As far as I know, the check ball in the vs diagphram housing should have a checl ball in it. Well the one 4160 carb that I am working on at the moement doesn't have one in it. In its place, it has this...



From what I've gathered, this is fine to have this in there without the check ball.. except in the case that I am having. After screwing arround with the car and replacing the whole igntion system, there is a 3000 rpm wall that the car hits. Once it hits that 3000 rpm wall, it breaks up and doesn't want to go anywhere.

After having a lil talk with Pony Killer yesterday, we finally decided that the secondaires are opening to quickly (not progressivly) and just killing the car. We linked it back to the check ball either missing or the wrong size.

My question is, what the hell do ya do? Remove that brass restriction and toss in a check ball? lol

BTW the car is a friends 89 firebird 305, l98 heads, summit 1103 cam 214/224 .454/.465 112°, 6° base timing, vac advance hooked up to ported, 3.42 gears, 700-r4, 2800 stall, stock exhaust manifolds, 2" exhaust (car was originally a v6 and am waiting for a y-pipe to put the hedders and 3" exhuast on it) and the fuel pump is a holley red.

Thanks

Kat

 

Forgot to mention it has comp 981 springs, the cam is a flat tappet, and the block is from a 96-98 truck. Oh and the VS has the silver spring in it.

Kat

 

If it was bogging due to the lack of the check ball, you would have trouble getting to 3000 RPMs, then it would scream (numbers used for illustration purposes, only).

I think you have a different problem. But, as far as "fixing" the VS housing, consider a Quick Fuel adjustable housing instead. It resolves the secondary adjustment/bog-avoidance problem the right way, by adjusting the restriction of the flow rate of the vacuum signal to the diaphragm (which changes opening rate only, not full-open capability).

 

It doesnt really have troubble getting to 3000 rpm it kinda breaks up a lil bit arround 2500 or so then compleltly falls flat on it's face then at 3000.

So may I ask what else are you thinking of? (btw the tranny is fine)

Thanks man

Kat

 

Some factory carbs like ones for F*rd and Chrysler cars in the 60s had a check ball with grooves cut in the seat to regulate how fast the secondaries opened. AFAIK none of the performance ones have that.

Sounds to me like the secondaries are opening (admitting air) but not admitting fuel. This would cause a tremendous lean-out. If the secondaries weren't opening, it would simply run up to the capacity of the primaries to flow air, and then probably blow out black smoke.

Check the simple stuff; like, is there fuel in the sec bowl, and are you using the right gaskets and not covering up some critical holes.

 

oook so I re checked the float level again and its fine. Just drbbles outta the sight plug. Hip check the car and it splashs out. As for the gaskets, the only one that I can think of that is could be screwed up is the one between the throttle plate and the main body. When I did the secodary metering block conversion, I'm purdy sure that I got the gasket in there the right way for that.

Thanks again fer the help

btw if the car was FI, I would have had this problem figured out by now. LOL

Carbs---> <---me

Kat

 

Sounds like ignition problems to me, unless you're really outrunning your fuel supply. Duck taping a fuel pressure gague to the windshield temporarily will help you instantly diagnose of this is the case (fuel pressure will nose-dive as the motor begins to lay down).

Fuel pressure and float levels at idle are almost meaningless. You GOTTA know what's going on at WOT under actual load conditions.

 

Another method is to drive the car until it does it; then while it is doing it, kill the ignition and take it out of gear at the same time and coast over to the side of the road and see what's in the fuel bowl. The goal is to prevent the engine from refilling the bowl by coasting down and/or idling, instead you want to capture teh exact state of teh fuel bowl at the moment of truth. Make sure you turn the key to "Off" not "Lock!!!!" And be prepared for no pwer steering or brakes.