Modifying Comp Eliminators to 4" Bore?

[Fasterbrit]

Anyone tried this? Possible? Or too much grief? I have a spare set that I wouldn't mind experimenting on for four inch bore. I realise there's a fair amount of welding and machining necessary, but this can all be done in-house. Just wondering if it's been done before and whether or not it's worth the hassle

Regards, Matt

[Tomi]

Yes it has been done. 2010 top20 no. 1 car has comp eliminators which he modified himself from 94 bore to 4". He has over 300hp so I think at least in that case it was worth the hassle.

[richie]

machine up some ally plugs to fill in the existing stud holes,press them in,the weld them in permanently.
Now  you can drill them to what stud pattern you require,and bore for your cylinder size.I have seen it done with older angleflows and comps,but you can buy comps blank which would make it alot easier.
After the welding is done they may need re heat treating which adds to the cost

cheers richie

[Fasterbrit]

Thanks Richie. The pair I have are already machined for 94mm bore, so I guess I will go the route of machining and welding. That would be a whole lot cheaper than buying a new pair

[Udo]

Mat
Order a new set without stud holes bored . Weld a little on the stud bosses left and right on top ones. i did this with good results.
Working right now on a 101,6 engine with this heads for a customer
Udo

[Fasterbrit]

Thanks Udo. I will have to use the heads I have already as budget won't allow for new heads. Welding and machining is no problem as I can do that inhouse.

Where the two cylinders meet in the middle of the head... I imagine it gets real thin and maybe even breaks through?

[Udo]

So do like richie said    No break through in my experiance

Udo

[Fasterbrit]

Thanks guys

[Fiatdude]

Break thru is a non-issue -- -- seals fine

[dangerous]

That photo above is a A/F head, and the casting is designed for a 4" plus bore.
The early comp eliminators will likely need something welded between the cylinders to support a 4" bore.