First Dyno Complete
 

Hey guys, I did not end up going to Smitty for my dyno work. I just couldn't see making the 2+ hour one way drive. I was however, able to get in at Performance Engineering in Jenison. They have a nice dyno set up and they were very easy to work with. Hoping to run the 2nd engine tomorrow. They have a little more work to do on the carb because there's a slight hesitation off idle but other than that it ran great. Looking at the printout, I plan on propping so WOT is now 5300 rpm. I can set the rev limiter with the distributor. Would you also set that for 5300? Thanks for your advice. https://cimg5.ibsrv.net/gimg/www.off...830289fbcb.jpg

My opinions/thoughts ….
Some rev limiters can stop dropping cyl’s just before rev limit set point. Also, i use rev limit to only limit rpm when engine is ‘winged’ by mistake (getting air/ cavitation/ missibg the throttle, something breaks / etc….so i like say before valvetrain will have issues. Anywsy, without knowing your set up, i’d go for 6k rev limit.

Speaking of valvetrain - looks like you may he running into lifter fuss or valve train fuss (starting to lose control) - see how hp lowers than rises and does it again. Just going by sheets - don’t know your specifics

I'd set the rev limit to around 5600-5700rpms.

He did say that he stopped at that rpm because he noticed that there might be some distress and it stopped making power. I have the AFR 265cc heads with the 112cc chamber. I did not upgrade the springs but I believe they are supposed to be able to handle a decent cam "as is". My cam is a roller 230 236 @.050 and the lift is .547. Full roller rockers too. I think somehow I ended up with a taller(?) roller lifters. The guy who built it for me said they were taller than what he usually uses. Could be the added weight of those is causing that if that is correct?

The up and down power up top is likely valve control related. What spring is it?

Before you talk about rev limiter you wanna fix that vave train before you run that thing .

What are the chances that the problem is a plug wire? I only ask because the #3 wire pulled on and off without any resistance and he suggested that I get new wires. I have ordered new wires regardless for both engines. If the twin runs without any distress I'm going to assume that was the problem. Any thoughts on this?

I try to educate myself on something every day if I can so...for those who have experience in these dyno pulls...what exactly is it that gives you concern about the valve train in the data from these pulls?
Thanks

I went to the AFR site and this is the spring package that comes with the heads.
PAC Racing Springs 1.550” OD Solid Roller Dual Valve Drag Race Spring, 220 lbs. on seat, .710” maximum lift, - 260* max recommended duration, Max RPM 7200-7400
PAC Racing #1940 1.550” OD Hydraulic Roller Dual Valve Spring, 175 lbs. on seat, .725” maximum lift, Max RPM 6500-6700
The only change I made when I ordered was for Inconel exhaust valves and hard anodizing which AFR recommended for marine use.

I'm pretty sure the 503 hp number is because of dyno inertia and not the valve train if this particular area is the concern