your neck stand up!!

[uneasyrider]

Originally Posted by hurryinhoosier62

...There's nothing like the sound
of a Merlin in high-speed supercharger at low(250 agl)altitude!! It just makes
the hair on the back of your neck stand up!!

Hmmmmmmmmm, I can't help it I'll darg off topic a bit here too. I live in the lower Columbia River Basin and there was NOTHING like hearing those nitro burning Allisons and Griffons engines out there! WOW! Those were the days! You could here them as far as Benton City when the weather was right and that is about 15miles from the race track. I sure miss those boats. It's not the same now with the "vacuum cleaners" on the water. The Miss Pay n Pack, The Miss Budwieser, The Atlas Van lines boat all running neck and neck!!!!!!! FREAKING ROARING out of the West turn... It's over now... Even the "classic" boats don't run on nitro so they aren't as loud but they are cool still. Actually, I think the Limited class is the coolest now with the BB engines in them.