19 replies to this topic

[scottyboy805]

Anybody have one they are not using or want to get rid of?

[DeadSquare]

Be a bit careful.

 

There are 7 port  aluminium heads about, whose inlet valves are more suitable for 1,000cc than 1,300, and were made to use 4 Amal carbs, which are OK when you get them equally set up.

 

Getting one just right on a single cylinder motorbike, is an achievement.

[Gaz66]

Usually they are over ported, especially the inlets so only really get going at high revs due to slow gas speeds low down.

[scottyboy805]

Thanks for the info both.

It is going on a blow through supercharged build so guess it becomes less of an issue. Not aiming for mega power or anything, more like fast road. It is more for packaging so that the supercharger can mount on the back of the engine in the usual spot and EFI with plenum on the front hence the 7 port. If it becomes an issue I guess bigger valves could be fitted down the line anyway? 

[DeadSquare]

Very wise to go for  'Blow through'.  Many a 'Suck' set-up's  long inlet manifold has been blown apart by a 'Back-fire'.

[scottyboy805]

Very wise to go for  'Blow through'.  Many a 'Suck' set-up's  long inlet manifold has been blown apart by a 'Back-fire'.

Yeah I read about issues with suck through setup like icing and problems with tuning etc. that put me off.

Didn't know about blowing intake manifolds though 

[scottyboy805]

Still looking for a 7 port head if anything is about. I would buy a new one but all the normal suppliers don't seem to have any stock and even specialist components are redesigning so wont have anything for about 12 months. 

[Gaz66]

With 7 and 8 port heads you are at the mercy of the suppliers and foundries.
Im approaching 18 months waiting for my 8 port

[IronmanG]

Still looking for a 7 port head if anything is about. I would buy a new one but all the normal suppliers don't seem to have any stock and even specialist components are redesigning so wont have anything for about 12 months.

Don't SC get theres from webcon?

[IronmanG]

https://www.webcon.c...2-bmc-a-series/

[scottyboy805]

https://www.webcon.c...2-bmc-a-series/

Thanks, I didn't consider a bare head until now but maybe it can work.
Don't suppose you know what state they come in as a bare head, as in how much work they need? I guess at a minimum the valve seats will need cutting unless they are done already, but is there anything else to consider?

[IronmanG]

https://www.webcon.c...2-bmc-a-series/

Thanks, I didn't consider a bare head until now but maybe it can work.
Don't suppose you know what state they come in as a bare head, as in how much work they need? I guess at a minimum the valve seats will need cutting unless they are done already, but is there anything else to consider?

Sorry I don't know. Any reason for going 7 port? Sorry just re read your post. Alex at car kitchen was working a supercharged 7 port a while ago. Not sure he far along he got with it

Edited by IronmanG, 22 February 2026 - 04:17 PM.

[PoolGuy]

I seem to remember a post here a while back where someone had bought a 7 port and complained about the finish and the porting, iirc it turned out that he'd bought a bare head. Unfortunately the search facility here doesn't work very well and the previous option of using Google to search the forum has been ruined because of how the frequent outages have been (almost) dealt with. You could try searching, but it's painful to say the least.

[Shooter63]

I'm pretty sure these cast 7 port heads all come a USA company called Pierce Manifolds, they also do some nice manifolds for the A series engine, it might be worth going to them direct, I've no idea what the import tariffs will be though.

Shooter

[scottyboy805]

I'm pretty sure these cast 7 port heads all come a USA company called Pierce Manifolds, they also do some nice manifolds for the A series engine, it might be worth going to them direct, I've no idea what the import tariffs will be though.

Shooter

Didn't know they all come from the same place. I contacted Pierce already because it would have been much cheaper even with import tax, but the reply was that there is no stock and he won't be making any more.