All: I took my 70 GS 350 out for its longest ride to date since my engine swap last season. The engine is a 73 350 4BL all stock beyond a mild cam from TA. When we freshened the engine last year, we sourced a new 350 front cover and oil pump from Rock Auto. I believe we used the middle tension of the three pump springs provided. No problems. Question: how much pressure should I expect at idle once the car has been driven? (warmed up at 185-190 degrees) I run 10W-30. I have been running the car with a rule of thumb 1lb per thousand RPM. However, should I be concerned with 7-8 lbs at a stoplight after the car is warmed? I may be paranoid. Which spring is ideal for a nearly stock 8.5:1 engine.? Should I run different oil? Thanks in advance.
10 psi per 1000 RPM. 7-8 psi at idle is low, but it won't hurt anything as long as the pressure climbs. You can try 10W/40 and see how that affects pressure. Oil pump end clearance is really important, so are bearing clearances. What you don't know can affect hot oil pressure.
Under 10 idle is low. Yea rule is 10 per 1000 but at idle should be 15 or better. Lower rpm less spray/splash onto moving parts. Did you plasticigauge bearings? Did you replace cam bearings? . That's the biggest question is cam bearing. It is the first place oil pressure feeds . If bearing is worn you lose right there. I would change front bearing on cam to the TA back grooved. Better oil control. . But first as Larry mentioned is oil pump clearance must be measured. But pretty sure the cam bearing will help either way. Also did you get a new oil pickup tube . You can use the 76 and up 5/8 pickup. That will make it easier for oil pickup to pump. Personally I would yank heads and shave .040 for an actual 8.9 compression vs the actual 8.2 you should have. But I'm alway looking to bump hp up.
Thanks Larry. I meant 10lb not 1lb. Lot's of pressure on initial cold start up with choke on. Also plenty of pressure underway. I have heard about the TA boost plate. Will that impact anything I describe given the pump cover and gears are new?
Yeah, I knew you meant 10 psi. Like I said, what you don't know can hurt you. The end clearance of the pump gears are critical to hot oil pressure. Preferred end clearance is .002-.003. The gear faces should sit above (.002-.006) the gasket surface of a timing cover in good shape. The gasket determines the end clearance. As an example, if the gear faces are .004 above the gasket surface, using a .006 gasket would give you .002 end clearance. TA performance has an oil pump shim kit to dial in your end clearance. The timing cover heats up and expands the clearances. In addition, oil viscosity drops off as the oil gets hot. Higher pressure when cold is the norm. When everything heats up, that's when you see pressure problems when clearances are excessive. Using a booster plate is a good idea, but you still have to check the end clearance. http://www.taperformance.com/proddetail.asp?prod=TA_1704 http://www.taperformance.com/proddetail.asp?prod=TA_1510
Larry: I just spoke to a very helpful rep at TA. I ordered the booster plate as it seems like a sound near and long term investment. Based on my discussion with TA, I will order the shim kit once I install the booster plate and new gaskets and determine if clearance is less than preferred. TA also mentioned trying 10W-40 at my next oil change. Thanks again.
If its any consolation I had very low hot idle pressure before my cam swap. Sometimes down to 5 or so! And never really went over 25 if I remember right. Since it was open I installed the front dual groove TA bearing, booster plate and adjustable reg. With stock type spring as suggested. and now I'm near 18# at warm idle and never below 15# and nice and high while cruising. Sent from my LG-H830 using Tapatalk
Yes. More and/or less I suppose. TA recommended I use my priming tool to be certain the gears are not bound on the new plate before starting.
Matt: Your new conditions are ideal expectations per my conversation with TA. I am glad it worked out for you/ Was the cam bearing difficult to swap?
If you put 120 weight gear lube in you might have 40 psi at idle but I would not suggest it. Point is this has been covered before. Using thicker oil just to boost the gauge reading does NOT provide more oil to the engine. In fact it could reduce the usable amount of oil available to the bearings as you are trying to force something bigger thru the same size hole. You are only dead heading the oil against the front cam bearing. If that bearing is worn out as it commonly is whatever oil pressure/volume you have is bleeding out right there before it gets anywhere near the rod and main bearings. Changing any springs supplied with the pump/cover won't help low pressure. They are for the pressure relief valve. Which releases excess pressure.
Hey Steve: Are you against 10w40 as something to try? Btw - I need some brake stuff for the 73. Can you help?
Not against trying anything. Just saying thinner oil will get to the bearings faster and work just as well if the bearing clearance is correct. If you have worn bearings with .003"-.004" clearance maybe thicker oil might help lube them. My point is don't use thicker oil just to raise the pressure gauge needle. All you're doing is deadheading the oil flow and backing it up to the gauge. Not helping the bearings at all which is the entire point of an oiling system. I can get X body brake parts as well. PM me with what you need.
These guys are a lot smarter on this subject than I am. I went through a lot of this on my stock 73 350. I changed oil filters from a FRAM to a Purolator and gained several PSI. It never goes below 10psi hot after driving now. Food for thought.
Thanks for the tip. I ordered the TA booster plate and will give it a try. I'll change the oil while I'm at it and use 10W-40. I'll try a different filter as well since I don't think it will hurt. I think I have a Delco filter on it currently.
As Steve said, thicker oil just makes the gauge show more because of where the sensor is located (front), and may hamper proper oil pressure to the back of the engine. I wouldn't go any thicker than 40 for sure, but if you can get satisfactory pressure with 30, all the better. The booster plate is something I'd recommend even if the timing cover was brand new and had good oil pressure without it. Why? Because over time, the steel oil pump gears can wear into the aluminum housing causing excessive clearance, which is exacerbated when the engine warms up and the aluminum expands, creating excessive clearances which harms oil pressure/volume. Using a booster plate serves as a type of oil pump girdle which holds the clearances in place better for a long-term solution to oiling woes. The adjustable oil pressure regulator is also a good idea to keep your pressure where you want it. Get your clearances where you want them with that booster plate, adjust the regulator to get your 10-15 PSI per 1,000 RPM, and you'll be set! :TU:
I have the TA cover with the larger gears with the adjustable pressure setting and I have never worn out the distributer gear or the cam gear. But I did have TA set it up for me and the holes in the cover are bigger to the motor and the engine has larger oil hole to the pan with a pickup that is square and is the same one used on the 455. That has been in there 20 years now, I run the MSD Dist. and the 6al. I run 4qts of 10-30 Mobile 1 and 3 qts of 15-50 Moblie 1 synthetic. This will show 1 qt low on the stick. I have a large oil pan with baffles to keep the oil at the bottom. I get 55 lbs of oil pressure at 3000 rpm, 70 at 6 grand, 18 at idle in gear at 700 rpm. So I think if you want to run the bigger gears the engine and the timing cover Must have the feed holes bigger to accommodate this set up. oil galleries are bigger too. Plus I have an index ground crank and it is cross drilled. I would run synthetic oil in the engine and I think you will have minimum wear. Mobile 1 Extended performance is my preference. :bglasses:
