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> Engine Rebuild, 2.5L Six
jfort
post Jan 19 2018, 02:39 PM
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Making progress. Took the heads up to Craig Barrett in Grand Rapids MI who will be drilling twin spark holes. Then, yesterday, Jay Kjoller started the rebuild with yours truly lending a hand and trying to soak up as much of his extended knowledge as I can. Turns out that the casting mark says the case was cast in June, 1966. Put new bearings on the newly machined pistons rods. Then new bearings for the crankshaft. Jay is very deliberate and meticulous. It looked like medical surgery, very clean. Loctite flange sealer then the case halves mated. All new fasteners torqued to spec in 3 phases.

When we get the heads back, we will calculate the compression ratio. May do the JE pistons as posters here have suggested, depending on what we find. Going with a modified Solex cam.

Can't wait.


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sixnotfour
post Jan 19 2018, 03:14 PM
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Is that a small oil pump ?? 3 rib or sandcast ? any other 4 rib would have been better..
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jfort
post Jan 19 2018, 03:51 PM
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3-ribbed later oil pump
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914forme
post Jan 19 2018, 06:15 PM
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(IMG:style_emoticons/default/poke.gif) 1966 (IMG:style_emoticons/default/poke.gif) did I read that right (IMG:style_emoticons/default/blink.gif) That is an early AL cases, that is like striking a gold vein in your basement. (IMG:style_emoticons/default/shades.gif) That case is worth $$$$$ if the numbers matchup. Great case to build off of also
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davesprinkle
post Jan 19 2018, 08:26 PM
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Love this thread. But can we please rotate the images?
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burton73
post Jan 19 2018, 11:08 PM
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You need some 1966 chain cases from the 69s Eng. from #41 when I bought it?

Bob B
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jfort
post Jan 20 2018, 05:36 PM
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I don’t understand the question
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jfort
post Jan 27 2018, 11:32 AM
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Spent the second day on the rebuild yesterday. Received the heads drilled for the second spark plug from Craig Garrett. He did a great job. Now, what is the current combustion ratio and do we need to buy higher compression ratio pistons to give effect to the twin spark? We suspect we will.

Here is what the heads look like. They were cast 7/73 for a 2.4L. They don't have a bevel where the flat edge meets the dome. Also, the 12mm spark plug is shrouded and that will adversely effect its exposure to the fuel/air mixture. Also, we measured the piston to head distance by having the piston at TDC smash a piece of solder and measuring its thickness. At .041 it is too close. All of this means another trip to the machine shop.Attached Image Attached Image
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jfort
post Jan 27 2018, 11:54 AM
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We next had to determine the swept volume and the combustion chamber volume to determine the combustion ratio.

The swept (cylindrical) volume is calculated knowing the stroke is 70.4 mm (7.04 cc) with a bore (diameter) of 90 mm, so r = 4.5 cc. Therefore = pi r squared stroke. = 3.1416 x 4.5 squared x 7.04 = 447.87 per cylinder, 2.687 total displacement. A good check to prove that the compression ratio calculation, next, will yield a reasonably accurate number.

The volume of the combustion chamber is measured empirically using a burette with a mixture of motorcycle strut oil and mineral spirits, The spark plug hole has to be at the very top for the liquid volume to be accurate

We measured (doing the procedure twice) 60.0 cc of fluid to the top of the spark plug hole, less 2.2 mL for the spark plug hole = 57.8 cc.

The compression ration, then, is v1 + v2 divided by v1 = 57.8 plus 447.87 divided by 57.8 = 8.75 combustion ratio.

Too low. JE pistons, 10.5 to 10.9, are on order and the heads are at the machine shop.

Attaching pistons, compressing rings, installing valves and valve springs, all necessary for what we did are a joy.Attached Image Attached Image Attached Image
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jfort
post Jan 27 2018, 12:01 PM
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A post script. Getting to know Jay Kjoller is a joy too. He built his race car, including the engine, and drove it in the Daytona 24 hour race. Finished 17th overall and 4th in class as a rookie in 1981. He builds 'em and races 'em. I am very lucky to be able to watch, assist and learn.
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mb911
post Jan 28 2018, 07:54 AM
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QUOTE(jfort @ Jan 27 2018, 09:32 AM) *

Spent the second day on the rebuild yesterday. Received the heads drilled for the second spark plug from Craig Garrett. He did a great job. Now, what is the current combustion ratio and do we need to buy higher compression ratio pistons to give effect to the twin spark? We suspect we will.

Here is what the heads look like. They were cast 7/73 for a 2.4L. They don't have a bevel where the flat edge meets the dome. Also, the 12mm spark plug is shrouded and that will adversely effect its exposure to the fuel/air mixture. Also, we measured the piston to head distance by having the piston at TDC smash a piece of solder and measuring its thickness. At .041 it is too close. All of this means another trip to the machine shop.Attached Image Attached Image


.041 is within spec what are you machining?
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gereed75
post Jan 28 2018, 09:12 AM
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What exactly are you measuring using the solder method? It seems to be head to piston clearance (that is usually what the solder method is used for). On one hand, you said it was too close, on the other you said compression was too low. These are contradictory.

Not trying to nit pick. Not questioning the competency of you or Jay, your builder. Just trying to understand so that you don't do some unnecessary machining (I doubt Craig would let that happen).

Have you checked and set deck height? This is generally adjusted by barrel shims that also affect piston to cylinder clearance.

There is so much at play here that there is a lot of room for confusion so sorry for the butt in, just trying to be helpful.
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mb911
post Jan 28 2018, 09:27 AM
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QUOTE(gereed75 @ Jan 28 2018, 07:12 AM) *

What exactly are you measuring using the solder method? It seems to be head to piston clearance (that is usually what the solder method is used for). On one hand, you said it was too close, on the other you said compression was too low. These are contradictory.

Not trying to nit pick. Not questioning the competency of you or Jay, your builder. Just trying to understand so that you don't do some unnecessary machining (I doubt Craig would let that happen).

Have you checked and set deck height? This is generally adjusted by barrel shims that also affect piston to cylinder clearance.

There is so much at play here that there is a lot of room for confusion so sorry for the butt in, just trying to be helpful.

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Deck height was what I was referring to.. Think you are in spec..
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jfort
post Feb 25 2018, 07:54 AM
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Did volume of combustion chamber measurement with new JE. Pistons and fresh from the shop heads. 10.78:1. Happy with that. Cams back, too. Described as Solex+. To attain proper piston to head clearance we had to add a couple of copper gaskets at the bootom of the jugs. Still, after a couple of “squeeze the solder” tests, where the curved crown of the piston meets the side of the head it was too tight. So, back to the machine shop to shave a little off the curved top of the piston. What will be gain in volume by that will hopefully made up be being able to use one less copper gasket at the bottom.

Also, the new pistons and rings with my otherwise OK jugs don’t yield the right clearance. So, they are off to Wisconsin for what I would describe as a new layer of Nikosil and some machining.

Back at my end, I completed the refinishing of the bottom of the car. Clean, primer and rubber undercoating. Looks good.

Got new Hawk HPS pads and fluid. Rotors are good. Bleed the brakes hopefully next weekend.

Then off to Track First in Richfield OH where new race seats and harnesses will be installed.
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jfort
post Feb 25 2018, 08:05 AM
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Had to add - I am continually impressed by engine builder Jay Kjoller. The level of thoroughness and attention to detail is incredible. He measures everything and compares to spec. Plus, he has done this hundreds of times so he draws upon a wealth of knowledge and experience. I guess all good mechanics are the same, but maybe not. It’s why his race car engines are so successful and he has a history of satisfied customers. It’s a joy to watch and learn.
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mepstein
post Feb 25 2018, 08:08 AM
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I just sold a rebuilt engine with an early sand cast case for $24k. It’s definately worth rebuilding yours.
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jfort
post Apr 8 2018, 03:56 PM
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Jugs are back from Wisconsin with new nikisol. (Siri is useless trying to spell it.). Jay confirmed again that the piston to head distance is too close. So, the new JE pistons are at a 3D lathe shop to slightly shave the curve to head distance. Getting close
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jfort
post Apr 11 2018, 03:16 PM
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almost too pretty to put back in

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flyer86d
post Apr 11 2018, 04:48 PM
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That should be one snotty engine!

Charlie
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jfort
post May 15 2018, 11:40 AM
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rebuilt carbsAttached Image
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