I'm trying to get a rough idea as to how much total timing I should use on the 509. It's 4.5" bore X 4" stroke. 6.8" rods. SInce I'm using a Holley EFI I can play around with it a biy after I get it tuned.

I checked with AFR, they couldn't be too specific since they didn't know of anyone using the 4.5" bore block. Thes heads are supposed to have a fast burn, but the EA Pro program came in at almost 40 degrees at max power. Doesn't sound too fast to me.

Anyone out there running these heads that has their timing diled in on there combo? I realize there are a lot of variables at work here, so I know I'll have to play with it a bit anyway. Just looking to get in the ballpark at dyno time.

Thanks!

Originally posted by TD509EFI:
I'm trying to get a rough idea as to how much total timing I should use on the 509. It's 4.5" bore X 4" stroke. 6.8" rods. SInce I'm using a Holley EFI I can play around with it a biy after I get it tuned.

I checked with AFR, they couldn't be too specific since they didn't know of anyone using the 4.5" bore block. Thes heads are supposed to have a fast burn, but the EA Pro program came in at almost 40 degrees at max power. Doesn't sound too fast to me.

Anyone out there running these heads that has their timing diled in on there combo? I realize there are a lot of variables at work here, so I know I'll have to play with it a bit anyway. Just looking to get in the ballpark at dyno time.

Thanks! =
Start at 34-36 total (less vacuum).
The heads ain't really gonna care if you have a bigger bore, they will just flow a bunch more air than with the small bore.
Big flow difference in bore size with these heads graemlins/thumbsup.gif
I found the AFR's don't seem to be real sensitive to timing changes & ended up at 34 on a 496. Power was pretty much the same from 34-40 so I didn't see much point in running more.

Thanks Mike, I appreciate the input. AFR tech did mention that they knew of a couple of guys running the 315 AFR's on 496's and they liked 35 degrees best. I was thinking that with the 6.8" rods, I may need to back the timing down a bit, but will have to see when it's on the dyno.

No vacuum advance with the Holley C950 EFI. Timing is with a MSD crank trigger inputing to the ECU, then through a Mallory Hyfire box.

Thanks again for your input! By the way, love your Arctic wolves. Only seen one when I lived up in the Canadian Arctic, but did see lots of foxes.

John

TD509EFI, I have some AFR's on 4.25" stroke "454". I spoke with Tony @ Aiflow and he told me that I should'nt need more than 36 degrees for my set up with those heads. I tried it as a base line.
I ended up having a little bit more compression for a pump gas setup than planned. But, for street action I run 36 degrees of total timing and 38 degrees on the "good gas" The motor seem to run a little rough with any timing less than 36 degrees. It still pulls like a bat out hell. I hope this can help ya. :D
Ohh. I have put in 40 degrees and it ran even better. I have'nt put it on the track yet to see the time difference with that yet.

TD509, I am running these heads on my 502 and I did some extensive dyno tuning of my combination and it ran best with 36 total. I am not running vacuum advance. My motor is a 10 to 1 502 with the 315's and a big solid flat tappet, ported Vic Jr. and Holley 1000 HP. I am running 12 initial with all 36 in by 3000 rpm. Mike, I just checked your site out for the first time and love the Wolves. That is really cool. Also love the knowledge you bring the forum. Bill.

Da_chevyman, 69ttop502,

Great info guys, that's just what I'm looking for. Looks like your experiences are the same as Mikes. I appreciate the input.

Basically just running a steep but short solid roller, 10.13 static /7.9 dynamic comp with 0.038 quenc;, mostly for street, cruise-ins and the occasional blast down the quarter.
69ttop502, did you have a chance to compare the AFR with the stock GM castings, especially the torque curve at low to mid range? I have a feeling that they give up very little at the bottom, and probably gain from the middle on up.

Thanks again for your input!

John

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"TD509EFI
Thanks again for your input! By the way, love your Arctic wolves. Only seen one when I lived up in the Canadian Arctic, but did see lots of foxes.

John "
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"69ttop502
Mike, I just checked your site out for the first time and love the Wolves. That is really cool. Also love the knowledge you bring the forum.
Bill. "

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Thanks Guys, I appreciate the kind words graemlins/beers.gif

Them's be are "babies" :D

John, I didn't get to compare before and after on my engine. The previous incarnation of my engine was in 8.5 to 1 compression crate motor form. It had the iron rect. port heads and a very small flat tappet hydraulic cam. It was the GEN V rated at 440 hp. It made 350 hp at the wheels before I tore it down. I tore it down because at 7500 miles it was using about 1 quart of oil evey 300 miles. My engine builder was so impressed with the AFR heads. My peak torque was 586 lbft. and the curve was very flat and came on very low. He was surprised at the curve for a flat tappet cam. My cam is 304 adv., 258 @ .050, .630 (with 1.8 rockers) on a 108 LSA. My car is a 3100 pound Corvette with a 4 speed so actually I was hoping to kill a little bottom end but these heads are so good I failed. I haven't put many miles on it yet but it is very streetable and runs very hard. The motor made 614 hp @6200 with a Holley Strip Dominator and a Holley 950HP. I have since added a ported Victor Junior and 1000 hp. I plan to chassis dyno at some point. Bill.

Bill,

Great info, you've got a strong running combo there, in a 3100 lb 'vette it must be a killer ride. It's good to see that the engien is very streetable, even with your cam and heads.
Mike (Wolfplace)mentioned in another posting of getting 670hp with a 496 with the 315's. Your gonna have fun! Thanks again,

John

Thanks John. Yes it is a fun ride. I am just getting the new intake on the car now so I will be curious to see any gains. Yours is going to be a great combo and I wish you good luck with it. Bill.