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Search found 7052 matches

by F-BIRD'88
Sun Sep 15, 2019 8:32 am
Forum: Engine Tech
Topic: Low speed (1500-1800 RPM) driveability issue
Replies: 104
Views: 2059

Re: Low speed (1500-1800 RPM) driveability issue

Best done using various spacers , to get plenum sharing, with the divider fully intact.
The spacers can be tested with various divider types and heights for effect.
by F-BIRD'88
Thu Sep 12, 2019 8:46 am
Forum: Engine Tech
Topic: Low speed (1500-1800 RPM) driveability issue
Replies: 104
Views: 2059

Re: Low speed (1500-1800 RPM) driveability issue

Likely a better camshaft for your purpose and driving would be the factory hyd roller cam from the GMPP 502-502 hp crate motor. 226-230 110 LSA 8 deg overlap. @.050
Verses current 28° overlap.

Or another cam like that.
by F-BIRD'88
Thu Sep 12, 2019 8:39 am
Forum: Engine Tech
Topic: Low speed (1500-1800 RPM) driveability issue
Replies: 104
Views: 2059

Re: Low speed (1500-1800 RPM) driveability issue

Make or get a combo spacer. (2 holes on the deep side
A oval on the shallow side) that supports your divider.
(Divider attached to combo spacer)

Good effort and progress.
by F-BIRD'88
Wed Sep 11, 2019 4:20 pm
Forum: Engine Tech
Topic: Low speed (1500-1800 RPM) driveability issue
Replies: 104
Views: 2059

Re: Low speed (1500-1800 RPM) driveability issue

The big throttle carb will seem more powerful as more air is allowed for the same throttle angle.
by F-BIRD'88
Wed Sep 11, 2019 2:35 pm
Forum: Engine Tech
Topic: Low speed (1500-1800 RPM) driveability issue
Replies: 104
Views: 2059

Re: Low speed (1500-1800 RPM) driveability issue

Does the other carb eliminate the drivability issue?

Should have gone multi carbed 650++ hp power capability
Street ability of a single street carb.

The perceived wot difference may be more seat of the pants impression than real measured acceleration difference.
by F-BIRD'88
Wed Sep 11, 2019 1:46 pm
Forum: Engine Tech
Topic: Low speed (1500-1800 RPM) driveability issue
Replies: 104
Views: 2059

Re: Low speed (1500-1800 RPM) driveability issue

I would make a carb spacer that has this divider attached. The divider would match up to and be also supported by the existing partial divider.
It has to be very sturdy.

Do you have another carb to try? Eg a 750 dp.
by F-BIRD'88
Wed Sep 11, 2019 3:48 am
Forum: Engine Tech
Topic: Low speed (1500-1800 RPM) driveability issue
Replies: 104
Views: 2059

Re: Low speed (1500-1800 RPM) driveability issue

This is why ALL oem carbed intake manifolds have heated plenums. Really helps fuel vapourization at idle and low rpm cruise rpms better drivability.
A cold intake plenum will always be more troublsome to tune for drivability.
by F-BIRD'88
Wed Sep 11, 2019 3:43 am
Forum: Engine Tech
Topic: Low speed (1500-1800 RPM) driveability issue
Replies: 104
Views: 2059

Re: Low speed (1500-1800 RPM) driveability issue

A 750 holley is always more responsive on the street than the big venturi big cfm 1000+cfm 4150 holleys. More than 500 hp capable. Where drivability is a priority it is usually a better choice overall. Tweeking the pcv valve flow rate +/- can have a nice effect right where you are having drivability...
by F-BIRD'88
Wed Sep 11, 2019 3:25 am
Forum: Engine Tech
Topic: Low speed (1500-1800 RPM) driveability issue
Replies: 104
Views: 2059

Re: Low speed (1500-1800 RPM) driveability issue

Fill in that partial plenum divider to isolate the dual plane plenums. Change diz curve for 24-26 deg at idle 38 total. Use ported vac adv not full manifold. Primary idle air bleeds will need slight fine tuning to correct off idle transition afr shift where when throttle is slightly opened... Slow c...
by F-BIRD'88
Tue Sep 10, 2019 6:47 pm
Forum: Engine Tech
Topic: 400 SBC Heads
Replies: 3
Views: 331

Re: 400 SBC Heads

Your 441(X)(?) Or 487(X) 400 heads have resale value to those that want a budget big chamber head for a low CR budget street roots supercharged 305-307-327-350 sbc project, if they are in good condition.
by F-BIRD'88
Tue Sep 10, 2019 6:29 pm
Forum: Engine Tech
Topic: 400 SBC Heads
Replies: 3
Views: 331

Re: 400 SBC Heads

Because of the net increase in the compression ratio your 400 may now need to use premimum unleaded gasoline. 87 octane may/probabily won't be enough.
by F-BIRD'88
Tue Sep 10, 2019 6:14 pm
Forum: Engine Tech
Topic: 400 SBC Heads
Replies: 3
Views: 331

Re: 400 SBC Heads

A big worth while boost in torque and hp both. On mine I did not drill steam holes. Just re routed the heater hose to the additional rear water port on the back of the manifold by the diz (drivers side) This aids cooling and thermostat function. Stops thermostat surging and keeps the 400 sbc cool wi...
by F-BIRD'88
Tue Sep 10, 2019 4:59 pm
Forum: Engine Tech
Topic: I am in need of some camshaft help.
Replies: 12
Views: 556

Re: I am in need of some camshaft help.

One way to lessen-minimize the performance loss effect of oil areation on hyd roller lifter function is to change the oil between rounds. You need not discard the oil. Save it, let it sit 1 -2 days till the air gets out and you can reuse that expensive racing motor oil again.
by F-BIRD'88
Tue Sep 10, 2019 4:47 pm
Forum: Engine Tech
Topic: I am in need of some camshaft help.
Replies: 12
Views: 556

Re: I am in need of some camshaft help.

Jones' milder cam may/should have more ex valve on seat time per cycle by nature of its shorter valve open time (duration). Once ex valve lash hot- cold lash compensation is found for your specific running conditions.
More ex valve on seat time per cycle means more ex valve cooling time when running.