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1976 351w running very rough after top end reassemble - aaargh!!

FstaRockr Burns

FstaRockr Burns

Regular Contributor
Sooo spent the last 2 weeks removing the intake, manifolds, pretty much everything except heads - painting / etc -

Reinstalled the lot and the motor is just running rough. At first I tried the firing order stamped on the intake (1-3-7-2-6-5-4-8).. All it did was backfire and wouldnt run, googled a bit on my phone and tried the other firing order 1-5-4-2-6-3-7-8, motor ran better.. but sounds like its off, and alot more vibration.

Before tear down it was super smooth and responsive..

Been struggling for few hours now. Ive quadruple checked the wires, numbered each one - set base around 10 degrees. Same carb/intake -

Im wondering if there is a possibility of a firing swap in the 1-5-4 sequence.. sounds like its running on 7 or 6 1/2..

Also - my water hose routing, I did label it but just wanted to double check..


Water hose routing - (do i need to fill block and hoses with water before running?)

DSC_0516 (Copy).jpg


Old distributor with wiring running correctly:

DSC_0354 (Copy).jpg

The front damper seems to have more vibration - this looks like a timing thing, or perhaps a plug is not getting good spark. I checked all wires from cap with timing light and they are all firing stable.

At my wits end! Wanted this running last night already and a full day later I struggling with a old points motor! Maybe ill pull valve covers and verify the firing order by the rockers!
 
Every time you change something on your engine you start a new thread. I cannot keep up with you!!!
recheck the position of your diz. It seems like you might be 180 degrees off.
 
Check for true TDC on the #1 piston with a piston stop tool it could be the damper is off giving you a false base timing? Are you setting the points with a dwell meter?
 
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Is the firing order on the intake manifold? It probably wont hurt running the engine for short spurts with no water but you will burn up the raw water impeller within a few seconds running it dry. If that is a stringer drive you need to pull the gearbox to get to the impeller. Never run it without water to the impeller.
 
Hi - I have water on the outdrive running so its getting water there.. heard some gurgling sounds from the water pump after shutting it down today so hopefully its circulating but anyways ill confirm flow later..

I used an approximate tdc stop using a screw driver, seems the timing mark is good or so close it would be negligible..

I noticed the damper outer ring is off center creating quite alot of vibration.. even turning it with the breaker bar / plugs out and a wire, the outer ring is off by as much as 3mm moving forwards and back.

Motor is also backfiring a bit.. might need to recheck the carb - just so odd, all i did was pull all the bolt on parts, paint em - reassemble! before the motor ran so smooth - im wondering if the damper got pushed out of alignment while it was backfiring with incorrect firing order.. the inner ring seems to be ok- could bad running make a damper move that much?

Im starting to wonder about all kinds of weird things that can go wrong.. thought this would be straight forward yesterday..
 
Your not going to even get close without a piston stop tool get another new vibration damper and go from there you can easily be 20-30 degrees off using a screwdriver. You can use a piston stop to find true TDC but it sounds like that can change any time you start the engine if it is wobbleing that much just get a new one so you have a good mark for future reference. Until you can confirm true TDC your spinning your wheels and can possibly damage the engine. It will run a bit smoother also I am sure your getting vibration also.
 
I doubt the firing order written on the intake is wrong...

Did you remember that # 1 plug is on the left side of the motor? Drivers side!!

If all of the above is correct then start over.

Find compression stroke of # 1 cylinder

make sure that cylinder is the correct one.

Then see where the rotor is pointing.

Most likely you had the distributor 180 degrees out when you first started it if all of the above is correct.

Based on the diagram below you had it correct the first time so get it back to that and get the distributor in the correct location.

Also make sure you have the firing order correct in the correct direction (counter clock wise) as in the diagram.

If you can move the dampener rotational 3-5 mm with no effort I would say the timing chain is toast!
 
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..."I doubt the firing order written on the intake is wrong..."

Not sure about 351s, but Ford used two different firing orders over the years for 302s. With those engines, the wrong firing order could be on a manifold not intended for (but still fits) that engine.

A show on the Velocity channel experienced this recently on customer's restore. I laughed as flames shot out of the carb, for I knew the cause.

Jeff
 
fastjeff said:
..."I doubt the firing order written on the intake is wrong..."

Not sure about 351s, but Ford used two different firing orders over the years for 302s. With those engines, the wrong firing order could be on a manifold not intended for (but still fits) that engine.

A show on the Velocity channel experienced this recently on customer's restore. I laughed as flames shot out of the carb, for I knew the cause.

Jeff
Click to expand...

dont joke, thats exactly what happened - was spitting and doing all kinds of things, i thought maybe a bad condenser as i swapped in a new prestolite, 3 swaps later same symptoms - i knew instantly sth was wrong.

I think the cam dictates the firing order, not the intake - they prob stamped it on there assuming a matching cam for the year..

Anyway the motor ran super smooth before - perhaps the bad firing sent enough shock waves thru to finally send the damper to its death? Just seems so unlikely that it would fail so soon before/after a simple tear down and re-assembley..

Now im sifting thru the myriads of threads trying to figure out which ones are compatible.

Apparently they early 302's and 351w all shared a 28oz weight. The thickness changes as does the bolt pattern (3 = early, 4=later). I read the dampers were compatible from 69-97!

I was thinking of snagging a combo from a newer ford (f150?) from a salvage yard, they run about 30 bucks a set - long as the offset / thickness is the same so pulleys line up -

Was hoping to be on catalina island this week! Seems not!
 
Firing orders are typically NOT stamped, They are cast into the intake metal..................

Regardless of all else. The firing order I posted is for ford...........Marine.............Period...............for 1976..............period.

The manual does not differentiate whether it is a 302 or a 351. Both the same.




Not buying your story any more............


You need to get your facts straight and when posting, post specifics and in specific order. What you did first second and on and on....and again be specific.

This is getting old, fast.

What you are speaking to is to here is Engines 101.................Not sure about others But I have never seen any of this.

It ran before you took it apart, there is no F'n way it would not run after putting it back together unless you F'd up.
 
kghost said:
I doubt the firing order written on the intake is wrong...

Did you remember that # 1 plug is on the left side of the motor? Drivers side!!

If all of the above is correct then start over.

Find compression stroke of # 1 cylinder

make sure that cylinder is the correct one.

Then see where the rotor is pointing.

Most likely you had the distributor 180 degrees out when you first started it if all of the above is correct.

Based on the diagram below you had it correct the first time so get it back to that and get the distributor in the correct location.

Also make sure you have the firing order correct in the correct direction (counter clock wise) as in the diagram.

If you can move the dampener rotational 3-5 mm with no effort I would say the timing chain is toast!
Click to expand...

Hi - thats the firing order that is cast into the intake which I tried first.

Yes I know cyl 1 is on the left front side looking from pulleys backwards. I did confirm #1 tdc was the compression tdc (no exhaust pushing out of hole) and the rotor was pointing to the correct "pin" in the cap before attaching wires.

When I switched the wires to the different firing (302? 15426378) order the motor instantly about started. See the attached pic, the white tape indicates #1.. the rest of the wires seem to follow the 302 firing order if u follow the plug wires..

I didnt really number/check the plug wires when i pulled it cos i thought it wd be a straight forward re-assembly.. anyway ill head back to the boat quick and see.. fyi the damper outer ring has about 3mm forward/backward movement as mentioned wbich seems a little too much. Ill recheck everything and see - was getting late and a long hot day working in the sun maybe I messed sth up.

Ill look for free play in the damper - if the PO put in a 302 cam wouldnt the firing order be different? just saying..


The original setup (ran just fine)
View attachment 15023



Intake casting:
DSC_0515 (Copy).jpg
 
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No

The manual lists both 351 and 302.........both have the same firing order. That is if all internals are true Marine and no PO made significant changes.

Again did you thy to spin the distributor 180* and see if that fixed your issue?

99% of the time when you get back fires when starting after (re) installing distributor and wires it is either the distributor is 180 degrees out or one gear tooth in either direction or mixed up spark plug wires (wrong order of one or two wires)

Personally I have never................Let me repeat this............Never....................seen a completely wrong firing order............But that is just me................................................................................................
 
im heading to the boat for an hour now to check - then I have to entertain the wife! wasted 2 days on this already. Anyway - will report back. Im still concerned with the damper moving so much. tx for the input -

On a side note, when installing the stat - when it sits in the groove, if the top part facing you, or the spring? I installed mine with the top section facing up / visible.
 
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Look closely again at Jack's image in post #9.
I know of no engine that does not follow this: #1 cylinder is always the cylinder that is furthest forward.

In the case of the 5.8L Ford (in an I/O scenario), this would be the FWD cylinder on the Stbd side.

Also note that the cylinder numbering is quite different from that of GM.
Ford numbers the cylinders on this engine from #1 to #4 straight back on that same Stbd side bank.
Cylinder numbers 5, 6, 7 and 8 are on the Port side bank.

Also note that this ignition distributor turns CCW..... not CW like the GM does.

Make dang sure that you have indexed the ignition distributor correctly.
Start with #1 cylinder @ TDC on the C/S.






.
 
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I just found this:
"All 302/5.0 engines built after 1994 use what is referred to as the 351/HO firing order... 13726548, and any publication that says otherwise is simply wrong."

The pre- 1994 5.0 and 5.8 do use different firing orders that would be determined by the camshaft profile.

Since the 5.0 and 5.8 intake manifolds are not interchangeable, and since your intake manifold does show 1-3-7-2-6-5-4-8, it is very likely correct!



58912497.gif
 
yep ive numbered them correctly and checked the compression stroke on cyl #1.. triple checked 8 degrees btdc, for some reason the spec firing order does nothing, not even a pop. when i swap to the 1-5-4 it fires up.. still vibrates tho. Pulled damper now - the sharpie mark i pulled across the 2 rings hasnt moved since yesterday..

Number on damper is 6318 and RA on the other side.

its 1 - 1/8 thick or 1 - 1/4 excluding the pulley ridge/lip.

as far as i can tell from the pics this is a 28oz weight too -

DSC_0524 (Copy).jpg

DSC_0525 (Copy).jpg

DSC_0526 (Copy).jpg

DSC_0527 (Copy).jpg

DSC_0528 (Copy).jpg
 
kghost said:
look here.
Click to expand...


Thanks,mines upside down then! Will swap it over. Havent run her hot at all yet - also.. few drops from the weep hole under water pump.. is this possibly a leaking impeller seal? its so small - not sure if i have to consider a new one at some point?
 
RicardoMarine said:
I just found this:
"All 302/5.0 engines built after 1994 use what is referred to as the 351/HO firing order... 13726548, and any publication that says otherwise is simply wrong."

The pre- 1994 5.0 and 5.8 do use different firing orders that would be determined by the camshaft profile.

Since the 5.0 and 5.8 intake manifolds are not interchangeable, and since your intake manifold does show 1-3-7-2-6-5-4-8, it is very likely correct!



58912497.gif
Click to expand...

Thanks - im not 100% familiar with fords yet (clearly) - but is it possible this could be a 351w with a 302 cam in it? Just saying.. Also, I dont really look at pictures, i find compression for #1, set dizzy in, rotate to set points opening and install plug wires from there. Having said that after doing #1 just now it was just off the clip of the distributor about 25 degrees like the pic.. could a damper offset itself so quickly and cause so much vibration? never had one go like this - it has as mentioned about 3-4mm of movement forwards and backwards while running / idling - thats alot!

Since i can gt the motor running with the 1-3 firing order something is def up.. i just never paid much attention while taking it apart.
 
Unable to edit above post -



Thanks - im not 100% familiar with fords yet (clearly) - but is it possible this could be a 351w with a 302 cam in it? Just saying.. Also, I dont really look at pictures, i find compression for #1, set dizzy in, rotate to set points opening and install plug wires from there. Having said that after doing #1 just now it was just off the clip of the distributor about 25 degrees like the pic.. could a damper offset itself so quickly and cause so much vibration? never had one go like this - it has as mentioned about 3-4mm of movement forwards and backwards while running / idling - thats alot!

Since i can gt the motor running with the 1-5 (302) firing order something is def up.. i just never paid much attention while taking it apart. tried the intake firing order again and nothing.. wonder if a plug wire could have become bad.. checked them yesterday and one had pulled out so ran thru all of them and they seemed fine.

another possibility is maaaybe i messed up the intake gasket.. really starting to look at all kinds of possibilities now :(
 
Don't think this too deep

highly unlikely they swapped a newer cam into an older engine...............For what purpose???? I am not an ford expert either but that makes no sense.


If you suspect the harmonic damper has shifted then you simply could be way off timing.........


May have to tweek the distributor clock wise or CCW to see if you can find the sweet spot without "degreeing the cam" to confirm absolute top dead center.

ALSO YOUR DIAGRAM is incorrect...........


look at mine I posted in post 9

Looking at the diagram # 1 plug should be at 4:00. Not 1:00


you are off by 2 wires
.

move then all on the cap so # 1 is at 4:00.
 
YOUR DIAGRAM is incorrect...........


look at mine I posted in post 9

Looking at the diagram # 1 plug should be at 4:00. Not 1:00


you are off by 2 wires
.

move then all on the cap so # 1 is at 4:00.
 
kghost said:
Don't think this too deep

highly unlikely they swapped a newer cam into an older engine...............For what purpose???? I am not an ford expert either but that makes no sense.


If you suspect the harmonic damper has shifted then you simply could be way off timing.........


May have to tweek the distributor clock wise or CCW to see if you can find the sweet spot without "degreeing the cam" to confirm absolute top dead center.

ALSO YOUR DIAGRAM is incorrect...........


look at mine I posted in post 9

Looking at the diagram # 1 plug should be at 4:00. Not 1:00


you are off by 2 wires
.

move then all on the cap so # 1 is at 4:00.
Click to expand...


Does it really matter where the alignment is? one can easily rotate the dizzy a tooth and re-adjust the rotor position.. imo the dizzy can be in any position in relation to the motor, just not the clips. If i changed the dizzy by 1 tooth the clip would move (duh) but the relationship to the clip and wire would stay the same - so 4 oclock technically is assuming the distributor is installed on a certain tooth and has no relation to setting timing - i could rotate a dizzy anywhere and set it up from there on #1 and be fine - ?
 
WHATEVER


Think what you want!

You got the firing order wrong so the rest is meaningless............

If someone changed that engines cam from a 351 marine cam to a 302 marine cam for that year engine there still would NOT be any difference in the firing order!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 
"""""""""""""""Does it really matter where the alignment is? one can easily rotate the dizzy a tooth and re-adjust the rotor position.. imo the dizzy can be in any position in relation to the motor, just not the clips. If i changed the dizzy by 1 tooth the clip would move (duh) but the relationship to the clip and wire would stay the same - so 4 oclock technically is assuming the distributor is installed on a certain tooth and has no relation to setting timing - i could rotate a dizzy anywhere and set it up from there on #1 and be fine - ? """""""""""""""""



Do it as it shows in the diagram.........................I don't give a F^ck what you think is ok...

Either do it correctly or go to another forum to get the answers you want and not what you need.

You did it wrong. you said it lined up just like YOUR diagram. Rotor pointing at YOUR number 1.

Guess what, YOUR WRONG!

Now do it right!
 
kghost said:
"""""""""""""""Does it really matter where the alignment is? one can easily rotate the dizzy a tooth and re-adjust the rotor position.. imo the dizzy can be in any position in relation to the motor, just not the clips. If i changed the dizzy by 1 tooth the clip would move (duh) but the relationship to the clip and wire would stay the same - so 4 oclock technically is assuming the distributor is installed on a certain tooth and has no relation to setting timing - i could rotate a dizzy anywhere and set it up from there on #1 and be fine - ? """""""""""""""""



Do it as it shows in the diagram.........................I don't give a F^ck what you think is ok...

Either do it correctly or go to another forum to get the answers you want and not what you need.

You did it wrong. you said it lined up just like YOUR diagram. Rotor pointing at YOUR number 1.

Guess what, YOUR WRONG!

Now do it right!
Click to expand...


dude-pipe down.. ill see if i can line it up with the pic. im just making a point - get off the steroids man lol. ur attitude is gettin a bit stinky - im here trying to troubleshoot a very whacky situation. Ive set hundreds of dizzies in the past 20 yrs - maaaybe i missed sth small but after 2 days its starting to seem a little less possible. dont bother commenting if ur gonna take it up the wrong way.. fyi the dizzy can be in any bloody position, as long as the rotor is matching the cap to plug wire to cyl (#1 compression tdc) - if u disagree i dont care but swearing etc isnt considered appropriate.

O&O.
 
Dont care what you or anyone else thinks of my attitude.
Most who reply on this forum reply to OEM specifications.
We do not speculate on a million possibilities that some may have done something to a 40 year old boat....we follow the factory manuals.

That is what trained marine technicians do.

If it is not OEM....in most cases.....your on your own...

Just like going to a auto dealer...they do factory only repairs.
Not vehickes that have been altered...

Most of us answer based on the same assumtions. The boat engine is still OEM.

So speculating on cam changes and NOT setting the wiring and location of number 1 is wrong.
It should at all times be made to or put back to original OEM specs.
That includes the wire locations on the distributor cap.
What i would suggest is get a OEM factory manual so you have the correct information.

So far you have shown you have niether.......
 
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