So for anyone who dosnt know let me bring you up to speed. I have a 95 f150 that had a blown 302 in it. i swapped it out for a reman 351w from Mabbco Motors. I have been having issues for months trying to figure out what is wrong and why the truck wont start. I have spent every extra dollar out of my paycheck replacing parts to the point that every single part on the engine is brand new from the sensors to the bolts, valve covers to oil pan. Nothing i did would seem to help though the truck would kind of try to fire on startup.

Today I found the issue. something I should have tested months ago but put my faith in the fact that I was buying a motor from a reputable place. The compression on all cylinders is between 106 to 110 psi ... I'm screwed. The reason I didnt build my own motor was because I dont know how to deal with these things. what the heck could be wrong???? ill call them on monday but I am very close to the end of my warranty because it took so long to replace every other part.

 

something simple first. have you checked your timing? if the valves aren't opening/closing when they are supposed to,you will get low compression numbers and the motor won't run. just a thought before you pull the motor for no reason.

 

Was that a wet or dry compression test? If it was dry, squirt a little oil through the spark plug hole, then do a wet compression test. If the numbers come up, it's rings. If the numbers don't come up, it's valves.

Now, about rings. It's a reman motor with new rings that most likely haven't been properly seated, unless they do a break in run before shipping.

 

Yep, you must be dead certain those are good, accurate numbers before you what is essentially start telling somebody they don't know how to do their job! Maybe you do, but not everybody knows how to correctly check compression.

For example, engine warmed up all the way. All plugs removed? Bit of engine oil on the rings? Accelerator floored, carb butterfly's all the way open? Charge battery up between a series of tests on all cylinders, average, divide by zero, and all that.

A whole bunch easier than compression testing, hook a vacuum gauge up on it and see if the timing is close and it's drawing good, valves and rings are good, etc. good test for the other guy's rebuild. Just do a few tests before getting all spooled up and throwing in the towel, you're probably fine. The rebuilders don't want to see the product come back.

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so i cant warm the engine up because it dosnt run, but i did just drain the oil and with it came a slight smell of gas. so i am guessing the rings have not seated yet.

the issue may have been due to the fact that the first dizzy i put on was bad and so i would have been pushing a lot of fuel through the rings. this means they wouldn't have seated yet and they are probably nice and clean. i pulled all the plugs, put 2 squirts of oil into each cylinder, filled with a good 10w40 to see if i cant get them to seal. I cycled the engine a few times by bumping the starter, then put the plugs back in and bumped it a few more times to try and drive that oil into the rings.

i tried very quickly to see if it would just fire and it didnt so i am going to leave it for a while and let that oil sink in.

if this dosnt work is there anything else i could squirt into the cylinders to try and get them to seat? maybe a spray of some kind to get goo coverage?

 

lol. just caught the divide by zero joke.

 

You need to start from base Zero, then. If it won't start it sounds like timing, as mentioned above. Find Top Dead Center (TDC) on the number 1 cylinder and make sure the rotor is pointing at the number 1 plug tower, the wires and firing order is correct, etc. if that's all correct try advancing the distributor body. May have to reinstall dizzy if it's not quite indexed properly.

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Building an engine is easy, the rebuilder more than likely did it correctly.
No matter what anyone says, 100psi per cylinder, on a new engine or used, or old, or newly rebuilt with 0 hours on it, is fine. As an example, my 13-1 racecar motor only has 100psi, and makes 540hp.
You need to verify spark, fuel, and air. It sucks, but you need to start from square 1.
Verify fuel pressure with gage, at rail. Buy a cheap oil pressure gauge and kit, they normally have the correct 1/16" fitting that screws into the rail.
It's unlikely the cam is off. Air is getting in. You can check it by pulling valve cover and seeing rockers move.
Spark is last. Does it even spark. How well. Is the distributor new or used. What color tfi module is it. Pull number 1 plug (passenger front) and stick a coat hanger in it, turn over until piston is at the top. Verify that the harmonic damper 0 mark lines up with the pointer. I've seen some outer rings rotate on the hub before.
Pull distributor cap and verify rotor is pointing to #1 wire. Even if it is, it could be 180* out. It's tough to verify both valves are closed with passenger valve cover on, and the plenum makes it hard to get it off. But if it's not running or trying to run now, bring engine 360* around again to zero, and put distributor on 1 again (or just turn dist 180*).

 

I guess I missed this in your other thread but this cam isn't gonna work in this application and it is likely the reason your compression numbers are low. Knock about 20 degrees off the 50 thou duration and the motor would run great.