C2 FI distributor overhaul specifcations

[Jerry G.]

Re: C2 FI distributor overhaul specifcations

I agree with the standard volume pump, but since I think Jerry is revving as high as 7500, don't you think he should run the 55-60 psi spring, which would essentially be a '65 OE spec SHP/FI pump and spring?

Duke

I am pretty sensitive about oil pressure( see black death posts from last year), I am using the melling pump and an acusump. My pressure is rock solid at 55 pounds throughout the rev range. However I'm going back to Portland to race in the July HMSA race and there is a long sweeper that I pull a recorded 1.8 Gs in and thats what got me last year. With the improvment I've made like the AVIAD pan and careful filling strategy that Clem taught me and the acusump correctly pressured up I should be good. Right now I've finished the distributor for the race car and I'm pondering what to do with 8 " of Hg at idle for vacumn with the FI unit.

[Dick W.]

Re: C2 FI distributor overhaul specifcations

I agree with the standard volume pump, but since I think Jerry is revving as high as 7500, don't you think he should run the 55-60 psi spring, which would essentially be a '65 OE spec SHP/FI pump and spring?

Duke

I know the source of the info is a dinosaur today, but Smokey Yunick told me that he set up the pump to have about 10 psi per 1,000 rpm's, cold.

[Duke W.]

Re: C2 FI distributor overhaul specifcations

Right now I've finished the distributor for the race car and I'm pondering what to do with 8 " of Hg at idle for vacumn with the FI unit.

At what actual idle speed?

Duke

[Jerry G.]

Re: C2 FI distributor overhaul specifcations

At what actual idle speed?


Duke

The 8" is at 1000 RPM but it really won't idle there. At 1500 RPM it's fluctuates around 9"Hg. That's where it will idle stably with the carburetor. my goal is to figure out how to get the FI unit solidly on the economy stop at 8"Hg. Tomorrow I'll be playing with the preload on the diaphragm that controls the rod for the economy and power stops.

[Jerry G.]

Re: C2 FI distributor overhaul specifcations

my cold oil pressure is around 75 pounds so the old dinosaur isn't too far off. The 55 is at operating temperatures which are usually around 220 degrees

[Duke W.]

Re: C2 FI distributor overhaul specifcations

The 8" is at 1000 RPM but it really won't idle there. At 1500 RPM it's fluctuates around 9"Hg. That's where it will idle stably with the carburetor. my goal is to figure out how to get the FI unit solidly on the economy stop at 8"Hg. Tomorrow I'll be playing with the preload on the diaphragm that controls the rod for the economy and power stops.

I was going to suggest a higher idle speed. Most serious racing engines won't idle much below 1500. My EP TR3 (back in the seventies) with the British Leyland G3 cam wouldn't idle below about 2000.

I'm surpised it will only pull about 9" at 1500 if it's 8" at 1000. The 30-30 cam offers about 10" at 900, and my advice to most 375 HP owners with the 30-30 cam is to idle them at 1000-1200.

Greater initial timing will improve idle quality. With an OE setup - 8" VAC and the centrifugal starting at 700 with 24 max @ 2350 the total idle timing should be in the low 30s at 900-1000. Assuming you have the OE centrifugal curve, which starts at 700, 14 initial for a total of 38 above 2350, and no vacuum advance, the total idle timing should probably be in the range of 20-25 at 1500.

You could also limit the centrifugal to about 20 and run 18 initial, but any more than this might cause starting problems.

Duke

[Jim L.]

Re: C2 FI distributor overhaul specifcations

I am pretty sensitive about oil pressure( see black death posts from last year), I am using the melling pump and an acusump.

In my opinion, running with an accusump is a good argument for also using a high volume pump. In the event the accusump has to momentarily supply engine lubrication, afterwards the oil pump has to not only supply oil for adequate engine lubrication but it also simultaneously re-fills the accusump.

Jim

[Jerry G.]

Re: C2 FI distributor overhaul specifcations

In my opinion, running with an accusump is a good argument for also using a high volume pump. In the event the accusump has to momentarily supply engine lubrication, afterwards the oil pump has to not only supply oil for adequate engine lubrication but it also simultaneously re-fills the accusump.

Jim

You are exactly correct Jim and it seems to be working that way. no more pressure issues.