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300/4.9L "reduced overlap" camshaft listed in 1982 Ford Light Truck Facts literature.

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1986F150six
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300/4.9L "reduced overlap" camshaft listed in 1982 Ford Light Truck Facts literature.

Post #1 by 1986F150six » Thu Nov 01, 2018 12:25 pm

Reading Ford supplied information on another forum, I saw that in 1982 a different camshaft [reduced overlap] was specified for all 300 [4.9L] engine manual / transmission trucks with 2.47 or 2.75 gear ratios for 49 state models.

http://www.garysgaragemahal.com/300-six1.html
Last edited by 1986F150six on Fri Nov 02, 2018 11:25 am, edited 1 time in total.

pmuller9
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Re: 300/4.9L "reduced overlap" camshaft listed in 1982 Ford Light Truck Facts literature.

Post #2 by pmuller9 » Thu Nov 01, 2018 10:15 pm

That's interesting.
I guess it was determined that if the engine was to operate at very low rpms it became important to reduce the 48 degrees of overlap due to the long .006" lobe lift 268* duration.
I wonder if they made the lobes asymmetrical?

Wesman07
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Re: 300/4.9L "reduced overlap" camshaft listed in 1982 Ford Light Truck Facts literature.

Post #3 by Wesman07 » Sat Nov 03, 2018 7:10 pm

It’s also strange that the trucks under 8,500 pounds shows an 8.9:1 compression ratio. I wouldn’t think it would be possible to raise the compression and shorten the seat to seat valve timing.
In-lines we trust

86 f150 300 efi with advanced stock cam. Np435, Dana 60/ 10.25, 35" BFG's, four link front suspension with 12" travel fox coil overs, custom deaver leaf pack in the rear.

J.R.
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Re: 300/4.9L "reduced overlap" camshaft listed in 1982 Ford Light Truck Facts literature.

Post #4 by J.R. » Thu Nov 08, 2018 12:37 am

A possible explanation for the variations in advertised ratings listed, for (otherwise claimed) identical engines, may be that the numbers reflect the myriad goals of the sales/marketing arm of a company on one hand, while the actual engines themselves are the end results of engineers, craftsmen & production staffs that could & did bring forth identical powerplants capable of performance that would ultimately satisfy customers with a wide range of assumed needs.

Ak Miller once told me that his own many engine dyno tests had shown, regardless of what Ford's sales materials claimed for the various years & factory-installed truck configurations, all the factory stock carburated 300" sixes actually delivered their true peak torque at 1800rpm. Seems that they likely delivered very close to whatever the sales literature stated (at anywhere from 1200 to 2000 rpm), and in some cases, quite a bit more.

Given that 'situational truth' approach to advertised peak torque ratings, it's conceivable the same logic was probably applied to posted vs. actual static compression ratios and cam specs: as in, "if it will pull & perform as one says it will, then the published ratings become 'believable', for sales purposes". Makes production simpler while still effectively marketing vehicles to a wide potential customer base.

J.R.
SoCal

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