Exhaust manifold gaskets & bolts
Discussion
What's the best option for manifold gaskets? I lost an ARP bolt last week somewhere around the NC500 and it's blowing badly now. I'm also looking for alternative stainless steel bolts, the flange head on the ARP's is too narrow for my liking so I'd like to bolt with something better
Has anyone got a spare ARP I could buy???
Has anyone got a spare ARP I could buy???
Edited by bobfather on Monday 21st May 14:33
I’d look at the gaskets and how they line up on the manifolds Bob.
Not sure about bolts as my standard ones seem to stay tight enough.
Just remembered I used gasket sealant on both sides of gaskets when doing mine so that might have helped but I’d be interested to see how well these line up with the manifolds Powers ones are as big as you can buy I think! Which look much bigger than standard heads size so shouldn’t clash there but as you can see from these pictures
The blacked out bits are to be opened up to match the gasket size and when this gasket is lined up properly with the bolt holes the gasket already sits very close to the floor of the port. Within 1/2 mm so if the manifold sits any higher at this point it will cause a step and I think could lead to gasket failure/ vibration of bolts.
I have used this gasket as a template and 3 holes line up on all the corresponding positions on heads once I’d opened the 4th hole a little it now fits either way very accurately.
Until I get a manifold to play with I can’t say if the manifold fits as accurately but for me to port the heads it’s vital to finish it properly by fettling (if I have too) the manifolds so there is no question of this matching.
I think this might be the problem on some cars. If the manifolds turn out to be bigger than the ports then there’s no restriction and nothing to worry about. I’d offer up the gasket to manifold and work from there.
But see even on standard heads the gasket sits extremely close the what is the port floor so any miss alignment here could cause turbulence and possibly a higher risk of gasket failure. We want those gases out as straight and as fast as possible.
Match porting badly alighted exhaust manifolds is known to give benefits,,, what I don’t know yet is if the Tvr ones line up well or not. Seem to think Peter sent me a pic that suggests they are indeed bigger than gasket so should not really be a problem.
Although I can’t answer your question your question raises some important details I think need to be considered.
Not sure about bolts as my standard ones seem to stay tight enough.
Just remembered I used gasket sealant on both sides of gaskets when doing mine so that might have helped but I’d be interested to see how well these line up with the manifolds Powers ones are as big as you can buy I think! Which look much bigger than standard heads size so shouldn’t clash there but as you can see from these pictures
The blacked out bits are to be opened up to match the gasket size and when this gasket is lined up properly with the bolt holes the gasket already sits very close to the floor of the port. Within 1/2 mm so if the manifold sits any higher at this point it will cause a step and I think could lead to gasket failure/ vibration of bolts.
I have used this gasket as a template and 3 holes line up on all the corresponding positions on heads once I’d opened the 4th hole a little it now fits either way very accurately.
Until I get a manifold to play with I can’t say if the manifold fits as accurately but for me to port the heads it’s vital to finish it properly by fettling (if I have too) the manifolds so there is no question of this matching.
I think this might be the problem on some cars. If the manifolds turn out to be bigger than the ports then there’s no restriction and nothing to worry about. I’d offer up the gasket to manifold and work from there.
But see even on standard heads the gasket sits extremely close the what is the port floor so any miss alignment here could cause turbulence and possibly a higher risk of gasket failure. We want those gases out as straight and as fast as possible.
Match porting badly alighted exhaust manifolds is known to give benefits,,, what I don’t know yet is if the Tvr ones line up well or not. Seem to think Peter sent me a pic that suggests they are indeed bigger than gasket so should not really be a problem.
Although I can’t answer your question your question raises some important details I think need to be considered.
They look good ^^^^^^^^
I used these last time - cheap and simple.
http://shop.roverp6cars.com/epages/es146747.sf/en_...
I used these last time - cheap and simple.
http://shop.roverp6cars.com/epages/es146747.sf/en_...
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