Strengthen your faith in God's word

Acts tells us that salvation is only through Jesus Christ, however, that name was not known in the Old Testament. So how were people in the Old Testament saved?

With this question someone is going to give the answer that you are saved in the Old Testament by looking to the Cross, and in the New Testament by looking back to the Cross. That is not true. In the Old Testament they were looking for a Kingdom not a cross. There was no second birth or spiritual circumcision. A better word word for salvation in the Old Testament would probably be "safe" instead of saved as we think of it. The reason being that no one went to Heaven. Not one person who died went to Heaven. They were all in the center of the earth at a place called paradise or Abraham's bosom. When did they get out of there? When they believed on Jesus Christ. Jesus descended into the heart of the earth to lead captivity captive at the time of His death (This is just one thing that He accomplished while there). Jesus preached to them the Gospel(I Peter 4:6), which is the death, burial, and resurrection.
So, how was a person safe in the Old Testament? Well that depends on what time period you are speaking of. The most commonly thought of is the period of the Law. How was someone safe during this time? The answer is that He belonged to the nation of Israel. What you must understand is that in the dispensation of the Law, eternal security did not belong to an individual, it belonged to a nation. I will even take that a step farther and say that it was possible to step outside those bounds. Several times in Exodus through Deuteronomy, the Bible says a man can be cut off from the nation, thus ending in "loss of salvation."
Fast forwarding to the New Testament though, salvation and eternal security belongs to the individual. Just be clear on this fact, works has nothing to do with salvation in the New Testament. Salvation is by grace though faith. That includes getting saved and staying saved. Just a side note: Faith is only mentioned twice in the Old Testament, as compared to over 200 times in the New.

this is a further question and comment, rather than a solution.

what does Acts 17:30 play into this? when is the "times of ignorance"?
Acts 17:30 - "And the times of this ignorance God winked at; but now commandeth all men every where to repent:"

Was there anything about rule by conscience?

If during the time of Law, Israel could be saved and anyone who joined with Israel and kept the commandments, what about other nations? surely not everyone knew of Israel or their laws. were they then judged by conscience?

God "winking" can at the very least be taken to mean that he doesnt use the same measure as punishing rejection of Jesus (which would be damnation.) What exactly is "winking" though, according to context and comparing scripture with scripture?

The name of Jesus had not been revealed yet because they were in the dispensation of the Law. We are in the dispensation of Grace. Those are two different plans of Salvation. In the Law the Hebrews did rituals for the forgiveness of sins. But now under grace, we have Jesus, our high priest and perfect Sacrifce.
The psalmist is speaking prophetically of the incarnation. Notice verse one says: "the prophecy". God had not been manifested in flesh YET for our Salvation. Jesus is THE God Almighty manifest in the flesh. "What is His name and the name of his Son?" The bible is telling us that the Father has a name, and the Son have a name. This name is JESUS, the only name under heaven given to us for Salvation. Compare this verse to John 3:13.

They weren't saved. Saved is a distinction of the Dispensation of the Gospel of Grace that was given to Paul. We are saved by grace through faith in the shed blood of Jesus Christ plus nothing - minus nothing. But because we are saved and we use the word "saved" people have a bad habit of assuming that everything that is that way for us was that way for them and you hear this rationalizing in the mind come out of the mouth in the form of phrases such as "as we are looking backward at the cross so they were looking forward to the cross" which, of course, is nonsense and trifling with the words of God.

If you just read the Bible with this in mind you'll find that the Disciples had no idea of the cross even though Jesus told them about it incessantly.

Mt 19:24 And again I say unto you, It is easier for a camel to go through the eye of a needle, than for a rich man to enter into the kingdom of God.
25 When his disciples heard it, they were exceedingly amazed, saying, Who then can be saved?

The disciples had no idea of the cross.

Peter had no idea of the cross.

Mt 16:21 ¶ From that time forth began Jesus to shew unto his disciples, how that he must go unto Jerusalem, and suffer many things of the elders and chief priests and scribes, and be killed, and be raised again the third day.
22 Then Peter took him, and began to rebuke him, saying, Be it far from thee, Lord: this shall not be unto thee.
23 But he turned, and said unto Peter, Get thee behind me, Satan: thou art an offence unto me: for thou savourest not the things that be of God, but those that be of men.

How can this lie be perpetrated for so many years?

Easy, they all go to the same Bible Seminaries.

If a man in the OT lived his whole life doing what the law told him to do that would never save him. He could be blameless as Paul said he was but still go into hell if it wasn't done by faith in what God told him what to do.

As far as salvation in the OT being a national salvation what about this ...

Eze 33:10 ¶ Therefore, O thou son of man, speak unto the house of Israel; Thus ye speak, saying, If our transgressions and our sins be upon us, and we pine away in them, how should we then live?
11 Say unto them, As I live, saith the Lord GOD, I have no pleasure in the death of the wicked; but that the wicked turn from his way and live: turn ye, turn ye from your evil ways; for why will ye die, O house of Israel?
12 Therefore, thou son of man, say unto the children of thy people, The righteousness of the righteous shall not deliver him in the day of his transgression: as for the wickedness of the wicked, he shall not fall thereby in the day that he turneth from his wickedness; neither shall the righteous be able to live for his righteousness in the day that he sinneth.
13 When I shall say to the righteous, that he shall surely live; if he trust to his own righteousness, and commit iniquity, all his righteousnesses shall not be remembered; but for his iniquity that he hath committed, he shall die for it.
14 Again, when I say unto the wicked, Thou shalt surely die; if he turn from his sin, and do that which is lawful and right;
15 If the wicked restore the pledge, give again that he had robbed, walk in the statutes of life, without committing iniquity; he shall surely live, he shall not die.
16 None of his sins that he hath committed shall be mentioned unto him: he hath done that which is lawful and right; he shall surely live.
17 Yet the children of thy people say, The way of the Lord is not equal: but as for them, their way is not equal.
18 When the righteous turneth from his righteousness, and committeth iniquity, he shall even die thereby.
19 But if the wicked turn from his wickedness, and do that which is lawful and right, he shall live thereby.
20 Yet ye say, The way of the Lord is not equal. O ye house of Israel, I will judge you every one after his ways.

You will stand on your own.

When Jesus said ...

Joh 14:6 Jesus saith unto him, I am the way, the truth, and the life: no man cometh unto the Father, but by me.

... He meant it and that goes for Adam and Abraham and David and anyone else in the Old or New Testament Books. You must have God's righteousness to stand before God and that is accomplished by faith in the OT as well as by faith in the NT its just that now we are saved and are safe whereas back then (and in the future Tribulation) they weren't safe until they were dead.