alecsammy

Hi, all

Has anyone ran a edlebrock RPM airgap instead of darts hp500 intake , I'm currently running edlebrocks intake with a holley 800 carb the stock jets are 72 primary and 87 secondary but after reading several posts I see that most jets are and the 80's 's and 90's . Holley tells you that you should notgo up more than 4 sizes from the stock jets. What size jets would someone recommend, the same has the hp 500 carb . The motor has dart iron eagle heads and a better set of pistons with crane 731 cam any suggustion would be helpful. The motor runs goodbut coming from idle to gear it always stalls the engine just can't recover fast enough. I heard running bigger primary jets will help the idle circuit is this true. Thanks Alec

BenPerfected

Is the carb set up with a power valve in the primary circuit only? If this is an non-marine Holley, check and see what the jets and PV's are set up in the same CFM stock marine Holley.

ezstriper

well I have never heard of not going over 4 sizes....thats BS..you jet to what the engine needs...is this a stock cam ? need to check engine vacume in gear, see what you have, if say you have 15" divide in half for your power valve, a 7.5, if the vacume is low and surges and opens the valve at idle, will cause problems, also a blown power valve would hurt the idle, that intake will work fine...Rob

Griff

What cubic inch engine???????

searaycer

on my 489ci, comp 270xm cammed, 088 rect port headed motor with an rpm airgap, and 850 holley I am now running 82front 87back 6.5 power valve in the front only, pv plug in the back, I just repowered and have been jetting every weekend to get where I am now.

alecsammy

The engine is a 98 gen 6 502 bravo one , I removed the stock pistons and replaced them with a better standard size piston , crane 731 hydraulic roller cam edelbrock airgap intake , iron eagle 308 heads holley marine 800 carb with only primary PV. I'm currently running a 4.5 pv 74 jets in the front and 89's in the back the vacuum at 1000 rpm is 13 inches. The problem is when it comes into gear the engine falls to low and can't recover .

blue thunder

I think the rule is not going up or down more than 10 jet sizes. I always found +5 was good all the way around making sure to maintain the split front to back. So, 77/92 for you. I believe you have the stock jetting now.

BenPerfected

The Holley 0-9022 #4150 Marine 800 CFM Holley is factory jetted (according to the Holley website) with 72 primary and 87 secondary w/6-5 PV's. Your cam selection at idle may be the issue....opening and inducing too much fuel (flooding) at idle in gear if your PV is not sized correctly.
I have been working on getting better dock manners from my carbs. My problem has been real low vacuum at at 650-700 RPM in gear. My vacuum is dropping to 2.5" at 650 in gear.
I have just got my idle back with 2.5 PV's. I could also go with no PV's, but then I am leaner than I would like at WOT. If I jet for WOT, then I am sucking fuel at the mid-range. The trade off for the 2.5 PV's is they now don't open until 5700RPM (WOT 6800 RPM).
My suggestion is to set your jets at the stock #'s. Connect a vacuum gauge and watch what happens when you shift from neutral to in gear...set your PV (or PV's) to just above this vacuum level. This should give you back your dock manners without stalling. Now run the boat and increase speed in 500 RPM increments and see where your PV opens to richen the mixture.
An Innovate Motor Sports A/F meter is very helpful. HP cams and carbs are a process...you can get right but some are just guessing.
Want it perfect?...switch to EFI.
Ben

Griff

If you are running a secondary PV, that is a lot of jet in the secondaries. I would just block the secondary PV.

What do you have your base timing at????
I had the same cam in my 525SC and it idled great at 850 neutral and 700 in gear. Base timing was at 13*.

For reference the Holley 800cfm HP500 jetting is:
Primary - Port 81, Stbd 75
Secondary - Port 89, Stbd 93

Power valve - front 6.5, rear - none

I would square yours to 78 primaries and 92 secondaries and block the rear PV.

ezstriper

assuming you have no power valve in the secondary, you have to much diff in primary to secondary jets, with out a power valve the jet sizes need to be 6-8 #'s higher, but you want to keep jetting pretty square(this is a std square bore carb right ?) you vacume is low, so that cam must be pretty radical, as stated look at timing...I had a set-up in mine when I got it and the only way i could get it to idle decent was to lock the dist and set the timing at 34, with a advance in it would not idle in gear...Rob