Yesterday my machine shop tried to measure the cam, installed in my 350 cui engine (1970, heads #11, c.r. 8.8, 4-bbl intake and carb, headers). First thing: Timing chain was stetched (about 12 °), so measuring will be inaccurate. We decided to pull out the cam. It was a crane powermax H-260-2. The cam shows wear at the top and the lifters are very, very easy to compress (so they are bad). My machine shop told me, that this came from wrong setting of the valve train (he told me, if he installes a new cam, he measures every valve/lift and put shims under the pivot balls or rocker studs to get the right valve setting). The next thing: the cam bearings show some wear too and should be changed. I don´t want to pull out the engine and pay a lot of $$$ to change the cam bearings (especially i don´t know the condition of the other parts (main bearing, pistons, crank). So i decided only to put in a new cam of crane H-260-2(with the old bearings), new lifters and a new timing chain and then set the valve train to correct specifications. And use a good HD30 oil (for good oil pressure) with ceramic additive. So i could drive the car this season (may be longer or shorter), until it is completely scrap and then build a strong 400 for the car. So what is your opinion ?
Sounds like you did the right thing. I would not spend another penny on that 350. Good luck in finding a 400(or 455) with some good heads. It is the way to go. Jim
I am with Jim on that idea, too. The 350 is still a good motor, but for the amount of work you will need to do, a better motor would not cost you more except the additional cost of the cylinder block and crank shaft.
In the mean time, you can drive and enjoy the car as it is. with the new cam, lifters and timing chain. The cam bearing wear is not a super-critical problem, but be very careful with your oil pressure. Make sure you watch it closely.
Especially at idle when hot. I'd consider 10W-40 or 20W-50 to keep the oil pressure above 10 psi if you need it. I've found that a straight weight thick oil is hard for worn rings to scrap off the cylinder walls when the engine is cold.
Last week the new cam and timing chain were installed. New oil filter and new SAE 30 oil with ceramic additive were added too. The car runs very good with a lot of low end torque. But the oil pressure is very low; about 5 psi at idle when hot and about 30 psi at 2500 rpm (sunpro mechanical gauge with plastic tube and no air in it). The idiot light didn´t turn on (i think it turns on under 5 psi). Now i ordered a new melling hp-oil pump (60psi) and will install it next week with engine in the car. Will this solve my problem a little bit?
It should help, since the oil pump will also wear as the engine does. When the pump is removed, also change the rod that drives the pump from the distributor. It's a relatively "small" investment. If not, make sure the "ears" are not starting to twist.
There are a lot of places on the motor that can lead to low oil pressure. You are not solving the problem with a new pump, but you will be putting more oil through it, which will help for the short term. Also go to a heavier oil, like SAE40 or SAE50. Anything you can do to keep the pressure up will help.
Did you order a high pressure or a high volume pump? A high pressure pump mainly has a stiffer spring on the pressure relief valve, while a high volume has taller gears and will make up for the extra oil that you have leaking inside your engine, and is what would help you the most. I found cam bearings to be pretty important in maintaining idle oil pressure.
not sure of your climate over there, but i'm with TOHCan on the multi-viscosity oil. i would go with 20w50. straight weights are okay when it is always really hot out, but a 30-weight is too thin for you, like Q said, and a straight 50-weight might not be nice to your engine on startup.
Today i installed the new oil pump. 10 hours of hard work (engine in car), but oil pressure is very good now: 20PSI@idle when hot, 60PSI@3000rpm. The old oil pump screen was very dirty with a lot of gasket parts.
