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Post by speedbuff on Feb 11, 2013 20:59:06 GMT -5
Now that I have your attention .I hope you scorpion gurru's can answer some questions for me .I understand the 6 stud cylinders are the best ones from a porting standpoint. What interchanges here ? will a 400 bottom end hold 440 jugs ? can you punch a 400 cylinder over to a standard bore 440? can you swap 440 and 400 heads back and forth .I know I want 6 stud cylinders but are there any differences ? I also know I want hemi heads but what else is there to know ? Come on scorp 11 divie up some info here I need to spank a yamaha !!!!!!
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Post by obj1 on Feb 11, 2013 23:34:24 GMT -5
To spank a yamahammer all thats needed is to rent a white spring from scorp11 and 1 qt of chuba bros apple pie in fuel tank.  |
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Post by scorp11 on Feb 11, 2013 23:50:46 GMT -5
From either 1975 or 1976 on, everything is the same on the fan cooled cuyuna's with the exception of the cylinders / Pistons / heads. Obviously this doesn't include bolt on items like Intake and Exhaust.
So, you can bolt 440 cylinders on a 400 or a 340 or a 290 bottom end if you want. Of course you'd need the 440 pistons and heads too.
There isn't much difference between a 440 / 400 bore, but I don't know if you can get by boring out a 400 to 440 size. I would recommend matching the head to the cylinder though. The chamber cutout in the head will be a different diameter between the two. You could take a 400 head and cut the chamber to 440 size I guess.
The 6 bolt head motors will be 6 port motors. I think the compression will be a little higher with the angle plug heads, but you can always cut the center plug heads down if that is your goal. The center plug heads are what I'd run. I'd also get one of the ultralight mag side heads to help with cooling the PTO side a little. Those are only available in center plug variety.
If you want peak performance, especially on top end, a CDI setup might be your best bet. The points setups are more reliable, but not quite as good on the top end.
And you'll need a Sting / TK pipe / exhaust manifold for it.
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Post by bubbanoz on Feb 12, 2013 20:03:36 GMT -5
oh yeh. apple pie ala mode! them yamabummers will be runnin away scared!! with the kitty cats behind em. thanks for the info scorp11! ill be usin that.
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Post by pararailer on Feb 12, 2013 23:01:04 GMT -5
Thats good stuff scorp11. What is the basic difference between angle or straight plug heads? Does the straight plug head really have a "hemi" sort of combustion effect or is that just BS? I wonder which head on the same motor will make more power on a dyno? You said the angle plug heads have more compression. That would make more power, right? I want to make a hot 400.
Good stuff!
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Post by scorp11 on Feb 12, 2013 23:28:28 GMT -5
Thats good stuff scorp11. What is the basic difference between angle or straight plug heads? Does the straight plug head really have a "hemi" sort of combustion effect or is that just BS? I wonder which head on the same motor will make more power on a dyno? You said the angle plug heads have more compression. That would make more power, right? I want to make a hot 400. Good stuff! One of the reasons Scorpion went to the hemispherical combustion chamber was the change in gas quality. Supposedly they got the same performance with the lower quality gas. I've never seen dyno numbers comparing the two. In general a hemispherical combustion chamber should be better, provided the squish band and dome are all correct for the motor. Or so the book says. If your making a motor for the max HP, I'd take the hemi head and weld / machine where needed to get max compression with a good chamber. There is nothing wrong running the angle plug heads, but I would make sure you run at least 95 octane gas, as that is what they were designed to run on. As far as a hot 400, get a set of 400 hemi heads off a 79 Sting 400. That is what I would run. They aren't very common though as that was the only sled that had them and they sold far more 440 Stings. The question really is what do you plan to do with the sled. Max HP is fine for drag racing, but if your going to trail ride it, 1 or 2 more HP isn't going to mean a hill of beans. Also remember that the gas you get now isn't what these motors were designed to run on. We pretty much only run 100LL Av gas in ours. Typically mixed 50/50 with non-Ethanol premium. |
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Post by scorpiondave on Feb 14, 2013 9:37:37 GMT -5
Where can a person get one of those ultralight type cooling heads?
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Post by speedbuff on Nov 10, 2013 10:29:29 GMT -5
Is cuyuna still in business in some way shape or form ? I would like to know where to get such a head as well
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Post by scorp11 on Nov 10, 2013 14:53:14 GMT -5
what was Cuyuna, is now 2SI. Last I heard they were not producing anything new and were in the process of either being sold or going under.
I haven't been able to get any of these heads for a while now, but I'll make a few calls and see if I can find any next week.
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