[Cammer-6]

Originally Posted by TheSilverBuick

*Full disclosure, I haven't yet built an engine*


Between 10 and 15 psi, I'm going to shoot for 12psi.


The stock main oil pressure was 30psi, I plan on bumping that to a full 60psi with 10w-30 oil if I can, while maintaining the lash adjuster galley at 12 psi constant.

I would go lower with that pressure and increase only if you get premature valve float and or hear ticking
Just curious where you came up with that pressure as a target

[scooter1966]

for this what is the normal set up in the head, do you just use a sealed tube in the head or just completely block off the port in the head and drill the cam housing and tap the location and run straight from the oil supply line before the regulator?

[TheSilverBuick]

From my understanding it was the target pressure by GM.

The cam still needs oil. I've been told a straight tube can be used, but I'm on the fence about that. Figuring more oil will go to the cam with the crimped tube and higher main line pressure, and the restriction will keep more pressure on the bottom end. On one hand I want to keep pressure down in the bottom end, the flip side is the oil holes in he cam lobes are pretty good sized and probably would benefit from more volume than even the extra pressure would provide.

[Cammer-6]

if you use a straight tube the front lifter galley wont be supplied the same as rear,or vice versa if you feed from the front.
actually the feed holes in lobes of cam are quite small and can plug up if proper maintenance isnt observed

[Formulabruce]

This is a great thread! ...And one of a few good reasons to run a stock oil pump. Many folks take the more is better route with oil pumps, like High pressure/high volume, etc..
A stock Melling pump with stock spring works fine in 99% of applications.
I have taken new pumps and put old springs in them a few times to address oil issues, leaking, over pressure etc.\
I ran external once on my OHC, but took it off when I got the motor out and took off the hi pressure crap. My Grandfather told me a few times........
" Pontiac paid for the research once already, why are you doing it?"

[GTOWAGON]

well pontiac realy never got it right excess lash adjuster pressure is the major cause of cam failures in the ohc6

[GTOWAGON]

so if you feed the lash gallery from the rear of the head what do you do about the factory feed tube, does the gallery need to be fed from both ends of the gallery.

[Cammer-6]

use an hourglass shaped tube

I have seen alot of feed holes eroded and obviously feeding more oil than designed for.
I would say major reason for failure is lack of maintenance,ie dirty oil,plugged up cam feed holes

[scooter1966]

so with either set up, factory or external line, what is the best type of oil to use? will it be better to use a very thin synthetic? what about the "new " oil with out the ZDDP additive, do these motors need this additive, i know there are no lifters but they were made back when this type of oil was used.

[Cammer-6]

I would run dino valvoline racing oil. It still has the additive
30w is fine for most,but take care if you live in cold climates,
and preheat or use out of a warm garage.

[Formulabruce]

Originally Posted by Cammer-6

use an hourglass shaped tube

I have seen alot of feed holes eroded and obviously feeding more oil than designed for.
I would say major reason for failure is lack of maintenance,ie dirty oil,plugged up cam feed holes

X2 I agree

[scooter1966]

is there anyone who has been successful with the factory oil system ( non external line, and psi) and 6k rpm consistently with no cam failures? any suggestions possibly dual oil filters or 2500 mile oil change?

[camerjeff]

I have run the factory oil system in all of my cars, I have never experianced a Cam failurre, and I used to shift the 230's at 7000 rpm on the street and track. I always ran 10W30 oil and the stock Pump and upper end restricter.
Things to look out for on the 230's is I have found several engines were the oil feed holes did not match up properly between the head and block, they were almost 1/2 hole off. Alittle fileing and gasket matching cured that issue. And as others have said regular oil changes, and watching the oil level is a must. Clean Oil is a must on these engines.

I could go into a long rant about my thoughts on the cam shaft wear issues they had in 66 & 67 but that would be long and boreing.

Also be aware that 250's with stock valve springs will not rev much more than about 6200 RPM, they actually put in weaker valve springs that cause the valves to "float" around 6000 RPM to limit warrenty claims and worries with the longer stroke cranks in the 250 engines.

[Cammer-6]

Jeff the counter sunk area around the oil feed tube is made to help with the misalignment

[scooter1966]

after messing around the garage this week and seeing the recent post from thesilverbuick's progress. I had a thought to the oil pressure difference in the engine.
I noticed there is a port behind every lash adjuster, and wondered if possible could you open each one up slightly in order to run higher oil pressure though out the engine. This way you can still use the factory hourglass oil restrict tube. I would think you would still get the same volume to the Lash adjusters but the larger ports would bleed off the excess. the rest of the engine will still receive the same amount of oil as well. Now alot of testing will needed to be done to make sure the port size will be correct.

Any thoughts to this?

[TheSilverBuick]

Yes A LOT of testing would be required to get the bleed off port right, and I'm not even sure how much oil actually flows through those ports in normal operation. They looked like to me they were designed to keep the lash adjuster seated and in the event they lifted the oil pressure wouldn't keep the adjuster up because it would then bleed into that bypass port and drop the adjuster back down. All the adjustment is supposed to be in the hydraulic upper part.

I could be wrong, but I think they are simply engineering safety features and won't have any direct influence on lash adjuster galley pressure. They are already way too large relative to the orifice tube size to do proper flow/pressure metering of the lash adjuster galley.


On my "good" engine, I will probably not drill the head and go more conventional like the picture Jeff posted and feed the lash adjuster from the rear galley plug. But first I need to see how much room I have at the firewall. I have little qualms hammering a firewall, but I have to make sure it doesn't impact anything else.