Some flathead ?'s

Hi, I have just rebuilt my 1951 8ba flathead in my ford f-1. It has a stock crank, edelbrock heads, max 1 cam, hollow johnson adjustables, stock distributor and the stock holley single 94 carb. It had to cracked cylinders before i rebuilt it, surprisngly it had never been rebuilt since the day it left the factory. Its running a t-5 ****** with a stock rearend with 3.92 ring and pinion. Anyways it runs great but im only making about 5-10 pounds of oil pressure at idle. It goes right up as soon as i give it some gas. The motors very quiet and i just got i running in the past weekend with my dad. We put 20 miles on it if that. It runs great but my fathers all worked up about the oil pressure. What do you guys think? Is it two low? If so what can i do to fix it?
I plan on driving the truck everyday to school when i turn sixteen.

Flatheads Forever

 

This question belongs on the main board, questions involving the operation of the board belongs in the Q&S forum.

 

Nothing wrong with 5-10 lbs at idle.

 

I have an almost identical engine, and expressed concerns about low pressure at idle, but the general concensus is that is about normal.

Drive it!

Rich

 

thats normal...i wouldnt worry about it.

 

thanks alot guys i appreciate the help

 

For an 8BA 5-10 at cold idle on a fresh build IS NOT OK!! 10# at a hot idle is BARELY OK, 15-20 is normal. And you should have 50-60# at over 2K all day long.

First of all be sure the gauge is accurate.

What oil pump is in there? Ford went to helical gears late in 49 which greatly improves pressure; it is the same as the Melling 19 sold today. There is always a possibility your engine was swapped in years ago from a 49 or an older pump was put in at some point.

 

Did ya change the cam bearings when you rebuilt it? Some people do, some don't. You should! What oil are you breaking in with? Any filtration beyond stock? Finally, how high quality gauge are you running?

Flatman

 

What is it above idle? What oil do you have in it?

 

when I worked at an engine machine shop the general rule of thumb was 10psi per 1000 rpm.

 

He didn't say anything about pressure at cold idle.

Mine runs about 10 at hot idle, and 40-50 at speed, and was told by several flattie experts that this is a tad low, but fairly normal.

Rich

 

I am running straight 40 weight oil and i have replaced every part in the engine except for the crankshaft and rods but i had them line bored, cut, and rods balanced. The oil pump is a melling pump for the 8ba from reds headers. It is not a high volume pump. I got all my engine parts from reds except for all of the bearings which were supplied by the machine shop. The machine shop did put the rear cam bearing in wrong(they didnt line the rear fuel pump rod hole completely up but it its more then 3/4 lined up, its just enough to stop the rod from going in) which forced me to put on an electric fuel pump which was fine because i needed it for when i change the carb and distributor for a 4 barrel. I put the blockoff plate from Offy on the intake and I also put the plug from flathead jack in the fuel pump rod hole but, there was a tiny whole in the fuel pump rod sleeve for oil to flow through. It was definately there from the factory( I think it could be in their because its a truck motor?). Could this be causing my oil pressure problem? If so could i cut the old fuel pump rod to size and sit it on the bearing in the fuel pump rod sleeve and put the flathead jack plug back on the whole thus restricting the whole in the sleeve creating more pressure? Thanks guys.

 

Here is a link to an older thread talking about my engine..

http://www.jalopyjournal.com/forum/showthread.php?t=88595

 

Some engines require the plug to maintain pressure and others dont. Ive never nailed down any pattern to dates or anything else. I always use the plug even if just to keep misting from sludging up the pump stand void.

Someone mentioned seating in the rings which is best done with a 30W ND for 200-300 miles or so. Then change oil/filter and run a 15W40 diesel grade oil such as Roetella, Castrol Tection, etc. The latest regular oil with the SM rating is bad news for older engines that require zinc additive to minimize cam wear.

Run it until the rings seat but keep a steady eye on the pressure at all times and I hope you are using an accurate gauge, not the stock one. If the idle pressure goes down then stop running until the cause is found.

BTW, what sort of oil filtering system are you using? If it is full flow DO NOT use a Fram filter as they WILL reduce the pressure.
If it is the original canister type be sure the line restrictor is installed. With it missing you will be cycling too much oil from pump to canister and back to pan and starving the rest of the engine.

A flathead CAN survive with 5-10# at hot idle but that level is usually a sign of a tired engine, not a fresh build. We are talking 8BA here, not the earlier style and some with minimal experience dont know the differences.