914 1.7 Knocking Sound -- New Here, First Post, Horrible knocking coming from the motor Options

[UberElectricEagle]

Greetings. I am new to the Porsche world and I purchased a 1972 914 1.7 about a month ago. It's a pretty nice car over all, but I think the motor, or part of the motor, might be toast.

When I purchased it, it badly needed a muffler. The knocking noise was harder to notice and sounded more like an exhaust leak over the horrible sound of the lack of a working muffler. The car seemed to run decent even with the poor exhaust and the price was good so I bought it. I just wanted a decent car over all that I could drive around for fun on sunny days before the winter gets here. It came with stainless heat exchangers I installed and I installed a really nice dual muffler from Dave at Triad.

When I fired it up with the new muffler, I really noticed the knocking when I drove it since the all the exhaust leaks were now sealed up and I wasn't wearing ear plugs. At idle it's not too bad, but once I get going, the knocking is very noticeable. It's odd too, because it's not real consistent under power in motion.
To me it sounds like the noise is coming from the #1 cylinder. I think the cylinder is providing no power, because when I take the wire off the cap, there is really no change in performance. (I put a video link of the horrible sound below.)

Any advice on where to go from here would be great. My gut feeling is telling me the motor is going to have to come out. If I'm going to do all that, I might as well put a 2.0 liter in or ????? I'd even settle for just a solid running motor with some minor upgrades to make it a little quicker. Any advice on what route to take on a good used motor would be great. I guess A motor that runs on 4 cylinders would be an upgrade. Thanks for your help, a mildly depressed Sam

http://www.youtube.com/watch?v=a5JhEd7SUH4...re=channel_page

[VaccaRabite]

Your idle jets are clogged for #1. I'd put money on it.

What kind of carbs are they? Weber IDF? Sorry if you posted that info, but I am getting dressed for work and don't have time to re-read the entire thread.

Find a good diagram for the type of carbs that you have, and blow out the #1 idle jets with compressed air after giving it a good squirt of carb cleaner. Clean the spark plug. Put everyhting back together and try it again.

If you are making 140# compression, I think you are in really good shape there. If you can borrow a leak tester, it is still a good thing to do.

I still think its easy/cheap stuff. POSITIVE WAVES! (IMG:style_emoticons/default/smile.gif)

When winter comes, consider pulling and rebuilding the carbs. If you have IDFs it will cost you about $70 (shipping included) for the kits and a few hours of your time.

Fresh rebuild is ~#150 compression. Over 130 is great compression. 130-100 is happy diving compression. 95-100 is start looking for rebuild parts compression. under 95 - pullit and start over time.

Also, you want to have compression in all 4 be ~the same.

AND, compression is just 1 part of the story. You really should do leak down too. You can have good compression, but still have crap leakdown. It sounds weird, but I had 115# compression @45% leak on my #1 cylinder. It lead to a full rebuild, as I discovered my case was collapsing at the cylinders and had to be fixed.

But, really. 140#, I think you are going to be just fine once you get fuel flowing.

Could you take and post a picture of the top end of your engine bay, so we can see your carb set up?
Zach

[UberElectricEagle]

Your idle jets are clogged for #1. I'd put money on it.

What kind of carbs are they? Weber IDF? Sorry if you posted that info, but I am getting dressed for work and don't have time to re-read the entire thread.

Find a good diagram for the type of carbs that you have, and blow out the #1 idle jets with compressed air after giving it a good squirt of carb cleaner. Clean the spark plug. Put everyhting back together and try it again.

If you are making 140# compression, I think you are in really good shape there. If you can borrow a leak tester, it is still a good thing to do.

I still think its easy/cheap stuff. POSITIVE WAVES! (IMG:style_emoticons/default/smile.gif)

When winter comes, consider pulling and rebuilding the carbs. If you have IDFs it will cost you about $70 (shipping included) for the kits and a few hours of your time.

Fresh rebuild is ~#150 compression. Over 130 is great compression. 130-100 is happy diving compression. 95-100 is start looking for rebuild parts compression. under 95 - pullit and start over time.

Also, you want to have compression in all 4 be ~the same.

AND, compression is just 1 part of the story. You really should do leak down too. You can have good compression, but still have crap leakdown. It sounds weird, but I had 115# compression @45% leak on my #1 cylinder. It lead to a full rebuild, as I discovered my case was collapsing at the cylinders and had to be fixed.

But, really. 140#, I think you are going to be just fine once you get fuel flowing.

Could you take and post a picture of the top end of your engine bay, so we can see your carb set up?
Zach

I ran some spray carb cleaner down the carbs while it was running. No change in #1. 1/2 side carb increased idle when I sprayed carb cleaner in. 3/4 side bogged down when sprayed in. Does this mean anything special?

I might be crazy, but I swear for 10 to 20 seconds about a minute after I started all this cleaner spraying while it was running, It seemed that the noise went away. But it was right back and I'm not sure if I'm making it up or not.

I did have black oil spatter (like it was forced out with pressure) on the ground under the inner driver's side half of the motor. just left of center. This was odd because the oil in the motor that leaks out on the ground is pretty clean.

I don't really know where to go from here.

What's the correct type or the best kind of pressure tester to have? Mine is pretty old and just has a rubber nipple that I have to hold down in the spark plug hole. I don't even think it will reach #2 spark plug hole. Is there one that threads in like a spark plug and has some reach to it or an hose or extension? I'm ignorant in this area, or most areas I guess.