Technical Cylinder head for 600cc engine

[itsalovelydaytoday]

Hi all. Just rebuilt a 600cc engine for which I do not have a head. Is it possible to fit a 650cc head as per pics?

 

[Toshi 975]

That will fit no problem, check what head gasket you use as you do not want hotspots

 

[the hobbler]

That will fit no problem, check what head gasket you use as you do not want hotspots

As 'Toshi' has confirmed, you can fit the '650' head on the '600' engine.What will help is that (a) you have a 'higher compression' head and (b) have the head skimmed to ensure flatness and bring up the compression ratio slightly---if the head has never been skimmed before, you can safely skim 40thou (1mm) off it.

 

[itsalovelydaytoday]

Many thanks to you both for your replies. Will go ahead and fit it as suggested. 2nd question - which pushrods should I use bearing in mind 600 block and cylinders and 650 head? I have two sets, one slightly shorter than the other - see pics

 

[Toshi 975]

As you probably know the rod style of the left was used on the 500 and certainly the early 594 engines. When they changed to the 126 style I do not know As there are a number of features on the 594 engine that are something of a crossover. I might be inclined to fit the later set.

 

[the hobbler]

As you probably know the rod style of the left was used on the 500 and certainly the early 594 engines. When they changed to the 126 style I do not know As there are a number of features on the 594 engine that are something of a crossover. I might be inclined to fit the later set.

I agree with David (Toshi)----I would fit the 'slim-line' pushrods as they are from a '126' engine.

 

[itsalovelydaytoday]

Do you think that being slightly shorter will cause a problem or is that difference taken up in the adjustment on the tappets?

 

[Bleeding Knuckles]

Hi, The standard length pushrod (126) is 235mm, providing you don't hack too much off of the head or have a 'wilder' cam there will be no problem. I would council you to trial fit everything and make sure at the same time you use the correct adjustments and torque and then turn the engine over (by hand) without plugs to check on valve spring clearance - at least 25thou between coils at maximum lift, but as you are keeping things largely standard there should be no problems.
Ian.