Advice Needed - Can't Start Rebuilt 273

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MoparGarage

Winter Sucks!
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This is the first engine rebuild I have done in 35 years and I cannot get it to run. It's a 1966 vintage 273, bored .040 with flat top pistons, solid lifters and adjustable rockers. Cam specs are not known. The engine was not running when I bought it years ago but I was told it had been newly rebuilt.

Now that I want to use it, I have torn it completely down, verified and checked everything, and carefully re-assembled it. I installed it in my car (replacing a running 340) and hooked everything up. I used the complete ignition system, including distributor and plug wires from the nice running 340 that was in the car.

The gasoline is fresh and the 4 bbl carb is from a running 318. The 273 turns over nicely and occasionally tries to start. A couple times it started and ran for a second or two but did backfire through the carb or spit out raw gasoline.

I have double checked everything I can think of. Compression is good in all cylinders. Distributor is installed correctly. Firing order is correct. I have checked, and rechecked the initial valve/rocker adjustment. I even changed the spark plugs to the ones that were in the running 340. I have tried setting the initial timing anywhere from 5 BTDC to about 35 BTDC.

I'm getting pretty frustrated. Any thoughts or tips from you experienced engine builders?

Thanks,
Bruce
 
are you sure you are getting spark at the plug? maby the module or something like that has went south. it sounds like there is no spark so my first thought was the dizzy is out 180degrees but if you say it is in right then thats not it. when it ran a little is that when it would puke out raw fuel?
 
I'd still lean really hard toward the distributor being 180° out. If nothing else, it's a relatively easy thing to try.
 
tyler_s18 said:
are you sure you are getting spark at the plug? maby the module or something like that has went south. it sounds like there is no spark so my first thought was the dizzy is out 180degrees but if you say it is in right then thats not it. when it ran a little is that when it would puke out raw fuel?
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Yeah, when it ran briefly, it puked the fuel. I am 100% sure the dist is not 180 out. I'm pretty confident that the ignition system is not the problem because I pulled the running 340 and put in the 273 with all the same ign stuff. I'm getting spark to the plugs, at least until I flood it out after numerous attempts to get it to run. I have taken the plugs out several times to clean them and dry out the cylinders.
 
doktor_x said:
I'd still lean really hard toward the distributor being 180° out. If nothing else, it's a relatively easy thing to try.
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I tried to start it by myself and double checked the dist orientation. Then I had some experienced help drop by and he checked the dist for himself. True, its easy to try and I've tried about everything else... but I'm really sure that's not it.
 
so you have visualy seen spark at the end of the wire? if so it is probably not spark. could the timing chain of jumped or broke? you gotta have spark, compression and fule. it sounds like there is plenty of fuel and if there is spark at the plug then that would mean its compression. could the valves be to tight and not closing all the way? i am kinda just thinking out loud. when there is a gremlin like this i think that kinda helps. you sound pretty smart with all this which i think makes it all more frustrating when you cant figure it out lol
 
I'm betting on the 180 out also. When the dots on the crank and cam gears are facing each other you are tdc at #6. Alot of chevy guys make that mistake since on a chevy it is tdc#1.
 
tyler_s18 said:
so you have visualy seen spark at the end of the wire? if so it is probably not spark. could the timing chain of jumped or broke? you gotta have spark, compression and fule. it sounds like there is plenty of fuel and if there is spark at the plug then that would mean its compression. could the valves be to tight and not closing all the way? i am kinda just thinking out loud. when there is a gremlin like this i think that kinda helps. you sound pretty smart with all this which i think makes it all more frustrating when you cant figure it out lol
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LOL, no doubt it's frustrating! I'm with you, thinking out loud helps. I thought I'd post the problem here so maybe that one idea from someone will spark something - uh, no pun intended.

Yeah, there is lots of fuel. Definitely has spark because it tried to run, and does kick over a lot. I checked the compression and I get 70 to 90 psi in all cylinders. Is that too low? Really seems like some timing issue with fuel spitting out the carb and a backfire through the carb...
 
63dartman said:
I'm betting on the 180 out also. When the dots on the crank and cam gears are facing each other you are tdc at #6. Alot of chevy guys make that mistake since on a chevy it is tdc#1.
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Holy crap, THIS I did not know! I've never done anything on a Chevy but I thought the dots on the crank and cam pulleys lined up at TDC for #1 so that's how I set it. We did check for the compression stroke in #1 and the rotor was pointing at the #1 terminal on the dist cap.
 
If it ran,but was spitting I would check firing order with your wires.I would also pull the dist. and install 180 out(just incase your timing gears are installed improperly)Also check #5,7 wires common problem.Just trying to help with getting it going.It,s hard when your not hands on.Good Luck!

P.S Do you have another carb?Have you checked squirters to make sure your getting even fuel?
 
The timing gear placement isn't important as long as you drop the distributor in at the right place. Alot of people just line them up pointing at each because it's easier to line them up that way. Then just drop the distributor in with the rotor pointing at #6 or they just rotate the crank until the crank gear is down and the cam gear is at the top and drop it in on #1. As long as the dots line up and you drop the dizzy in right your good.

70 to 90 on compression is wwaayy low! I would think you should at least be in the 160-170 range. Almost sounds like the valves are staying open. You didn't put a preload on the rockers like hydraulic lifters take I hope? Just trying to help out.
 
pettybludart said:
If it ran,but was spitting I would check firing order with your wires.I would also pull the dist. and install 180 out(just incase your timing gears are installed improperly)Also check #5,7 wires common problem.Just trying to help with getting it going.It,s hard when your not hands on.Good Luck!

P.S Do you have another carb?Have you checked squirters to make sure your getting even fuel?
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Thanks pettybludart. I checked the firing order by following the wires two different times. The carb is squirting good - I have lots of fuel.

After reading the above input, I'm also now beginning to think my distributor is 180 out. I definitely installed the cam and crank sprocket marks facing each other thinking that was TDC for cylinder #1. We later again checked for #1 TDC by physically feeling for the compression stroke. Tonight I have read in two different places that feeling air coming out of the spark plug hole is not a guarantee that it is near TDC.

If it wasn't the middle of the night right now, and if I had mufflers on it, I'd go outside and try it. Oh, and also if I wasn't currently at work :)
 
63dartman said:
The timing gear placement isn't important as long as you drop the distributor in at the right place. Alot of people just line them up pointing at each because it's easier to line them up that way. Then just drop the distributor in with the rotor pointing at #6 or they just rotate the crank until the crank gear is down and the cam gear is at the top and drop it in on #1. As long as the dots line up and you drop the dizzy in right your good.

70 to 90 on compression is wwaayy low! I would think you should at least be in the 160-170 range. Almost sounds like the valves are staying open. You didn't put a preload on the rockers like hydraulic lifters take I hope? Just trying to help out.
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Thanks 63dartman. Yeah, I kinda thought the compression would be higher. I was thinking maybe it was low because the rings haven't seated yet. Definitely no preload on the valves. I have adjusted them twice to be sure of that.

I am hoping we've nailed the problem with being 180 out. I guess I'll know in a few hours.
 
Yea I'm at "work" too. 7pm to 7am. If your not sure about the distributor then just line up your balancer to TDC and pull out the distributor and put it in 180 out to see if it helps. Good luck
 
I would try to rotate that rotor 180 deg and try it. This is a easy mistake to make. I had the same problem once, a budy came over and said its 180 out, I said your crazy it went back in the way it came out. Well we loosend the dist. lifted it enough to turn the rotor 180 and it fired right up.:-D
 
A better way to get the motor at TDC on compression is to watch the intake valve. After it closes, the piston is on it's way up. That's TDC compression stroke.
 
from everything i have read with the amount of compression it has it sounds like it mite have some valves to tite i would think that motor should be around 110to130 compression.id try backing them off a little.just trying to help.
 
Keep us posted if the 180 deg. thing works out. When you install the drive gear for the distributor and oil pump into the block it has 18 teeth so it can go in one of 18 different ways and only one way is correct. As long as the valve timing is correct (timing chain and gears) the distributor can be installed any way as long as the firing order on the cap starts where ever the rotor is pointing when #1 cylinder is at top dead center. I static time engines by
bumping the engine over with #1 plug out and my finger covering the plug hole.
When the compression pushes against my finger the cylinder is coming up to tdc. You should be able to bump the starter to line up the timing marks on the balancer and #1 will be at tdc. Pop the distributor cap and start the firing order at the post where the rotor is pointing (1-8-4-3-6-5-7-2 clockwise) #1 should fire when it is at tdc and the rest should follow in proper order. You can then set the timing with your timing light to 10 deg. before or what ever spec is.
Hope this helps, toolmanmike
 
I had this problem a few years back. What I did was pull #1 plug got a heliarc welding rod about 2 feet log and dropped it down the spark plug hole. Took off the valve cover over #1 cylinder. Marked #1 tower on dist body and took off the dist cap. Slowly cranked the engine over untill the rod would push up and then just start to fall and the intake valve was closed. Would turn the engine back wards just a touch so the rod would just fall again. This put me a hair in front of TDC. Reinstalled the dist until the rotor was pointing at the mark for #1 tower. Put it all back together and it fired. Then just did minor timing adjust. Works every time.
 
Follow toolmanmikes instructions.(FINGER OVER SPARK PLUG HOLE)
After you get the piston to top dead center and pull the distributor cap, you will know if it's 180 OUT, by the position of the rotor.
Use the firing order that he gave you and make sure the plug wires are going in the same direction as the rotor turns.(most important)
When trying to start a new motor it's so easy to mess this up because you can't wait to hear it run.GOOD LUCK!!!
 
UPDATE Friday Morning:
I pulled the left valve cover and found TDC for #1 by watching the intake valve just start to open. Then I backed up the crank a bit to get the timing mark right at zero. Popped the distributor cap - yes, 180 out. I had left the plugs out overnight to dry everything out - even blew air into the cylinders - wire brushed the plugs. Reinstalled everything - retraced the wires to verify correct firing order. I hit it with a bit of starting fluid and - NO START! I got a couple of backfires out the headers, but other than that it doesn't even try to kick over now. So after trying a while, adjusting the distributor each time, I now have wet plugs and a weak battery. I did pull a wire and hook it up to a plug to make sure I had spark.

I am just at a loss. It makes it worse to have this frustration after working a midnight shift. I was so sure it would fire right up when I corrected the distributor. Arrrghhhh.
 
Plug wires are in order..........But are you sure that they are in the correct rotation for a small block? I think the rotor spins clock wise someone PLEASE correct me if I'm wrong.
 
BigSlim said:
Plug wires are in order..........But are you sure that they are in the correct rotation for a small block? I think the rotor spins clock wise someone PLEASE correct me if I'm wrong.
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Yeah it's clockwise. 18436572 is burned into my brain :)
Actually the distributor, plug wires, all ignition got transferred straight over from the running engine I took out. I have now started to question why I pulled a perfectly good running engine to do this :)
 
I noticed the 70#-90# of compression in all cylinders. You should have 150# I would say. It should run with low compression but have no power. If you haven't done it yet you should adjust the valves properly. If that doesn't cure it you may have to check the valve timing. Did you say that you checked the spark at the plug? It should be blue/white colored and not yellow/orange. My brother-in-law had a 65 Riviera with a no start condition. I came over and checked it out and the spark was orange colored and very lazy. It had a bad coil. He replaced it and it started and ran like a champ. toolman
 
toolmanmike said:
I noticed the 70#-90# of compression in all cylinders. You should have 150# I would say. It should run with low compression but have no power. If you haven't done it yet you should adjust the valves properly. If that doesn't cure it you may have to check the valve timing. toolman
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Thanks Toolman. Yeah, I guess if I don't have success soon, the next place to look for a problem is behind the timing chain cover :( I tried to assemble everything very carefully... maybe I am one link off on the timing chain.

The sparked looked good. Snapped with a nice blue color.
 
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