TreDeClaw

Swapped 305 cross fire for 350 carbed.
-Holly 650 vaccum secondary,
-Comp cams Xtreme energy cam 12-262-4
-69 Corvette double hump heads
-Edelbrock performer Rpm air gap intake

Set timing a few degrees advanced.
I have good vacuum.

I had this happining before, and I adjusted the shooter valve on the outside of the carb to be a little tighter and adjusted the mixing screws and it was better and 0 or little boging when the engine was warm for two weeks. Still happened when it was cold but never backfired.

When it's cold it's worse and when it warms up it gets better. Will bog any more then half throttle in park when revving, dead stop, crusing, and right after it shifts. Which I assume is when the secondarys start to kick in Is when it bogs And occasionally backfires.

For example: Last night, shifts 1-2, 3/4 throttle, cold, bogs and then backfires and then slowly regains itself and I can push it full throttle. And shifted just fine into 3rd.

Another example: Warm. 30-40 mph, and I go to wot and it bogs.

So I assume it's the jet or whatever it is called. I took it out and I can see size 31.

I don't know the "cam".

**I'm really not into carburetors and I'm just trying to get a baseline of what I should do to start tuning this carb to my application.**

*** full list ***

357
-10 to 1 compression
-Comp cams Xtreme energy cam 12-262-4
-69 Corvette double hump heads
-Edelbrock performer Rpm air gap intake
-650 Holley vacuum secondary
-1.5 rockers
-2500 stall Hughes torque converter
-Hooker Super Comp Headers 3 in.
-Hooker Y-pipe 3-2.5 in.
-Custom 2.5 exhaust, small cat, y-pipe to 2, 10" glasspacks rear.

3.23 posi rear

Transmission
-700R4
-Corvette servoStage 1 shift kit
-Complete bushing kit
-Heavy duty clutch packs
-Updated sun shell
-Heavy duty band
-Hardened pump rings
-Teflon pump bushing
-10 vane pump
-Shift kit street strip
-500 boost valve


Thanks for the help in advance.

sofakingdom

iTrader: (1)

See the Holley tuning "sticky" at the top of this forum.

Meanwhile, the thing with 31 on it, is not the "jet"; it's the pump squirter. Leave it alone. Adjust the pump screw with the spring around it by manually operating the little lever it works to the end of its travel; opening the throttle to WOT; and setting the length of the screw by way of the nut, until there's about a .050" gap at WOT between the fully buried lever and the screw. Then leave it COMPLETELY alone until you've gone through THE ENTIRE "sticky", start to finish, IN ORDER, skipping NOTHING. Not, "I think I need a bit of this or that" and bypass all the stuff that comes before it; start AT THE START, go through EVERY STEP, and SKIP NOTHING. Then come back and tell us what happened. That means, fuel level, jets, PV, & transition slots, IN THAT ORDER, SKIPPING NOTHING. Go to www.holley.com and download the blowup diagram for your carb if you don't know what's inside it.

Without knowing exactly what carb you have or anything else (although if I were the guessing kind I'd guess it's a list # 1850), I'd be inclined to guess that you'll end up with the jets somewhat smaller than stock, and the PV about a 105 or 125 instead of the stock one (most likely a 65), and the sec idle stop screw about 1 - 1.5 turns in from where it came from the factory.


Oh, in case I forgot to mention; don't forget, go through the sticky step by step, each step in the order listed, without skipping any of them or taking anything out of order or doing some later one before you do the earlier ones. Do it in the order given.

TreDeClaw

This is my carb. I read the sticky and I can see I don't have the sight holes. about 1 and a half paint cap cups of fuel came out when I bled it out the bottom screw hole. How do I adjust it if i don't have sight holes?
My jet size is 64.
I'm going to my local carb shop today to get more jets.

92RS_Ttop

iTrader: (3)

The sight hole is on the other side of the bowl you're holding. The side that isn't visible in your pic. It's normally closed off with a brass screw.

TreDeClaw

This one? where do I adjust the bowl?

92RS_Ttop

iTrader: (3)

That's the idle mixture adjustment screw. Looking back at your pics, I dont even see a screw for the float level adjustment. There appears to be no sight plug on that bowl. If you look on Holley's site, you can use the list # of the carb to find and download diagrams of the carb(as mentioned above), and also instructions on how to adjust things like the float level, idle mix, and all the other adjustments needed in Sofa's tuning sticky. The list number is usually stamped on the side of the choke tower on top of the carb.

sofakingdom

iTrader: (1)

That's a side-hung float bowl... no sight plug, no external adjustment. Gotta just bend the float to set it.


Take the bowl off, turn it upside down, adjust it per the specs. Get the list # off the air horn, driver's side, in front of the choke blade; precisely, the spot that can't be seen in the first pic because of the glare. Go here http://documents.holley.com/techlibr...al_listing.pdf to get the spec.


Go here https://www.holley.com/support/resources/ to learn all you can about Holley carbs; except, IGNORE COMPLETELY the page about power valves. The way they tell you to select them is WRONG WRONG WRONG WRONG WRONG WRONG and has been for 50 years that I know of that they've been spewing the same NON-WORKING GARBAGE about that. DO NOT use ANYTHING AT ALL about idle to set the PV!!! The PV isn't active at idle, isn't controlled by anything about idle, doesn't affect idle, and is otherwise unrelated in any way to anything related to idle. Correct vacuum readings for selecting it, are of vacuum at cruise, when it's active and its effects are felt.


That pump linkage is pretty much messed up. It's not supposed to be like that.

MSgt Luttrell

The reason Holley says to check your vacuum at idle for power valve selection, is that if you are running a camshaft with long enough duration, your manifold vacuum at idle may be low enough to cause the power valve to think the engine is at cruise, while the engine is still at idle; which will cause a very rich condition at idle. If you find yourself in that predicament, you will need to select a power valve that will not open at the lower than stock idle manifold vacuum.

sofakingdom

iTrader: (1)

The PV has NO EFFECT WHATSOEVER on idle mixture. That's just one of those myths that just won't die.


The PV works by richening the main system. Since the main system isn't flowing fuel at idle in the first place, it doesn't matter to idle in the slightest what you do to it; it doesn't affect idle.


The real reason they did it was probably because of the parts and whatnot that were available and popular in 1963. Think, 60 Chevy 283 Powerglide with 3.08 rear gears, a "3/4 race cam", a big Holley, and stock exhaust. For a mess like that, their "formula" almost works, if only by sheer accident and dumb luck. And, it has the added advantage of being able to be done with the car sitting still.


The CORRECT way to select a PV is to FOLLOW THE STICKY STEP BY STEP: to wit, after adjusting the floats, find the correct jets by leaning them down until the engine just barely begins to noticeably surge going up a small hill at the slowest constant speed that the car would ordinarily be driven at in high gear (say, 40 mph); then selecting a PV about 2 #s lower than the cruise vacuum at a normal moderate speed (say, 55 - 60).

92RS_Ttop

iTrader: (3)

I don't see any problems with the pump linkage. To me it just looks disconnected cause he's holding the fuel bowl in place. Or am I missing something?

sofakingdom

iTrader: (1)

TreDeClaw

The issue was a fuel leak!!!!

On the back bowl of the carb it was chipped inside where the screw would go. Never took that off and it was pretty hidden for a long time.

replaced the bowl.
Idle is now steady at a good 7-800

I had put the 68 jet size in, turns out probably to big now that I can actually tune my car, so I put the 64's back and will start again from there.

Thanks everyone.

sofakingdom

iTrader: (1)