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Has anyone ever had the time to sit down and write a list of the various port timings of the mac engines ?

McBob.

Please explain your question better.

Bob i have pretty good records of every motor i monkey with ..most are west bends but i have some good numbers on a real 49 and various 91s

Standard Port opening and closing degree's thought it would be nice to have a ready reference on my site

Bob.

WKA & IFK tech manuals have the stock port layouts, rib widths etc....

It's the degrees i need not the measurements in inches

Bob,

You will get an opinion favoring just about every combination of port timing you can dream up. The "right" port timing is dependent on so many other things that you would have to ask a question like this....
For sprint racing running around a 7 to 1 gear, on alky, with a pipe and using a slipper clutch that hooks up at 9K, running dual Tillys on a Hartman intake with a Big Mouth header and a full circle crank.... what would the best port timing be???? If you simplified the question like that then you can knock the number of opinions down to a low number like 50 LOL
Otherwise your web site doesn't have room for all the different opinions you will generate!
When I was a teen in 1968 learning this stuff from Tony Maglizzi the rule of thumb for a 6.1 ci mac was exhaust at 90 degrees and transfers at 70 from BDC. That was in the pre pipe era running dry clutches.
By the time I ran an IKS reed open at Road Atlanta the exhaust was 8 to 10 degrees closer to the top and the transfers were only a degree or two different. That reed Open 91 turned 16,000 rpm on top and had to have the clutch slip to 10K to get going.... two totally different applications for the same basic engine.
In other words, there is really no good answer to your question other than to list what the different models had from the factory and let the tuners go from there.
Regards,
Steve O'Hara

steve ...i think the gentalman was looking for standard (stock) numbers like rob said ive seen them on some kinda wka/ikf rule site ..as far as just throwing out numbers it might take few months my note book prolly has 100 pages with couple hundred motors ..theres numbers in there for 8 or 10 different 49s i been messing with ..i dont really like giving up my notebook info since im the one that sat there for hours and hours with a degree wheel ,dial indicator and file ..,heck ive spent days on a motor... record info put it together run it tear it a part change somethin ..lotta lotta trial and error ..and ive used same specs on two different motors with two sets of results ..heck its a wonder my stuff runs as good as it does mostly wore out from messing with them so much ..lol..

if anyone wants to convert port heights into degrees .. you will need to know how to convert piston travel into crank rotation degrees. I attached a conversion table I made for the McCulloch kart racing engines. You can use this chart several ways, zero degrees can be assumed to be TDC or BDC.

Also, this chart can be used for analyzing port timings, but is probably more practical for setting ignition timing using a dial gauge.

Jeff

Thanks fellas well you's have answered my question ......... my brain if i have one will soon be toast as it crunches the numbers again many thanks Jeff ............. McBob.