Motor timing 180* out?

[Bent]

I don't mean to hi-jack here Turbo, but I'm having the same issue right now on my initial start-up.

I am getting a "backfire" thru the carb, and actually blowing off one of my loose fitting vacuum hoses, manifold vac. I made my first attempt at starting my engine after my almost 4 year rebuild.
However, when I assembled the engine after a new timing chain and sprockets, I left it where the marks/dots on the sprockets lined up. This is also where the timing mark on the balancer was at zero and the front piston was at the top of the bore. When I inserted the dizzy the rotor was pointing at or close to plug wire #1. So that said I assume it's not out of time 180 degrees. Am I missing something? Can you offer some guidance for me?Could the dizzy just need rotated cw slightly?

Make sure to count the pins. Its been my experience that AMC motors are not like SBC where you can just align the timing marks and you're good. The gears are farther apart and the marks are smaller. A small rotation to get the gear on to the shaft can leave you one pin off. I experienced this on my AMC 258 i6 / 4.2l overhaul. For the V8, after you get the gears installed you need to rotate the crank clockwise until the cam gear timing mark is at the 3 o'clock position. Then count the number of pins in the timing chain between the two timing marks. It should be 20. For the AMC 258 i6 / 4.2l , rotate the crank until the cam gear timing mark is at the 1 o'clock position. You should have 15 pins between the marks.

I was one pin off and it caused backfire out the carb. It is a huge pain to get the cover back off!

 

[Turbogus]

Good tip Bent, not up to doing a gear change yet but, it turns out the "battery won't take a charge" So, I've got to pay the pro-rate of $72.00 for the warranty of this battery that was used 25 out of 84 months. I think I'm going to go with a new Interstate battery for the same cost and longer warranty.

 

[PaRenegade]

Make sure to count the pins. Its been my experience that AMC motors are not like SBC where you can just align the timing marks and you're good. ....

Yes, pins were counted and alternate position verified. The problem was that is the exhaust stroke position so I was 180 out of time. Rotor should have been pointing away not towards #1 plug. That problems been solved, I'm onto the next problem .

 

[Turbogus]

Well I cleaned up the rotor, reinstalled the cleaned up spark plugs (along with some new ones that I exchanged for ones that didn't thread easily) connected the plug wires and fired it up. I got it to run for about 3 minutes holding the throttle open, in the hopes of warming it up to set the timing. My friend came over and verified my work and it wouldn't start thereafter. He capped the bowl vent and giving it another go we found fuel leaking from the carb. I suspect it's on account of that capped bowl vent. Going to uncap it tonight and open the air bleed screws a little more and try it again.

 

[Hedgehog]

What? Your bowl vent is capped! Your carb has fuel flowing from it! You NEED to do some simple carb. float work, possibly a new float is in order. The fiber floats will become saturated and won't work correctly. Unplug the over flow, get it started and see if fuel comes out the tube.

 

[Turbogus]

Got it running in the same way last night and despite the bowl vent now unplugged this venerable AFB 'Black Stallion' seems to be leaking from both the primary and secondary shafts. It never did leak from the bowl vent, and the floats are brass floats as this is an AFB, the thermoquad got the phenolic floats.

 

[Hedgehog]

Leaking from the shafts, sounds like you have a seriously warn out carb. Some shops will take care of warn shafts, don't know how, but they will or used to. It's getting to be hard to find decent carburetor shops these days.

 

[Turbogus]

Since fuel was seeping from both of the primary and secondary shafts I found a carburator rebuild shop up in Washington that I'm going to ship the throttle body to for bushing installation.

 

[Hedgehog]

If your carb is THAT warn it is no wonder that you've been having problems. And it's no surprise that you thought it might be a spark problem. Both mimic the each other. Frequently an older vehicle owner will religiously follow the wrong path. I had a Harley Davidson that would run really well then seemed to run lean and would keep going with the choke on. I'd pull the carb., clean it out and the thing would run well again. Then I realized that it ran well around town, on short trips, but almost to the mile, about 100 miles, it would start having troubles. Hmmmmmm maybe it's heat related! After changing out the ignition system the old girl ran great.

 

[Turbogus]

Originally I bought this carb to set upon an SBC I was building in the hopes of getting another '66 Malibu to set it in. By luck I fould a 10/10 steel crank to set in the four bolt main block both were magnaglowed for cracks and both checked out good. Got as stiff of a hydraulic cam as I could get from Sig Erson and a High Volume Moroso oil pump. As luck would have it the cam in my pickup ('77 Chev Short-wide lowered) I had at the time went flat and not wanting to go through a re cam on a motor that was an unknown quantity I stuck the built 350 sbc in and that truck just screamed. However, I lost what I thought was a lifetime career and I had to sell stuff off. Luckily I had the presence of mind to seperate the motor from the truck and sold it seperately, (for only $900 clams) but I kept the AFB since it only had a few months on it.

Some time later I sold it to my best friend and although he said he tried it on his 283 he couldn't get it to idle right. This 9638 S was just too much carb for his mouse motor. He shelved it and after that Edelbrock Carter clone burned up I bought it back from him and dialed it in for my 360. So it doesn't seem to have been run for very long at all.

 

[Turbogus]

WOW! The postman stopped by and he had this on his truck on Saturday! I had only sent this throttle body on Thursday! The throttle shafts are tight now and I don't think they'll be giving me any more issues. I'm going to put Carbs Unlimited on my resouce list, these guys are GREAT!
CARBS UNLIMITED INC. carburetors including Weber Edlebrock Holley Quadrajet

Since the recent rebuild all the gaskets are in good shape, but I'm flirting with buying new.

 

[Turbogus]

Now, the Echlin rebuild kit I got from NAPA included two sets of Needles (needle and seat) one pair with internal springs and one pair of solid. The instructions mention the spring type are for late model AFB's and the solids for earlier ones. In this process I've noticed these; that are for Marine and Off Road, are these the same as in the rebuild kit?

 

[Hedgehog]

I'm confused with all this talk of rebuilding kits. Didn't you have your carb rebuilt? I must admit to being intrigued by the a off road needle valve.

 

[Turbogus]

I did rebuild the AFB, with the help of a Carter Carburators book by Dave Emanuel c 1983 with a Echlin kit from NAPA, the drilling out/bushing installation was by a shop up in Washington state - stellar work that!

 

[Hedgehog]

Hmmmm they did the bushing work, but didn't rebuild the carb. Seems like a big opportunity for metal filings to contaminate everything. ... maybe not though.

 

[Turbogus]

For comparison this is what came in the Echlin rebuild kit, they look the same to me;

 

[Torxhead]

Thanks for showing that Gus. I guess that spring loaded needle would prevent the shock against the seat and float and help the float level from getting out of adjustment due to vibration and sloshing in the float bowl.

 

[Turbogus]

I had already stripped down that AFB to get at the floats needles and seats, Hedgehog and it saved that remote shop time/effort that I sent them the bare throttle body. When it returned it was clean as a whistle and those bushings did the trick, there's no play in the shafts at all now.

They do seem to be a dead ringer for those Marine/Off Road needles, Torxhead so I reckon I'm going to go with them. I've got the solids as backup if something goes nutz, and I'm hopeful this'll be, at long last the end of my issues for a spell~just in time for the rainy Oregon winter.

 

[Turbogus]

Well, I assembled the AFB using these needles and something that has troubled me in the reassembly process is the fact that the tension springs for the air bleed adjustment screws are too long, so to achieve 1 1/2 to 2 turns from bottoming out, the springs need to be shorter if my eyeball measurements are correct. I've got another Chrysler AFB and the Edelborck Carter clone at home so I'm going to see if there's any difference.

 

[Turbogus]

I dropped by the local hardware store and got one gauge lighter springs that I'll cut to length so to achieve the initial air gap (mixture) 1.5 to 2 turns out.