I bought a modified head from ebay ages ago and have just come to use it, but the valves seem to be further in than my old head. Its a big valve head (37mm, 31mm valves if i remember right) and ive just tried to fit roller rockers but i had to grind the rocker posts first of all (because the rubbed on the springs) to then find that the rollers seem to be too far past the top of the valves, also the posts wont fully seat all the way down because the rocker arms hit the springs!
Couple of questions! Is this a common thing and also is there anyway i can use my r/rockers or will i just have to use standard ones that look like they will be ok?
Its hard to tell if there is an angle on the valves from those pictures, can you get a right angle on the head and tell for sure?
Also have a look on the head for any stamping that looks like it shouldn’t be there, I’m thinking it could be a Longman head, as i know they did some with angled valves, about 3 deg i belive.
What I notice is that the springs do not sit centrally in the the machined seats. Take a valve spring off and see if there is a tubular steel insert around the valve guide. The trick was to drill out the valve guide hole, plug it and redrill at an angle. So the insert plug can be seen. I agree with BMC eccosse that the rockers and pillars are probably the problem, as they were not a problem on angled valve heads originally.
Just had a look at the photos again and the valve spring retainer looks very close to the rocker shaft stud. What is the history of this head, what was it made for by whom and are there any marlings on it around the heater tap hole? I am wondering if it is a first attempt at an angled valve head, with too much angle or the valves non offset, so the inlet is not moved away from the rocker pillar.
That last photo does suggest that the roller rockers you have won’t fit that head, yet the standard ones will. What cam are you planning to use as you may not need to have the high lift rockers as well - as sometiems you lose more if running a high lift cam and high ratio rockers.
> That last photo does suggest that the roller rockers you have won’t fit that head, yet the standard ones will. What cam are you planning to use as you may not need to have the high lift rockers as well - as sometiems you lose more if running a high lift cam and high ratio rockers.
A MED fast road cam.
looks like an incorrect mix of rockers and posts to me … whatever it is the rockers you have there will destroy your head very quickly… as it “rolls” off the valve stem the load increases exponentially on the bore of the valve guide etc…
It does appear that there are ‘inserts’ where the valve guides sit! Are the valves larger than normal ? This is sometimes done to move the valves apart - so extra large valves can be fitted - although this doesn’t seem to be the case here! . I don’t think the valves have been ‘angled’ - but for some mad reason they appear to have been moved nearer to the rocker pillars. But in any case - with high ratio rockers - do you not need special pillars that move the rockers back, to correct the geometry and ensure they operate directly on the valve tips? But with this head - i think you may need to move even standard rockers back - to get decent geometry.
As regulars on here will know - I am dead against high ratio rockers anyway - on this head there seems to be very little hope of using them.
I think that is a longman head, the stamping rings a bell for some reason… anyway…
high ratio Roller rockers need to be moved away from the valve due to their increase in ratio, that is why they come with their own pillars, the pillars take this into account, in your picture you have the roller rocker pillar with a std rocker, this puts the rocker nearer to where it needs to be.
in the early days of high ratio rockers they did not come woith pillars and you had so drill the pillars larger and push the rockers toward the back of the engine, you could try that, but its a bodge IMO.
