460 Straight up Timing Chain upgrade

[ArdWrknTrk]

390/429 medium trucks use a really weird thermostat housing, a governed carb and a long snout on the crank that you can't fit into a pickup.
I believe they were also all internally balanced.
For sure there was never a car 429 that was external.
And I don't recall ever seeing a tomahawk on any bucket trucks that I had to fix.

[viven44]

Maybe The plate on there, I do hope thats the case. But I couldn't find anything!! I'll scrub everything well tomorrow and send more pics.

(The pics above show the original timing set...)

Cloyes own catalog shows C3079X as the recommended chain for BBF. The other with only 1 keyway that we discussed doesn't show up on their catalog, probably discontinued. Rockauto shows to have it, but its probably old stock or possibly returned.

I am paying about $40 for the set with 3 keyways. It has 2 extra key ways that I will ignore. I will install it with the key way with the timing mark straight over it.

[ArdWrknTrk]

Ifitaintbroke wrote

Jim, I think you're looking at the pic wrong. In middle of the picture, that large hole should be cover by the plate, if it were there. Pic is at weird angle so that makes it difficult. And I would like to see what a plastic 460 timing gear looks like. And what in the world was it used in?

Maybe I am half blind from arc flash and I'm looking at my phone in the dark, sitting here in my truck?

There definitely needs to be a backing plate.
I think I gave the # in the other thread. (Which is one reason it frustrates me no end to chase stupid questions around the forum again and again)

Plastic gears were in every 460 off the factory floor, except some super rare homogulation special race cars with the SCJ's
Ford used them to meet noise limits.
It was plastic teeth bonded to a alloy gear blank.

You don't really need me to go find pics for you, do you?
There might be some in my 2008 engine swap thread on FTE
I think I'm still all paid up at Flickr.

[Ifitaintbroke]

No I believe you. It's just that I'd never heard of it. Probably because the aftermarket pieces are always metal, AFAIK. (Could be wrong there too though).

[viven44]

The stock fan clutch on the 460 is "heavy duty" so no issues there. I will keep whats stock.

I had a 1/2 ton truck with the 351m, which after installing an RV cam (Yes I was going to tow but never did ever!) and new timing set, ran hot.. Low-end torque was awesome but The gauge would creep past halfway while stopped in traffic. I probably should have upgraded the radiator to a 3 row or something but instead went with a heavy duty fan-clutch that I pulled off my 460 truck. It cured the idling heat creep issue... But again, on a stock truck I am big fan of keeping everything stock. On a modified truck.... I'm not sure.

I'm building an animal here (460 in a 78 Bronco) that never existed in the wild! Hoping it will gel with the flock!

[ArdWrknTrk]

This is why the 460 distributor is controlled by the thermal switch in the water neck.
If the truck starts to overheat while stopped in traffic, the three port valve switches from restricted vacuum to manifold vacuum, and the increased timing revs up the pump and fan.

It's not digital, but it's not wrong...

[ArdWrknTrk]

Yeah, nobody in the aftermarket used plastic gears, but dealers had to.
They couldn't install a part that would violate federal regulations at the date of manufacture.

Sometimes a garage would buy parts from the dealership.
If so they'd get a plastic gear and retarded hyvo chain too.

[viven44]

Here is a pic with both entities side by side. I don’t see a backing plate, if it does exist I hoping I’m just not seeing it.

[viven44]

Wow, did not know that!! I will look more into this.

I'll see how "Big Blue 2WD" is hooked up and copy that. Still has the emissions and all vacuum connection on it so I'm sure it will be a good reference.

Can i use the same thermal switch that will control EGR ?

Edit : Just realized that the Edelbrock carb is on "Big Blue 2WD".. i.e. its ported vacuum is connected to distributor.

[ArdWrknTrk]

Nope
It's missing entirely.

That's why it was overheating and the idiots pulled the thermostat hoping it would help.

But nothing is going to help the water pump push if the impeller is not closed off.

[viven44]

Man, i'm glad you made me do this timing set, else I would not have found this issue. Thanks for your teaching "service"!

[ArdWrknTrk]

I do what I can with my superpowers....  

[ArdWrknTrk]

Look at the routing sticker.
You will see VREST in one of the lines going to the thermal switch.
If the coolant hits 220 the port shifts to full manifold vacuum and the advance plate gets pulled in more.
Which brings the timing up and the idle is increased.

[ArdWrknTrk]

460 pickups are one of my "special interests"
Along with material science, propellant chemistry, genetics and biology, long distance firearms and a few others.

Way back in the early '70's they didn't have a category for autodidactic kids with an IQ over 160.
I was "Profoundly-talented and gifted" but I couldn't get along with my peers....

[viven44]

I sure am glad it is a special interest of yours!!

I did check on the vacuum diagram on the truck. Looks like we have a 3 port vacuum valve, When cold it connects distributor to VREST (restricted vacuum) and when warm it connects distributor to full manifold vacuum. Not sure what restricted vacuum means on this truck.

Maybe instead of VREST I could use ported vacuum from the edelbrock carb, which is No vacuum at Idle.

[ArdWrknTrk]

VREST is a tiny winged plastic orifice that fits inline of the vacuum tube.
Different colours denote different restrictions.

Lots of people with automatics like ported vacuum, but it won't step up the idle if needed.

I'm not sure why Ford never seemed to use ported.
Many Autolite/Motorcraft carbs have an E port for the EGR, and I'm pretty sure that is ported.

[Gary Lewis]

If you put ported vacuum to where Ford had VREST then you won't have any vacuum at idle until the temp gets to HOT.  Then, assuming you have the other port to manifold, you'll get a lot of vacuum and advance.  But that might be enough to move you at a stop if you didn't have the brakes on hard as the idle would go up quite a bit.

[viven44]

Good point. It will take some tweaking.

[ArdWrknTrk]

It's possible to tune for ported if you're going to recurve the distributor and install a new vacuum advance, but at that point one of Scotties custom curved distributors is only a few bucks away.

But not back in the day when the advance was $15 and the springs 2.
A Reman distributor was $35 and you only needed a welder or some brass tube from the hobby shop to tighten up the slot.

[viven44]

Immediate thoughts/solutions are to find a NOS vacuum restrictor or create a restriction in vacuum by using a smaller diameter hose, something like the one that runs to the HVAC controls, see if that provides sufficient restriction to keep the idle where it needs to be until warm.

The other option is to use a vacuum delay valve between the VCV manifold port and distributor when hot so the change is not abrupt. Looks like I will need a vacuum delay valve to run EGR anyway so I need to find a source for it.