NullHead

So I just put a stock (or so I am told) 305 into my Firebird ... when I started it up a few days ago, this thing definitely doesn't sound stock. Has a somewhat rough idle. I got the engine with the rear camshaft freezeplug gone, so before I put one in, I snapped a picture of the rear of the cam.



From my googleing, I found it to be this camshaft: http://www.summitracing.com/parts/HRS-242371/

And based off of the Howard's website, looks like I could possibly have one of their "rough idle" camshafts.

Now the engine "sounds" like it idles smooth, but inside the car it vibrates like no other ... so I'm thinking I also have a mount/flexplate/harmonic balancer issue cause there is a heck of a bad sounding engine vibration around 1400/2300 RPM. Anyone have any ideas? Is this just a stock camshaft or what?

cuisinartvette

Yikes that thing is HUUUUGE for a 305 pull it out of there it will never run worth beans. Be fun in a larger carbed SBC with good heads, gears etc not what you have though.

make sure when putting the rear plug in it isnt too far in or too shallow.

NullHead

Well I did my best. Not allot I can do about it now, but it's in there. I didn't jam it all the way in, but I put it in just past the lip on the block there. Camshafts shouldn't walk more than a few thousanths anyways, right? It was a narrow style plug too so I think there's plenty of room.

I have a check engine light on for code 43 knock sensor ... but that could be due to something else. For all I know, my engine mounts are bad and the vibrations of the mounts are setting the knock sensor off. I really need to get my ALDL cable working so I can tell ...

NullHead

Another thing I noticed is that the engine runs soooo much smoother at 20 degrees + of timing. But it backfired like crazy when I'd rev the engine ... so do I need to get a chip burned to be able to use this camshaft or what?

I'll get a video of it running so you can decide for yourself ...

NullHead

Well actually here is the video of the very first startup.


So, what's going on in the above video, and not currently, is i had plugs 5 and 7 reversed (my mistake, I switched the boots on the wires after putting the headers on), the ignition timing is whatever it was at when I originally stabbed the distributor (Pretty good if you ask me), and she's running on open headers.

I'll have to get another video of it running with the exhaust on it, and timed to 0 degrees like my stupid little sticker says it should be at ... ... and with all the plug wires where they should be at. Also I was burning wires in that video on the side of the header ... so I've since fixed that too.

So over all, poofy sounding exhaust (Not a solid flow of exhaust pressure comming from the tail pipe), the inside of the car vibrates really badly when it idling and in gear, code 43 was set last time I took her around the block, the engine vibrates really badly around 1200/1300 and 2400 RPM. Feels like an off balance in the engine or some thing. Harmonic balancer? Who's got ideas ...

NullHead

Here's a video I took yesterday showing my engine vibration, the weird sounding exhaust and an explanation.


Anyone have any ideas? I'm going to start replacing mounts until I figure it out I guess.

Also, I just now thought about it ... if my harmonic balancer spun, my timing would be off , hence the code 43 indicating spark knock, and it would vibrate like no other ... I'm definitely going to be installing a new harmonic balancer now.

Anybody have any other ideas or suggestions for me?

TreeFiddy

That cam you linked to is a Ford cam?? Don't know if that would work too well

A spun balancer may not necessarily vibrate. Get a piston stop, find true tdc and verify the timing marks before throwing cash at a new one.

Vibration doesn't seem too bad - engine mounts maybe? Sure you've got that firing order right?

NullHead

That's a good idea with finding TDC and then looking at the mark I'll definitely have to do that.

I'm sure a mount is bad, because the vibration is worse when I put the car in drive/reverse. I just need to figure out which mount it is ..

I honestly don't know if that's the cam ... I mean that's what I found by googling the number on the back of the camshaft seen in the first picture.

I'll start my making sure my mounts are tightened properly. I suppose they might not be tight enough, because I had to take them off to get my headers installed. It could also be the trans mount I guess ..

And firing order goes 18436572 starting at the post that's closest to #1 piston, the one on the driver side closest to the front of the engine, and goes clockwise around the distributor. I also double checked that all my wires go to the right place.

I suppose I could have damaged a sparkplug when I was installing the headers ... but they're all brand new ACDelco plugs, with premium carquest 8MM wires.

TreeFiddy

Those are all things to check. It's not that cam - unless someone pressed a BBF cam into your poor 305 with extreme prejudice

I assume you've just obtained this motor and installed it - what do you know about it's history? Sounds like there may be a problem with a single cylinder - like burnt valve, bent pushrod, cam lobe etc.

Do some basic engine health checks. Pull the valve covers and give the rockers the once-over, see if there's any looser than others. Crank it over and make sure they all move the same amount. Then do a compression check.

NullHead

The engine came with the car, with a history ... this is the original engine to the car, but it was blown up at its original milage of 148,xxx. It was delivered to a shop to be rebuilt, and it was rebuilt, but blew up again 10 hours after the rebuild. The pistons were destroyed ... so the original owner took the car back again, had someone else build it (the guy I got the car from - he actually knows what he's doing) and it was rebuilt, and then the project sat for approximately 3 years. So the car's been off the road for a while due to the first mechanic taking about 6 months to rebuild/work on the car, then it setting, then going to the PO, then setting some more.

So the engine blew up twice, was rebuild twice, and now I have it. It pulls about 20in/lb of vacuum, and it seems to have lots of power. I installed the engine, and was the first person to fire up the engine after its last rebuild. It literally has never had oil in it before I got it (other than assembly and what not). I was careful to prime the oil pump with a drill, I was careful to turn the engine over by hand nice and easy several times with all plugs removed before I installed it. All the rockers looked good, they all seem to move about the same amount.

Believe it or not, the engine seems to be running a little better the more I run it. Perhaps the cam is gradually being broken in? I know the exhaust smells sorta fishy. I checked the tank with a tube and didn't come up with any gas on it ... so from what I can tell, the tank was empty when it was stored for those 3 years. But I added 5.5 gallons of gas for startup and the gauge showed 1/2 tank. So far it's down to a hair above E .... I've driven it a grand total of 3 miles, and the engine has been running for maybe 12 hours on and off with throttle changes ... not just idling all the time.

When I find TDC and check the timing that way, I'll just pull all the plugs and inspect them, and I'll get a compression tester and run that test too.

I wish I could get my ALDL cable working ... I think I got a bad cable. I'll shoot them an email and see if they'll exchange it. Maybe the data winadl can give me will help with diagnosing this ...