Help with timing on 454?

[Chevy454CUCV]

its been a long time since I’ve set timing on an engine And I wanted to see if you guys could help out with any tips!? I’ll try to give you as much as I can about the engine and set up. I have a timing light I got from the part store but not sure what degrees it should be sent to? Any tips on process to get timing set? It runs now, starts up decent but I’m sure it’s not perfect and want to dial it in.

Engine – 454 bored over 30. Forged crank shaft. Howard’s cam but not sure which is in it, I did not install it. Scorpion roller rocker arms. Flattop pistons with gm 7/16 dimple rods. GM to 15 kids with square port exhaust. Valves are 2.25 - 1.88.

Taylor spark plug wires with ngk plugs.

MSD 6AL With HEI Accel disto

quick fuel technology 750 mechanical secondary, Electric choke.

Sanderson headers 3” exhaust to 2.5 pipe with flow master 44 series mufflers.
2.5

Turbo 400 trans

456 gears 1 Ton axles detroit lockers front/rear

Let me know if you need any more info, appreciate any help!!

 

[Bent77]

What is your current base and total timing?

Also, what makes you think something isn't right?

 

[1-ton]

The way I have done it in the past is with a vacuum gauge. first I disconnect the vacuum advance. Then I connect a vacuum gauge to manifold vacuum, and then advance the timing while the engine is idling until it reaches maximum inches of manifold vacuum. Then I retard the timing back down 1-inch of vacuum from maximum vacuum, and tighten down the distributor there. I am sure everybody is going to be hating for this way of doing it, but it has always worked for me with no problems. Especially with engines that have aftermarket camshafts, which are not ground to absolute perfection in tolerances.

The distributor does need to be set into the engine correctly. Too many times people will ask about timing an engine, only to have the distributor set into the camshaft distributor gear all screwed up, and then expecting the engine timing can be fixed by turning the distributor one way or the other.

 

[nvrenuf]

What did you do with the fender well headers?

Looks like you have manifolds on it now.

 

[Chevy454CUCV]

Appreciate the help guys, sorry for the delay. work then vacation in sunny florida has kept me away from the hobby!

@Bent77 Well, I added the MSD, changed the wires, not shown in pic, and also noticed distributor wasn't super tight and moved it some accidentally so doubt I put it back perfect and not sure it was set perfect from the get go.

@1-ton Thanks for the tips on timing. what should I look out for to make sure the distributor is in correctly? I had a shop put it in when i bought the truck because it went out on me on the drive from IN to TN and just needed it fixed while in transit. Hoping its in there correctly from that. I can get a vacuum gauge and go off of what you said, doesn't sound too difficult there. What about hitting it with a timing light? any reason just using vacuum gage is good enough or even better based on what my engine setup has?

@nvrenuf - the Fenderwell headers are going to be for sale along with the whole exhaust it came with. I"m also going to be selling the manifolds too... They just don't fit with the bolts that are on holding the heads on. I bought some Sanderson headers and looking to install those next weekend hopefully if time permits. The headers I cleaned, sandblasted, and had painted with high temp heat paint. practically new now. i've been planning to post these for sale but just haven't gotten around to it yet. Let me know if interested.

 

[nvrenuf]

- the Fenderwell headers are going to be for sale along with the whole exhaust it came with. I"m also going to be selling the manifolds too... They just don't fit with the bolts that are on holding the heads on. I bought some Sanderson headers and looking to install those next weekend hopefully if time permits. The headers I cleaned, sandblasted, and had painted with high temp heat paint. practically new now. i've been planning to post these for sale but just haven't gotten around to it yet. Let me know if interested.

I would really like a set of headers like that because, at some point, I want to do some things to make my motor friskier so they'd be perfect. It just depends on the price but I'm probably not a player as I just dropped some money on bender parts and a/c work on my dd.

 

[Chevy454CUCV]

Yeah when they were on the truck it was a really noticeable difference in power when I’d punch it. I just need some that go inside the frame rails for my goals with the truck to put the Fenders back in.

I’m thinking $400 for complete headers, 3” exhaust pipe and flow master super 10 exhaust.

 

[ChrisPerry]

I have to disagree about the distributor caring how it's dropped in. As long as the firing order is correct and you can turn it far enough to get the desired initial timing without the vac can hitting, it will run the same.
The only reason to set the distributor with the rotor pointing at #1 cylinder when at tdc on the firing stroke is so the wires look pretty.

 

[1-ton]

without the vac can hitting the firewall.

That is exactly what I have seen happen when a distributor is not placed in correctly the way the factory designed it to.

 

[1-ton]

Thanks for the tips on timing. what should I look out for to make sure the distributor is in correctly? I had a shop put it in when i bought the truck because it went out on me on the drive from IN to TN and just needed it fixed while in transit. Hoping its in there correctly from that. I can get a vacuum gauge and go off of what you said, doesn't sound too difficult there. What about hitting it with a timing light? any reason just using vacuum gage is good enough or even better based on what my engine setup has?

If your truck starts and runs correctly for the most part, then the distributor has to be set correctly enough or it would not run. As mentioned about the vacuum advance canister hitting the firewall, when trying to set the timing, is the only problem you could run into if the distributor was not set in good enough. The only reason I can see for needing a timing light using the method of timing I suggested is to see at what RPM's the timing is "all in", but that is not critical to know with a street driven engine...only on race cars would that info be something that could help for tuning purposes.

 

[folkenheath]

In my opinion you should set the timing simulating the engine under load to reduce the chances of engine damage.

That means, unplug the vacuum hose to the advance can. Then rev the engine to 3000 - 4000 RPM, (or whatever RPM the mechanical advance stops advancing). Set the timing around 34 at 4000 RPM to start with (34-38 is where it will probably run the best, 34 is safe)

Once it is set, then plug the vacuum advance hose back in to full manifold vacuum (not ported unless it's required for emissions testing).

If your idle or part throttle wants different timing you need to limit or increase the mechanical or vacuum advance. The method of setting the base timing at idle is for stock engines where the timnig curve and load conditions are somewhat known. But when stuff is not stock, you need to set it where it's most critical, under load.

Ideally you will change the advance weights and springs and vacuum can to optimize the whole curve, but either way, the most critical area is the max timing under load. And if you set it at low RPM where the mechanical advance isn't fully engaged and it climbs to 50 degrees at 5000 RPM while under load you can do some serious damage.

Now 50 degrees at cruise on a BBC with the vacuum advance engaged and low load, thats no problem, and good for fuel mileage.

 

[1-ton]

In my opinion you should set the timing simulating the engine under load to reduce the chances of engine damage.

That means, unplug the vacuum hose to the advance can. Then rev the engine to 3000 - 4000 RPM, (or whatever RPM the mechanical advance stops advancing). Set the timing around 34 at 4000 RPM to start with (34-38 is where it will probably run the best, 34 is safe)

Once it is set, then plug the vacuum advance hose back in to full manifold vacuum (not ported unless it's required for emissions testing).

If your idle or part throttle wants different timing you need to limit or increase the mechanical or vacuum advance. The method of setting the base timing at idle is for stock engines where the timnig curve and load conditions are somewhat known. But when stuff is not stock, you need to set it where it's most critical, under load.

Ideally you will change the advance weights and springs and vacuum can to optimize the whole curve, but either way, the most critical area is the max timing under load. And if you set it at low RPM where the mechanical advance isn't fully engaged and it climbs to 50 degrees at 5000 RPM while under load you can do some serious damage.

Now 50 degrees at cruise on a BBC with the vacuum advance engaged and low load, thats no problem, and good for fuel mileage.

With the engine specs listed this would be a good way to go, but stock Original Equipment (OE) vacuum canisters are only capable of about 32-degrees of advance max. You would have to go with an adjustable aftermarket vacuum canister, in order to get more than 32-degrees of advance. The average carbureted engine, with a stock distributor set at close to stock timing, is "all in" at about 32-degrees at about 3200 to 3300 RPM's. That is spec I have seen for "all in" timing using the vacuum gauge method I mentioned for timing. Your method I agree would be better for the engine we are talking about because this engine sounds pretty stout, and will probably be driven around with a lead-foot sometimes.

 

[folkenheath]

With the engine specs listed this would be a good way to go, but stock Original Equipment (OE) vacuum canisters are only capable of about 32-degrees of advance max. You would have to go with an adjustable aftermarket vacuum canister, in order to get more than 32-degrees of advance. The average carbureted engine, with a stock distributor set at close to stock timing, is "all in" at about 32-degrees at about 3200 to 3300 RPM's. That is spec I have seen for "all in" timing using the vacuum gauge method I mentioned for timing. Your method I agree would be better for the engine we are talking about because this engine sounds pretty stout, and will probably be driven around with a lead-foot sometimes.

I don't know if I've seen one that gives you that much advance, most are only 20 or so. But it doesn't matter because I usually limit the total cruise timing to 52 max with an old SBC or BBC with the vacuum advance and mech all in. So If you have 36 total at 3K all in mechanical, then I limit the vacuum to 16 additional. Some are adjustable or you can just add a tack weld to limit it and file it back down.

Also, you want to make sure the vacuum can is all in at idle, so if you only make 12" of vacuum, don't have a can that's still increasing at 16", or your idle timing will be unstable with full manifold vacuum. But most decent street engines like the full manifold vacuum if tuned right. A hand vacuum pump is a good way to test this.

If its an engine that the cam doesn't make enough vacuum for a vacuum can, then I just lock the distributor out for no mech or vacuum advance. I've found that usually works better than mechanical only in that situation since you usually have a relatively lopey cam and converter to match.

 

[1-ton]

I don't know if I've seen one that gives you that much advance, most are only 20 or so

You are correct come to think of it. If I was getting a total of 32 degrees at 3200 to 3300 RPM about 10 or so degrees of that 32 degree total had to be initial timing. The timing method I mentioned with a vacuum gauge just gets an engine in the comfort zone, and not set for optimal timing. The method of timing you suggested would be better for an engine that is going to get pounced on from time to time, and the timing needs to be more optimal.