Thank you.

Re: what Ted said. The Trick Flows on the 408" Windsor in my truck like 28-30 degrees. This is a 9.5 to one motor. anything over 30 degrees loses mph in the quarter. But, It'll run just fine on 89 octane on the street. I'd expect John's chambers will be at least that good. We are all used to 50's and 60's style IRON heads that needed 36 to 40 degrees to work right. Some of my Pontiacs liked 42 degrees with 110 octane. Now I realize that this was a sign of a lousy chamber design.

Frank/Rebop

Bristol, In ( by Elkhart) 

I am working with some of the newer heads that like a total timing of 26° which is by lieu of the spark plug placement so I’m not clueless in this regard.  The testing for the new heads will quantify if current ignition curves are adequate or if a warning statement must be included where ignition timing attributes must be addressed.

Lorena, Texas (South of Waco)

Most heads with the new fast burn designs need a max advance of 30-32 degrees, not the 36-38 degree of the older designs. Going by the old Hi po FE  (18 initial 38 total) as stated in the old HI po books with advance all in by X rpm were good rules of thumb starting points. These were good until you get into the current fuel variations. Marginal fuel will obviously reduce the maxim advance allowed. In my experience compression (until 11 +) seemed to have little effect with flat top pistons. I think John has enough experience building and tuning to offer some general extrapolated advice on these points. I am not asking for anything but guide lines. I will guarantee that if someone bolts these heads on and uses the stock ignition curves there is a real possibility of an unhappy customer. Having $2000+ to buy a set of heads or $300 for a distributor does not guarantee enough knowledge to make them work properly.

I do know that the set of AFR heads I bought for my 393 windsor had general recomendations.

Just speaking a bit from experience, my cousin developed and had cast a cylinder head for tractor pulling. It developed a bunch more power than previously atainable, but you know the racers ( at 25k+ a pop) knew more than the guy that designed it. After changing valve sizes etc etc throughly ruined the set up and then it was the  the vendors fault.

I can and will run my combination through my Engine Analyser Pro software to get some starting points.

While a change in combustion chamber design can have an effect on igntion curve attributes, changes to the camshaft, intake manifold, carburetor, and/or static and dynamic compression ratios are also valid considerations and will typically prove to be more significant.  Spark plug placement is the biggest player in combustion chamber design as far as necessitating changes in total timing or the curve itself.  Because of the myriad of combinations in regard to combustion chamber, camshaft, intake manifold, carburetion, etc., it would be difficult at best to nail down any specifics in regards to an optimum curve if simply bolting on the new heads.  A range of ignition curves is something that can be considered after the heads are tested on a variety of combinations but this kind of testing is expensive unless being sponsored so there’s a good chance it will not happen in the near future.  And even with the main stream engines, you don’t see this kind of testing with the published results.  Short term, the heads will be simply tested on what will be considered a normally hopped up Y engine (aftermarket camshaft and intake) and not a variety of combinations.

Optimum total timing for the combination that is tested will be a given though and if significantly different than with using the oem cast iron heads, then that information can be provided with the cylinder heads so the end user can make the appropriate judgement call on whether their own combination warrants a similar adjustment.

A chart for head milling or recommended cut for a 1cc reduction is doable though.

Lorena, Texas (South of Waco)

Add to instruction sheets recommended ignition curve, inital, total, vacuum advance for street and strip (centrifual only).

Edit:

Possibly a chart for milling the heads .0xx/CC then a chart for deck Vs intake cuts.

Edelbrock was approached a few years back on another project. They didn't even bother to answer. I am aware of the Edelbrock Foundry, it's supposed to be very complete and modern. Thay don't have, and won't have anything to do with Y-Blocks until the volume level reaches something that interests them, and then it would be done under the Edelbrock name. Not Rebop or Mummert. 

Frank/Rebop

Bristol, In ( by Elkhart) 

Davis: To expand a bit on what Daniel says, the late Vic Edelbrock senior produced parts for the Y-block. However, nothing has been done for our engine by Edelbrock in many years. In a recent interview when the subject came up about the Ford Y-block, Vic Edelbrock "junior", reportedly described the engine as "terrible"!

Paul

Carbs are just an old AFB they didn't design them.

   God Bless.   Tim                           http://yblockguy.com/

350ci Y-Block FED "Elwood", 301ci Y-Block Unibody LSR "Jake", 312ci Y-Block '58 F-100, 338ci Y-Block powered Model A Tudor

tim@yblockguy.com  Visalia, California    Just west of the Sequoias

Edelbrock sold out to the scrub and gm crowd long ago. Not Vic Sr, but Vic Jr has made the comments about the Y. All that and they still have decent carbs - ones on my 55 now

Daniel Jessup

Lancaster, California

aka "The Hot Rod Reverend"
check out the 1955 Ford Fairlane build at www.hotrodreverend.com