Looking for drawings of BCD intake and exhaust valves

[johnmead]

I am having some Titanium valves made for my race motor and have found a company that will do it. I can send them new valves from the spares company but would prefer to get copies of the original or aftermarket valves. I think they will be more accurate that way.

John

 

[vibrac]

The Spares company valves are made from the drawings how do you know the provenance of 'aftermarket' valves

 

[timetraveller]

My advice is not to make the valves like the original ones anyway. Valve design has moved on in 60+ years and you will find that the modern valves do not have the same shape as the originals. The radius of the curve at the rear of the valve head where the stem turns into the head is not optimim and the face in the middle of the valve head is now recessed to aid gas flow. Also if you are hoping to go for very high lift on the valves it makes life easier if the thicker part of the stem is about 0.1 inch longer than standard but the overall length needs to be as the original. Terry Prince can supply springs which have the same seat pressure when closed but allow longer valve movement.

 

[johnmead]

The valves will have a modern tulip section. They will also have a real retainer groove instead of the thin wire one. What I need the drawings for is to get the correct stock length of both the valve and where the step down section begins. I and the manufacturer is aware of the extra length requirement of the lower valve stem section.

For springs I am using beehive type springs with Ti retainers/keepers. Beehive springs use oval wire instead of round allowing you to use greater lift and still keep the seat and maximum spring pressure down.

So, can anyone supply me with the factory specifications for the length of the valves and where the step begins?

 

[timetraveller]

Here are some figures to get you started. I do not have drawings so I measured three old valves I have lying about. They are well used and might have stretched. I measured one inlet and two exhausts. Overall length, inlet 4.656, exhausts, 4.610 and 4.632. Diameter of upper stems, 0.308, 0.309, 0.310. Diameter of lower stems, 0.368 0.373, 0.370. Distance from top end of valve stem to start of thickest part of stem, 2.212. 2199, 2.198. Note that these last three measurements are the least reliable as I do not have good way to locate the very top end of the valve stem. Good luck. Maybe someone will have access to factory figures.

 

[johnmead]

Thank you. I will include your numbers with the measurements I got from new Alpha valves that I bought back in the 70s.

 

[clevtrev]

John, I`ve e-mailed you a copy of the exhaust valve.
Beware what grade of titanium you use, some grades have a tendency to let the collar loose. Vanadium grade would be the best, unfortunately not for price.

 

[johnmead]

Thank you Trevor. I received the drawing and used my CAD software to draw one with the higher lower stem and modern keeper groove. I measured some new and used intake valves, including a 2" on that came with parts I got from a dragracer (sprinter) and will draw the intake valve.