rekain

What would compression be on a stock '69 Toro 455 with C heads, milled .010, with fel-pro permatorque gaskets?

OLDSter Ralph

Milling .010" off the heads would be more than offset by what I am assuming to be thicker head gaskets. In other words, not enough change to notice.

rekain

Just wondering what it might be. Engine has been together for 20 years, and although it runs pretty good, I have always felt it was under-performing. Some of the changes made over the years did not yield the results I expected.

Lonnies Performance

Likely the tune (fuel or ignition advance) or cam timing will have more of an effect on performance.

Typically 1 full point of compression has less than a 3% HP & 5% peak torque change within the ranges of 8-13:1 compression ratios.

OLDSter Ralph

You would need to know head cc's, head gasket thickness, piston dish cc's, distance below the block surface the piston is, to compute actual compression ratio. Not sure what changes you made and what you expected.

rekain

None of that was measured at the time the engine was assembled. The condition of everything was so good, that the cylinders we're just honed, crank polished, new rings, bearings, cam & timing set installed. The heads have since been ported, I've had 2 different Edelbrock intakes on, several different carbs (now TBI), trans changed to 200R4, 3 different rear gears (3.23, 3.42, 3.90), have Hooker supercomp headers w 3" mandrel bent exhaust, cam was also changed to a Voodoo 60803. Yes, the car runs good, yet when I have taken it to the strip, have yet to break into the 12's with it.

Fun71

The change in head gasket thickness (larger) and milling the heads (smaller) would result in around 0.1 to 0.2 drop in compression ratio.

OLDSter Ralph

HUH ? We are not talking about a '69 Toronado ? What is this engine installed in ?

rekain

'69 442 convertible.

Lonnies Performance

Post your ET's & specifically the MPH... The MPH is a direct indicator of the HP it produces.

rekain

Best ET is 13.01, just shy of 103 mph. Usually 13.10 to 13.20. Only get 2-3 passes in before the track officials come to talk to me about a roll bar. Best mph was just over 104. Have not been to the track since FiTech TBI was added. First full throttle blast took out a clutch in the trans. That's fixed now, butt-dyno says it pulls a little harder than it used to, won't know how much until gets timed. Might put the 3.90 rear back in (3.42 now), without the OD trans, rpm and drone from the exhaust was too much at cruise back then, might be okay now.

rekain

Going to do a cranking compression test when I get home from vacation. My suspicion is that my cam might have a little too much duration for the compression it has.

cutlassefi

rekain

As far as I can tell. The FiTech unit is set up with full timing control, I have a Spectre FI tank with in-tank electric fuel pump and return line. A fuel pressure gauge was taped to the windshield, did not see any pressure drop at full throttle. Have also confirmed that the throttle is opening fully. Spark is through MSD Pro-billet distributor/6AL box.