Police Engine?

[interceptor1985]

it's mainly what happens when you have to make your "high performance" engine work with a 1200rpm torque converter and give it a carb designed from the ground up for "crisp throttle response," and use heads with intake ports that haven't changed significantly since the 60s, and exhaust ports that have actually gotten more restrictive.

It sorta boggles the mind that they couldn't find a way to make those air injection holes without them covering almost literally half the exhaust port.

They could have done what Jeep did in the late 70's and inject the air into the exhaust manifolds.

[gadget73]

They actually did that on the 80s 351 4V truck engines that were put in the F250's. Two smog pumps too, one fed air to the heads, one fed air to the exhaust manifolds. No catalytic converter though, so no idea what purpose the air was supposed to serve.

[86VickyLX]

so no idea what purpose the air was supposed to serve.

Burn the extra gas in the exhaust with the extra air.

[1987cp]

True, air injection did emerge prior to catalytic converters, didn't it? I seem to recall seeing smog pumps on junk from the '60s!

[johnunit]

yes, by 69 it was fairly common.

air pumps facilitate combustion in the exhaust even without the cats being present and warmed up.

[TomO]

My father had a '73 C10 w/350, and it had a pump that divided into eight little metal tubes, and each tube injected air into one of the ports of the exhaust manifolds.

As others have said, it was to facilitate further combustion of the exhaust gases in an attempt to decrease emissions.

No cats, just the air pump.

[86VickyLX]

My father had a '73 C10 w/350, and it had a pump that divided into eight little metal tubes, and each tube injected air into one of the ports of the exhaust manifolds.

As others have said, it was to facilitate further combustion of the exhaust gases in an attempt to decrease emissions.

No cats, just the air pump.

It works... hahaha

[gadget73]

Burn the extra gas in the exhaust with the extra air.

well, what it did do was make fireballs blow out of the tailpipe on a semi-regular basis while driving. I ripped all that shit off, and the truck ran like a completely different animal. It would actually idle instead of huffing and chugging and stinking so bad your eyes would burn.

[Brown_Muscle]

Tom_O, where did you get your power figured from? I have a book that has some conflicts with those numbers but they may be wrong...

Johnunit, where did you find the 1200 stall? Mine is definitely higher, i'd say around 1800, but our difference in years may have something to do with that. Mine has similar shift points as well, 4K-4100, I have noticed that mine shifts later then civi 5.0 tranny's, perhaps the police valvebody is designed to shift later? I hadn't heard of someone else with the 351 police having the same shift points at WOT, interesting.

[johnunit]

Keep in mind that mine is a civi canadian car, so that the converter and trans are police spec is an assumption. After 100,000 miles it's also an assumption that it's a factory torque converter in working order.

[Brown_Muscle]

Ahhhh i forgot about that, true true.

[1987cp]

Mine has similar shift points as well, 4K-4100, I have noticed that mine shifts later then civi 5.0 tranny's, perhaps the police valvebody is designed to shift later? I hadn't heard of someone else with the 351 police having the same shift points at WOT, interesting.

My one rebuilt AOD shifted at probably 4200-4300 when I was running it a few years ago. Now it has the AOD-HIREV governor kit.

I recall both Nates reporting WOT auto shift points below 4000rpm with their P72s - I want to say somewhere between 3500 and 3800.