Carburetor After-Market Question

[Green Mesa XJ]

Looks about right. I’ll look at the marks on the motor I’m building .


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[Green Mesa XJ]

Ok. I set TDC on the 2.8 I’m building using the methods I posted. With the timing cover just loosely bolted and the harmonic balancer not pressed on this is 0.

 

 

Here are the marks on the on the timing cover

 

If I can find a distributor cap to show me cylinder 1s location I can tentatively show what that should look like.

What is you motor supposed to be set for? How many degrees off according to the sticker on the firewall ?

 

 

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[Green Mesa XJ]

During compression/power cycle, both intake and exhaust valves are closed.

it is as Ohm says.
Like in the video and instructions you’ll feel the air presses out the spark plug opening because the exhaust and intake valves are closed, the compression stroke. Keep an eye on the Piston with a screwdriver or wooden dowel rod for it reaching the highest point in its stroke and you’re at TDC for whatever cylinder you do this on.



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[carnuck]

it is as Ohm says.
Like in the video and instructions you’ll feel the air presses out the spark plug opening because the exhaust and intake valves are closed, the compression stroke. Keep an eye on the Piston with a screwdriver or wooden dowel rod for it reaching the highest point in its stroke and you’re at TDC for whatever cylinder you do this on.



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For a novice, a plastic drinking straw or screw in “stop” would be better. Less chance of damage.


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[AMC86Kid]

i will look at my firewall sticker tomorrow but I'm pretty sure it won't say anything about TDC 

and i have no clue about how many degrees i should be off by 

[carnuck]

i will look at my firewall sticker tomorrow but I'm pretty sure it won't say anything about TDC 

and i have no clue about how many degrees i should be off by 

 

I would start at 10 degrees static timing advance. I used to know all that stuff from setting Chev Celebrity with 2.8L but the bigger motor probably doesn’t have the offset crank that the smaller motor tried with an external balance before ‘86.

 

 

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[Green Mesa XJ]

Good points carnuck
Do you remember where #1 on the distributor was? I thought it was at one of the minting points for the dis cap.
I’m looking at my spare distributors they can be set just about anyway you can imagine, like most old school distributors. More modern distributors have on or two ways they can be installed.
What I’d like to do is set my new engine i’m building to the timing needed here to get a picture to demonstrate where the distributor would be positioned. It’s the only way I can think of to setup it near correct long distance.

Far as the 3.4 goes it’s just a bored out 3.1/2.8
Camshafts interchange efi/tbi engines 1985-1995
Crankshafts interchange 1987-88 until 1995 for the 3.4 & 2005 with the 3500 FWD motors

Hell I heard you can drop a Malibu 3500 engine in a s10 2.8 engine bay, the block still has the place for the distributor. Engine mounts probably need to be fabricated.


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[Green Mesa XJ]

i will look at my firewall sticker tomorrow but I'm pretty sure it won't say anything about TDC 

and i have no clue about how many degrees i should be off by 

It’s not going to say TDC it’ll say BTC because these engines are timed before TDC. Usually these old engines either are timed ATC (after top center) or BTC (before top center), more modern use TDC and the computer moves the timing around.

 

You looking for something that says “ignition timing” it’ll have the rpm + or - and the degrees BTC + or -.

I think the standard was 12 to 13 on automatic 2.8 but don’t know for sure.

 

 

 

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[AMC86Kid]

ok i found it 

here it is 

 

[Green Mesa XJ]

Ok. Have you got TDC now?
If so loosen the cap to take a look where it thinks cylinder 1 is.

Depending on where it is you can just line up the rest of the spark plug wires with that place as one now.
If that’s lined up perfectly then setting 10 BTC is the real trick because as the distributor gears mesh it turns as well, I try to turn the position the distributor rotor face enough to offset it so when it turns as it’s installed it close to correct.

Here is a (sort of bad) example of where to set the timing, imagine if yellow mark is TDC white is about 10 BTC. I can try to find a better example or maybe somebody here can explain this better than I can.

See if this works for you, if you have TDC you ought to be pretty close.



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[AMC86Kid]

ok so i turn the crankshaft pully till i feel compression from spark plug 1

then i have to turn it back about 10 degrees (so counter clockwise 10 degrees)

and then when i drop my distributor in how do i know where to line it up 

i see your yellow and white spots but what are they suppose to line up with 

[Green Mesa XJ]

Those marks are about where the rotor lines up. Again if yellow is TDC white is about 10 BTC.

I’d get to TDC, don’t turn it backwards cause with no markings there is no telling where you’ll be. Once you set at the very top of the #1 cylinder compression stroke you’ll be able to time the rest of the engine off that.
Once you’re at TDC see where the rotor lines up with the distributor cap, if it’s dead on a post you can adjust the rest of the cylinders in firing order from there with that spot being the new #1. Then loosen and adjust it just enough so the housing is approximately 10 degrees off from where it was at the TDC. The distributor rotor turns clockwise so a nudge counter clock wise.

If you current setting is way the hell off you’ll have to pull it and practice resetting it, as I said the gears meshing like move the rotor during instillation so it a trick to get it perfect.

For instillation these kind of distributors can be indexed from just about anywhere as long as #1 is designated with the rest of the spark plug wires following in firing order.
It can be confusing as hell but Welcome to 1980s engine management!


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[AMC86Kid]

ok so i turn the crank shaft till i feel compression then stop 

and line my first spark plug up with the distributer then turn it a little bit counter clock wise

and then follow the firing order in a clock wise motion around the distributer with the rest of the spark plug wires 

and see it she will start from there 

does that sound right to you 

[Green Mesa XJ]

Um when you feel the compression keep turning until it gets to the top of that stroke, eyeball it or use something in the spark plug hole to show when the piston reaches the top.

 

Once at TDC is set check where the distributor is at, if it’s in line with one of the post in the distributor cap just adjust it slightly to approximate 10 BTC and with that as the new #1 go from there.

 

Basically you need to see where the distributor is at when the engine is at TDC and decide what the next best step is.

 

Its more complicated writing it out than it is doing the job.

 

 

 

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[AMC86Kid]

ok i will try tomorrow and see how it goes

if i can't get it to start then i guess i will take it to a shop and get them to do it 

i just really wanna make sure i don't break something and cause even more damage 

[Green Mesa XJ]

Well it’s not like the timing chain moved, the pistons and valves are opening as they used to. The engine shouldn’t be in danger of self destructing from the valves and pistons intersecting.
Its just the ignition timing is off, so the spark is mistimed.

I thought the 2.8 to 3.4 were non interference engines, but now I’m not so sure why I thought they weren’t.


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[AMC86Kid]

ok so i looked at the first cylinder hole 

and it appeared to be 180 degrees out of phase so i repositioned the distributer and tried my best at it 

but just got some bad noises and a back fire so i think I'm gonna tow it to a shop and pay someone else to set the timing for me 

i really don't want to test it further for fear that i could ruin something else 

[carnuck]

ok so t looked at the first cylinder hole 
and it appeared to be 180 degrees out of phase so i repositioned the distributer and tried my best at it 
but just got some bad noises and a back fire so i think I'm gonna tow it to a shop and pay someone else to set the timing for me 
i really don't want to test it further for fear that i could ruin something else 

As long as the timing chain is set right, you won’t hurt it. If the timing firing order is 165432 then you need to find the overlap of #4 (where intake and exhaust are both closed but slightly turning the motor either way opens on or the other)
That is where #1 should be at TDC and ready to fire.


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[carnuck]

There was a kit to mount the FWD motor in place of the RWD version but the dist for carb version isn’t dependent on an internal sensor for # 1.

 

Caddy FWD V8s can be bolted in too but cooling and transmission longevity suffers. I considered using an AX-15 with the Dodge Dakota 2.5L bell and clutch/flywheel.

 

 

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[AMC86Kid]

the firing order is 123456

[carnuck]

the firing order is 123456

So it’s an odd fire? That’s what the 84-86ish 2.8s have. But then my memory isn’t as good as it was.


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[Green Mesa XJ]

There was a kit to mount the FWD motor in place of the RWD version but the dist for carb version isn’t dependent on an internal sensor for # 1.  

Caddy FWD V8s can be bolted in too but cooling and transmission longevity suffers. I considered using an AX-15 with the Dodge Dakota 2.5L bell and clutch/flywheel.

 

 

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I thought the distributor cap had a #1 designated, I couldn’t see anything marked. I think when I replaced the distributor before #1 was right by the screw on the left side of the cap, but your right that distributor can be set to cylinder 1 just about anyway you’d want.

 

Which caddy v8 was that ?

I was reading about 2.8 upgrades, one of them is the heads from a 3400 or 3500 engine, but it’s easier to use the whole engine. The 3500 block I saw pictures of look very close to the 2.8, including placement of engine mounts and the place for the distributor. Haven’t found a good write up on it but it’s been done successfully.

 

 

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[carnuck]

4.5, 4.9L and Northstar.


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[Green Mesa XJ]

4.5, 4.9L and Northstar.


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Ah, yes. The 4.5 was a popular swap for the 4.1 I think it was. The 4.1 was a big POS. I didn’t realize those v8 had the same bolt pattern as the amc & Chevy 2.8


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[carnuck]

Ah, yes. The 4.5 was a popular swap for the 4.1 I think it was. The 4.1 was a big POS. I didn’t realize those v8 had the same bolt pattern as the amc & Chevy 2.8


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It sure did and they never intended for it to have a standard transmission so the size of the bell didn’t matter as much because transmission torque converter design improved since the big block days but changing the starter under the Northstar V8 intake in a Jeep sounds like a nightmare job.
My God daughter’s mom had a caddy with 4.1L and it was horrible to work on plus GM refused to warranty it when the water pump went out and it started to run like crap.
After trying for 2 years, she gave up and we did the 4.9L swap. She drove a ‘78 Matador with 304 during that time which had its own idiosyncrasies but was easy to fix 90% of the time.
We met when the flexplate and starter were stuck engaged and she had her 4 kids in the car on the way to a job interview. I got it going in two seconds after she had fought with it for an hour and it turned out she was my neighbor.


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