Rebirth of my 1970 GTX!
- Thread starter t.flatt
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- Jul 17, 2008
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t.flatt
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Wow, that's gorgeous! Gotta love a slab-side shovel!
t.flatt
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OK, I think harley time is over so now I gotta figure out what I was doing with all this crap! I know the rocker arm spacing needed to be addressed, so I'll start there!
t.flatt
Well-Known Member
I got one side all spaced out. About .010 clearance between each pair of rockers. In a previous post I said I was running Harland Sharpe rockers. I ended up going with some from Hughes Engines. Got some more spacers ordered to do the other side.
t.flatt
Well-Known Member
I got the new valve covers about 6 months after ordering them and it looks like one got dropped, put in the box and shipped off to lucky me! And, I do mean lucky. I bent up the passenger side of the old pair and someone else bent the driver's side of the new pair! So, I have one good set! I'll be very careful if I have to modify them to get the rockers to not hit the baffle.
t.flatt
Well-Known Member
I straightened the bent brand new valve cover and used that for a practice run for rocker clearancing. You can see how I ruined the first one I worked on. Don't want to do that again! I heated up the baffle and with a little persuasion from my press the rocker arm doesn't hit the baffle! Now to do the same thing on the covers I want to use. I'm using two gaskets as well...
t.flatt
Well-Known Member
All right! I did a much better job of clearancing this time! I only bent the parts I wanted to bend!
t.flatt
Well-Known Member
So, here are the pieces that B3 Racing Engines makes to get the rocker arm geometry correct. You take a handful of measurements on your current set up, send them off to Mike and he will machine up a custom set for you! They relocate the rocker shaft up and away from the valves. Pretty cool!!
t.flatt
Well-Known Member
And here are the results! I've got a shot of no lift, max lift and mid lift of the valve. With and without the spacers. Mid-lift with the spacers looks like a perfect 90 degree angle. Money well spent!
t.flatt
Well-Known Member
Ok, wrong pictures in the last post! Here are the 3 without the spacers.
t.flatt
Well-Known Member
All right, I think the heads are in great shape! And, here I have piston #1 at TDC. I'll think of something else to do later...
t.flatt
Well-Known Member
Sweet, I got the compression ratio calculated! Looks like it will be 10.45 to 1. Perfect for aluminum heads. 440 Source stated the compression ratio would be 10.5 to 1. Pretty close! The burette is definitely the star of the show here. You gotta find the volume above the piston at TDC, the volume in the head and the compressed volume of the gasket. I found those to be 18.8, 82, and 9.9. The gasket volume was steted on the package. You just drill a hole in some plexiglass seal it to the surface with some grease and fill it up. So, I have 110.7 cc above the piston at TDC. I have a 4.25 stroke and a 4.375 bore. That will displace 1046.904 cc per cylinder. Add that to the 110.7 cc above the piston and get 1157.604 cc above the piston at BDC. Divide volume at BDC by volume at TDC. 1157.604÷110.7=10.457. Done!!
t.flatt
Well-Known Member
I also checked the cam centerline. For the rear-end ratio I have (3.54), my cam guy said to have 110-111 degree centerline. I measured cam lobe lift at 0.050 before and after max valve lift. I got 70 degrees before and 152.5 degrees after. The exact center of those is: 70+152.5=222.5
222.5÷2=111.25
So, the centerline is 111.25. No adjustments needed! Sweet!!! And, the extensions for the dial indicator make things so much easier!
222.5÷2=111.25
So, the centerline is 111.25. No adjustments needed! Sweet!!! And, the extensions for the dial indicator make things so much easier!
t.flatt
Well-Known Member
Better make sure the pistons and valves don't get too friendly with one another. I took an old lifter apart and put some washers in place of the spring so it doesn't collapse. Don't be a dumb *** like me! I crushed the little nipple piece inside the lifter that holds that small spring. The pics show a whole lot of clearance but officially measured the exhaust clears by 0.234" and intake by 0.185". Over twice the recommended clearance. Good to go!
t.flatt
Well-Known Member
Well, here is the cause of my delay on the motor. I bought a 1984 CJ7!! Good or bad decision it's mine now. It's rust free and 300 miles in a rebuild! I bought it for a daily driven work vehicle. The guy said there is nothing wrong with it, but once I got it home I found all kinds of **** that needed to be addressed. It's all sorted out so now I can get back to The X!
t.flatt
Well-Known Member
I did manage to get the cam and crank installed! Got my fingers crossed they will stay there for a very long time. Here is today's project, putting the rods on the pistons. Pretty straight forward but those spiro-locks for the pin are a pain!
t.flatt
Well-Known Member
I know it's not a very pretty picture but there are 8 pistons with connecting rods attached! The spiro-loc was much easier on the last compared to the first. Just gotta get your groove on!
I'll take the spiro locks any day vs. having to heat up the rods and pressure fit them on. I have found that to be a real pain in the arse!
Regardless: Good progress and good luck with the rest of your build!
Oh, and make sure you CHECK ALL YOUR TOLERENCES AND DON'T ASSUME ANYTHING, especially with your mains and rods.
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