1974 D300 360 fresh rebuild will not start

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PlantJesus

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Hi, everyone. First post here, long time lurker.

My 74 Dodge started making some horrible noises about 5 months ago, and I thought I had spun a rod bearing. Two weeks prior, replaced the flywheel and clutch, and installed a pilot bearing (there wasn't one???). After teardown.... Pretty sure what happened was I sheared an engine mount, and the other one was missing the nut to hold it in place :/ This thing sad for 13 years before I got it, it's been a work in progress. A year ago I fit an edelbrock intake and 4 barrel to it, which made a world of difference. During the tear down, I scrapped the old headers and went with a cheap pair of Hedmans.

So, engine already torn down, time to replace all relevant parts. All bearings, (pistons looked fine) new rings, lapped the valves by hand, did minimal 'porting' (removed the worst of the casting blemishes). Assembled engine, cam indicator at 6, crank at 12, 1st cylinder TDC. Spent 100 hours hunting down electric gremlins, wasted S*&t tons of money replacing the ICU, ICU plug, ballast resistor, dist, etc.... :/ Completely bypassed my wirewall connections and wired to a brand new ignition. Got my cranking voltage to at least 10 (from like, 6). Spark indicator shows voltage to the plugs, but.... I'm only showing 60 PSI compression when cranking.

Beat my head around, realized my leakdown test was lying; I had a one way check valve in the hose I was using... So, realizing my stupidity and doing it again properly... it blows air out of the other three cylinders on that bank. Realize my more stupidity; I used RTV on the head gaskets. Minimally, but.... F me. Take it apart, scrape, clean, new gaskets. TDC, timing on point... 60 PSI cranking. I was a mechanical engineer dropout long ago, and fancy thinking I understand what's going on, but this has me completely tossed.

Adding air to #1 at TDC does not leak past valves, but does past rings. WHY!??!? I'm seriously at the end of my abilities here, it seems. Any wisdom, whomever helps solve this, will become my new messiah.
 
The things that come to mind for me is.
Did you check the cylinder bores for taper and wear and diameter?
Did you hone the bores?
Did you gap the rings?
Did you turn the ring gaps opposite to each other?
On my first build I made that mistake I wasnt getting any cylinder pressure at all hardly and I couldn't figure out why. I had the top and the bottom ring gaps aligned. Lol we all learn from our mistakes I guess haha
 
Compression, Ignition and Fuel

In that order, no compression nothing else matters.

Google your questions, there is a lot of useful information on the internet. Also youtube videos are good at explaining things too. I use them all the time.
 
Is it possible you got so much fuel in the cylinders that you washed the oil out?

and above, compression fuel and spark.

Throw a bit of oil into each hole. Not too much, 'about' a teaspoon. Re-run leakdown.

Double check timing. You can do that in about seconds of starter time with a timing light. You want some advance, depending on cam. Maybe, 8-10 BTC with a stocker, 12-15 or more with a mild to hot cam, and at least 15BTC with a wild cam

Make CERTAIN fuel is fressh. If it's been sitting "awhile" rig it up with freshe fuel, IE prime the carb with a bulb squrit a bit down the carb throats, FRESH

If nothing CHECK SPARK. "Rig" a solid core wire, not radio suppression, off the coil to a gap to ground. Crank engine USING THE KEY. You should have at least 3/8" hot blue spark, and likely more like 1/2"
 
PlantJesus said:
Hi, everyone. First post here, long time lurker.

My 74 Dodge started making some horrible noises about 5 months ago, and I thought I had spun a rod bearing. Two weeks prior, replaced the flywheel and clutch, and installed a pilot bearing (there wasn't one???). After teardown.... Pretty sure what happened was I sheared an engine mount, and the other one was missing the nut to hold it in place :/ This thing sad for 13 years before I got it, it's been a work in progress. A year ago I fit an edelbrock intake and 4 barrel to it, which made a world of difference. During the tear down, I scrapped the old headers and went with a cheap pair of Hedmans.

So, engine already torn down, time to replace all relevant parts. All bearings, (pistons looked fine) new rings, lapped the valves by hand, did minimal 'porting' (removed the worst of the casting blemishes). Assembled engine, cam indicator at 6, crank at 12, 1st cylinder TDC. Spent 100 hours hunting down electric gremlins, wasted S*&t tons of money replacing the ICU, ICU plug, ballast resistor, dist, etc.... :/ Completely bypassed my wirewall connections and wired to a brand new ignition. Got my cranking voltage to at least 10 (from like, 6). Spark indicator shows voltage to the plugs, but.... I'm only showing 60 PSI compression when cranking.

Beat my head around, realized my leakdown test was lying; I had a one way check valve in the hose I was using... So, realizing my stupidity and doing it again properly... it blows air out of the other three cylinders on that bank. Realize my more stupidity; I used RTV on the head gaskets. Minimally, but.... F me. Take it apart, scrape, clean, new gaskets. TDC, timing on point... 60 PSI cranking. I was a mechanical engineer dropout long ago, and fancy thinking I understand what's going on, but this has me completely tossed.

Adding air to #1 at TDC does not leak past valves, but does past rings. WHY!??!? I'm seriously at the end of my abilities here, it seems. Any wisdom, whomever helps solve this, will become my new messiah.
Click to expand...
Are you saying that all 8 cylinders have only 60 psi or just #1? If all 8 are close to 60 then the cam is off at least 1 tooth on the timing chain.
 
dartfreak75 said:
The things that come to mind for me is.
Did you check the cylinder bores for taper and wear and diameter?
Did you hone the bores?
Did you gap the rings?
Did you turn the ring gaps opposite to each other?
On my first build I made that mistake I wasnt getting any cylinder pressure at all hardly and I couldn't figure out why. I had the top and the bottom ring gaps aligned. Lol we all learn from our mistakes I guess haha
Click to expand...

I had the block caustic dipped at a machine shop, he checked out my heads, cylinders, and crank for wear. I did not hone the bores; on machine shop recommendation. He told me it would be a waste of time/they weren't glazed.... Rings are installed properly with ring gaps opposite. I did not gap them (I assume you mean file down the ends).
 
PlantJesus said:
I had the block caustic dipped at a machine shop, he checked out my heads, cylinders, and crank for wear. I did not hone the bores; on machine shop recommendation. He told me it would be a waste of time/they weren't glazed.... Rings are installed properly with ring gaps opposite. I did not gap them (I assume you mean file down the ends).
Click to expand...
Was there any crosshatch left in the cylinder walls?
 
George Jets said:
Compression, Ignition and Fuel

In that order, no compression nothing else matters.

Google your questions, there is a lot of useful information on the internet. Also youtube videos are good at explaining things too. I use them all the time.
Click to expand...

Now, why didn't I think of google??? -Not to be a smart ***...- There isn't a video on youtube I haven't watched, or a post on this forum I haven't read. I'm reaching out to the wealth of knowledge here exactly because I've been lurking for years and have a lot of respect for the intuition and knowledge of the posters here. I am by no means unfamiliar with mechanical theory, and like to think I'm actually even pretty savvy on my 360 in specific. That being said, I'm beyond stumped, obviously.

Adding oil to the cylinders does absolutely nothing for my compression. Each cylinder is at the exact same 59 PSI. I've dumped fresh fuel right down the carb to no effect. It had been sitting for a while with about a gallon in the tank, and then topped it off with another 5 ethanol free, in case it was feeling old n funky.

-And correction, cam at 12, crank at 6 :p Also, if my cam were off by a tooth, then I should have valve blowby during a leak down test at TDC, correct? All I hear is through the rings. When cranking over by hand, I can hear the valves begin to open/air escape through their respective valves.

I DO have spark, using a spark tester currently not rigging a gap. It shows a fairly bright light, and testing the same light against my 76 Ford, it's about the same/brighter on the Dodge. Not sure about a fat blue spark though :/
 
PlantJesus said:
-And correction, cam at 12, crank at 6 :p Also, if my cam were off by a tooth, then I should have valve blowby during a leak down test at TDC, correct? All I hear is through the rings. When cranking over by hand, I can hear the valves begin to open/air escape through their respective valves.
:/
Click to expand...
A 360 should be timed with the cam dot at 6 o'clock and the crank dot at 12 o'clock so the dots are as close together as they can possibly be, now a Gen3 Hemi is timed the opposite way with the cam dot at 12 and the crank dot at 6. Cam timing wont necessarily cause leak down at TDC but will cause low compression as the intake vales close to late after the piston has already started moving up the bore before the air is closed off essentially reducing the effective stroke.

Even (all 8) low compression could only be cam timing, starter cranking way to slow, or a faulty gauge. its very unlikely that all 8 cylinders have an even loss of compression from wear. Also the distributor shaft can be installed 180 off because it just drops into a slot, if this is the case you can pull the distributor and spin the shaft around to the other side and reinstall.
 
Northern Grit said:
Even (all 8) low compression could only be cam timing, starter cranking way to slow, or a faulty gauge. its very unlikely that all 8 cylinders have an even loss of compression from wear. Also the distributor shaft can be installed 180 off because it just drops into a slot, if this is the case you can pull the distributor and spin the shaft around to the other side and reinstall.
Click to expand...

Def not the starter; brand new micro starter to get around the new headers. Tested my gauge; it is working correctly. That's what I was thinking about the low compression; it just wouldn't be that even across the board from wear. And, before rebuild, I was getting about 120 in each cylinder. I think I'm just having a dyslexic moment on the direction of the dots. You are correct on where they were supposed to be; just checked my Chiltons which I followed during the rebuild. They're almost certainly in the right orientation... but maybe off a tooth I guess, somehow. I'll do a teardown of the water pump/timing cover/whole damn front after work today.
 
If oil does not increase compression, the valves may be open at wrong time or "just open." This nonsense of cam timing is stupid. Check them with a straightedge at the very least or learn to degree them. And you cam time them EITHER at "6 and 12" or at "12 and 12". When you rotate the crank one turn, the marks will be the opposite location of where they were at first.
 
If u r at 6:00 on the cam gear and 12:00 on the crank gear u r on #6 compression and #1 overlap. U need to rotate the engine 1 full turn to be on #1 compression. The dots r just at 6:00 and 12:00 to make it simple to line up them up. Kim
 
I am surprised the machine shop didn't think a hone was necessary. Even a glaze breaker bead hone gives a little texture for the new rings to seat against.
 
67Dart273 said:
This nonsense of cam timing is stupid.
Click to expand...
I disagree, this is what makes the most sense with the information provided.

67Dart273 said:
the valves may be open at wrong time or "just open."
Click to expand...
Enlighten us, how dose that happen without fouled up cam timing?

67Dart273 said:
And you cam time them EITHER at "6 and 12" or at "12 and 12". When you rotate the crank one turn, the marks will be the opposite location of where they were at first.
Click to expand...
Yes the CAM can be at 6 or 12, but if the crank is timed at 6 then the cam will always be 90 degrees off (1/2 a crank stroke) and his compression when from 120 to 60 (about 1/2).

No one is saying that this IS the problem but based on the data I think its a very viable place to check.
 
You are way out of time on the crankshaft timing in relation to the camshaft.

To get you engine to fire TDC on #1 on the compression stroke, you need to have cam gear dot at 12:00, an the crankshaft dot at 12:00. This is to fire on #1.

So your crankshaft at 6:00 and Cam at 12:00, is quite backwards to the way it needs to be timed and no wonder you are only getting 60 psi per cylinder.

20200824_131338.jpg


Good luck, it is easy to get it wrong. Only one way to get it right.
 
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Northern Grit said:
Yes the CAM can be at 6 or 12, but if the crank is timed at 6 then the cam will always be 90 degrees off (1/2 a crank stroke) and his compression when from 120 to 60 (about 1/2).
Click to expand...


The ignition timing will be of 90 degrees but the cam timing will be on whether you time the cam at 6 and 12 or 12 and 12.
 
So if I am reading this right, all the machine shop did was clean things up for you? You hand lapped the valves (which can be OK if they were fairly decent to start with). Other than that, all you did was put the block back together with some new parts. No honing, no bearing to crank clearance checking and it looks like there was no ring gap checking. That is NOT a Fresh Rebuild. I would not even call it a refresh, since nothing was checked. Did you use a new cam and lifters? Did you use a new oil pump? If your cylinders were bored at one time, or if there is excess wear and/or taper new rings won't do much. Specially if the bore has worn and tapered a lot and you installed standard rings. It also sounds like you may have lined up the cam and crank incorrectly. Also, did you mark the bearing caps and get them back in the same spot? Here is what you need to do. BUY A COPY OF "HOW TO REBUILD YOU SMALL BLOCK MOPAR". It sounds like you need it. I have rebuilt lots of engines, and I would still use it. Pull the engine, put it on an engine stand and disassemble it completely. check the cylinders for wear and taper. Bore the block if necessary. IF the bore and taper are OK, hone the cylinders lightly. Then check ring gap on each cylinder. Then put rings on pistons. Then buy some Plasti Gauge and check the spacing at every crank to bearing surface. If bearing gaps and ring gaps are too big, you are wasting your money.
 
Northern Grit said:
I disagree, this is what makes the most sense with the information provided.


Enlighten us, how dose that happen without fouled up cam timing?


Yes the CAM can be at 6 or 12, but if the crank is timed at 6 then the cam will always be 90 degrees off (1/2 a crank stroke) and his compression when from 120 to 60 (about 1/2).

No one is saying that this IS the problem but based on the data I think its a very viable place to check.
Click to expand...

I was talking about the argument over "6 and 12" Sorry I should have worded that better. I agree it could be the cam is OUT of time.

For me there is ONLY ONE CORRECT WAY and that is to align the marks BY THE BOOK or degree it if you have the cam specs
 
67Dart273 said:
I was talking about the argument over "6 and 12" Sorry I should have worded that better. I agree it could be the cam is OUT of time.

For me there is ONLY ONE CORRECT WAY and that is to align the marks BY THE BOOK or degree it if you have the cam specs
Click to expand...
Agreed!
 
67Dart273 said:
I was talking about the argument over "6 and 12" Sorry I should have worded that better. I agree it could be the cam is OUT of time.

For me there is ONLY ONE CORRECT WAY and that is to align the marks BY THE BOOK or degree it if you have the cam specs
Click to expand...
Ok then I totally read that in the wrong context, all good on this end.
PlantJesus said:
I'll do a teardown of the water pump/timing cover/whole damn front after work today.
Click to expand...
When you get it apart post some pictures, just curious about your key way orientation.
 
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