Cascade Crew

91RSVert · Posted: Sat Nov 03, 2012 3:07 pm Post subject: Help on holley carb

So I have never touched a carb tell I went to remove it off this truck to rebuild it. My dad has rebuilt many in his day so I was counting on him to guide me.... however he has failed me, he just ripped into it after taking pics of the outside, not the inside as we took it apart. So questions..

Holley 6772, 650cfm double pumper.

1. Jets. I am assuming the smaller jets go on the primarys? I have a pair of 56, and a pair of 61.
2. Power valves. One is a 6.5, other is 8.5 (or my kit comes with 1 6.5 and 2 8.5's.) Which goes where? Or should I run both of same size?

aaron_sK · Posted: Sat Nov 03, 2012 3:12 pm Post subject:

What is a double pumper doing on a truck?

In my experience I usually ended up with the larger jets on the primary.

Rear PV should be plugged and jetted up. Front should be the higher one unless it has a huge cam.

chevymad · Posted: Sat Nov 03, 2012 3:34 pm Post subject:

Well i'm going to go against Aarons advice here. The leaner jets go up front to get slightly better mileage. I'd say the 8.5 valve goes up front too to cover the leanness when more throttle is applied. The 6.5 would go in the rear and should only open then when your foot is really into it.

As for deleting the power valves. That can be done too to simplify tuning. You lose "lean cruise mode" though. Basically you would need to measure the size of the 2 ports behind each valve in the metering blocks and figure out the area of the orifice. These are tiny. This surface area is then added to the current jet size and you figure out what size jet has this combined size. Then plug the power valve hole and use that larger jet.

Power valves are giving you "adjustable" jetting. At each vacuum point more fuel is allowed into air stream. The 8.5 valve opens at 8.5" of vacuum etc.

91RSVert · Posted: Sat Nov 03, 2012 3:34 pm Post subject:

Which pv is the "higher one". I have no clue whats done on this motor.

chevymad · Posted: Sat Nov 03, 2012 3:37 pm Post subject:

To correctly set the power valves you'd need to be able to operate the truck. There's a formula you use taking cruise vacuum level and subtracting.. But right now i'd use the stock valves to get her up and running.

aaron_sK · Posted: Sat Nov 03, 2012 3:42 pm Post subject:

Leaner primary makes logical sense, but I always ended up with the secondary a bit leaner on mine. Quite possibly due to the lack of PV. Shrug

I wouldn't plug a front PV, it makes sense there, just the rear. Makes it much easier to tune the secondary.

91RSVert · Posted: Sat Nov 03, 2012 3:43 pm Post subject:

Thanks mad. Will put it back together when i get home

91RSVert · Posted: Sun Nov 04, 2012 3:26 pm Post subject:

damn thing still wont start, but its getting fuel. Rolling Eyes

I could have replaced the motor and wired a fuel injected one in the time Ive been screwing with this thing.

chevymad · Posted: Sun Nov 04, 2012 3:55 pm Post subject:

It's something simple.. you have spark? it's in time? and there is compression? You don't get much more simple then a carb'd chevy.

91RSVert · Posted: Sun Nov 04, 2012 5:34 pm Post subject:

aaron_sK · Posted: Sun Nov 04, 2012 5:45 pm Post subject:

91RSVert · Posted: Sun Nov 04, 2012 5:53 pm Post subject:

double checked points and fire order after it wouldnt start.

I did have a minor fuel leak on my hose, so its apart trying to fix that. Then shall try again.

91RSVert · Posted: Wed Nov 14, 2012 12:06 pm Post subject:

So I thought I would update this. Got all my leaks fixed... fuel and vac.

Still wouldnt fire.
tested power to coil, tested spark at plug, good.
Tossed timing light on it for giggles, while cranking the timing mark was so far off, it was under the waterpump and could barely see it.

How the eff it ran at this, I have no clue.

Attempted turning the dizzy, no go. Ended up hammering on it to get it to turn, turned it wrong way and was even futher off. So it needed to be restabbed to make it correct (vac thing was hitting the intake runner).

Ended up snapping the dizzy off in the block, so I have to pull the motor to get it out, and get new dizzy.

aaron_sK · Posted: Wed Nov 14, 2012 2:13 pm Post subject:

91RSVert · Posted: Wed Nov 14, 2012 2:36 pm Post subject:

just the base is snapped, the "shaft" is still in it. So intake wont come off. Reading around, the only way to get it out is drop the pan, oil pump, and use something to hammer it out from the bottom.

Yes I know the oil pump, n dizzy are connected. I'm sure I will end up effing up the block trying to get the oil pump off, so I can hammer from bottom side.

chevymad · Posted: Wed Nov 14, 2012 6:01 pm Post subject:

Take one bolt out and oil pump falls off. I don't get why you can't pull the intake though.

Also why is it so far out of time? Did you put new wires on and not put them back where they were? If not then the timing chain probably has slipped. Engines just don't go out of time on their own.

aaron_sK · Posted: Wed Nov 14, 2012 6:35 pm Post subject:

91RSVert · Posted: Wed Nov 14, 2012 6:57 pm Post subject:

we tried moving them over, and it was backfiring.

No clue why it was out of time, thats my thought. It ran before, why not now?

I have a feeling that shaft that connects the dizzy to the oil pump is rusted everything together.

http://www.youtube.com/watch?v=vh7GWroEdSQ&feature=youtu.be

chevymad · Posted: Wed Nov 14, 2012 7:46 pm Post subject:

The dizzy to oil pump is just a simple blade connection and even if that was rusted together the lower connection from the driveshaft to the oil pump is another blade... held together by a plastic collar.

If the lower part of the dizzy broke off in the block.. and the gear then is preventing the shaft from lifting up.. you should be able to cut the mechanical advance mechanism off of the dizzy, unbolt the intake and lift everything off. Then the rest of the dizzy will be exposed in the lifter valley.

Once you get it out, throw that points thing away and get yourself an HEI. One can be had complete for $40, brand new on ebay.

91RSVert · Posted: Thu Nov 15, 2012 10:00 am Post subject:

Yea, Ive been looking for HEI's in the junkyard. There is a guy on the truck board Ive been giving tpi help to that has one, said hes willing to hook me up on it.

Just need to get it apart w/o damaging the block first.

There are other smaller reasons for pulling the motor, butchered "cross member", looked like oil pan was leaking, lots of rust under the vc's so I want to see what the rest of the motor looks like, and massive sludge the first time I drained the motor. Plus inside one of the cyls has what looked like a mouse nest partly built (I know I can take heads off w/o pulling motor).

Hopefully the motor will be out for just a few days. It is alot easier to pull an old school motor, not near as much crap connected to them.