Missing engine lid release knob

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neilbardsley
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Re: Missing engine lid release knob

Post by neilbardsley »

mycar wrote:After a week of knob wrangling a new muffler should be a walk in the park.
New muffler in fine but the car is still back firing under de-acceleration. There were actually holes in the old muffler that I hadn't seen so it couldn't of been welded.

Could be

-> leak at the front exhaust ports

-> I didn't install the new muffler correctly. However, it was a very tighter fit.

The backfiring only happen when on the main circuit and dropping to the idle circuit. I'm inclined to think that there is another issue
“A REMINDER. I would be grateful if those members who have borrowed bits from me in emergencies (e.g starter motor, oil cooler, etc) would return them and/or contact me”. – Chris Turner RIP
mycar
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Re: Missing engine lid release knob

Post by mycar »

My only experience of this is when the top flanges of the exhaust do not marry up perfectly with the engine and do not make a gas tight seal. The flanges are sturdy and may not pull up if the exhaust is poorly formed.

If this is the case the gaskets will show witness marks where the exhaust gases have been escaping. This poor joint will cause popping on lift off.

I had to resort to filing the flanges, offering up and filing again to ensure a tight fit.

Leaks can also occur at the other end of the exhaust system when these clamps do not nip up well enough.

Image
neilbardsley
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Re: Missing engine lid release knob

Post by neilbardsley »

Thank you Mike. I will check again.

My only experience of this is when the top flanges of the exhaust do not marry up perfectly with the engine and do not make a gas tight seal. The flanges are sturdy and may not pull up if the exhaust is poorly formed.

If this is the case the gaskets will show witness marks where the exhaust gases have been escaping. This poor joint will cause popping on lift off.

I used double gaskets in the hope of avoiding this issue. Interesting whoever fitted the previously exhaust also used double gaskets. I believe this was Larry Markham who has forgotten more about 356s then I know :)

I did do a quick check before putting it all back together but will check again. I sprayed wd 40 around the joints to see if it interacted with any escaping gases but will do the spray check for a an increased idle too. I believe that Mike Smith also recommended blocking the exhausting and listening too!

"Leaks can also occur at the other end of the exhaust system when these clamps do not nip up well enough."

I had so much trouble getting the old pipes I had to hit the exhaust with a large rubber hammer. When that didn't work I had to heat the joint and hit harder with the hammer not leaving the old exhaust in a good way. I'm hoping too avoid having to do that.
“A REMINDER. I would be grateful if those members who have borrowed bits from me in emergencies (e.g starter motor, oil cooler, etc) would return them and/or contact me”. – Chris Turner RIP
roy mawbey
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Re: Missing engine lid release knob

Post by roy mawbey »

Neil,

Check your idle jets on the carbs. Worth 30 minutes just to see if one is blocked. I presume your plugs are fine.

Roy
RHD 356A coupe super 75 106954
neilbardsley
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Re: Missing engine lid release knob

Post by neilbardsley »

roy mawbey wrote:Neil,

Check your idle jets on the carbs. Worth 30 minutes just to see if one is blocked. I presume your plugs are fine.

Roy
I've checked one side :(

This weekend I'm going to work from valves up. Replace plugs and clean jets and tune it all again.
“A REMINDER. I would be grateful if those members who have borrowed bits from me in emergencies (e.g starter motor, oil cooler, etc) would return them and/or contact me”. – Chris Turner RIP
Winston Teague
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Re: Missing engine lid release knob

Post by Winston Teague »

My gut feeling is that doubling up the exhaust flange gaskets is a terrible idea. To work, a gasket needs to be clamped evenly all around, twice the thickness will not improve things. Flanges need to be flat and not fighting the rest of the exhaust or the cylinder head. All the elements of the system must assemble smoothly and in repose. Achieving this may need heat, filing, grinding and in extreme cases rewelding........ Good luck! W
Winston
'61 356 BT5 & a lot of broken chain driven stuff
marc500
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Re: Missing engine lid release knob

Post by marc500 »

Your backfiring is likely related to the exhaust but it could also be the mixture is a touch too lean - a quarter turn on all four carb screws stopped mine back firing on overrun.
mycar
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Re: Missing engine lid release knob

Post by mycar »

Neil, now you have easy access to your engine compartment, take the opportunity to lubricate the locking mechanism and fit an emergency release pull.

A length of stainless steel wire attached to the release mechanism, passing through a hole drilled through the engine compartment wall, exiting under the nearside wing will offer a foolproof option for you, or future owners, should the release knob fail again.

Terminate the wire pull with a nice finger loop.

Image

https://www.ebay.co.uk/itm/2mm-3mm-STAI ... 2004268232
neilbardsley
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Re: Missing engine lid release knob

Post by neilbardsley »

Lots done.

Valves adjusted
Brakes bleed
Right carb off to check
Timing advanced a little
Linkage ball joints replaced. Removed play
https://www.berger-tools.co.uk/Din71802 ... nc_Plated/
Checked carbs balanced through the rpm range
Adjusted idle mix and set a bit richer than normal.
Sprayed wd 40 never exhaust gaskets but didn't hear a change in idle
New clamp on exhaust

Rain on and so haven't test drove let

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“A REMINDER. I would be grateful if those members who have borrowed bits from me in emergencies (e.g starter motor, oil cooler, etc) would return them and/or contact me”. – Chris Turner RIP
neilbardsley
Nurse, I think I need some assistance
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Joined: Mon Apr 16, 2012 4:31 pm

Re: Missing engine lid release knob

Post by neilbardsley »

Still back firing. I will try to seal tomorrow

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“A REMINDER. I would be grateful if those members who have borrowed bits from me in emergencies (e.g starter motor, oil cooler, etc) would return them and/or contact me”. – Chris Turner RIP
neilbardsley
Nurse, I think I need some assistance
Posts: 8637
Joined: Mon Apr 16, 2012 4:31 pm

Re: Missing engine lid release knob

Post by neilbardsley »

Resealed but the lazy way. Didn't take off exhaust entirely but got a gap and put paste in. One of the boots wasn't tight. Took off right carb again because it looked like it had a leak. Not backfiring at much but work still needed.

Bit too much work and too little drivingImageImage

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“A REMINDER. I would be grateful if those members who have borrowed bits from me in emergencies (e.g starter motor, oil cooler, etc) would return them and/or contact me”. – Chris Turner RIP
BD55
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Re: Missing engine lid release knob

Post by BD55 »

Did it backfire before you changed the exhaust ?...from my limited experience i would second Winston's reply.
64 356C
neilbardsley
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Re: Missing engine lid release knob

Post by neilbardsley »

I changed the exhaust because it was backfiring

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“A REMINDER. I would be grateful if those members who have borrowed bits from me in emergencies (e.g starter motor, oil cooler, etc) would return them and/or contact me”. – Chris Turner RIP
mycar
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Re: Missing engine lid release knob

Post by mycar »

Good plan.

What did you change it for ?
BD55
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Re: Missing engine lid release knob

Post by BD55 »

Ah, so any evidence of the old exhaust leaking at ports?
64 356C
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