Need help timing 318/360 Magnum

[70Swinger510]

So I have my motor in all the way and running, But its really hard to start if its cold, and when I throttle up to WOT fast it backfires through the carb and spits a flame out the carb, I have the timing set at 10degrees advanced. I'm running full MSD setup, wires,distributor,coil and 6al. What should my overall advance be?

Motor Specs:

318 bottom end .60 over, pretty large cam, 360 magnum heads, ported polished, aluminum intake and a edelbrock 650cfm.

Where can I get the little timing strip I can place on my Balancer?

Any help would be greatly appreciated.

Thanks
-Chris

 

[dgc333]

Depending on how big the cam is you will likely find that the engine will likely 15-20 degrees BTDC for the intial timing. The initial is determined by what gives you max manifold vacuum. This will also result in you needing to change the stop bushings in the distributor to limit the total. MAgnum heads like 32-34 degrees so pick the bushing that give you initial plus timing in the distributor = 32-34.

 

[needsaresto]

I would sugest that the lack of a heat crossover passage in the magnum heads is whats causing it to be a bear in the cold. I would put some sort of warming plate setup under the edelbrock. The original la heads/intakes had a heat crossover passage to help with this.

Or switch to a throttle body.

 

[dgc333]

Can't imagine the lack of a heat cross over prevents it from starting. A heat cross over will help it warm up faster but won't have any impact on starting.

My magnum headed 360 will start instantly after sitting for a week or more in temps down in the teens. Certainly takes a good 10 minutes before its happy about taking gas but it starts right up.

 

[70Swinger510]

I mean it starts when its cold, but it idles low and cuts out and definatly if i give it gas it stalls out. any idea one what I should set me overall advance too?

 

[fishy68]

Sounds to me like it's running lean in addition to not enough initial timing. They'll backfire out of the carb if their running lean. Do you have the choke hooked up and working properly? If not that's why it doesn't start and run good cold. But the first thing to do (after repairing any possible choke problems) is what DGC333 suggested because if the timing isn't right it'll never run right. Once you get the timing dialed in you need to dial in the carb. If you have a big cam with not much manifold vacuum you'll need to put lighter power valve springs in it for a start. Then work on jetting.

Oh yeah you don't need timing tape if you use a dial back timing light but if you can't find a dial back light most any high perf. parts supplier (Jegs, Summit, etc) can get you timing tape. I don't like it though cause I haven't had good luck getting it to stay on. That's why I bought a dial back timing light.

In addition I'll add that I have a pretty big cam in my 360 and even with the choke set the best I can get it and the carb dialed right in it's still cold natured for the first 10-15 minutes until it gets warmed up good. That is just the nature of big cams. They decrease vacuum and have allot of valve overlap so fuel doesn't atomize well causing it to run rough.

 

[needsaresto]

Can't imagine the lack of a heat cross over prevents it from starting. A heat cross over will help it warm up faster but won't have any impact on starting.

My magnum headed 360 will start instantly after sitting for a week or more in temps down in the teens. Certainly takes a good 10 minutes before its happy about taking gas but it starts right up.

Wont prevent it from starting,just makes it difficult. Fuel puddles on the floor of the intake. Heat crossover helps it atomize

 

[dgc333]

But it still has no impact on starting. A cross over is cold like the rest of the engine when you first start it, takes a minute or two before it will warm the intake enough to have an impact.

 

[mullinax95]

I would sugest that the lack of a heat crossover passage in the magnum heads is whats causing it to be a bear in the cold. I would put some sort of warming plate setup under the edelbrock. The original la heads/intakes had a heat crossover passage to help with this.

Or switch to a throttle body.

That's the first time I have ever heard anything like this... strange. I guess it would help in -20 degrees.

I mean it starts when its cold, but it idles low and cuts out and definatly if i give it gas it stalls out. any idea one what I should set me overall advance too?

If you have the vacuum advance on the distributor hooked up unhook it and leave it unhooked, plug the vacuum advance port on the carb. Let the motor warm up and set your total timing at 34* at 2500RPM and see it this helps. Then go from there with the timing. My 360 has a small cam compared to most but I believe this might get you in the ball park. That's what I run mine at and I have no troubles.... runs good. Let us know how it goes.

 

[needsaresto]

I must confess. It's not my idea originally. I got it after reading a paragraph in Frank Adkins book called "How to build hi performance Chrysler engines". I just happen to agree with it. So we agree to disagree,lol!!

 

[70Swinger510]

My choke isnt hooked up... acually... and I'm running an msd distributor with no vaccum advance so its all plugged up, i will try to hook my choke up.

thanks for all the info!! I am going to work on that this weeknd.

 

[needsaresto]

Aha!

I remember a couple years back,trying to start my M body in the dead of winter. Had a tq,no choke. Talk about a *****. I temporararily ran 12 volts directly to the coil bypassing the ballast entirely. Extra spark helped,I actually got it started,and once the engine was warm, disconnected my bypass. You could run 12 volts from the battery to a switch on the dash and then to the coil as a cold start aid. Get your choke working. That will help a lot. Adjust it correctly too!

Is it a manual choke model? You can convert it to electric style. Thats what I did to my Eddie thunder series avs 650 cfm.

 

[70Swinger510]

I'm sure its manual, thier are no wires coming off the carb for an electronic choke.

 

[mullinax95]

I'm sure its manual, thier are no wires coming off the carb for an electronic choke.

Have you had a chance to set the timing?

Is it really that cold in Oakland, California for heat crossovers and a choke?

I don't even use a choke cold or hot weather. My Holley HP doesn't even have a choke.

 

[70Swinger510]

Well I set the initial timing, I havnt changed the springs in the distributor yet, I'm going to get a good timing light from a buddy and try setting the overall timing. Will keep you guys updated.

 

[dgc333]

You don't really need a dial back timing light. As I previously posted find the initial the engine likes then use the bushings that came with the MSD to set the total. So if your engine likes 15 BTDC initial then use an 18 degree bushing.