49cc valve angle

[deuce x]

I was wondering if the valve angle on the 49cc platinums is different then on the 64 cc heads? I was told the 49cc heads are "angle milled" from the factory to acieve that chamber size. I have a flat top 3.250 stroke...4.155 bore and would like to use the 49cc platinums to bump the compression upto run Alky. I was under the impression the valve angle on them is 21.5 degrees and my pistons may need flycutting. Could someone set me straight on the valve angle of these heads? Brad

[PRO 1]

Our 49cc head is a made from cast to be a 49cc finished part. Being that it is made from a raw casting, that way there is no angle milling done to this head. We all know the corrective factors that would need to be employed if we angle milled a 64cc head. The intake face, the exhaust face, head bolt hole elongation, and correcting all the other bolt holes. Guys who do this kind of work charge alot of money to do this, we could NOT sell the head for the same cost if we were angle milling 64cc heads down to 49cc.

We machine the head, from scratch, therefore we are putting in the seat and guide locations, and machining every surface on the head from scratch, making a chamber size different is easy when starting with a raw head.

Thanks
PRO 1

[Trmnatr]

Our 49cc head is a made from cast to be a 49cc finished part. Being that it is made from a raw casting, that way there is no angle milling done to this head. We all know the corrective factors that would need to be employed if we angle milled a 64cc head. The intake face, the exhaust face, head bolt hole elongation, and correcting all the other bolt holes. Guys who do this kind of work charge alot of money to do this, we could NOT sell the head for the same cost if we were angle milling 64cc heads down to 49cc.

We machine the head, from scratch, therefore we are putting in the seat and guide locations, and machining every surface on the head from scratch, making a chamber size different is easy when starting with a raw head.

Thanks
PRO 1

I may be using a set of 49cc heads maybe, i have always used 64cc and milled and decked to get where i need to be

I thought i have heard the valve angle is 21° and not the std 23° and thats why piston companies offer pistons for the 49cc heads

[PRO 1]

The reason for the 21° piston is due to the valve being closer to the deck when closed. When you move the valve closer to the deck when closed it changes its relationship to the centerline of the cylinder bore, therefore making the need to change the piston valve pocket location.

Thanks
PRO 1

[want-a-be]

I've had good luck with them. Ran up to .670" lift with around 270°ish duration@ .050 on a roller can with plenty of Piston - valve clearance. Maybe I've had good luck because of the amount of contouring of the pistons I did on that build. That piston had a .163" dome on it in a 383ci. It wasn't a 21° piston that I know of.

Runs in a circle track car ....so if there was going to be any problems I'd say they would have presented themselves by now. Engine is bad a$$ed fast.

Don