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Silicone issue

Posted: Sun Apr 20, 25 10:35 pm
by sublimemike
I'm attempting to move up to a more free flowing inlet manifold on my 440RB. All bolts ,carb linkages off etc. The inlet maifold has been silliconed down and despite trying to lever it off against the valley pan its solid. Feels strong enough to lift the motor. The Valley pan is Indy ally so not sure how much pressure I can give without incurring damage Not easy to get a cutter / craft knife in in without removing the rocker covers. Am I looking at greater methods of leverage , cheese cutting wire?? Thought this was an hour to do.
Thanks

Re: Silicone issue

Posted: Mon Apr 21, 25 9:07 am
by Pete
My 16 bolt Hemi inlet was the same.

I solved it but cutting all the way around with a Stanley knife - most of the grief is on the valley walls - and then I loosened but did not remove the Inlet bolts, then I used a lifting strap (you could use a lifting plate but more risk) and then put the engine hoist on it.

Yes, you are correct, I got the front wheels off the ground!

However, it eventually broke free..... scary stuff!

Re: Silicone issue

Posted: Mon Apr 21, 25 11:14 am
by sublimemike
Thanks Pete .At the moment I'm thinking of borrowing a more heavy duty breaker bar and giving it some more leverage on the valley pan but am I risking damaging the ally valley pan?

Re: Silicone issue

Posted: Mon Apr 21, 25 12:27 pm
by Pete
The Valley Pan will take no load at all..... you need to lever on the Block or worst case the Heads....

Re: Silicone issue

Posted: Mon Apr 21, 25 2:12 pm
by mygasser
Pete wrote: Mon Apr 21, 25 12:27 pm The Valley Pan will take no load at all..... you need to lever on the Block or worst case the Heads....
agreed, maybe put a block of wood on the end of the valley pan where it sits on the 'china wall'. you'll be safer levering there as there's support under the pan, plus the wood being soft will spread the load without damage. you'll probably need to remove the valve covers to get a blade under the inlet to cut the silicon first though as mentioned.
neil.

Re: Silicone issue

Posted: Mon Apr 21, 25 4:16 pm
by sublimemike
Thanks Neil, Yes , I've tried a bit with the wood and get the spreading the load aspect. I will cut the silicone and look for some heavier duty leverage tools tomorrow. If all else fails, Pete's method of some lifting apparatus with the bolts loosely on makes sense.

Re: Silicone issue

Posted: Mon Apr 21, 25 11:28 pm
by V8DVE
How about a single handle hacksaw blade holder? Something like Screwfix code 188TF, or cheaper 1046X

Not sure if its possible to grind down the blade to a sharp edge so no teeth to damage anything, so it would be like a long stanly blade with a handle... As mygasser said, all depends how compressed the silicone is under the inlet, to be able to get a 1.5 / 2mm gap to get the blade in though 😬

Re: Silicone issue

Posted: Tue Apr 22, 25 9:36 am
by sublimemike
I've got a really thin bit of ally - Originally was the door plate cill from a Mazda MX5! I've put it through a knife sharpener to try and get an edge. I' ll wrap in in some foam so I don't cut myself and see if I can squeeze that in between to make headway. I've got a hacksaw as you mentioned but the blade is too thick. The gap I've got to work with is marginally thicker than a fag paper.

Re: Silicone issue

Posted: Tue Apr 22, 25 8:51 pm
by sublimemike
Well after some head scratching and cursing I got there. Not a nice job and I wasn't looking froward to resorting to Pete's method. I started my cutting as much as the silicone as I could. Next was to try and pry the inlet off courtesy of a pry bar with an extended length of piping for additional leverage.


mopar leverage.jpg
mopar leverage.jpg (72.19 KiB) Viewed 7568 times



This wasn't working and was absolutely solid. I managed to make a gap the thickness of some flexible sheet tin. Just in the lower corner you can see a crack.



mopar gap.jpg
mopar gap.jpg (114.33 KiB) Viewed 7568 times


The mazda cill plate was too thick and i had to abondon that. I decided I'd try and shock it off or vibrate it possibly . With a sharp wedged instrument and a few blows with a claw hammer it gave .


mopar heads.jpg
mopar heads.jpg (154.4 KiB) Viewed 7568 times


I guess the person who built it didn't use gaskets because my ports are too big. Thanks for suggestions and it cleanup on the silicone tomorrow

Re: Silicone issue

Posted: Tue Apr 22, 25 9:27 pm
by Pete
You should always use Gaskets, the silicon is not sufficient and will eventually break down with the incoming fuel....

Re: Silicone issue

Posted: Wed Apr 23, 25 9:28 am
by sublimemike
Yes , thanks Pete. When it is cleaned and reassembled gaskets will be used