Moparts

Hemi guru's

Posted By: MoparJunkie

Hemi guru's - 03/12/15 09:05 PM

I am trying to get a good baseline distributor curve and timing setup for my 472 which has:
2/4 street hemi intake Eddy 600's
MP aluminum heads(the latest greatest ones)
10.5 compression
comp cam 248@.050 duration
582/563 lift on 108 LSA and centerline.
Running 2 1/8 TTI's through full 3" exhaust.
What are the suggestions for timing curves and total...ie intiial, mechanical and when all in???
TIA
Posted By: mickm

Re: Hemi guru's - 03/12/15 09:16 PM

18-20 initial, all in by 2500 at most, 32 total.

start there. in general hemi's like less total, but some combinations do like more.
Posted By: Cab_Burge

Re: Hemi guru's - 03/12/15 10:54 PM

The best total timing(max advance) will be determined by the fuel type and quality,fuel jetting, AFR tune up, altitude and spark plug heat range The higher the altitude them more timing you can use, the hottor the plug the easier it is to get the motor to detoanate, same thing on the air fuel ratio and gasoline quality What altitude are you driving the car at the most? What type(E10,E15, non ethanol) and octane gasoline are you using and what brand and heat range spark plug are you using?
Posted By: MoparJunkie

Re: Hemi guru's - 03/12/15 11:31 PM

Obviously I have to start somewhere, and that's why this post was written. I am at about 1000 ft elevation in central Ky. I am gonna start with autolite AR53's. So, that being said... any suggestions for a baseline? I'm leaning on 32 total, but was wondering about a good start for initial then I know how much mechanical. The hydraulic FT cam grind makes power from 2500-6500. So, again my question for good start suggestions of all in by???? Most gas is E10 here...
Posted By: grncpe

Re: Hemi guru's - 03/12/15 11:54 PM

Quote:

18-20 initial, all in by 2500 at most, 32 total.

start there. in general hemi's like less total, but some combinations do like more.






This
Posted By: Cab_Burge

Re: Hemi guru's - 03/13/15 12:41 AM

The AR 53 may be to cold but it is better to start with them and go up one step hotter later As far as the total timing start with 32 at or above 1500 RPM and drive it, then try 34 total and maybe then 35 or 36, pick which ever one that works best in your opinion to use Some things are not the same appearing to all people the same way, what looks like 32 degree to me may look like 31 or 33 to you with the same timing light one the same day Bottom line is to start safe and work your way up to where you don't like it anymore, little bitty steps at a time
Posted By: RUNCHARGER

Re: Hemi guru's - 03/13/15 12:48 AM

Everyones gas and altitude are different as well. I would also start at about 20 initial with 32-34 total. The springs in the carbs are important as well and getting the staggered jetting adjusted at all 8 corners takes some thought with a stock manifold.

Sheldon
Posted By: Hemi ragtop

Re: Hemi guru's - 03/13/15 01:32 AM

Since you asked, and I have a VERY similar combo and car weight and since I have been "through it" with the timing, let me share with you what I found. First, with the exception of our trans, (I have a 727/Gear Vendor w/3,000 converter), our cars are very much the same. In my experience, you don't have a CLUE where your timing is until you verify it YOURSELF! First thing, where is top dead center on #1. Think about it, did your balancer, timing chain cover come off the assembly line together? If they did are they accurate? Mine came from a hodge podge of parts. My "professional" engine builder said that when we dynoed the engine it made more power @ 32 degrees vs. 34 degrees. 635HP@ 5,900 rpm. WRONG! When I put it in the car and started driving it,it didn't "feel" right so I checked the true TDC with a piston stop that I made from an old plug. I am embarrassed to tell you how many degrees it was off! Lesson one, don't ASSUME ANYTHING!. So first thing is, KNOW where TDC #1 REALLY is! Step #2, your engine will TELL you how much initial timing it wants, with a warm engine, use a vacuum gauge on a MANIFOLD port. Increase timing until the gauge is "topped out". Then adjust idle circuit until gauge it at highest point. THEN check initial timing @ idle. Then slowly with no load, increase rpms until you see the total timing and at what rpm. If it is over 35, you will have to limit the curve. I won't go into that as I am already "long" on this post and I don't know what kind of distributor you have. I had to take mine apart, weld shut the advance slots, check, pull, grind weld slowly, and check again etc. A long process but, when I was done, I found my engine liked 35 TRUE degrees total and 20 degrees at 1,000 rpm idle. After driving it "before" and "after", I am SHURE that I am making at least what the dyno showed!
Posted By: Hemi ragtop

Re: Hemi guru's - 03/13/15 01:50 AM

Post note: How fast should the curve be? In other words, at what rpm should your timing be "all in"? You have a 4 speed. A clutch loads the engine totally different than a converter. Then your driving style.
Do you tend to "lug" the engine to keep from shifting so much? Mine liked to be "all in" at 2,500rpm, but yours may need to be higher. Listen carefully, check plugs for shiny spots, DO NOT DETONATE THE ENGINE! Then the most argued point, do you or don't you run vacuum advance? I do, my engine has 45+ degrees WITH vacuum advance with no load, trust me, it LOVES IT at part throttle "tip in". By the way, I am not a "guru" just a basement built "hot rod".

Attached picture 8458068-141027_Coronet_0171.jpg
Posted By: MoparJunkie

Re: Hemi guru's - 03/13/15 02:24 AM

Sheldon, I need to get with you on jet selection and springs. As I saw your post about your setup.
Posted By: Dragula

Re: Hemi guru's - 03/13/15 02:27 AM

I find the smaller Hemi's like more timing than people are posting...I have had many, and they seem to really like about 20-23 initial what ever will still kick over reasonably and as much as 38* or so total....Ever engine is a little different, but as you give it more timing, your fuel curve needs to be right. An engine will take in more fuel with more timing...
Posted By: quickd100

Re: Hemi guru's - 03/13/15 03:59 AM

My 605 likes 28 initial and 35 total. My 528 made max power at 33 degrees. Dave
Posted By: RUNCHARGER

Re: Hemi guru's - 03/13/15 04:07 AM

gg: Ill see if I can find what I used with a setup similiar to yours. I usually write down different combos when I try them, especially when they work.

Sheldon
Posted By: MoparJunkie

Re: Hemi guru's - 03/13/15 04:25 AM

Thanks Sheldon. You da man!
Posted By: 71birdJ68

Re: Hemi guru's - 03/13/15 04:58 AM

There's something real uncomfortable about seeing a man that drives around in the daytime with the lights on.
Posted By: Cab_Burge

Re: Hemi guru's - 03/13/15 05:09 AM

Quote:

There's something real uncomfortable about seeing a man that drives around in the daytime with the lights on.


Everything I drive has the lights on before I move it, day or night
Posted By: polyspheric

Re: Hemi guru's - 03/15/15 05:37 PM

What steps will help you avoid a woman pulling out or making a left turn in front of you, in order of results (best first)?
1. Mars light
2. 150 db horn
3. brights on
4. be 20 feet high, 30 feet wide, and on fire

I have an intermittent flashing headlight on my Harley Fat boy, and I can tell you that many, many drivers look at me, don't see me, and start to pull out.
Then the flash catches them and the nose sags as they brake.
Personally, I'd put a 10mm warning shot through their windshield but that simply trades being dead for a different problem.

Wait! Exception: anyone who causes an accident by texting should be burnt alive in her car.
Posted By: dakotawilly

Re: Hemi guru's - 03/16/15 12:33 AM

Quote:

There's something real uncomfortable about seeing a man that drives around in the daytime with the lights on.


in a mini van too with his gonads locked in his wifes lock box under her side of the bed.....
Posted By: B G Racing

Re: Hemi guru's - 03/16/15 01:06 PM

Quote:

I am trying to get a good baseline distributor curve and timing setup for my 472 which has:
2/4 street hemi intake Eddy 600's
MP aluminum heads(the latest greatest ones)
10.5 compression
comp cam [Email]248@.050[/Email] duration
582/563 lift on 108 LSA and centerline.
Running 2 1/8 TTI's through full 3" exhaust.
What are the suggestions for timing curves and total...ie intiial, mechanical and when all in???
TIA





This combo should not exceed 35* and you want the full advance as soon as possible.
© 2024 Moparts Forums