Timing gear considerations on 1978 Ford 460

Propane, Butane, LPG, GPL, C3H8, C4H10
storm
Posts: 777
Joined: Wed Jan 10, 2007 10:10 pm
Location: NSW, Australia

Re: Timing gear considerations on 1978 Ford 460

Post by storm »

Over the last few years I have learned that each engine is different. That is why I now say give each engine what it wants and can cope with. The 460 is a decent engine, not as good as the earlier 427-428 but still a good engine in its own right. They weren't designed for mid to high rpm performance by any stretch of the imagination but rather were designed for low end torque. If it is ok with 20 degrees idle timing +15 mechanical then that's fine. Just ensure your starter is coping with the extra load of more timing and that your engine is not detonating under load. Until you can get a datalog or verify acceleration times you are going to be tuning by the old butt dyno which is notorious for its inaccuracy.
Fuel flow requirements calculations
Engine air flow requirement calculation: CFM = Cubic Inches x RPM x Volumetric Efficiency (VE) ÷ 3456

Lou
Posts: 4
Joined: Mon Feb 22, 2021 3:24 pm

Re: Timing gear considerations on 1978 Ford 460

Post by Lou »

I think storm has some great advice for you . Your low compression engine is not ideal for propane but that doesnt mean you cant get it too run somewhat better . it takes time patients especially with out a chassis dyno. i thought all the roads in saskatchewan were good.

evranch
Posts: 36
Joined: Thu Dec 13, 2018 11:11 am
Location: Saskatchewan, Canada

Re: Timing gear considerations on 1978 Ford 460

Post by evranch »

Yup thanks to everyone for their input on this one. I'm hoping to get fuel tanks mounted this weekend and hit the highway for some better testing. Might even make 10MPG cruising on the pavement.

I'm ordering a 3-keyway timing set which should actually boost compression by getting the intake valve closed on time. Might try the advance keyway for 4 degrees more of camshaft advance as apparently that will get me even more low end (and that's what I need in this truck, as mentioned these are not high RPM engines). And I just picked up a set of good used dual exhaust pipes with blue bottles that should get the exhaust flowing properly. Hoping these will help get my mileage up a little, at least they are low cost upgrades.

Tom68
Posts: 50
Joined: Mon Jun 18, 2018 2:46 am
Location: Australia

Re: Timing gear considerations on 1978 Ford 460

Post by Tom68 »

evranch wrote:
Wed Jun 16, 2021 3:41 pm
Yup thanks to everyone for their input on this one. I'm hoping to get fuel tanks mounted this weekend and hit the highway for some better testing. Might even make 10MPG cruising on the pavement.

I'm ordering a 3-keyway timing set which should actually boost compression by getting the intake valve closed on time. Might try the advance keyway for 4 degrees more of camshaft advance as apparently that will get me even more low end (and that's what I need in this truck, as mentioned these are not high RPM engines). And I just picked up a set of good used dual exhaust pipes with blue bottles that should get the exhaust flowing properly. Hoping these will help get my mileage up a little, at least they are low cost upgrades.
4 degrees cam advance is good, most street aftermarket cams are keyed to be 4 degrees advanced from straight up.

As you are aware 70's era engines had all sorts of weird cam phasing angles in an effort to meet emissions targets.

As for closing the intake valve early to increase trapped volume at low engine speeds, make sure you know your cam timing numbers including lobe centres, a small cam won't need much advance over straight up.

P.S. Apologies for asking questions on things you'd already stated in your first post, hopefully I haven't missed your cam specs. :oops:
Last edited by Tom68 on Fri Jun 18, 2021 2:51 am, edited 1 time in total.

storm
Posts: 777
Joined: Wed Jan 10, 2007 10:10 pm
Location: NSW, Australia

Re: Timing gear considerations on 1978 Ford 460

Post by storm »

"Cam timing" is often spoken about as though there is some dark secret cam grinders and oem manufacturers have deliberately hidden from everyone. The specs written on a cam card are there simply so the installer can verify the grind is what is advertised. Where the cam is actually installed is, and always has been, totally up to the person installing it. No dark secret, no hidden agenda, no BS, no problems. People who know this don't talk about "dark secrets" they dispel the myth and install cams where they calculate it will work most efficiently for them.

The concept of "dynamic compression" I have said it before and will say it again, there is no such thing. Compression ratios are a direct result of swept volume and remaining volume. It is a purely static mechanical relationship. The cam does have an effect on cylinder pressure, through pressure bleed off etc, but it does not have an effect on compression ratios.
Fuel flow requirements calculations
Engine air flow requirement calculation: CFM = Cubic Inches x RPM x Volumetric Efficiency (VE) ÷ 3456

Lou
Posts: 4
Joined: Mon Feb 22, 2021 3:24 pm

Re: Timing gear considerations on 1978 Ford 460

Post by Lou »

Just wondering if you have tried advancing your cam yet. I feel it would be difficult to get decent power and economy out of a engine designed for regular gas. Maybe advancing the cam would help build up cylinder pressure. Hopefully it helps you out somewhat.

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