Flathead - Controlled valve float - slapper cams

[Randy H]

https://web.archive.org/web/20001020034424/http://www.dynocams.com/archives/tech/002.htm

I've tried to explain this a couple of times. Unfortunately I don't think I did an adequate job. This old tech article from Dynocams does a much better job.

I think it's important for flathead guys to understand this because these cams show up frequently on Ebay and other places.

If you look at cam spec sheets, they often mention the need to weld the exhaust lifter bore. Because of the way these cams operate they are hard on the block.

Hence the term "block breaker cam".

https://web.archive.org/web/20001020032127/http://www.dynocams.com/archives/tech/001.htm

 

[JTSpeedDemon]

FAQ sticky??

 

[Flyinhillbilly]

Those were designed to get around lift rules. Also known as “launcher” cams because they launched the litter off of the lobe to get more valve lift without having more lift at the cam.

 

[JTSpeedDemon]

I would imagine they would require a pretty generously clearanced head.

 

[Randy H]

I would imagine they would require a pretty generously clearanced head.

I don't think that was allowed in the rules.

 

[JTSpeedDemon]

Hmmm, true.
Speaking of cylinder heads, I think I have a chance to pick up 2 stock flathead heads and a fire slot head, so I'll let you guys know if it works out. Really hopin'! :arf:

 

[Randy H]

Hmmm, true.
Speaking of cylinder heads, I think I have a chance to pick up 2 stock flathead heads and a fire slot head, so I'll let you guys know if it works out. Really hopin'! :arf:

Uh oh, I feel terrible now.

Just joking, I saw those someplace.

 

[wenee9w]

I would imagine they would require a pretty generously clearanced head.

No the head stopped the float on some of ours. And he is correct cutting the head there not allowed by the rules. They actually worked really great.

 

[JTSpeedDemon]

I just realized I needed to report back.
Well, in summary, I saw a set of 2 stock flathead cylinder heads and one racing clearanced fire slot head(minor casting flaw and seller didn't know what it was other than the fact that it was a "racing" part), and it started the auction at like, 99c, so I was like:
Then on the last night of the auction it got bid up a ton, so I couldn't nab 'em.
Oh well, ya can't win 'em all.
PS I wasn't really saying where I found them since I wanted them so bad and didn't want competition.

 

[Randy H]

You mean these.

I didn't bid cuz I figured you'd be all over em.

 

[JTSpeedDemon]

Yup.

 

[Randy H]

Lol.
I wasn't interested in three junk heads.
The Horstman I would have paid maybe $20 total, for a novelty item. Not highly regarded plus it was damaged and butchered.