advance timing - more power?
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Mountain Pass
Joined: May 2002
Posts: 100
Likes: 1
advance timing - more power?
I have an 88 F250 (351 with C6) with a 1700lb camper in the bed. I drove it from the east coast to Montana a few years ago. The truck really struggles with the hills or even on the flat in a strong head wind - in each case dropping to 45mph. Not too bad on a flat road with no wind - can easily maintain 60 to 65mph.
The compression and plugs are good so the mechanic wants to advance the timing - I presume beyond the factory specs. Is this a good idea? What potential problems does this create?
Thanks, DR
The compression and plugs are good so the mechanic wants to advance the timing - I presume beyond the factory specs. Is this a good idea? What potential problems does this create?
Thanks, DR
Cargo Master
Joined: Jan 2004
Posts: 2,512
Likes: 8
From: Cook Forest and Irwin PA
Tehre was an article in a boating mag of all places a few years back listing the degrees vs power gains vs cyl head temp gains (which cause pinging) and really 4* is the max you wanna go off spec (assuming all advances are the same) with 6 in some cases if you have a good knock control.
that being said, 32-36* is typically the 'all in max advance', but I know for a fact (cuz I had it on the scan tool) that a z-motor blahzer with TBI will see 41* if the timing is right (no pun intended). Meaning the ability to detect incipent knock is key.
that being said, 32-36* is typically the 'all in max advance', but I know for a fact (cuz I had it on the scan tool) that a z-motor blahzer with TBI will see 41* if the timing is right (no pun intended). Meaning the ability to detect incipent knock is key.
Cargo Master
Joined: Jul 2009
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From: Des Moines
How many miles are on the engine? If it's over 100k, I don't think you'll get too much of a gain by just advancing the timing. That's not to say you won't gain anything, but probably not enough to make much of a difference.
You may want to consider a rebuild to beef up the engine or maybe find another motor to put in it altogether.
You may want to consider a rebuild to beef up the engine or maybe find another motor to put in it altogether.
Fleet Owner
Joined: Jan 2008
Posts: 26,898
Likes: 3
From: southern md
mostly I hear 10 degrees is a norm on these for stock timing-check it 1st off and see if it's in specs-have heard of advancing it to 12 or 14 -by a few guys on here! ya just don't want it pinging!
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Mountain Pass
Joined: May 2002
Posts: 100
Likes: 1
Thanks for all the suggestions. It may all be moot. The mechanic confirmed that timing was 8* and that factory specs are 10* so it needs some advancement. Unfortunately the distributor is frozen in its housing, haven't been able to budge it.
Thanks, DR
Thanks, DR
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FTE Legend
Joined: Jun 2006
Posts: 31,930
Likes: 1,499
From: Ottawa, Ontario
Timing isn't your problem it's the stock exhaust and cam that's absolutely smothering the motor. That truck has got to have at least 3.55 gears and with the C6 60mph that puts then engine at 2300-2500rpm or so which it should have no problem maintaining up any hill on the eastern seaboard. Start by chopping off the exhaust right behind the first cat and throw it away. Hollow out the front cat and then have a muffler shop weld on a 2.5" catback with whatever muffler you like. If you aren't pepared to swap the cam add 1.7 rockers instead, this is a bolt-on upgrade that will help the motor breath better and make more power. This is simple and proven stuff on this motor guaranteed to deliver the goods and cooperate with the EFI system.
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Cargo Master
Joined: Jul 2009
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From: Des Moines
I forgot to mention this before, but personally I'm leery of altering the timing at all unless you've made modifications that require it. That's not to say it can't safely be done [obviously], but the timing is set at a certain degree for a reason. Even if there's no immediate harm to the engine it can have potentially serious consequences over time.
Just my opinion...
Just my opinion...
Fleet Owner
Joined: Jan 2004
Posts: 26,007
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From: Brentwood,CA
The timing can be brought up to 12 BTDC but what really hurts is not so much the stock cam its the fact the stock timing gears are retarded from factory. So if a full cam swap is not in the future a new straight up timing set and retimng it will help a lot. Also what others have mentioned new exhaust and 1.7 rockers. But in the end its all up to you.
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Mountain Pass
Joined: May 2002
Posts: 100
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You all have provided interesting suggestions and I'm not knowledgeable enough to respond intelligently.
I'm not inclined to put in a new cam; the new rockers and exhaust are a possibility.
I hope the mechanic measured the timing correctly ("spout" disconnected). But if he didn't disconnect the "spout" wouldn't a measurement of 8* BTDC indicate a very retarded timing?
There was an engine light on last year, but I had an oxygen sensor replaced and there haven't been any more engine lights.
I don't know what a new "straight up timing set" is. Are you talking about replacing the distributor or any of its internal parts? I was under the impression that the only moving part was the rotor and the only adjustment on the distributor was timing.
Once again, thanks. I'm feeling confident that some improvements can be made.
DR
I'm not inclined to put in a new cam; the new rockers and exhaust are a possibility.
I hope the mechanic measured the timing correctly ("spout" disconnected). But if he didn't disconnect the "spout" wouldn't a measurement of 8* BTDC indicate a very retarded timing?
There was an engine light on last year, but I had an oxygen sensor replaced and there haven't been any more engine lights.
I don't know what a new "straight up timing set" is. Are you talking about replacing the distributor or any of its internal parts? I was under the impression that the only moving part was the rotor and the only adjustment on the distributor was timing.
Once again, thanks. I'm feeling confident that some improvements can be made.
DR
FTE Legend
Joined: Jun 2006
Posts: 31,930
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From: Ottawa, Ontario
Not on these EFI motors.. the cam is installed straight up.
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