My home inspection of Speedmaster heads

PRH said

These RPM heads, and the copies have been around for quite a while now.
Tons of them have been on the dyno.
I don’t ever recall hearing of anyone having to run the timing at 40* to get the most power when using these heads.

I have to chuckle.......a few exposed threads around the plug has people in a tizzy.
But that big fat low flow valve job is a non-issue.

Click to expand...

I've seen it. Many times. Had a customer with a 572 at MATS and he called and said I keep adding timing and I keep going faster.

I said keep an eye on the plugs and as long as they are happy, you're ok.

After he went a few rounds and red lit, he called and said he was at 42 total. I'm thinking damn, is his timing light junk or something.

So I had him snap me a picture of the plug. He needed a 3/4 reach plug and had a 3/8 reach plug in there.

It ran, just took much more timing.

When he put the correct plugs in there, it went back to 34-36 total.

I've seen that many, many times.