oil pressure (yes again)

I've been running a TFX96 combo for the last few years and always had good oil pressure. (std Pleuger 2 stage pump, 50wt oil, 90lbs hot idle, 130lbs on the hit, 130lbs at the finish line, no bearing problems). Recently put a Brad Billet in and the oil pressure drops of as it runs. I've run two different blocks, two std pumps and one with an external adjuster screwed right in, 50wt oil and 70wt oil. With the jacked up pump and 70wt oil I had 190lbs on start up but was down to 40lbs after the burnout. Pressure comes up to 70lbs at stage rpm, then 120lbs on the hit but dropped of to about 75lbs at the finish line. I've had afew people tell me the Brads do this. Just doesn't sound right to me. Any ideas, comments. Thanks Murray

 

Make sure you have the hollow roll pins in place in the holes that run from the main bearing to the cam bearing, you could be losing a lot of oil there. Also make sure you are getting good return from the lifter valley and cylinder head areas if using a wet sump, you might just be running out of oil. I believe these blocks were made for a dry sump, you need a tank that holds 18 or 19 litres of oil so you still have lots of supply after the motor has run for a minute or so.

If you are running a dry sump, I highly recommend that you drill some more holes in the lifter valley somewhere. Remember the old KB's used to have 4 long slots that allow oil to flow into the pan, there was a reason for that.


Ken Sitko
Sitko Family Racing TAFC

 

Where are you tapping in for oil pressure. You should be tapping in at the oil pump.

 

I hook my oil pressure to a port on the side or back of the block, as I want to see what the real oil pressure is in the engine, not in the pump.

 

Make sure you dont have a steel braided oil line from the pan to the pump. It will suck closed and cause things just like this.

 

The Brad billit block does not have tapped holes in the side like the KB because the oil passage has been relocated and rerouted. I have seen other brad blocks do this if you are trying to get oil pressure from the top back fitting, this is the last place to receive oil on a brad block, does not mean you dont have oil press.

 

Its got a dry sump, 20 litres of oil, pressure comes of the manifold on the oil pump. Will tear it down later in the week and look into the roll pin deal and see if there is any restriction in place. Yes I'm using -20 braid on the inlet side, but have been doing so for the last 7 years without problems. The hose on the car is only 6 runs old but I will probably put a Teflon/Kevlar one on anyway. Thanks Murray

 

Doug, the TFX and the Brad are both very similar in the routing of the oil passages (unlike the KB) which is why I cant work out where its all going wrong. What works in a TFX should work in the Brad. You've just got to love Drag racing some days. Thanks Murray

 

Gee, I would hate to drill holes in a beautiful brad block. Sorry Ken. Your set up is very similar to the set up I am familiar with. I would be checking to make sure the pressure relief valve is not stuck in the bore or the spring is broken. Then do a visual on the pump components first. I don't remember any roll pins in a brad. Big oil passage to the main with bearings to match. Any chance a clip has fallen out exposing the o ring and plug. Now leaking internally. Maybe stuck behind the cam gear. Should have 70-80 lbs backing up with 60 weight. That is my 2 cents worth.

 

Murrey, from what you saying it sounds like the motor loses oil pressure as it heats up. I spent a year tearing out the small amount of hair i have left with the same problem!! changed pump, oil, pan,bigger spring, put more oil in(20 quarts in wet pan) nothing worked, the data showed that oil pressure started to decrease 2-3 seconds into the run. It seems the temp of the motor heatsoaks from the heads down into the block (mains) and the clearance grows enough in 2-3 secs to start lowering oil pressure all the way to the line!!
The cure, line bore size, line bored it to min size, BINGO problem gone, so i suggest you chech your line bore size

Dave Wilson

 

oil pressure ?

I ran a TFX92 in my AA/Fuel altered for 11 years ( the same motor ) , used a
Keith Black Billit oil pump, wet sump, 13 quarts of 70 wt. Lucas Nitro oil and 15 oz. of Justice Brothers HDV additive. The engine idled at 110 lbs. and 160 on the run, I've never had a bearing problem.I also have Polymer Dynamics in Texas coat my bearings. I brought a new Brad Billit 2 years ago and used my same KB oil pump as I ran on the TFX.
The oil pressure is identical as it was on the TFX. I think you should be looking in other places ! Are you getting oil to the rocker arms ? Did you call Brad and ask him?
Hope this helps.
Ricky