upgrade cam and intake for 305

[Phoenyx]

Well now I think I can scrap this whole idea. I think my 305 is finished now. Went for lunch today. When I left it was running fine. Then after about 5 minutes it started running really rough and knocking REALLY bad. It has always made a bit of a ticking sound. But now there's also a hard sounding knock. And also, when idling there is a loud bang every few seconds. Sounds like someones smacking the engine with a sledge hammer. If I rev it or push it at all it gets louder and more often.

I pulled over right away and checked the oil. Was just under 2 liters low (usually only uses 1 a month, but I just topped it off a week ago). I topped up the oil and the knock got a bit (and I mean just a bit) better. I was only about 3-4 minutes from where I was going, so I drove it (basically idled it the whole way). Noticed that any time the engine needed to 'work' that loud banging would get really bad.

So I'm sure that it is just toast now. And there's now way I'm gonna spent the kind of money it will take to get that fixed. So I guess it's time to find a 350 now. But at least I'll be happier in the end lol.

 

[Phoenyx]

Ok here's something weird. I went yesterday to grab something out of my Malibu. I figured I would start it to see if the noise would be 'magically' gone lol. And no it still sounded the same. As I expected.
But then today I go to do it again, but this time the noise is gone. I let it warm up, revved it a bit, even put it in gear and revved it up (while holding the break). And no funny noises (other than the tick it has had since I got it lol). So now I don't know what to think. I'm still looking for a 350 because I'm sure this is to good to be true.
Anyone know what might be going on?

 

[mickey-d]

My suggestion would be to focus more on torque than HP (that's really what a 305 was intended for anyway). The small bore size is what your real limiting factor is and there's nothing you can do to get around that. The Comp XE256 might be a good choice. I ran one on a 307 Chev with a Performer intake and a 600cfm Edelbrock and was pleased. It pulled strong (for a 307) up to about 5000, had great throttle response, and got decent mileage. It had just a hint of choppy idle. Spend the extra money on good rockers if you want - I doubt you'll notice any difference though. My Dyno2000 would estimate HP in the 240 range and torque around 320 (peaking right at 3000rpm) with that combo. Figure out the RPM range where you spend most of your time and optimize it. That's essentially what the OEs do with their constantly shifting 28 speed automatics :lol: .

I believe Driven is right on the money. The only other thing I would do,is to put on a set of 1.6 rocker arms. They will give you a little more performance from your cam at a relatively low cost. :lol:

 

[Oldsmoletick]

Shot in the dark, but check your torque converter bolts. Have had a couple vehicles (including my malibu) loosen and sound like a rod was about to come through the hood, was heat sensitive as well.

 

[axisg]

trans mount, motor mount, TC bolts. Does it do it with engine speed or the rotational speed ?

 

[Phoenyx]

I will have to check those things out.

As for how it was sounding. First off, it has always had a tick. Now, at idle in park or neutral it was ticking as usual. But there was also a hard knock. It got faster as the engine revved. And the loud banging, it seemed almost random. Not consistent with the knock or tick. And revving it in neutral or park made it happen a bit more often, but not to much. But if it was in gear and the engine was put under a load then it got really bad. Still not really consistent with the other sounds, but a lot more frequent and a lot louder. It almost sounded like it was backfiring, but from under the engine lol.

Would be nice if it's something easy. The I would have more time to find a good 350.

 

[Phoenyx]

Oh, and like I said earlier, when I started it cold the other day the knocking and banging was gone. But the day before when I did the same thing it was there. Weird.

 

[jae]

Phoenyx,

As the others stated I think you may have a loose TC bolt or bolts or a mount, especially if when you rev it you get some engine "torque" or movement. Not sure what the sound is but you may also have lifters totally shot - they could've just bled down and collapsed. I'd pull a valve cover and check for loose rockers too.

In terms of the parts swap versus engine swap, there's something I'm not understanding. If you don't have room to do the 305/350 swap how do you have room to do the cam/intake/oil pump swap? In either case you're draining fluids, disconnecting & removing parts, jacking things up, etc. Also, if you're doing the cam swap with the engine still in I hope you have enough room to pull the cam all the way. I guess my point is, if you have "space" to pull a cam, drop the pan (if you're doing the oil pump) and the like, you have space to pull the motor, unless you're plan is to do this at the curb in front of your house / apartment. You don't need a shop to do it, believe me - my cousin & I once did an engine swap in the alley behind the house in the city. :shock: Took about 9 hours from start to finish, including a parts & burger run, but she was running at the end of the day.

But if you're really looking for a 350 upgrade I'd run her until she quit, in the mean time saving up $$ and trying to find a good 350. Also, whether you stay with the 305 and upgrade it or go the 350 route the exhaust bottleneck is going to have to be addressed at somepoint. Have you thought about shorty-type headers, along with a mandrel-bent crossover pipe since you don't want to hack up your almost new exhaust?

 

[Phoenyx]

Hmm, more things to check out. The reason I can't do an engine swap, but can do smaller things is this. I live in a rental place that has it right in the lease that we can't work on our vehicles. And they seem to have it out for me so I don't wanna push it. I have a buddy with a garage, but he's a truck driver. Ad only in town a few days at a time. SO whatever I do (myself) I only will have a few days to do it.

 

[megaladon6]

also check the harmonic balancer. sometimes the outer layer slips off the steel ring and causes a knocking sound.