23 replies to this topic

[IronmanG]

Why don't you use a 7 port head, you get all the looks without the agro, mind you if you go 7 port buy yourself some port filler and have some fun.

Shooter

My job for the winter, filling the ports. Any tips?

You might want to try Belzona, I was put onto this by a guy who restores classic Lambo's which evidently suffer from crap/porous castings surprise surprise, it does take along time to fully harden and the area you use it on has to be meticulously clean but it will knock something like JB Weld into the long grass.

Shooter

I've watched a few vizard videos on you tube where uses a product which I will have to look up. Its American and I'm struggling to source it in the UK. Place called Gosneys does it apparently. I've spent a lot of time doing maths stuff and it looks like the diameter needs reducing in the region of 10mm

[PoolGuy]

Devcon always used to be my go to, is JB Weld better?

[Shooter63]

Why don't you use a 7 port head, you get all the looks without the agro, mind you if you go 7 port buy yourself some port filler and have some fun.

Shooter

My job for the winter, filling the ports. Any tips?

You might want to try Belzona, I was put onto this by a guy who restores classic Lambo's which evidently suffer from crap/porous castings surprise surprise, it does take along time to fully harden and the area you use it on has to be meticulously clean but it will knock something like JB Weld into the long grass.

Shooter

I've watched a few vizard videos on you tube where uses a product which I will have to look up. Its American and I'm struggling to source it in the UK. Place called Gosneys does it apparently. I've spent a lot of time doing maths stuff and it looks like the diameter needs reducing in the region of 10mm

I think you are talking about Goodson port filler, which is also an epoxy 2 pack, Devcon make good stuff, but Belzona is british it goes off like rock, you can actually machine it to a decent finish

Shooter

[IronmanG]

Why don't you use a 7 port head, you get all the looks without the agro, mind you if you go 7 port buy yourself some port filler and have some fun.

Shooter

My job for the winter, filling the ports. Any tips?

You might want to try Belzona, I was put onto this by a guy who restores classic Lambo's which evidently suffer from crap/porous castings surprise surprise, it does take along time to fully harden and the area you use it on has to be meticulously clean but it will knock something like JB Weld into the long grass.

Shooter

I've watched a few vizard videos on you tube where uses a product which I will have to look up. Its American and I'm struggling to source it in the UK. Place called Gosneys does it apparently. I've spent a lot of time doing maths stuff and it looks like the diameter needs reducing in the region of 10mm

I think you are talking about Goodson port filler, which is also an epoxy 2 pack, Devcon make good stuff, but Belzona is british it goes off like rock, you can actually machine it to a decent finish

Shooter

Yep that was the one.
Just looking at belzona I'm supposing the 1111 is the 1 I need
I will email them for details and ask what makes them stand out from other products

[mini13]

My SC rods clear the cam in my motor, I was under the impression that all H beams would, as they have rod bolts rather than stud's so there is more clearance.
That said my cams not huge, (RE13)

[Java_Green]

Why don't you use a 7 port head, you get all the looks without the agro, mind you if you go 7 port buy yourself some port filler and have some fun.

Shooter

My job for the winter, filling the ports. Any tips?

You might want to try Belzona, I was put onto this by a guy who restores classic Lambo's which evidently suffer from crap/porous castings surprise surprise, it does take along time to fully harden and the area you use it on has to be meticulously clean but it will knock something like JB Weld into the long grass.

Shooter

I've watched a few vizard videos on you tube where uses a product which I will have to look up. Its American and I'm struggling to source it in the UK. Place called Gosneys does it apparently. I've spent a lot of time doing maths stuff and it looks like the diameter needs reducing in the region of 10mm

Just curious. Hos did you end up with port size of around 30mm in diameter (I would happily take part of your calculations and assumptions)?

[IronmanG]

Before I started using maths I looked at other engine sizes just as a comparison and what DV says about valve sizes etc.
For example in a crossflow head the port size is approx 80% of the valve size
The SC cast 7 port is about 120%
And engines with 40mm throttle bodies are found on anything up to 1800cc engines running 180hp.
Watching the DV videos he always says going smaller is way more beneficial and its surprising how small you can go amd to err on the side of small if you have a range

[Java_Green]

Before I started using maths I looked at other engine sizes just as a comparison and what DV says about valve sizes etc.
For example in a crossflow head the port size is approx 80% of the valve size
The SC cast 7 port is about 120%
And engines with 40mm throttle bodies are found on anything up to 1800cc engines running 180hp.
Watching the DV videos he always says going smaller is way more beneficial and its surprising how small you can go amd to err on the side of small if you have a range

I see your point. I did a Google tour myself and came up with a lot of examples. As I interpret it, port shape is more important than port size. And then I got a bit of philosophical... Where are we suppose to measure port size? The ports in the 7 port head is roughly 30mm in diameter about an inch or so upstream and the interface is for a pair of Weber 40. If you instead mount ~90mm long intake runners, should that be considered as part of the ports? (Compare to the MED intake plenum for their 8 port head, 30mm towards the head and 40mm in the carburetor end)
What is the port size of the MS/Arden 8 port head?

Edited by Java_Green, 01 October 2024 - 06:04 AM.

[IronmanG]

According to MS website the 8 port is 31mm at the mouth so I assume amals are similar size to that.
Reducing the diameter at the point reduces the port volume and should increase velocity. My maths says by about 75%
For me it's worth a shout. Then I'llpossibly be looking at a plenum and single throttle body