Are you sure you asked for main and not rod journals? the clearance is dependant on diameter, larger diameter mains and rod journals demand larger clearances. See my point?

 

yes, we talked about main bearing clearances...

I'll let you know what he says.. I PM'd him earlier and asked about what he thinks about using 0.0030 - 0.0035 clearance on the mains..

 

.003-.0035 on the mains is were you want to be. I doubt that crank is perfectly straight, most are not. What you have to keep in mind is a slightly crooked crank (my last Scat was .00075 out of round) takes away some of the clearance as it spins around in a slightly oblonged rotation in the main bearings, particularly on the end mains.

Rehermorrison recommends .0035 on mains and .002-.0025 on the rods. If you fudge a little on a drag motor fudge a little to the looser side. Too tight is a worse than too loose........on bearings anyway

Is it killing the same bearings it was in the last motor? I gotta admit I do not have an oil temp gauge on my drag motor yet either. It is going to get one. I warm the car up good and then feel the oil filter with my hand. If it is HOT to the touch I am good to go. I usually warm the coolant up to 190 or so and then check the filter. I cool the coolant back down with the electric water pump and fan and go make a run. On a side not the car made its fastest pass yet going into the waterbox at 185 last week (131.65 1/8 mile). I usually like to go into the box at 140 or so......I can't imagine the motor would like more heat in it, but you never know.

 

just heared back from the rebuilder..

We are going now with 0.003

He told me that I'll have to rebuild after a season or 2 with that clearance.. but that's ok with me.. I want to get about 100 - 150 passes out of the engine between rebuilds.. I run about 75 passes per season..

Before the rebuild, ALL main bearings were spun.. On the rebuild, they weren't spun, but the 2 outter bearings had too much wear for 2 passes..

 

I run ~.00275 clearences in my motor but I don't go over 6500. I did them all my self.


With .0035 clearences I don't think you whould want synthetic? That seems pretty loose .


But what do I know


Have you had your cranked turned and polished?


Maybe hes not blue printing it right. I doubt it though.

 

Crank was polished and turned at the initial rebuild and will be polished and turned again..

 

Something still doesn't sound right. Please make sure of crank runout. Once a bearing is fried, the crank often bends. You can turn one and still not have it all perfect.

The rule of thumb is .001 per inch of journal diameter. So that means .0022 on rods and .00245 on mains. If things are right..they will live there just fine. But I agree..a little more on them is better than a little less for sure! On a drag motor....out near .003 will be OK...

How's oiling system? Any chance we're starving bearings? Weird things happen sometimes. I've seen pans work on one combo and then when things get more serious they don't anymore.


JIM

 

They installed a high volume oil pump and the engine has restrictors (needed to race a 400 based engine to restricte oil flow to the top of the engine to get enough oil to the bearings)

 

I forgot this is a 406 isn't it? I assume it has 400 main sizes then..not 350 size? Then you have a 2.650 crank I think..so a little more clearance is needed..but .003 is still plenty loose.

The restrictors help keep some oil in the bottom, and since you're only racing they will be Ok...but realize that most folks aren't even using them for racing much anymore. They do help if a pushrod breaks and the lifter gets out of hole somehow to keep pressure up.

What pan and windage tray is on it?


JIM

 

I believe that the pan is a moroso 7 qt pan...

 

Everyone I know has problems with the clearnces on there 400 blocks.

 

Oh heck, I was thinking Big block then yes .030 is more than enough.

I glad we have guys like Jim around to catch these things.

 

Really doesn't matter....you can run 9000 rpm with less that .003 on a BBC if oiling sytstem is good. The .001 per inch works on just about anything. Maybe have to juggle it a little for aluminum stuff....

Now I'm not too sure about that ".030" there now John.....time for bed...you're slipping your decimals!!


JIM

 

 

John, Engines like that heat in the 180-210 range drag racing,makes them very efficient and sealed up.Every 5 degrees of hotter temp needs more jet.

 

re: the tranny cooler location. That's a really good idea. Now tell us the truth, did you think that up or did ya see it somewhere else??

 

Build small aluminum panel boxes with plug-in disconnects...they can be velcro'd, temporarily wire tied, or bolted to the passenger side(a permanent one)....add as many gauges as you want...put a pic of your wife on it if you want to.
By doing so; you can add or subtract any gauge as needed, build it any shape you want.
The complete panel box(s) come out for calibrating gauges (for gauges that can be calibrated, very important to have accurate readings).
I done this on my AMX when I ran with a kelvinator and water induction (yes, I am that old).
I didnt have enough places for all the gauges .
I also had a vacuum gauge on my panel, that one gauge clipped to my console by my foot and stayed in the car always.
I made all the panels leads long enough to reach under the hood from an open window (when not running) for tuning at the track.
The only gauges I did NOT put on that panel was tranny/engine oil pressure gauges...I wanted the shortest lead possible there, and I used copper and not plastic.

I stashed the connect harness(s) behind the center console when not in use.

I now also use this method on my boat and they come out and is packed away in a home-made foam box to keep the weather from corroding the conections.
My "boat brain box" (as we call it) also has a seperate panel box made using air-craft fasteners to connect them as one unit, it has the stereo and speakers in it.
Plug it in...and go...
Un-plug...stash away.

You can build for as many gauges as you want and add aux. panels as needed...add lights for the panels, ect...


Also; by adding the aux./break away panels, it makes them smaller and can be stashed in the glove box or tool box...the aux. panels can also be the panel with the long leads for under the hood tuning.
Can be removed from the interior as to leave the interior looking "stock" per se'.
(also keeps the competition from seeing what gauges you have)

It sounds complicated but is really simple.



G/L


Jim

 

Norm (forum member LOTAHP) gave me the idea!!

He uses two 12 inch coolers which are mounted sideways on the crossmember and he said that the only way that he could imagine the 18 inch coolers to fit would be through the exhaust holes in the crossmember... That's what I ended up doing!!

 

Most restrictors are sold as tiny .060 flow holes. While your engine is out drill them with a .110 and it more than doubles the top end flow, but flow is still much less than no restrictor.

The reason is spring life. Without much cooling of the .060 we found that springs would loose 25# of seat pressure in a short period of time. The drilled out restricted motors could still retain 75 psi hot oil pressure even with thinnner than 20W-50 oil if the bearing clearances are correct.