Start the unstartable 302
Cargo Master
Joined: Dec 2004
Posts: 2,232
Likes: 3
From: NE Texas
Have you MEASURED the compression? Did you degree the cam?
Typically when a fresh engine has low compression the problem is the camshaft is installed one tooth off. Another problem could be the valves are too tight. Did you prime the lifters with oil before installing them? Did you adjust the lifters properly?
Putting oil in the cylinders will not be the solution. If you do that, make sure you don't put too much and cause liquid lock.
Good luck,
Doc
Typically when a fresh engine has low compression the problem is the camshaft is installed one tooth off. Another problem could be the valves are too tight. Did you prime the lifters with oil before installing them? Did you adjust the lifters properly?
Putting oil in the cylinders will not be the solution. If you do that, make sure you don't put too much and cause liquid lock.
Good luck,
Doc
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New User
Joined: Mar 2005
Posts: 17
Likes: 0
From: Maple Hill, NC
I haven't measured compression yet. I've got a lot of tools, but not that one. I did prime the lifters and everything is adjusted properly. The cam is set 10 BTDC as per manufacturer's instructions. I've also tried it at TDC and 10 ATDC. Both valves are closed when the compression stroke starts and the exhaust valve doesn't open again until right around BDC. I'm beginning to think this is just one of those once in a million cases.
Elder User
Joined: Nov 2002
Posts: 620
Likes: 8
From: USA
I just recently had problems with my fresh 390 after installing it. It would turn over just fine and would pop and bang every so often.
Rechecked timing over and over again, pulled and reseated the distribitor 180 and was just about at a loss when I just decided to pull all the plug wires off the cap and start them 180 from where they were, i.e. pulled #1 and started it straight across from where it was. The turd fired right up after that. I wasted 8-10 hours for that stupid little thing. For some reason I forgot for every full turn of the crank the cam goes 180. I'm not even sure now how to tell when the cam is in the right position when you install the distribitor. The #1 piston is at TDC when the cam is right on and again at 180 out.
I know you said you've checked this already, but so had I for hours.
Jordan
Rechecked timing over and over again, pulled and reseated the distribitor 180 and was just about at a loss when I just decided to pull all the plug wires off the cap and start them 180 from where they were, i.e. pulled #1 and started it straight across from where it was. The turd fired right up after that. I wasted 8-10 hours for that stupid little thing. For some reason I forgot for every full turn of the crank the cam goes 180. I'm not even sure now how to tell when the cam is in the right position when you install the distribitor. The #1 piston is at TDC when the cam is right on and again at 180 out.
I know you said you've checked this already, but so had I for hours.
Jordan
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New User
Joined: Mar 2005
Posts: 17
Likes: 0
From: Maple Hill, NC
Yeah, I had that happen once before in a parking lot in New York. That was an all day affair. This time I know it's where it's supposed to be. When it's right both valves are closed when it gets spark. When it's 180 out both valves are open just a hair when it gets spark. That's what causes the sputtering and the popping. I appreciate the help though. With a little luck we'll figure this out.
Senior User
Joined: Sep 2003
Posts: 151
Likes: 0
I suspect your compression is too low. IMO you need to check the comp before you do anything else.
Was it running before you changed the cam?
If you put a performance cam in you may need spacers under your rockers or shorter push rods.
not even .02 cents worth but my opinion none the less.
Was it running before you changed the cam?
If you put a performance cam in you may need spacers under your rockers or shorter push rods.
not even .02 cents worth but my opinion none the less.
Junior User
Joined: Dec 2002
Posts: 56
Likes: 0
From: tucson USA
A few thoughts
When you installed the timing set did you line up the marks on the gears correctly? There are marks on the gears thers hve to be lined up to get your cam turning in the correct relationship to your crank shaft. also early small block Fords do not have positive stop on the rocker arms. you have to tighten them enough to get the motor running and then adjust by sound until they are quiet. If they are over tightened you won't have any compression. If it ran before there is no reason it shouldn't now unless the timing gears are installed incorrectly or the distributor timing is off. I don't know if any of this helps just a few thoughts 
Fleet Owner
Joined: Jan 2004
Posts: 26,007
Likes: 575
From: Brentwood,CA
Originally Posted by HollmansHotrods
After last night's work I think I've got some compression, but not enough. I was able to get it to fire on a couple cylinders, but not all, and not all the time. Any ideas on how to build compression? I've alreay soaked the cylinders with oil to help. I think I need a 24 volt system to get it spinning faster.
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New User
Joined: Mar 2005
Posts: 17
Likes: 0
From: Maple Hill, NC
I got it figured out. I used an air compressor to blow more air into the carb while I was cranking it. That got me enough compression to get it started and afterwards it built it's own compression back up. Once again, it's alive.
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