Big backfire, 2.7L CIS from 1976 911 |
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Big backfire, 2.7L CIS from 1976 911 |
Kansas 914 |
Jul 4 2020, 10:08 AM
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#1
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Advanced Member Group: Members Posts: 2,999 Joined: 1-March 03 From: Durango, Colorado Member No.: 373 Region Association: Rocky Mountains |
I tried to start the car as I normally do but back fired (pretty loud) I tried to re-start (it did this once before a few years ago) but this time it didn't restart.
I pulled the air cleaner cover and saw a hole in the filter and the pop-off valve was in pieces. I haven't taken the air box off yet but that is next if I can't get the old pop-off valve out. It looks like the engine builder sealed the air box (and the pop-off valve) with some kind of "goop". Fun times... |
Kansas 914 |
Jul 4 2020, 11:18 AM
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#2
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Advanced Member Group: Members Posts: 2,999 Joined: 1-March 03 From: Durango, Colorado Member No.: 373 Region Association: Rocky Mountains |
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sixnotfour |
Jul 4 2020, 12:15 PM
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#3
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914 Wizard Group: Members Posts: 10,423 Joined: 12-September 04 From: Life Elevated..planet UT. Member No.: 2,744 Region Association: Rocky Mountains |
Well, better than the box blowing up...You should be able to pry the base out.. Usually the whole thing pops out... Happy 4th of July
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Kansas 914 |
Jul 4 2020, 12:45 PM
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#4
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Advanced Member Group: Members Posts: 2,999 Joined: 1-March 03 From: Durango, Colorado Member No.: 373 Region Association: Rocky Mountains |
Well, better than the box blowing up...You should be able to pry the base out.. Usually the whole thing pops out... Happy 4th of July Hi Jeff, Yep - I hope the box isn't blown. I will work on the pop-off valve and see how it goes. Happy 4th of July to you and Suzie - cheers! |
rgalla9146 |
Jul 4 2020, 01:17 PM
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#5
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Advanced Member Group: Members Posts: 4,549 Joined: 23-November 05 From: Paramus NJ Member No.: 5,176 Region Association: None |
Put the toilet seat back on ......see if it starts.
Maybe put something on top of it to keep it seated |
914Toy |
Jul 4 2020, 01:19 PM
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#6
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Senior Member Group: Members Posts: 717 Joined: 12-November 17 From: Laguna beach Member No.: 21,596 Region Association: Southern California |
Also check the cross-over black rubber boot was not blown off the throttle body or the fuel injection module.
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rgalla9146 |
Jul 4 2020, 01:25 PM
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#7
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Advanced Member Group: Members Posts: 4,549 Joined: 23-November 05 From: Paramus NJ Member No.: 5,176 Region Association: None |
Put the toilet seat back on and see if it starts.
Maybe put something on top of it to keep it seated. A big backfire is usually caused by a lean condition. If the plenum survived (fingers crossed) check fifth injector, points and the other usual suspects |
Kansas 914 |
Jul 4 2020, 02:24 PM
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#8
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Advanced Member Group: Members Posts: 2,999 Joined: 1-March 03 From: Durango, Colorado Member No.: 373 Region Association: Rocky Mountains |
Put the toilet seat back on and see if it starts. Maybe put something on top of it to keep it seated. A big backfire is usually caused by a lean condition. If the plenum survived (fingers crossed) check fifth injector, points and the other usual suspects It did start with the toilet seat on and weighted down - but ran poorly then died. |
windforfun |
Jul 4 2020, 02:30 PM
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#9
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Senior Member Group: Members Posts: 1,779 Joined: 17-December 07 From: Blackhawk, CA Member No.: 8,476 Region Association: None |
Too many spicy tacos. Happens to me all the time.
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sixnotfour |
Jul 4 2020, 02:37 PM
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#10
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914 Wizard Group: Members Posts: 10,423 Joined: 12-September 04 From: Life Elevated..planet UT. Member No.: 2,744 Region Association: Rocky Mountains |
Got Gas ? in da tank.. $th of july
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Kansas 914 |
Jul 4 2020, 02:38 PM
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#11
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Advanced Member Group: Members Posts: 2,999 Joined: 1-March 03 From: Durango, Colorado Member No.: 373 Region Association: Rocky Mountains |
The old pop-off valve is SECURELY glued in place. I may have to remove the airbox (and all the other associated goodies).
It doesn't look like fun. I am reading some articles on the Bird Board now - ugh. I love my Type 4 motors even more now... |
sixnotfour |
Jul 4 2020, 03:08 PM
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#12
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914 Wizard Group: Members Posts: 10,423 Joined: 12-September 04 From: Life Elevated..planet UT. Member No.: 2,744 Region Association: Rocky Mountains |
Type 4 sale.... dont come home with one..REDRUM..
Pulling the CIS assm. on a 914 is way easier than a 911... (IMG:style_emoticons/default/popcorn[1].gif) Attached image(s) |
sixnotfour |
Jul 4 2020, 03:11 PM
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#13
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914 Wizard Group: Members Posts: 10,423 Joined: 12-September 04 From: Life Elevated..planet UT. Member No.: 2,744 Region Association: Rocky Mountains |
Just throw Carbs on it.. (IMG:style_emoticons/default/idea.gif) (IMG:style_emoticons/default/lol-2.gif) (IMG:style_emoticons/default/av-943.gif) (IMG:style_emoticons/default/popcorn[1].gif)
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Kansas 914 |
Jul 4 2020, 03:32 PM
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#14
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Advanced Member Group: Members Posts: 2,999 Joined: 1-March 03 From: Durango, Colorado Member No.: 373 Region Association: Rocky Mountains |
Type 4 sale.... dont come home with one..REDRUM.. Pulling the CIS assm. on a 914 is way easier than a 911... (IMG:style_emoticons/default/popcorn[1].gif) Thanks Jeff, I was going to ask you if it is easier in a 914 than a 911. My only problem when reading the "how to" thread on Pelican everything will have to be reversed (right side = left side). (IMG:style_emoticons/default/smile.gif) |
Kansas 914 |
Jul 4 2020, 03:33 PM
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#15
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Advanced Member Group: Members Posts: 2,999 Joined: 1-March 03 From: Durango, Colorado Member No.: 373 Region Association: Rocky Mountains |
Just throw Carbs on it.. (IMG:style_emoticons/default/idea.gif) (IMG:style_emoticons/default/lol-2.gif) (IMG:style_emoticons/default/av-943.gif) (IMG:style_emoticons/default/popcorn[1].gif) I had thought about ITBs and Megasquirt....... But my wallet ran out of the room. |
porschetub |
Jul 4 2020, 03:49 PM
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#16
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Advanced Member Group: Members Posts: 4,697 Joined: 25-July 15 From: New Zealand Member No.: 18,995 Region Association: None |
Just throw Carbs on it.. (IMG:style_emoticons/default/idea.gif) (IMG:style_emoticons/default/lol-2.gif) (IMG:style_emoticons/default/av-943.gif) (IMG:style_emoticons/default/popcorn[1].gif) I had thought about ITBs and Megasquirt....... But my wallet ran out of the room. Shit that was a big bang...blew the hinges on the flap right off (IMG:style_emoticons/default/sad.gif) . Check to see the plenum runners are still tight on the heads,they are known to loosen up on the gaskets and leak. Good luck sorting this,guess its about finding the cause after the airbox is fixed,hopefully no further damage done. |
Kansas 914 |
Jul 5 2020, 08:33 AM
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#17
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Advanced Member Group: Members Posts: 2,999 Joined: 1-March 03 From: Durango, Colorado Member No.: 373 Region Association: Rocky Mountains |
Shit that was a big bang...blew the hinges on the flap right off (IMG:style_emoticons/default/sad.gif) . Check to see the plenum runners are still tight on the heads,they are known to loosen up on the gaskets and leak. Good luck sorting this,guess its about finding the cause after the airbox is fixed,hopefully no further damage done. Thanks for the suggestion to check the runners - I will do that. I agree - I hope there was no further damage. I am under the gun to get this fixed since Red Rocks Classic is being held here (Durango) in September and I have never worked on CIS before. |
Kansas 914 |
Jul 7 2020, 10:49 AM
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#18
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Advanced Member Group: Members Posts: 2,999 Joined: 1-March 03 From: Durango, Colorado Member No.: 373 Region Association: Rocky Mountains |
@sixnotfour
Jeff - I did as you suggested and got the pop off valve out. The new on is on the way (next week probably). What adhesive do you like to install the new POV? I have some Honda Bond HT but I think that stays "rubbery" after it cures. |
sixnotfour |
Jul 7 2020, 01:07 PM
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#19
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914 Wizard Group: Members Posts: 10,423 Joined: 12-September 04 From: Life Elevated..planet UT. Member No.: 2,744 Region Association: Rocky Mountains |
Did you notice,It was actually 180 out of proper flapping flow ?
Any thing is good but if it backfires, you need to check the seal, Ive seen em pop out ,instead of breaking a few times,,, |
Kansas 914 |
Jul 7 2020, 01:11 PM
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#20
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Advanced Member Group: Members Posts: 2,999 Joined: 1-March 03 From: Durango, Colorado Member No.: 373 Region Association: Rocky Mountains |
Did you notice,It was actually 180 out of proper flapping flow ? Any thing is good but if it backfires, you need to check the seal, Ive seen em pop out ,instead of breaking a few times,,, Thanks! I have seen them installed both ways and didn't know which way was right. |
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