Principles of porting an engine and big valve conversions

[obi_waynne]

The inlet and outlet ports on the engine block are usually larger than those of the manifolds that connect to them. This allows for scope in the manufacturing process to allow for mismatched alignment. Generally the engine ports are larger in the upstream flow direction avoiding turbulance but power gains can be made by matching these up.

Continue reading... or post your comments below on this article.

 

[TAZ67]

Matching manifold to ports definitely helps increase power. Having pins fitted is needed so alignment always matches. Turbulence of incoming air/fuel is beneficial. Port shape also play's a big part. Combustion chamber can also determine how well mixture behaves entering, then how well flame front expansion spreads out efficiently at tdc. Understanding engine's is hard as not all engine's behave the same!?

 

[thexav]

That was an interesting read.

Is this something a DIY'er can do at home?

 

[TCJBOLDIE]

That was an interesting read.

Is this something a DIY'er can do at home?

I have done this way back (before I was married) on a mates Wolsey6/80 IIRC I blended in the inlet and exhaust ports to the manifolds and removed casting dags in the ports with carborundum grinding bits and smoothed whatever I could get at with a flap wheel. When working from the CC side you need to be careful not to damage the valve seats.

So any DIY'er would need to have the tools and skills to remove and refit the head for starters.

How many of you even know what a 6/80 is or looks like ?

Here you go. https://www.classicandsportscar.com/features/guilty-pleasures-wolseley-680

 

[obi_waynne]

Oh those days when you had spare time to tinker!