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BoxheadTim
BoxheadTim MegaDork
5/27/17 4:24 p.m.

Another vote for rebuilding the carb unless you want to spring for a known good quality one like an Edelbrock - I hear too many things about the lack of quality of "professional" rebuilt ones.

klipless
klipless Reader
7/6/17 1:00 p.m.

Sorry for the lack of updates. Life has a way of getting in the way. A new dog and a new-to-me Miata have proven to be more interesting that the Camaro lately. I did changed the oil, filter and plugs. I also shot a little marvel oil in the cylinders and turned it over a few times by hand. After that it sat for about a month.

Because I work for one of the big three, I have to burn some vacation time and take the week of the 4th off. After a couple days relaxing next to Lake Huron, I now have a few days to work on the carburetor while my daughter is still in daycare. Well, more like two days, since I spent yesterday trying to fit my long torso in Miata. After studying up by watching a few youtube videos (mainly this one), this happened:

I misspoke when I said it was a 4130, it's a 4150. 4130 is my preferred steel alloy for bike frames, doh.

The main differences between my carb, and the one in the youtube link is that I had idle screws only on the primary side, not the secondary. The secondary didn't have a power valve, and I didn't have any air bleed screws on the main body of the carb. I disassembled the primary side first, and it was pretty dry due to the shriveled up gasket that sits between the metering block and the body. The secondary bowl was also empty, but everything still had a good coating of varnish on it, so on when the nitrile gloves.

A couple of question for the experts:

  • There were eight screws holding the base plate to the main body. I've heard recommendations to leave out the two that might fall in to the engine. Should I, or should I just loctite them?
  • I'm going to soak the main metal parts overnight. I was going to skip the base plate since I didn't want to mess around disassembling the accelerator cams. I'll just shoot carb cleaner through it.
  • After soaking, should I rinse them off with water, or just blast them with compressed air (safety glasses!)
  • What the best way to check the floats? I was going to dunk them in water and look for bubbles.
  • When reassembling, should I use the gaskets as-is, or spray them with silicone?

Any other words of wisdom besides the obvious use the correct gaskets?

klipless
klipless Reader
7/6/17 1:02 p.m.

This is more for my own documentation, but here's a link to a bunch of pictures I took while disassembling it.

Google Drive - Carb Rebuild

81cpcamaro
81cpcamaro Dork
7/6/17 1:15 p.m.

Most new Holleys don't have the two bolts in the baseplate. If you use them, Loctite is a good idea, and use a gasket that covers them, for a little insurance.

You can rinse them with water, but use carb cleaner afterwards to get the water out. Or just rinse with carb cleaner.

If the floats have leaked, you usually can hear liquid in them when shaken. Dunking them in water can work, other just see if they float in a container of gas.

Use the gaskets as is. I usually get the reusable ones for the metering blocks and float bowls, better than the cork ones.

APEowner
APEowner Reader
7/6/17 2:21 p.m.

Part of a really good carb rebuild is making sure that all of the passages are clear. That requires more than just dunking it in solvent and hoping for the best. While some people just use air pressure I find that the easiest way to make sure a passage is clear is to spray something you can see through it. I use WD40 because I usually have some and it hurts less than carb cleaner if you get it in your eyes. With the exception of accelerator pump circuits pretty much every passage on every carburetor that leads to the venturi is fed by both fuel and air. If, for example you spray into the holes where the mixture screws go you should get fluid out of the idle air bleeds and the passage that leads to the transfer slot on the throttle body. I go through and make sure every passage is clear with the WD40 and then hit them again with some carb cleaner before blowing it dry. That process will also make you more familiar with how that particular carb works.

klipless
klipless Reader
7/10/17 7:38 a.m.

I reassembled the carb yesterday. It went together pretty easy. I have to take the metering blocks back off so I can install new 'whistles'. The old ones would not go back in at all. I guess they must have swelled.

I only installed six of the eight base plate screws. If I can find a gasket that covers them, I'll reinstall them down the road with a bit of loctite.

My rebuild kit came with the blue Holley gaskets that apparently don't have as much of a tendency to stick. It also came with nylon gaskets for the bolts that hold the bowl and metering block to the body.

Anyone in the Detroit area want a bucket of free carb cleaner? Used once! That stuff is nasty. I'd like to get it out of my garage sooner rather than later.

BlueInGreen44
BlueInGreen44 SuperDork
7/10/17 9:44 a.m.

Milford? That's just next door to me. Hopefully I'll see you cruising around when you get this beauty on the road.

AngryCorvair
AngryCorvair UltimaDork
8/9/17 12:14 p.m.

update? woodward is less than 2 weeks away...

klipless
klipless Reader
8/21/17 9:35 a.m.

No real update to speak of. Since the last time I posted, I managed to buy an wreck an NA miata.

The carb went together pretty easy. The only thing I couldn't install were the float bowl vent 'whistles'. They appear way to big to fit in to the metering block, even though I removed them myself. I even bought new ones that also seem to wide. I'm just going to leave them out for now. Apparently they help with fuel slosh during braking and accelerating. If I have issues there, I'll put them back in.

I did buy a new fuel pump, water pump, and valve cover gaskets. Hopefully all of those will be going on this weekend. After that, a short run of fuel line to a jerry can and I should be ready to fire it up. I left the distributor and plug wires alone for now, but there's new plugs installed.

klipless
klipless Reader
10/30/17 12:55 p.m.

A small update that was supposed to be a big one....

I was all prepared to fire the engine for the first time on Saturday, but due to a lack of oil pressure, I decided against it. I had a buddy come over to help me wrap up a few small things and to man the extinguisher in case things got a little hot under the hood during start up. But his services as a firefighter were left un tapped.

Before pushing it out of the garage we pulled the valve covers and the distributor and dropped in a modified (ie, no gear) one that Angry lent me. After spinning it with a 1/2" corded drill for a couple of minutes, we never saw it build pressure on the gauge or saw oil coming out of the push rods. The bottom couple of inches of the distributor shaft were wet, but oil wasn't getting up much higher. As a last resort we reinstalled the original distributor and cranked it for 10-15 seconds and didn't see any improvement. Not wanting to roast the bearings, I decided to call off the first start a go do some more research.

I could only think of two reasons why we never built pressure...A) I'm doing something wrong B) there's something wrong with the oil pump. 'B' seems highly unlikely, as this car did run when parked 11 years ago. I could stick a boroscope through oil pan drain to see if the pickup tube fell out, but that also seems unlikely. I really don't want to pull the pan on  this car if I don't have to.

Occam's razor suggests I'm screwing something up. And after talking it over with a couple guys at work, it sounds like I'm not spinning the oil pump long enough or fast enough. They were saying it sometimes takes five minutes or more before the oil makes its way to the top of the engine, so I'm going to give that a shot.

Any other ideas on what I might be doing wrong?

Dusterbd13
Dusterbd13 MegaDork
10/30/17 12:59 p.m.

Make sure youre spinning the pump in the right direction. 

klipless
klipless Reader
10/30/17 1:16 p.m.
Dusterbd13 said:

Make sure youre spinning the pump in the right direction. 

Yup, righty-tighty. And yeah, there is oil in it wink

81cpcamaro
81cpcamaro Dork
10/30/17 1:32 p.m.

I have primed a few small blocks that didn't show oil at the rockers, but started up and ran just fine. If you see oil at the bottom of the distributor, then the oil galleys are getting oil, thus the mains would be getting oil as well. Where are you getting the oil pressure reading from? Which port on the block?

NOHOME
NOHOME UltimaDork
10/30/17 2:50 p.m.

You should be able to feel the oil pressure when holding the drill. It's pretty apparent when the pump starts pumping cause the drill wants to tear out of your hand; if you are not feeling a bit of torque on the shaft, I would go looking for a cause.

klipless
klipless Reader
10/30/17 3:50 p.m.
81cpcamaro said:

Where are you getting the oil pressure reading from? Which port on the block?

I don't recall the exact location, but it's somewhere on top of the engine close to the coil. I think it's just behind the intake manifold. I don't have a good shot of it handy, but you can just make out the thin translucent white tube in this picture.

 

klipless
klipless Reader
10/30/17 3:54 p.m.
NOHOME said:

the drill wants to tear out of your hand

I can spin the shaft pretty easy with just my fingers. But at that speed I'm not generating any pressure. When I spin it with a drill, it definitely doesn't want to rip my arm off...another sign that it's not building pressure. I've been told the chevy pumps are self priming, but I'm wondering if it's worth putting some extra oil in it just to make sure the pump is submerged. I'd drain the extra off before starting it.

Would I be getting these same symptoms if the pressure relief valve is stuck open?

Crackers
Crackers HalfDork
10/30/17 8:00 p.m.

You probably haven't filled the lifters yet. If it's a higher mileage motor you could be a while depending on how much oil is blowing past the bearings. 

You see this on motors that have a little extra bearing clearance machined in too. 

klipless
klipless Reader
12/4/17 3:20 p.m.

It's been too long without and update. With the number of warm days dwindling, I've been spending more time with the family and less time wrenching. I wouldn't have it any other way. I still have a shot at getting this thing fired up before Christmas, so that's what I'm trying to do.

I didn't have much time to spend out in the garage this weekend, so my goal was modest, diagnose lack of oil in the valvetrain. My bet was user error, and I was proven correct. I spun the oil pump for a good seven minutes with a half inch drill before I started to see the smallest trickle coming from a couple of the push rods. After ten minutes it was a bit more steady. My drill has a trigger lock, so I was able to leave it spinning while I turned the engine over by hand a few times. By the end, oil was coming out of every push rod and spilling over the rockers on to the springs.

Now it's time to reset the distributor timing.  Now please call me out if you see something incorrect or stupid. I've done a fair amount of googling, and have put even more thought in to logic and reasoning, but I'm fully aware I could screw something up. So, first things first, turn the engine over until cylinder one is at the proper top dead center (the one at the end of the compression stroke, not the exhaust stroke). I did this by pulling the plugs and turning the engine over by hand, watching for the number one cylinder exhaust valve to close, then I kept going until the intake valve opened and closed (exhaust valve remaining closed during this time). Turn it over some more (somewhere between a quarter and a half rotation of the crank shaft) until the timing mark on the balancer lines up with 0 deg on the timing gauge. Ideally you'd have someone turn the engine over for you as you put your finger over the spark plug hole. If you're at the correct TDC, then you should feel pressure build as you approach TDC and hear it escape as you take your finger off. I was worried about rounding the balancer bolt off, so I used two hands to turn it over and couldn't check for pressure.

Since having the wrong TDC (post exhaust stroke) is extremely undesirable, I wanted a way to double check my work, so I mapped out the timing for the valves for each cylinder. The diagram below isn't extremely accurate. For instance, I swagged the valve duration and overlap. Spark is actually the TDC after the compression stroke, so the actual spark is likely before that. Where I want the engine to be is at the far left of the graph at 0 deg. 

So now that I think I have my engine at the correct position, I noticed that the #3 intake and the #5 exhaust valves seem to be almost fully open. The #7 exhaust valve seems to be partly open, and the passenger-side bank of valves seem to be all shut. If I check the left side of my graph, I see that's exactly what I should expect (ok, maybe the #4 intake should be slightly open, or maybe my cam doesn't have as much dwell as the graph). If I was at the wrong TDC, then the drivers-side bank of valves would be mostly closed with some of the passenger-side valve open. So now I'm reasonably confident that I'm good to go. 

Rough estimate of small block chevy valve timing:

 

Drivers-side valve (cylinder 1-3-5-7)

 

At this point I had to wrap things up for the night. I'm hoping to install the distributor tonight. My plan is to follow this youtube video: https://www.youtube.com/watch?v=3xgBp9JY9mY. The only difference I that mine isn't an HEI distributor. Should the alignment process be the same?

AngryCorvair
AngryCorvair UltimaDork
12/5/17 3:08 p.m.

In reply to klipless :

yes, that's all there is to it.   remember that the small-diameter wire from the distributor goes to the (-) side of the coil.  

klipless
klipless Reader
12/22/17 8:48 a.m.

Installed the distributor last night per the video linked to above. Sure enough, the rotor button was lined up with the cylinder 1 plug wire. Put the cap back on and all my reference marks on the distributor housing, cap, and intake manifold all lined up. Sweet. Here's what it looked like before I put the cap back on. The sharpie mark is cylinder one the cap.

After that, I tightened the spark plugs, attached the plug wires and connected the distributor to the negative side of the coil.

Time to fire this engine up....or not.

klipless
klipless Reader
12/22/17 9:04 a.m.

So I pushed the car out of the garage this morning. Grabbed my fire extinguisher and explained to my wife how to use it. Reassured her that she probably, most like, wouldn't need to actually use it....maybe. Set up my jerry can and ran a length of hose to the fuel pump. Battery is only a couple months old and 100% charged. 

I went to crank the engine for 10-15 seconds and....nothing. Start going through the list. Fuel seems to be working, I see some in the inline filter. Crank some more...nothing. Actuate the throttle by hand and fuel squirts, sweet. Try cranking some more, goose the throttle a bit and it stumbles like it want's to start, but won't. After about 20 seconds the fuel sitting on top of the throttle plates catches fire. Wife freaks out. I tell her to holster the extinguisher, we don't need it yet. Calmly get out of the car and blow it out like a birthday candle.

Rinse and repeat this a few times (minus the fire). When I feather or pump the throttle, it starts to catch, and then looses it. So I back of the idle screw a bit and it gets a little better, but still won't start. Had a tiny backfire through the tailpipe, so fuel is definitely making it's way through the engine.

Here's a video of the last time I tried to start it. Sorry for the portrait mode, it was the only way I could get my phone to balance on the hood hinge.

I'm leaning toward air being the problem, but I don't want to discount spark either. The coil, distributor, and wires are 12+ years old. The plugs are new. I'd rather not go throwing parts at the car willey nilly right now. The throttle blades are pretty much entirely shut when I'm of the pedal. Any use in trying open up their stop? When I feather the throttle trying to start, it squirts a decent amount of fuel.

Another reason I'm leaning toward air at this point is that when I rebuilt the carb, there was a sizable port on the back of the throttle plate that wasn't plugged. I put a cap on it since it looked like a huge vacuum leak. Everything else on the carb was set back to how I found it. Maybe by plugging it, I choked off the air to the carb . 

Thoughts?

NOHOME
NOHOME UltimaDork
12/22/17 9:27 a.m.

play with the distributor timing. I always seem to have a minion around to either spin the dizzy or turn the key while I do so when starting a new engine. Timing light would also come in handy right about now.

 

Pete

klipless
klipless Reader
12/22/17 10:21 a.m.

Another video of it trying to start. It wants to go! Especially around the 1:23 mark.

 

In reply to NOHOME :

I have a timing a light, am I looking for a particular range for the timing?

 

I've lost my minion for a few hours. Anything else I can try? I'm thinking about dropping in a new coil. My spark tester has the wrong sized end for my plug and wires.

klipless
klipless Reader
12/22/17 1:23 p.m.
NOHOME said:

play with the distributor timing. I always seem to have a minion around to either spin the dizzy or turn the key while I do so when starting a new engine. Timing light would also come in handy right about now.

 

Pete

 

It runs! Thanks for the tip Pete. I didn't have a minion around, but I would adjust the dizzy, tighten it down, try to start it. Rinse and repeat. After a few tries it fired up. It can't idle worth a damn, so I have to keep the throttle tipped in, but other than that it sounds fine. Video incoming as soon as I can get it uploaded.

 

Edit: Here's the first time she's started in 11+ years.

 

wvumtnbkr
wvumtnbkr UltraDork
12/22/17 2:31 p.m.

You dont need to crank down the distributor locking plate.  You can make is snug enough so the distributor doesnt move itself but will move when you turn it by hand.  This can help you get it "just right".

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