AR Racing motor 355cid/425hp what degree of timing?
02-26-2003, 09:55 PM
#1
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AR Racing motor 355cid/425hp what degree of timing?
I have the engine mentioned in my post and was wondering if anyone had a similar engine ...and where you were adjusting my timing. The engine likes allot of advance. Various mechanics and friends have adjusted it...every time someone looks at it and says something like "thats strange" and adjusts it. I need to talk to Mark at AR but was hoping for some input about experience with this.
It was running well until my last tank of gas (hoping that is the problem). I retarded it a bit after that and it actually ran better at WOT. Now it idles too rough. My plan is to refill tank and readjust timing... thanks for your feedback.
:auto::smash:
It was running well until my last tank of gas (hoping that is the problem). I retarded it a bit after that and it actually ran better at WOT. Now it idles too rough. My plan is to refill tank and readjust timing... thanks for your feedback.
:auto::smash:
02-28-2003, 09:42 AM
#2
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Re: AR Racing motor 355cid/425hp what degree of timing? (Marc80)
Set the initial timing at 12 deg with the vac can unhooked and carb port plugged. Use full 'manifold' vacuum if possible for your vac can. Adjust air/fuel mixture to best vacuum on a gauge.
02-28-2003, 10:15 AM
#3
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Re: AR Racing motor 355cid/425hp what degree of timing? (Marc80)
I have the engine mentioned in my post and was wondering if anyone had a similar engine ...and where you were adjusting my timing. The engine likes allot of advance. Various mechanics and friends have adjusted it...every time someone looks at it and says something like "thats strange" and adjusts it. I need to talk to Mark at AR but was hoping for some input about experience with this.
It was running well until my last tank of gas (hoping that is the problem). I retarded it a bit after that and it actually ran better at WOT. Now it idles too rough. My plan is to refill tank and readjust timing... thanks for your feedback.
:auto::smash:
It was running well until my last tank of gas (hoping that is the problem). I retarded it a bit after that and it actually ran better at WOT. Now it idles too rough. My plan is to refill tank and readjust timing... thanks for your feedback.
:auto::smash:
:cheers:
Olivier
02-28-2003, 05:51 PM
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Re: AR Racing motor 355cid/425hp what degree of timing? (Marc80)
Set total timing at about 36º for a baseline. Road test and adjust up or down to see what works best. Big cams do like a lot of vac at idle, often much more than is practical to set initial at so running vacuum advance off manifold vacuum will usually show a noticeable improvement in idle. Big cams also don't make for much vacuum at idle, often not enough to deploy a standard vacuum canister, so you may need to replace yours.
02-28-2003, 07:22 PM
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Re: AR Racing motor 355cid/425hp what degree of timing? (Marc80)
Marc80...
I've got somewhat the same AR engine(thinking yours has the edelbrock aluminum heads) and here's the basic info that Mark gave me last night. I'd suggest you contact him(as others have suggested) as your tune-up will probably be different than mine as your supporting components(intake, carb, headers, ignition, distributor) may not be MSD/Single Plane/750 Carb as I have. Anyway.... here's what he gave me as a baseline...
16 degrees initial advance at 900RPM
Timing curve should come in at 2400RPM full advance of 38 degrees
Go figure the initial start-up of the new motor. Crank it up and run it for 20 minutes at 1800RPM. Shut it down and drain/change the oil and filter. Definitely will be a time to see if there are any leaks and the cooling aspects I have.
I've got somewhat the same AR engine(thinking yours has the edelbrock aluminum heads) and here's the basic info that Mark gave me last night. I'd suggest you contact him(as others have suggested) as your tune-up will probably be different than mine as your supporting components(intake, carb, headers, ignition, distributor) may not be MSD/Single Plane/750 Carb as I have. Anyway.... here's what he gave me as a baseline...
16 degrees initial advance at 900RPM
Timing curve should come in at 2400RPM full advance of 38 degrees
Go figure the initial start-up of the new motor. Crank it up and run it for 20 minutes at 1800RPM. Shut it down and drain/change the oil and filter. Definitely will be a time to see if there are any leaks and the cooling aspects I have.
03-01-2003, 10:40 AM
#6
Team Owner
Re: AR Racing motor 355cid/425hp what degree of timing? (bgrice)
Marc80...
I've got somewhat the same AR engine(thinking yours has the edelbrock aluminum heads) and here's the basic info that Mark gave me last night. I'd suggest you contact him(as others have suggested) as your tune-up will probably be different than mine as your supporting components(intake, carb, headers, ignition, distributor) may not be MSD/Single Plane/750 Carb as I have. Anyway.... here's what he gave me as a baseline...
16 degrees initial advance at 900RPM
Timing curve should come in at 2400RPM full advance of 38 degrees
Go figure the initial start-up of the new motor. Crank it up and run it for 20 minutes at 1800RPM. Shut it down and drain/change the oil and filter. Definitely will be a time to see if there are any leaks and the cooling aspects I have.
I've got somewhat the same AR engine(thinking yours has the edelbrock aluminum heads) and here's the basic info that Mark gave me last night. I'd suggest you contact him(as others have suggested) as your tune-up will probably be different than mine as your supporting components(intake, carb, headers, ignition, distributor) may not be MSD/Single Plane/750 Carb as I have. Anyway.... here's what he gave me as a baseline...
16 degrees initial advance at 900RPM
Timing curve should come in at 2400RPM full advance of 38 degrees
Go figure the initial start-up of the new motor. Crank it up and run it for 20 minutes at 1800RPM. Shut it down and drain/change the oil and filter. Definitely will be a time to see if there are any leaks and the cooling aspects I have.
:cheers:
Olivier
03-01-2003, 02:21 PM
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Re: AR Racing motor 355cid/425hp what degree of timing? (GrandSportC3)
The specs for my 383/465HP engine were 23 degrees at idle and 38 degrees total timing.. However - if I set the idle timing to 23 degrees - my total timing goes to 42 degrees... When Lars was visiting - he set my total timing to 37 degrees and I'm very happy so far with the setup.. My timing at idle went down to around 16 - 17 degrees..
:cheers:
Olivier
:cheers:
Olivier
03-01-2003, 02:25 PM
#8
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Re: AR Racing motor 355cid/425hp what degree of timing? (Vetterodder)
The specs for my 383/465HP engine were 23 degrees at idle and 38 degrees total timing.. However - if I set the idle timing to 23 degrees - my total timing goes to 42 degrees... When Lars was visiting - he set my total timing to 37 degrees and I'm very happy so far with the setup.. My timing at idle went down to around 16 - 17 degrees..
:cheers:
Olivier
Oliver, that sounds about right. You could shorten the curve some to achieve 23º initial with 37º total but your starter might protest, especially when hot. A good way to get a lot of advance at idle, which is usually a good thing with a big cam, is to use a vacuum canister that deploys at low vacuum and hook it to manifold vacuum. It's important to make the distinction between "idle" advance and "initial" advance as they aren't always the same. Engines with higher idle speeds and light springs are often already into mechanical advance at idle. In that case, the advance reading at idle might be a few degrees higher than the actual initial.
:cheers:
Olivier
Oliver, that sounds about right. You could shorten the curve some to achieve 23º initial with 37º total but your starter might protest, especially when hot. A good way to get a lot of advance at idle, which is usually a good thing with a big cam, is to use a vacuum canister that deploys at low vacuum and hook it to manifold vacuum. It's important to make the distinction between "idle" advance and "initial" advance as they aren't always the same. Engines with higher idle speeds and light springs are often already into mechanical advance at idle. In that case, the advance reading at idle might be a few degrees higher than the actual initial.
:cheers:
Olivier
P.S. My main concern is the total timing for max. performance... The car idles ok with my current setup.. When racing - the initial or idle timing doesn't really matter because during drag strip passes - the timing will be at total timing anyway...
[Modified by GrandSportC3, 2:26 PM 3/1/2003]