More Cam Questions


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By Joe Johnston - 18 Years Ago
I have a 57 Bird with a built forged crank 292 truck motor.   The engine was professionally rebuilt 20 years ago and has less than 3000 miles since.   It sat for 17 years and is now running.   My problem is the lopy (but awesome sounding!) cam and a 1700 rpm idle with a stock Cruise O Matic.   NOT the best combination in the world.   The previous owner enjoyed it this way but lost interest.   Although fun to drive anywhere except in low speed traffic, I want to slow this thing down and change the cam to something more in between stock and what I have.    Currently the engine has an Isky #301300 cam 448 lift, 286 duration, 250 duration @ .050, 108 lobe centerline.   I wish I knew what all those numbers and terms meant!!!   That being said, what should I be looking for to mildly increase performance from stock but still be civilized with the old Cruize-O (which I want to retain)?    The engine has been bored to accept higher compression 312 pistons, headers, and a 600+ cfm Elderbrock AFB.    I also want to downsize the carb too but want to keep the headers (looks good under the hood factor).   A local shop is going to take it in next month and I would like to understand and be aware of my options.   Any suggestions/advice would be appreciated.   Thanks in advance to all who reply.   J
By pcmenten - 18 Years Ago
You'll need to know what the compression ratio is. We can give you an educated guess if you can tell us which heads you have. You will probably have ECZ-G or -113 heads. Look at John Mummert's web site to see where to find the casting numbers www.ford-y-block.com



Speaking of John Mummert, he also can recommend a cam once you know what the compression ratio is.



On the subject of carbs, you might want to look for a small Holley 450 cfm, or an AutoLite 1.08" carb. There was a recent thread on this board about carbs and the AutoLite 1.08 looked like the best.
By Joe Johnston - 18 Years Ago
Thanks for your reply.

The heads on the engine are ECZ-G, and are supposed to have hardened seats installed.   I have no idea the valve diameter or the compression ratio.   Perhaps I can find part numbers for the pistons in the receipts, and also find the machinist's work order to see if any mention of milling the heads or block was done.    There are a lot of receipts in the folder that came with the car as well as a lot of other performance parts that were accumulated over the years. 

By pcmenten - 18 Years Ago
While looking through your receipts, you might find references to 'decking', 'zero-deck', or similar. That will help with guessing at static compression ratios.



Starting with the assumption that your engine is a 292 bored from the standard 3.75" bore to a 3.80" 312 bore, making it a 299 cubic inch motor. I'd guess if the pistons were flat-top, it has about 8.7-1 compression ratio, assuming 69cc heads, and about a .045" deck. That's a pretty high static CR. If you've got domed pistons, the ratio will be rather higher.



I think one of the other regulars here can help with the dynamic CR with your existing cam.



You'll have to have a pretty hearty cam to deal with the high CR, but I think you can advance it to get some low RPM torque back.



Edit; ECZ-G heads are 69cc's
By Doug T - 18 Years Ago
The Isky cam you mention is a beast on a street driven car but they make pretty good power. I got mine to idle about 1200RPM but it wasn't a happy experience.

You should be careful of the mechanics you take the engine to.  Too many of them will recommend that you go for a late model crate motor and some times even a Scrub.

Run a compression check to see if the rings and valves are sealing.  Then I would suggest that you pull the heads which sound like a lot of work but actually isn't. Then you can have the head volume measured (called CCing) and determine your exact static compression ratio. If you are going to change cams anyway pull the whole engine and turn it upside down to check main and rod bearing and install new lifters which are needed with a cam change. 

Once you know all that stuff you are ready to discuss what you want with a cam grinder. He will ask a lot of questions about how you want to drive the car and what kind of issues you want to put up with.  John Mummert is very good this way.  Also Berry Cams in Minnesota advertises in Y Block magazine and can also help you.  This doesn't cost any more than a catalog cam from a mailorder shop who have forgotten all about Y blocks.

By PF Arcand - 18 Years Ago
In John Mummert's ads in Y-Blk Mag, he lists a performance cam that is suitable for the Fordomatic. Someone else on this site recently complained about his cam's compatibility with a Fordo. He didn't pay attention to Mummert's recommendation.   
By pegleg - 18 Years Ago
Quote: "I am not a Newbie"  Boy is that true!!!