Ok this may be long so hang with me here. Im trying to figure out what all is wrong with this motor. Its a friends 1970 351C 4v in a mustang. It was "supposedly" rebuilt by a good mechanic, but Im not seeing results lol. First off is the oil pressure. Im not sure what weight oil is in it, but when first fired up it has about 60psi , about 10 mins later its down to 35-40 at highway speeds. After that its about 20 psi at highway speeds and 8-10 psi idle. Also after a lil while of driving it has a terrible ticking in the top end which I think is due to the low oil pressure. Temperature wise it runs around 180, but jumps to 220+ if sitting somewere over a few mins. Other than that, I think the flywheel is missing a few teeth due to the grinding when you crank it sometimes. To add to the list of problems, they had the timing tight enough it would barely crank , so I adjusted it back some and it was fine, then someone adjusted it back and now this time around when you get on it , it sounds like the valves are gonna come out they rattle so bad. Im gonna guess spark knocking? Also seems to smoke greyish black out the drivers side pipe when revved a lil. I don't know the history on this engine, or even if it was rebuilt, all I know is it's an automatic car, that they supposedly put somekind of aftermarket cam, with headers, 3inch exhaust , stock manifold and a 3.25 rear. Ive been asked to fix this car, but don't know were to start. I do know one other thing, I was told at one time number 7 cylinder wasnt firing and the guy working on it said it had broken the rocker arm on that cylinder, dont know if it was the intake or exhaust though. Btw, what would cause the oil pressure to go down when you rev it up and then go up when you let off? They are brand new guages so I hope they are not bad. I think this is all for now, may add on later when I figure out were to start
Thanks ahead of time for any help

 

the oil pick-up screen might be too close to the bottom of the pan, or the screen could be covered with lint from shop towels. low oil level will also cause the pressure drop and rise syndrome. i'd start with as complete a diagnosis that you can do, compression test, read the plugs to ID which cylinder(s) is burning oil, establish accurate TDC on the balancer and put a timing tape on it so you can find out what the distributor is doing for total timing. what kind of dizzy is it? set the timing for a reasonable total(34-42) and a reasonable initial(8-14). Clevelands use a specific thermostat, if the wrong one is in there it could allow some higher temps. there is also a very important brass restrictor under the thermostat that gets removed during "rebuilds". the stat and restrictor work together, without the pair who knows what could be going on in there? the advanced timing could be causing the high temps too, or the fan shroud missing? after you ID the oil pressure problem, tear it apart and find out what it's made of. closed chamber heads? ID the cam and make sure it's not too big if it has stock rockers.(around .540 lift) check ALL clearances and make repairs. get the heads done right. sounds like fun to me! BTW, if it has stock or replacement 2 piece valves, get rid of them! make sure it has 1 piece valves or he might have a "window block" pretty soon! i got lucky and only had a "window piston"
http://raceabilene.com/kelly/hotrod/wreck.html

 

Its a stock dizzy and the oil level isnt low, so Ill start with the plugs and compression test and see what I get. There is going to be some pretty upset people if I have to tear this thing down.

 

i'd pretty much figure on dropping the pan right away to find out what's up with the pick-up screen. that car might have a removable crossmember that'll allow you to not lift the engine. you can pretty much ID the cam using the timing tape and a dial indicator on the valve retainer. smoke from one side, good luck! motor in a can?

 

Sorry for the long delay , been busy, but I did pull the valve cover off the side that was making that loud ticking. The 2nd rocker arm from the back of the motor had the push rod shoved clean thru the cup, busting the rocker and and the next rocker up was really lose, come to find out the pushrod was bent so bad you could hardly pull it out. Now what does everyone make of this

 

I would guess the oil pressure is low because of to much rod and main bearing clearence.

I think you stated this had a bigger cam installed, depending on how the heads were set up, thee may be some binding in there causing the push to do that. Parts don't bend for do reason, some sort of resistance.

 

sometimes the lifter can jump out of it's bore without the pushrod in place, then you'll have an enormous internal oil leak that would make it near impossible to make any oil pressure. can you see down in there to verify that the lifters are in place?

 

Lifters look to be in place, im thinking maybe its the cam, no 1 has told me the specs, cant find the cam card, but you could tell the car had a bit better than stock cam in it, when you heard it run.

 

I'd ask the guy what he wants out of that motor and what he is willing to put into it to get it there. If your working on it to get it on the road asap I'd better understand your piece work getting into it, but if he wants it right- given what you've found thus far....

I'd want to yank it out where I can get to it easy on my stand and check everything like whether the valve springs match that cam and go all the way down to the rod and mains for clearance. The cleveland isn't the best oiling machine as it is so i'd want to know that everything is right.

That probably isn't this guys idea though per the fresh rebuild so I would pay attention to the springs and rods first and go from there. My $$ is on the springs causing some of this havoc and would not trust the build if that is so. It would make sense that the pressure would get crazy as more pressure is put on parts that keep the oil path contained. Also- has it been hotrodded heavy since the build- was it broke in right yada yada.