Can't seem to find an answer to this it is barley touched on in the info I could find. I have an 86 F350 460 4V I am thinking of freshening it up a bit and was going to ad a straight up timing set. How will this come into play when I go to smog it? Can I retard the timing down to where it should be and adjust the carb a bit so it will run right for the test? The truck is non catalyst and has only EGR and smog pump.

 

The retarded cam timing supposedly helps the NOX numbers. How much no one knows, but if someone failed their smog check after the timing chance, we damn well would have heard about it. We haven't so I suspect this was another EPA screw job in their made rush to gain more power regardless of the truth.

 

I've had great luck with the smog ***** by keeping the visible stuff stock looking while doing invisible things that make power. Jetting, distributor curves, porting, milled heads/decked blocks, cam changes etc are all hard to see during a smog check. I even ground the "edelbrock" off an intake, textured and painted the thing and it was never noticed. Keep it well tuned and running clean oil and you'll likely pass the sniffer test easy. A chrome aircleaner will get noticed every time..

 

What state are you in?

 

California, I agree 100% on the internal mods but stock looking, I learned this many years ago when I had an old Buick with a built motor and the smog guy would have to richen the carb to get the sniffer to work. I thought he was BS'ing me but he said with all the mods it ran cleaner than stock. I have a local carb guy who is going to rework the 4180 for me and I plan on some mildly ported/cleaned up heads and bump the compression up a tad. Still in the research phase needs to be done carefully and on a budget.

 

You may have an issue passing CA's NOx testing it can be a real pain to pass that on a modified vehicle as the margin for error is slim. I just gave up on that and I just instead found a "good" smog guy that makes sure I pass.

 

Not really looking to modify. My engine builder is just talking milling the heads a small amount to gain a bit of compression (it's just his suggestion because the heads will be off for valve job and mild porting) he has a cam that he has had good results with with no real impact on emissions but he is not sure how the smog tech will check timing or if he even will. Just looking for 460 guys who installed a pre-smog timing set and passed with no issue or failed because of it.

 

I keep reading that "the cam timing was retarded 4 degrees" on
certain 460's like the OP's, (7DF250).

So does that mean 8 degrees at the crank?
Or is it 4 degrees at the crank and so only 2 degrees at the cam?

Or what? :)

I'm wanting to experiment with my '91 351w but feel a need to
understand the history of this and just how much does what
before I start, thinking of just using an offset woodruff key. :)

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I've swapped out the E4OD with a ZF and could use some more
low end torque like my 360FE's got with its straight-up Comp
252/252 cam in it. Tire diameters, gear ratios and cubic inches
are about the same ...but the two engines feel way different.

The Motorcraft 2100 is kicking the EFI's butt on the low end. ;)

Any help will be appreciated.

Alvin in AZ

 

Yes, exactly.

 

No, just 4 degrees at the crank. All timing numbers are off the crank, always.

 

Thanks guys, well I guess that clears that up! LOL :)

It's no wonder I couldn't find a definitive answer by searching huh? ;)

It's easy as pie to buy a timing set with a + or - 4 degree cam timing
change at the crank but wondering if it won't be too much for my '91
351w?

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Also for the OP... advancing the timing will get you better gas mileage
over the "smog cam" timing! :) Gas price increases and retarded cam
timing came together at the same time and really turned off a bunch
of new vehicle buyers "back when".

Alvin in AZ