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in a billet head, when it comes to water jackets can you mill pockets around the combustion chamber and connect to the water passages in the block and then weld a plate on top of the pocket. i guess its hard to explain. i know welding on that big of a piece of aluminum is hard do to the heat dissapation(sp?) but i don't see why it couldn't be possible. I have been toyin with machining my own head at work. i am brushing up on my solidworks learning from the engineers at my shop and hopefully will find a spare head along the way so i dont have to remove the one on my running engine.
i started looking into the jag stuff while this thread was discussing it and think using the jag hemi type pistons for the 3.8l and longer rods would can make a nice bottom end. Then i was going to model the combustion chamber after the 3.8L head design.
my motor is a 320. i know you are working on a 263. with the info i have found the overbore would be minimal. you would need custom rods anyways and then you can deck to suit. i need to look at my notes at home but i believe like others have done my rod would have to be about 9 inches long.
i don't mind the extra rod to stroke ratio because i would be going the forced induction route.
also the website that the jaguar aftermarket longer rods were on mention the jag motor having a 1.9 rod to stroke ratio using these long rods. not to far off what i am looking at doing.
this is all still in planning but hopefully will start coming together soon. i am looking for a jag parts car with the 3.8 and going to use the front and rear suspension in my build also.
sorry so long...
ken
Senior Member
Janderson, I know you don't want to loose possession of said head. I'm not even sure if you have identified the particular model Buick straight 8 it came off of. However, can't photographs, the casting number, and/or dimensions, be supplied to persons who may be interested in reproducing its design for the 248/263 and/or 320? As it is now, will it fit and work on a 248/263 block?Originally Posted by Janderson
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Paul, Untame etc
As promised I went and obtained a 4.2 Jag rod and here are the measurements and some photos.
It is 198mm long center to center
30mm wide across the crankpin area(can someone tell me what the width of the 320 and 263 rods are please)
Bearing is 24.5mm wide
Tunnel dia is 57.5mm
Bearing bore with this used bearing is 53.5mm
The piston pin height for this Jag 4.2 piston is 40mm, about what a 263 needs, so a 3.4 or 3.8 liter piston if it has a small dome and the same pin height could work in a bored 263, 3.3" bore, versus the 3.1875 of the 263, thats a .1125 overbore which may be marginal.
It is 81.6mm across, so the bore will need to be 82mm min to fit the rod down it on a 263. However it could easily be clearanced for the STD bore.
The rod is a nice peice of forging. Do Nascar and road racers use Billet-NO, they use forged steel, do drag racers use billet rods-NO, they use forged aluminium!
So this is a nice rod for the 263 for most people and they are very cheap second hand, I have now found a forged piston from another application with a popup dome at 81mm with the correct pin height but need to see if I can order one at 82mm and then ill cut it in half to see what the dome can be machined down to.
NOTE: the Jag 4.2 stroke is 4.2" with a standard redline of 5000 RPM, the 263 is 4.125"
JAG P3090004.JPG
Jag P3090003.JPG
Jag P3090002.JPG
Jag P3090001.JPG
More later,
Cheers
Kevin
Member
It is a very famous car, but we didn't have anything to do with it. IIRC, it just recently went to auction. I personally don't care for it, but if someone wants to order one, we'll build it.
Senior Member
KevinPaul, Untame etc
As promised I went and obtained a 4.2 Jag rod and here are the measurements and some photos.
It is 198mm long center to center
30mm wide across the crankpin area(can someone tell me what the width of the 320 and 263 rods are please)
Bearing is 24.5mm wide
Tunnel dia is 57.5mm
Bearing bore with this used bearing is 53.5mm
The piston pin height for this Jag 4.2 piston is 40mm, about what a 263 needs, so a 3.4 or 3.8 liter piston if it has a small dome and the same pin height could work in a bored 263, 3.3" bore, versus the 3.1875 of the 263, thats a .1125 overbore which may be marginal.
It is 81.6mm across, so the bore will need to be 82mm min to fit the rod down it on a 263. However it could easily be clearanced for the STD bore.
The rod is a nice peice of forging. Do Nascar and road racers use Billet-NO, they use forged steel, do drag racers use billet rods-NO, they use forged aluminium!
So this is a nice rod for the 263 for most people and they are very cheap second hand, I have now found a forged piston from another application with a popup dome at 81mm with the correct pin height but need to see if I can order one at 82mm and then ill cut it in half to see what the dome can be machined down to.
NOTE: the Jag 4.2 stroke is 4.2" with a standard redline of 5000 RPM, the 263 is 4.125"
Cheers
Kevin
Nice Work! Well Done!
I put my calipers away and broke out the micrometer.
The rod big end width on a 263 measures 1.025"
It would be better to turn the crank pin to fit the Jag rods than to machine the rod width to fit the crank.
Since the bearing width is only 24.5 mm, you can have a generous radius on the rod journals.
If you machine the rod width to fit the crank there is very little room for a rod journal radius on the crank.
Yes, try not to bore the block more than 82mm.
As discussed in previous posts, the rods do not have to fit through the bore for assembly but it looks like you are ok at 82mm.
Plan your piston/rod/stroke combination so you don't have to machine very much off the block deck.
The 263 block is unique with blind head bolt holes that involve a bridge between the water jackets and the outside of the block.
This minimizes deck distortion when the head bolts are torqued.
Just for an FYI, forged rods are good because the grain is forced around the big end radius but forgings for both crank and rods only come in a certain range.
Once you need a crank stroke or a rod length outside the available range you end up having to go billet.
Paul
Last edited by pmuller9; 03-08-2012 at 07:16 PM.
Member
Hi Paul
Thanks for the measurement, did you get a chance to get the STD valve centerline measurement?
I dont think we can just machine the crankpin wider as then huge swathes of the counterweights would have to be machined which would not help with crank resonance, narrowing the rod across the bearing bore is something machine shops do all the time, and they will be lighter then.
We can still get a bit bigger radius due the the crankpin diameter being smaller.
Just on the 3.4 Jag piston, I cannot find the piston pin height amywhere, also the 3.8 is a bigger bore than the 3.4 so no good.
I think it was you that mentioned the cylinder walls were only .168" thick, was that on the thrust walls or at 90 degrees to the thrust side.
BUT an MGB has a bore of 3.160" so a 1mm overbore would be just right, and they have a 41mm pin height which is what we want and are available easily in various forms including forged, unfortunately mostly flatops or dished.
Ill still checkout the other piston I mentioned first as we could replicate a type of turbulator dome with it! Or in Utames case a 4 valve pentroof machining job.
But heres an MGB piston anyway, JE Forged .040:
JE MGB 101526.jpg
Kevin
PS: The other thing I have noticed from the service manual is that the rod to crank side clearance is very tight on the 263, on a Chevy V8 its typically 15-20' not the 10' of the 263 and thats with no crank torsional flexing either, so the rods could GRAB the 263 crank during flex, so I think I will run in the 15-20' range.
Senior Member
Hey Kevin
I will get the STD valve centerline measurements tomorrow.
With the freeze plugs removed from the block, we measured the wall thickness on the thrust side at .165"
You can also measure the distance between the walls by way of the freeze plug holes and it works out to be about the same thickness.
Nice looking MGB pistons!
Have you found a 263 engine yet?
Where are you located?
Paul
Member
Absolutely! I am willing to share the info with anyone interested. I would have to dig it out but I can do that.
Member
Hi Paul
I appreciate that.
Oh dear that wall thickness means the motor will never get to 2HP/Cu In. On a smallblock Chevy the thrust wall is usually .250" or more, the jacket longitudinal sides average at .125. Thats with a much shorter deck height with more rigidity on a bigger bore which adds strength by way of the diameter.
For street use the SBC can still be used on a bad core shift block if the thrust wall is .180" so the 263 is marginal from the getgo!
Perhaps a sonic checker could find some more thickness somewhere, maybe its thicker only an inch below the deck(Wishfull thinking)
I have a guy I know in Henderson, Nevada looking for me. I am in Wellington, New Zealand so theres not much over here, there was a 1935 small straight eight some weeks ago up north from where I live, but back then I was wanting a 320, now its gone.
The problem will be getting one back here once I find one, but there are companies that import engines so I will try and add it to one of their container shipments, usually they ship out of CA.
Heres a sneak peak of the piston I have mentioned, my thoughts are to just machine the dome flat to a height of about 1/8" or so, but some work could be done to make it like a turbulator. It is supplied by one of the major US piston companies so I should be able to get it without the valve reliefs. They retail at $800 USD for 8.
P1.JPGP2.JPGP3.JPG
Cheers
Kevin
Janderson's "miracle" head looks a lot like my '34-'36 233 head. The valves feature the same three dimples, and the head has very sharp outside corners. Spark plug threads are larger than the later 14 mm. However, my port and valve diameters are smaller. Also, the inside radius at the T-junction is just as sharp as in any 40's 320 head. Combustion chamber is awfully large. Janderson's head probably comes from the same age but from the bigger engines. I suspect the previous owner has already done some work on Janderson's head. I just don't buy the fact that all the surfaces had been machined at the factory.
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