Plug reading

[Aron Gleason]

I haven't shown him the plugs. He just mentioned going with the 10.5 pv to help overcome the stumble issue i had.

 

[HEMI-ITIS]

How much vacume does the csrb have at idle in gear?

 

[Aron Gleason]

How much vacume does the csrb have at idle in gear?

12 in.

 

[HEMI-ITIS]

That 10,5 PV would be correct.

 

[Aron Gleason]

That 10,5 PV would be correct.

Yes it is

 

[HEMI-ITIS]

Does the carb have an idle adjustment on the secondaries?

 

[RJRENTON]

Yes the mixture screws are the same left to right, front to rear. And I have a 1/2 spacer.

The 1/2" spacer causes a pressure loss and subsequently a mixture velocity slowdown. The slower mixture velocity is likely to cause uneven fuel distribution and non uniform mixture composition, especially on the long branch runners. This has NOTHING to due with the idle mixture screws position or power valve (PV) opening point. Do you need the spacer or just because someone said you do? Try and remove the spacer to see what occurs......just a thought.......
BOB RENTON

 

[gtxrt]

is it a 4-speed manual ?

 

[Aron Gleason]

is it a 4-speed manual ?

Automatic transmission.

 

[Aron Gleason]

The 1/2" spacer causes a pressure loss and subsequently a mixture velocity slowdown. The slower mixture velocity is likely to cause uneven fuel distribution and non uniform mixture composition, especially on the long branch runners. This has NOTHING to due with the idle mixture screws position or power valve (PV) opening point. Do you need the spacer or just because someone said you do? Try and remove the spacer to see what occurs......just a thought.......
BOB RENTON

The spacer is in place to keep the fuel from percolating.

 

[gtxrt]

Yesterday I took the car out for a cruise, it was running really good. No more stumble when I stab the throttle, but the tip of the plug is white and the rest is black. Just wondering why its like that?

in your first post. so it had stumble and then you changed the power valve to 10.5 and the stumble is gone but now the plugs are black. sounds like you answered your own question.

 

[Aron Gleason]

in your first post. so it had stumble and then you changed the power valve to 10.5 and the stumble is gone but now the plugs are black. sounds like you answered your own question.

I've had the 10.5 pv in the carburetor for a couple years now, and during that time it had the stumble. The biggest problem was the cam going flat.

 

[gtxrt]

just one more thing lol now I sound like Lieutenant Columbo .what size cam went flat and what size cam did you put in. what duration and LSA were both cams.

 

[Aron Gleason]

I had the 284 484 purple shaft cam 108 lobe. With possibly a [email protected] duration
The new cam has [email protected] 495 lift on a 108 lobe

 

[gtxrt]

the 284-284 had 241 duration the 480-480 cam had 238 duration.

 

[Aron Gleason]

the 284-284 had 241 duration the 480-480 cam had 238 duration.

Well what i was told, the old purple shaft cams were not accurate on their duration. The 284 cam was closer to 238 duration.

 

[RemCharger]

Well what i was told, the old purple shaft cams were not accurate on their duration. The 284 cam was closer to 238 duration.

Yes they were just a simple calculation, MP didn't want to give up the actual specs

 

[BSB67]

Well what i was told, the old purple shaft cams were not accurate on their duration. The 284 cam was closer to 238 duration.

That is correct. The 284 will measure 236-238, the 280 will be about 232-234.

 

[BSB67]

10.5” PV may, or may not be the best. We don’t have enough information to determine this. Simultaneous vacuum and AF reading while driving is needed. My experience is that a PV +/- 2” of ideal will still run well.

 

[Aron Gleason]

Well I can't tell what my afr gauge is actually reading since its stuck at 14.7. It does its normal countdown then stays right at 14.7. I replaced the o2 sensor but it doesn't change. Then I was told to hook the brown wire to key on power. And still no change.