We are running an older 548ci BBC BRODIX 8B 2000A in our six twenties ProCharger Top Dragster and have been having bearing issues on #3 and #4 rod bearings after just around 15-20 runs.

The rest of the rod and main bearings look OK, but this has happened a couple of times.

I will call BRODIX on Monday to see if there have been any oiling upgrades or changes over the years, but I was hoping some of you running this block might have some ideas.

Thanks...

i wonder if one of thse two cylinders is lean,if oiling issue looks like 2 and 2 would be affected

Like Rusty said, check your tune up. Might have some detonation going on in those cylinders hammering the bearings.
I ran a Brodix block for 5 years and never had any oiling issues, 35lbs boost running 6.0x@235.

What kind of main bearing clearance?

Need to know more about what the "issues" are???
Hot / burned?
Something jammed in the oiling passage?
Irregular wear?
Excessive clearance premature?

If detonation / tune related it should show problems at the pin end.

Vacuum pump?

Correct me if I'm wrong, but if it was an oiling issue, even though Rods #3 & 4 share a crank throw/journal, Rod #3 is fed from the #2 Main, and Rod #4 is fed from the #3 Main, right? If that is the case, and there was an oil supply issue with Main Bearing # 2 it would affect Rods #2 & 3, And if Main #3 wasn't oiling right, it would affect Rods #4 & 5?

I am thinking you may also want to take a hard look the crankshaft... Mike the rod journal diameters in several places, then place it on saddle blocks under Mains #1 & 5, rotate it and check it for straightness. (Or remove the upper main bearing shells from saddles 2, 3 & 4 and lay it on 1 & 5 to measure the runout at the three center main journals).

My BRODIX block is from 2009 and still going through multiple combinations from NA single carb, dual carb back to single carb, and finally setup for ProCharger since 2018 to present.

I generally run it around 500 passes before each freshen. 582 with F1R running 4.0's-4 teens

I would check the tune up carefully and go from there.

I'm thinking tune up, but.... that leads to a question.

If one is running a blow through carb and pro charger, how do you tune individual cylinders? If grid or similar equipped, you could go in and adjust individual timing but you can't really change the fuel mix because there's no port tuning ability with a carb.

How are those that are proposing tune up change doing this on your blow through applications?

If MFI equipped the answer is simple, add ports if not already equipped, and richen up those 2 cylinders assuming the plugs tell you this is what's going on.

There is port injection on some cars, I used to use it , it helps, but richening up the total fuel to cover the leaner holes would be the first move, or pull some timing in those two holes

quote:

Originally posted by seabass:
There is port injection on some cars, I used to use it , it helps, but richening up the total fuel to cover the leaner holes would be the first move, or pull some timing in those two holes

I agree.

David Target Fuel pressure should be 15-18lbs of fuel pressure OVER the Boost number. Example if you are at 10lbs of boost your target fuel pressure should be 25-28lbs. I assume this is a blow through combination?

and make sure the hose to the fuel regulator is hooked to the hat or blow pipe, (before the carb)