F-2 Speedy

that clearance rocker is in the correct location needs to be that way to clear the stud boss

502nova3

Ya there was some self clearing going on who ever put it together last with the roller rockers forgot to cut the oil dripers off the valve cover and she did some self clearing found the pieces in the oil pan lol

Dont think the block froze as it has a closed loop cooling system had the heads at an engine shop and its cracked between the valve on one cyl on each head cam don't look new but no lobes are ground off from just looking at it maybe a collapsed lifter never thought of

seemd to be loosing a very small bit of rpm all the time last summer than lost 200 or 300 all at one the last day it ran and I Knew something was up came of plane and it never had the power to get back up

articfriends

Back in September I dynoed a 548 with tiny little 290 afr oval ports BUT a huge cam even though the flow goes flat then backwards at .650+ lift, made 750+ hp and if i remember right 680 ft lbs of tq (might have been 660) but had a Chinese oval port copy of a vic jr and a modded 4150. But, was a non marine engine with lots of lift, duration and compression. We expected MORE tq then it made, we never finished extracting every bit of power from that engine before dyno waterbrake broke. Im just know getting the new dyno setup in place, Smitty

getrdunn

When you have up and running you think? Jim and I like to bring over one of the 565,s

Smitty275

At what RPM were the peaks and was it a long broad torque band?

articfriends

so to answer your question the hp peak was at 6500 then flattened out to 6800 or so, even at 7300 it wasn't falling off face of earth. (for those that missed earlier comments was talking about a 548 with compression with large cam BUT a set of AFR 290 cc oval ports because they were what customer had left off his 496 he blew up) The heads were like a "governor".on top, had enough cam, in the high 270s/280 (@50) range with lift approaching 800.
This was partly thru the dyno session, we had top end tune about dialed in, our torque was lame at slightly less then 650 at 5000 I expected to see 700. In subsequent pulls changing cam timing, bleeds, ignition timing, carb spacers, we got tq closer to 700 when the dyno impellers started screeching on casing from coming loose on main shaft so we never found full potential of this one, Smitty

articfriends

This picture with the tq peak was after playing with cam timing, tuning changes, carb spacers . I forgot that we saw 691 on last pull.
the graph below is the same pull as post 26 with the 757 hp, before picking up tq from tuning changes.

502nova3

The two cams I'm looking at are both comp cams exteram marine

1000-5000 rpm range COMP Cams Xtreme Marine CamshaftsCamshaft, Hydraulic Flat Tappet, Advertised Duration 262/268, Lift .505/.515,

COMP Cams Xtreme Marine Camshafts 1600 to 5800 rpm range

Camshaft, Hydraulic Flat Tappet, Advertised Duration 270/286, Lift .544/.547, Chevy, Big Block, Each

Which one would be best would for my boat it's got a 1.5 bravo one drive and ran 52 ish with 23p prob @ about 4600 and 49 with 21p prop but like I say idk if the engine was ever at its best since I owned it. So what I'm wondering is if I got the bigger cam (5800 rpm) and it still would not rev above 5000 would it make less power than the 5000 rpm cam below 5000

I belive I should be around 8.6 to one with my pistons with the 119cc heads I'm looking at if thats what this chart means. My end goal is to have a running boat so not really interested in changing from the stock manifolds and through hulls i have now consider intake if enough gains but the boat dynoed @ 420 hp when that engine was put in in 2006 if I'm with in 20 ish hp of that I'll be happy but will take cheap hp if possible while I have it appart

Highlited is the pistons i have