3810 holley

[Gerard F.]

Re: 3810 holley

At this point the car seems very good, idle is at approx. 550 RPM. I think the IFR and IAB is good so AFR in the idle circuit is good. I am going for a drive soon and want to try # 63 main jet to lean main circuit at cruise and light load then start checking vacuum readings so I can taylor power valve timing.

Tim,

A great learning experience for all of us.

Just a note. After I restored this dated 3810 I got on ebay, I ran it with the main jets it came with, #62's. For some reason, it would overheat at high speed cruise. Can't explain why, maybe it was dumping too much fuel through the power valve.

I went back to new #65 jets and a new 65 power valve. The overheating problem at high speed cruise just went away.

[Timothy B.]

Re: 3810 holley

Jerry, I have read much about Holleys and some people say they are jetted rich and to lean main circuit until surge is felt at cruise/light load then up two sizes. At that point to maintain wide open throttle A/F ratio, the sq.in. area reduced in jet size (if any) should be added to PVCR so A/F ratio at WOT is the same factory setting. All this after idle circuit A/F ratio is correct because it effects cruise as it's still metering fuel.

Power valve timing just controls the point of enrichment which is supposed to be approx 1-2" below light load vacuum readings. Gas milage can be improved here because cruise is leaned but the correct WOT enrichment is maintained by the power valve circuit enlarging the PVCR.

Same principle with Carter only these carburetors have metering rods which can be changed without taking the carburetor apart. Some say much work for not much gain but it's good to understand how to tune the carburetor.

It will be interesting to see how close to the factory mark this tuning takes me. I suspect we can lean the 300 HP some, keep in mind this carburetor is the same as 350 HP engine and jetted the same as the 4150 Holley for 64-65 HP engines.

[Clem Z.]

Re: 3810 holley

Jerry, I have read much about Holleys and some people say they are jetted rich and to lean main circuit until surge is felt at cruise/light load then up two sizes. At that point to maintain wide open throttle A/F ratio, the sq.in. area reduced in jet size (if any) should be added to PVCR so A/F ratio at WOT is the same factory setting. All this after idle circuit A/F ratio is correct because it effects cruise as it's still metering fuel.

Power valve timing just controls the point of enrichment which is supposed to be approx 1-2" below light load vacuum readings. Gas milage can be improved here because cruise is leaned but the correct WOT enrichment is maintained by the power valve circuit enlarging the PVCR.

Same principle with Carter only these carburetors have metering rods which can be changed without taking the carburetor apart. Some say much work for not much gain but it's good to understand how to tune the carburetor.

It will be interesting to see how close to the factory mark this tuning takes me. I suspect we can lean the 300 HP some, keep in mind this carburetor is the same as 350 HP engine and jetted the same as the 4150 Holley for 64-65 HP engines.

all carbs are jetted for sea level and should be leaned out 2% for every 1500 ft above sea level