Engine Turns Over Slowly And Unevenly

[RedPonyGT]

it sounds like it gets to a easy spot and turns over quick then slows down. Imagine a circle that represents the engine turning over and when it's at the top it's easy and moves fast but when it gets to the bottom it has some sort of resistance and turns slowly.
it's all together slow cranking too. Any help will be appreciated!

 

[horse sence]

could be the starter ,but it sounds like you need to do a compression test

 

[RedPonyGT]

could be the starter ,but it sounds like you need to do a compression test

yeah i guess i'll have to do that...what are the possible causes of this though? What will a compression test reveal?

 

[Falcon79]

Do you have the correct balancer up front and flexplate in back? Have you done any work to the engine recently? The compression test may reveal if you have compression on some cylinders and not on others, causing the crank to turn over easily on some spots and hard in the others. If all the cylinders read close to the same, I would replace your started and go from there.

 

[RedPonyGT]

Do you have the correct balancer up front and flexplate in back? Have you done any work to the engine recently? The compression test may reveal if you have compression on some cylinders and not on others, causing the crank to turn over easily on some spots and hard in the others. If all the cylinders read close to the same, I would replace your started and go from there.

well it's off to advance to rent a compression gage. I hope I don't find my engine needs to be rebuilt. Yikes!

 

[The_Dude]

This will also happen if your ignition timing is too far advanced. Check this first.

 

[robbz28]

Sounds like timing to me...like The Dude said...just a slight adjustment there can make a huge difference. Try turning the distributor counterclockwise just a tad (i think counter will retard the timing, not sure off the top of my head).

 

[RedPonyGT]

ok let me ask you this, what if it happens with the ignition disabled?

 

[The_Dude]

If you disconnect your coil wire and still have the same problem, I'd say it's not the timing. BTW, you turn the distributor clockwise to retard the timing.

 

[woodsnake]

From here, I'd go with either a tired starter motor, and or timing.
But...Is this a new development, or has it been getting worse? Do you know when the timing gear set was last changed?

 

[horse sence]

another thing i would check is the battery conections ,starter cable and ground connections from the motor ,does the battery cables get hot when cranking?

 

[RedPonyGT]

thanks all for the advice. I'm going today to get a compression gage a new starter and getting my battery checked. The started was starting to smoke from cranking over. I'll post when I install the new battery.

 

[woodsnake]

If you literally "smoked" your starter, or had smoke coming from it, that is now the first place to start...

 

[RedPonyGT]

the wire for the starter was burned up i think from the headers so i rerouted a new one as best i could. i had gone to get a new starter becuase i was using the pro torque starter from summit and it didn't line up right but i ended up getting a spacer for it. However, while at advanced auto they told me that if i have a high compression ratio engine the starter is turning over the engine fine until it gets to the compression stroke and stalls out for a minute and then picks back up. he said i would need a pretty beefy starter. is this the case? what do you guys say? also, how many cranking amps would i need from my battery if i have a 10:1 or higher compression ratio? it seems like the starter needs every ounce of power from the battery that it can get. if it's even a little low it performs poorly.
thanks for all the replies!!!
also, new issue....i turned the ignition to off and the engine kept running like i never did anything. any ideas? one thing after another LoL

 

[woodsnake]

Any other modifications to the engine? Big cam, etc? I thought you were working on a stock engine...

 

[RedPonyGT]

Any other modifications to the engine? Big cam, etc? I thought you were working on a stock engine...

I'm sorry, I should have mentioned that it was reworked. It has been rebuilt by the guy I bought it from. Don't know much about the pistons or the crank but I know it's bore 30 over and i put in edelbrock everything: cam, lifters, pushrods, heads, intake manifold, and carb.

 

[robbz28]

You have bad wiring somewhere it sounds like. Maybe you should unhook all of the wires from the starter and bypass them with some fresh wires from the solenoid and see if that does any good...maybe one wire at a time.

 

[The_Dude]

also, new issue....i turned the ignition to off and the engine kept running like i never did anything. any ideas? one thing after another LoL

Your solenoid is bad.

 

[woodsnake]

If the motor is fresh, with better compression and a performance cam, (which is what I now know you are working on,)
Then it seems reasonable that either the starter is working as it should be, against a new, tight engine, or your timing may be too far advanced. Or, you have a starter that is just tired, and the fresh motor is too tight for it to keep up. Is the any way you can post an audio/video clip?