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914World.com _ 914World Garage _ Ideas please, engine knocking.

Posted by: theo May 16 2011, 07:33 PM

I have a 1.7 with carbs. on Thursday I had the air filters off while I was cleaning them, anyway after cleaning I reinstalled them and took the car out and drove it several miles and everything ran perfect. I was out of town all weekend and when I started the car up for school this morning there was a loud knock that sounds like metal on metal so I immediately killed it. anyway I cant find where the noise is coming from and I am not going to start it up again. the only thing I can think of is that maybe something dropped down into the intake. anyway I am about half way to having the head off and decided to take a break and see if anyone has any input. Also, I removed the spark plugs and there is no sign that it had been struck.

Posted by: r_towle May 16 2011, 07:46 PM

Have you synced your carbs lately?
Did you possibly drop a screw or nut down the carb into the intake?

Rich

Posted by: theo May 16 2011, 08:00 PM

it has been a while since Ive synced them. they have seemed very smooth. and I have not touched any of the geometry in the last week. and I idk I was stupid, in a rush and didn’t bother to stuff a rag down, so its always a possibility. and can i pull the head off w/o taking the rockers off. just pull the pushrod tubes and rods out of the case side?

Posted by: kg6dxn May 16 2011, 08:05 PM

I sucked a screw into my V8 one time. It was the loudest clank I ever heard. It forged the screw into my aluminum head. Pulled it out, new gaskets and drove it for many miles...

Posted by: theo May 16 2011, 08:14 PM

well. i am in the middle of a 2.0 build but its not done yet and i need a daily driver haha

Posted by: vsg914 May 16 2011, 08:20 PM

there are two bolts that are blocked by the rockers. The tubes also require removal of the rockers.

Posted by: r_towle May 16 2011, 08:20 PM

QUOTE(theo @ May 16 2011, 10:00 PM) *

it has been a while since Ive synced them. they have seemed very smooth. and I have not touched any of the geometry in the last week. and I idk I was stupid, in a rush and didn’t bother to stuff a rag down, so its always a possibility. and can i pull the head off w/o taking the rockers off. just pull the pushrod tubes and rods out of the case side?

Half day, pull motor, pull head...look.

Rich

Posted by: theo May 16 2011, 08:52 PM

yeah I've got the head separated from the cylinders and it dos look like there is one of those sheet metal tinnermans that the bolt for the air cleaner goes into :/ must have broke.

Posted by: 76-914 May 17 2011, 09:36 AM

QUOTE(r_towle @ May 16 2011, 07:20 PM) *

QUOTE(theo @ May 16 2011, 10:00 PM) *

it has been a while since Ive synced them. they have seemed very smooth. and I have not touched any of the geometry in the last week. and I idk I was stupid, in a rush and didn’t bother to stuff a rag down, so its always a possibility. and can i pull the head off w/o taking the rockers off. just pull the pushrod tubes and rods out of the case side?

Half day, pull motor, pull head...look.

Rich

That's right, Rich; rub it in. 1/2 day for you and a full day for the rest of us. sad.gif beerchug.gif

Posted by: SGB May 17 2011, 10:40 AM

dontcha love it. The weakest link will get you. Fuching screw.

Posted by: stugray May 17 2011, 10:52 AM

Yeah, when I broke down my webers all the way I couldnt believe how hard it was to get the screws out of the butterflys.

Then I realized they had blue loctite, and thought "Oh yeah, it would be very bad if one of those came loose" ;-)

How did you manage to get the head off with the engine still in the car?
Arent the engine tins in the way?

Stu

Posted by: Drums66 May 17 2011, 11:47 AM

QUOTE(kg6dxn @ May 16 2011, 07:05 PM) *

I sucked a screw into my V8 one time. It was the loudest clank I ever heard. It forged the screw into my aluminum head. Pulled it out, new gaskets and drove it for many miles...


...If you catch it early.....this can be done! idea.gif
bye1.gif popcorn[1].gif(If that is what it is?)

Posted by: SUNAB914 May 18 2011, 08:02 AM

Are you sure that one of the lifters just isn't sticking till it gets oiled up? My hydro lifters will do that if it hasn't been driven in awhile? Mile or so, and super quiet again. good luck.

Posted by: theo May 18 2011, 11:20 AM

No, it was a little sheet metal nut that got sucked in. I have already got it out, and the head back on. I have just not had time to get it buttoned up completely. .

QUOTE(stugray @ May 17 2011, 09:52 AM) *

How did you manage to get the head off with the engine still in the car?
Arent the engine tins in the way?
Stu


I was working on the passenger side head, you can t get the head completely off because of the tin for the oil cooler, but you can separate the head from the cylinders a couple inches which is all you need to remove a screw or something.

Posted by: Drums66 May 18 2011, 04:45 PM

.......Good deal glad you got it!!! idea.gif
smoke.gif (boing)

Posted by: ewdysar May 18 2011, 06:15 PM

QUOTE(theo @ May 18 2011, 10:20 AM) *

No, it was a little sheet metal nut that got sucked in. I have already got it out, and the head back on. I have just not had time to get it buttoned up completely. .

QUOTE(stugray @ May 17 2011, 09:52 AM) *

How did you manage to get the head off with the engine still in the car?
Arent the engine tins in the way?
Stu


I was working on the passenger side head, you can t get the head completely off because of the tin for the oil cooler, but you can separate the head from the cylinders a couple inches which is all you need to remove a screw or something.


Nice work! Good calls all the way around (except maybe the lack of rags in the intake). Congrats on catching this before things took a worse turn.

beerchug.gif

Posted by: theo May 22 2011, 02:56 AM

this weekend I finally got everything buttoned up; head, exhaust carbs back on. I adjusted the valves, looked at the pushrods on the cylinder i did work , everything seemed normal. i made sure the carbs were synced up as well. anyway when the car is warmed up I am getting quite a bit of smoke coming from the carbs on the side I did the work. (coming from both the front and the back butterfly valves). I need to get a new gasket as I don’t think its baking a great seal. but any reason why it would smoke? (smells like oil) ive not dialed in the timing but I wouldn’t think it would affect only one half of the engine...... the more I think about it, is it likely that the poor seal between the carb and the head is making it too lean and causing a backfire and smoke in the carb?

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