[soupman]

I have a 428 with pocket ported 96 heads. I have 9.8 compression with the stump puller type cam, 230/236 with 1.65 rockers. What is a good total timing suggestion for this type of head I estimate the heads probably flow 230, i did the Jim Hand treatment but not as aggressive. I know everyones combo is different, but was thinking 36 total? I have heard the KRE aluminum d dports like about 32, but what about plain old cast iron d ports?

I have tried running 14 initial with 18 mechanical and seems to be fine, then i flipped my hei centerplate to get 24 mechanical, and but initial to 12. I can't seem to feel the difference much, i don't hear any pinging or detonation, but the exhaust is load. Any suggestions what others run for total?

[tom s]

I have found 36 -38 right for 9.5 CR with our CA 91 gas.Tom

[JLMounce]

Gotta get out and road tune it with a stop watch and plug inspection. If you're not hearing any audible ping, you're likely safe, but you may not be maximizing the combination. Really it's up to you how much time you want to spend on that.

Generally speaking, the more you do to make the combustion more efficient, the less timing lead you will need. If you've got good quench and the piston is at or near 0 deck, with your slightly increased static compression ratio, you may not need as much spark lead as you think.

I'd start at 32 total and do some averages timed runs in 2nd gear. Increase the advance 2 degrees and average the same runs again. Went faster? Add another 2 degrees and repeat. Do this until you either hear ping or the car fails to go faster, or slows down, back the timing back 2 degrees from that point. That's going to be pretty close to what your engine wants.

You can do the same thing with your fueling.

[Scott Stoneburg]

My 428 and 455 with D-ports liked 34* total..

[steve25]

Every motor can be concidered different in there timing needs so there’s no blanket coverage!
Factors like
Compression
Rpm
Cam.
Cylinder pressure rise in conjunction with stroke
Rod to stroke ratio
Cylinder head flow
All can have a major impact on the optimal timing needed for the highest hp production.

Assuming your cooling system is good and with iron heads and a 9.8 compression I would not go above 34 degrees on pump fuel at full throttle when the vacuum advance has dropped out.

[Formulajones]

Every engine is different, camshaft timing plays a roll, what gas you want to run in it, etc...

Best to take it to your local track for a little fun test and tune day and move the timing around, see where it mph's the best. Chassis dyno would be even better.

I've had iron headed engines that liked as much as 40 degrees but most of the time I find somewhere around 34-36, sometimes 38, works good. Too many variables to suggest one number.

My current 400 with 12 D ports likes 34 degrees. I've had it all over the place at the track. 36 doesn't do anything at all. 38 slows it down and 32 slows it down. Since I can't find any difference with 34 and 36 I just leave it at 34. Runs fine on 91 pump gas.

[soupman]

Thanks for the suggestions. The car is very responsive, no hesitation at all. I was using 2nd gear roll on at 3000 but breaks the tires loose. I do have zero deck and plugs look great. Idles perfect and cooling stays right at 180 even in traffic. At 5400 I can feel it running out of breath, probably need more porting, but I wanted to keep velocity up for throttle response.

For some reason my butt meter tells me that the 14 initial +18 mechanical feels better from 3500-5500, but the 12 initial + 24 mechanical feels better below 3000. BTW it has the TKX 5 speed with 3:27 gears.

[Formulajones]

Sounds like it's running good. You're probably right in the ball park.

[steve25]

Different fuels of the same octane can call for changes in what needs to run for timing, so stay where you are at 34!
If you ever do go to the track to see what the car can do you will find that the timing is the least thing that’s keeping the car from running it’s best times. It will be traction followed by how good you are at rowing the shifter!

[Formulajones]

Well I never meant "go to the track unprepared"

I figured it was a given that anyone considering that option would at least put a sticky tire on the car and their driving capabilities aren't horrible. Even though traction isn't a huge player, as long as 60 foots are within a range, it's the MPH you're looking at when tuning the engine.

You'd be surprised at how little timing changes will, and do, affect the car.

[soupman]

I used to drag race many years ago, I was always told mph determines horsepower. Our local track is closing soon.

[steve25]

Yes, but even a 3 degree change in timing will not make as much of a difference at the track as weather changes will!

[Formulas]

What did you adjust to get 9.8 compression with that combo ?

[soupman]

Heads milled to 90cc with a .027 head gasket.

[Formulajones]

Originally Posted by steve25

Yes, but even a 3 degree change in timing will not make as much of a difference at the track as weather changes will!

Pretty sure you can make the timing change in the pits before a drastic DA change lol

[Formulas]

Thanks, Was curious I have the same parts never put them together but have modeled it before,

My 462 with 6X-8 heads close to 9.1 likes 36 total

[soupman]

Timing change for me was flipping the centerplate. Funny thing is I left the distributor clamped down and just flipped the centerplate and when I started it I had 45 degrees initial. Was surprised that flipping the centerplate changed the initial that much. Also the timing curve came in faster with the centerplate numbers up. I also went from 18 total to 24 total.

[lust4speed]

Soupman, you didn't mention at what RPM the timing is fully in at or whether you are running 91 or 93 octane.

I've seen several 9.2:1 to 9.3:1 engines with nicely ported heads and cams at or a little larger than the Old Faithful with a fairly flat timing curve all in at 3,200 produce best power on the dyno with 38°. Raising the compression a half point and decreasing duration has me thinking that I wouldn't run over 34° and possibly 32° might be the magic number if you are running 91 octane.

Rolling the throttle on in high gear from 2,600 to 3,400 on a warm day and listening for detonation would be a good test.

[soupman]

Timing is fully in at 3000. I am using 91 gas, but have run it on 89 and not heard detonation, but usually I use 91. When I nail the throttle at 2800-3000 hard to get good feel because the tires breaks loose and start going sideways. A roll on in 3rd is little too high mph on the back country roads. I just wonder if I can hear detonation because when I nail the gas it gets pretty loud. Would I clearly hear it over the exhaust?

[soupman]

I hate to admit this but I was reading my timing tab incorrectly. I thought the line I was reading was 12 degrees , but actually it was 16. So flipping my centerplate with 24 mechanical, I was actually getting 40 total and not 36. No wonder it felt weak in the upper rpm’s. I am going back to the original install which was much better. At least until I get to a track or chassis dyno.