SSC

:edit: wide reading I'm too tired to square it up.


Planning posted a few weeks ago. Stock non CC setup 80 model base (GM crate engine pulled 18in of vac at altitude). Mods planned/done, ported & polished 601's (55cc) 1.94 intake valves, Z28 springs, comp 268XE cam, HEI trick kit, 2200 stall converter, performer RPM intake, performer 1406 carb, triangle of death was the only avalibe air filter that would fit. Attempted a 750 carb but it would not jet down enough and altitude changes prevented using a holley 5000-10000 ft above sea level changes = a PV nightmare.

End results after tuning and tuning were a not very impressive. A bit of tq at lower speeds was lost even with the higher stall converter (actual stall 1600rpm). Pulled slightly better in the midrage. Upper RPM there was a bit more of an improvment, pulled well at high RPM/speeds but who drives 100+MPH?

Only thing left is the factory exhuast but its a fairly high flow system compared to our stock setups so I dont think it would hold back major HP.

Builds that go like this suck!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Even if it does plant you fairly well from 3rd to 1st downshifts.

F-BIRD'88

Sounds like the stock exhaust is holding you back more than you expected.

If your stall speed is only 1600 rpm, the cam is way too big.
Something around 210/216@.050" would have been better.

The holley should work fine at altitude with about 3 to 4 sizes leaner jetting.
I think you may have confused a rich idle with rich main jetting.
Not the same.

Your actual compression ratio may still be too low (for the cam)even with the 305 heads on a dished pistoned crate motor.
A 14x3" aircleaner will fit but you need to use this Z28/corvette
air cleaner base from the 60's. The choke horn/ vents needs to be shortened on a holley. (old 60's OEM holleys already had this mod). A edelbrock requires a 3/8" plastic air horn spacer for clearance. But they fit with room to spare.

If the aircleaner lid is too close to the airhorn or vents on a holley
it will seem to run rich and not want to make power at high rpm.
"jetting down" will not cure this.
The cure is to shorten or remove the choke airhorn and vent tubes. Aftermarket holleys with straight venturi boosters have a tall choke airhorn. Old 60's OEM holleys had a much shorter air horn and "Downleg boosters". allowing the aircleaner lid to be closer to the carb without restriction or messing up the fuel calibration.



Corvette BB Aircleaner Base

SSC

I'm sure the exhuast is holding some back but one step at a time for this build. I looked for one of the air cleaner sets your talking about but nothing was avalible quick enough so when in need use what you have avalible. I dunno 750 On a SBC at this altitude is trick, large carbs just dont get the air they need and always tend to run rich. A 600 should be plenty for some umph, they always worked well for me at least. The only reason we went with the edelcrock was to eleminate the need to change PV's, the owner lives 10,000ft above sea level and where he works is 4900ft. It just would have been a pain to find a happy medium since the engine only pulls 10in of vac now @4900ft.

I honestly expected these mods to free up around 100hp. Granted thats alot but the componets on the non HO crate engines suck. I still think theres alot more compression gained with the smaller chamber heads. With the timing set at 13* running 91 octaine (85lg, 87mg 91pg) theres a slight ping still reguardless of dis spring tension.