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Author Topic: XXO engine requirements  (Read 900 times)
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panic
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« on: June 08, 2018, 05:32:55 PM »

Not sure if this were ever answered?
XXO is pre-1956 pushrod L6 etc. using some head other than the original casting. Since fabricated is legal, it doesn't have to be of pre-1956 design and manufacture.
Does any head qualify as legal as long as the pushrods & rocker arms are operated by a cam in the original position?
No, I won't live long enough (or have enough money) to attempt this, but it appears to me that there are modern OHC engines where the head casting has enough features in common with an XO engine that a rocker assembly can be adapted and run off (new lobe positions) in the original cam & drive.
Specifically: Chevy 235/261 with Ford "Essex" 3.8 60 V6.
I've made some notes on this for anyone interested.
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RichFox
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« Reply #1 on: June 08, 2018, 05:51:46 PM »

I ran in XXO for a number of years. I used a cast Howard head. The Salt Cat guys used a stock Buick 8 head with lots more ports cut and brazed in. I ran in V4 with a 57 Ford head on a Plymouth block. All of these things seemed OK. So I would bet that any pushrod head you can find or make, you should be OK. I seem to remember somebody using several Subaru heads. Three in your case. Might work better for the bore spacing.
 
« Last Edit: June 08, 2018, 05:53:52 PM by RichFox » Logged
panic
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« Reply #2 on: June 08, 2018, 06:33:16 PM »

Thanks, just passing it along for someone with more nerve and skill than I've got.
Yes, the staggered bore pitch of many old L6 engines is always a problem, but some of it can be dealt with by having the join between 2 X 3 cylinder sections (at the 3-4 bulkhead) adjusted to take up much of the alignment error.
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Stan Back
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« Reply #3 on: June 08, 2018, 09:00:28 PM »

Huh?
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RichFox
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« Reply #4 on: June 08, 2018, 09:09:34 PM »

Yeah. You need to pair 1 &2.  3 & 4. And 5 and 6. There was a long thread here and on the HAMB,  on a Chrysler 360 head i cut up and stretched to go on a 26 Dodge. Hopefully it will show up at El Mirage this year. I don't know why anybody would start with an OHC head. There are plenty of crossflow, newer heads made of aluminum in junk yards. Can you say LS?
« Last Edit: June 08, 2018, 09:15:02 PM by RichFox » Logged
panic
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« Reply #5 on: June 09, 2018, 08:56:40 AM »

It looks like the LS pushrod would fall completely outside the stovebolt block, with a really bad pushrod angle from the tappet.
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floydjer
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« Reply #6 on: June 13, 2018, 09:19:56 AM »

Fun project


* 1 chev 300 ford.jpg (255.57 KB, 1024x768 - viewed 111 times.)
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RichFox
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« Reply #7 on: June 13, 2018, 11:07:20 PM »

I have not ever worked on an LS motor. So I don't know how wide they are. You said you had some notes, Wish to share?
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panic
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« Reply #8 on: June 14, 2018, 08:11:19 AM »

I'd like to help but I have nothing of any value to donate.
As I may have written here, the LS is a pushrod, wedge, quench chamber engine with parallel valves, much like the 1949 Oldsmobile. The valve gear innovation consists of one brilliant stroke: move the cam tunnel way up in the air so that the pushrods are closer to horizontal and much shorter. The LS head's deck surface projects far across the valley area.


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RichFox
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« Reply #9 on: June 14, 2018, 09:26:10 AM »

I see what you mean. The good thing about OHC heads is they can run ports where they want them instead of around the pushrods. So if you want to convert it to a pushrod head, I think you will run into problems with the ports being where the pushrods need to go. On my Dodge, Zenon looked at bore centers of the Dodge and newer V8 engines. Found that Chrysler LA engines were the same. First I got a junk iron LA head and cut it in half to see if this might work. So he bought a new aluminum head and we cut it up. I guess you guys are going to have to look around until you find something that works. May need a billet cam if you can't duplicate the 235 valve sequence. But something will work eventually.
« Last Edit: June 14, 2018, 10:05:02 AM by RichFox » Logged
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