65 Dart 273 Engine Rebuild

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nm9stheham said:
I noticed in your pix that the measurement of the .5" below deck was done at the thrust faces, where I wouild expect pistons rocking in the bores a bit would make that vary. It would best to measure at 4 points around the piston top (above both thrust faces and above both pin bores) and then average. I suspect that unless you followed procedues like that in the measurments then there is some variability in the measured data... Lots of hard work there, and all very interesting.
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I also noticed this. I would take your measurements on the centerline of the piston pin on both sides.
 
I think the picture you guys are referring to was back when I first measured the dome volume. At that time I used the end of my calipers to measure .500 down from the deck.

I've since compared this method of measurement to a dial indicator and found that the calipers are not very accurate when used in this way. So I mounted a dial indicator to the deck with a magnetic base, zeroed it with the piston at TDC, and then ran it down .500.

Your point is still valid because I placed the dial indicator in the same area. I'm thinking I will try swapping some pistons/rods, and I will measure above the wrist pin going forward.
 
65DartGTConv said:
Isky E4. Intake closing event at 48 degrees. Doesn't bleed that much pressure.
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Perhaps not, but you can retard the cam a couple degrees if needed/desired, and that 48*--is that the closing event @ 050" or actual closing event valve on seat? In any case, I saw in previous threads from a few years ago, people ran the E4 cam with their 10.5:1 domes and had no problems...assuming they used the same pistons as you and similar head volumes, they're running similar CR.

I really don't think you'll have much to worry about...as nm9stheham mentioned, your static CR isn't that high to really worry about detonation...and for a few reasons. 273s, because of their smaller bore diameter, actually promote a little more tolerance to detonation because the flame front has less area to cover, and with those 273 runners and chambers, you'll probably have enough intake velocity to keep the mixture from becoming lazy and falling out of suspension.

And really, unless you run an overly aggressive timing curve, lug the engine, or your mixture is way off, you likely won't run into any issues.
 
txstang84 said:
I really don't think you'll have much to worry about...as nm9stheham mentioned, your static CR isn't that high to really worry about detonation...and for a few reasons. 273s, because of their smaller bore diameter, actually promote a little more tolerance to detonation because the flame front has less area to cover, and with those 273 runners and chambers, you'll probably have enough intake velocity to keep the mixture from becoming lazy and falling out of suspension.

And really, unless you run an overly aggressive timing curve, lug the engine, or your mixture is way off, you likely won't run into any issues.
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The compression numbers I posted are with an .039 head gasket. If everything you're saying is true, and if I could shave some compression off the highest cylinders, then I could switch to an .028 head gasket.

That's the value of getting the compression even in all the cylinders. Then you can run higher overall compression, or buy cheaper gas and not have a problem. In contrast, if I have to run a thicker gasket or buy premium fuel to make one cylinder happy, then I've lost something in all the rest.
 
I'm aware of the importance of making everything consistent, all I was saying was that I don't think your combo will be as sensitive to detonation as you think it may. I also don't think you'll really have a need for pump premium unless the gas in your area is garbage.

Every engine build is different, but just for perspective, my Mustang had about 9.2:1 N/A with a 270 Comp Magnum...I ran aggressive timing (36* all in by 2500), and drove the snot out of that car but I didn't lug the RPMs and my carb was fairly well tuned...I could run 87 in a pinch or 89 all the time...anything higher was just burning my money for no good reason.
 
When I measured how far down the pistons were in the bores, I was reading the dial indicator wrong. The needle was turning counter clockwise so, for example, a reading of .055 would actually be down .045". This caused my dome volume calculations to be off as well. Here are the corrected numbers.
View attachment Dome Volume.JPG
Domes are smaller than I previously calculated, but still quite a bit of variability. Because I'm cc'ing the piston in the bore, these numbers are not used in my calculations. As long as I've accurately moved the piston down .500" my CR numbers should be correct.
 
I swapped pistons between cylinders 5 and 6. I did not swap the rods, only the pistons. The rod in cylinder 6 seems to be about .002" longer than the rod in cylinder 5. The rods differed in weight by 2 grams or less, which seems to be the accuracy of my postal scale. But the piston/pin/ring assemblies weighed the same according to my scale. I don't think I've affected the balance enough to matter.

This improved the compression balance. Cylinder 5 is no longer the lowest, although cylinder 6 is still highest. I think the next step is to swap between 2 and 6.
 

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I pulled out 2 and 6 and measured the rods. The #6 rod measured .006" longer then the #2 rod. .006" works out to a volume difference of about 1cc. So I swapped the rods, but I didn't get the result I expected.

#6 volume did go up 1cc with the shorter rod as expected. But #2 volume went down 3cc. Since I cc'ed it twice and got the same answer both times, I'm confident in the new measurement. So the initial measurement must have been incorrect which means I swapped with the wrong cylinder. That sucks because it takes quite a while to make the swap and do all the measurements.

Next step will be to swap #2 with #7.
 

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I pulled out #2 and #7 and compared the rods and found about .009" difference which should equate to a 1.5cc difference. So I swapped the rods between those two cylinders after confirming that they weigh the same and that the crank journals are the same diameter. It had the expected effect in both cylinders and improved my situation by increasing CR in #7 and bringing it down in #2.
 

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Wow-looks like you've mapped it out pretty well. Cool deal man.

That sucks because it takes quite a while to make the swap and do all the measurements.
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I understand how you feel here...ever try to degree cams in a 4.6 4V? Long story short, it sucks. I think I spent the better part of 6 hours doing that crap.
 
Since cylinder #1 was so far out of line with all the rest, I decided to cc it again to make sure I had a good measurement.

I cc'ed the piston in the cylinder twice and got an average number that was 2 cc's smaller than what I had previously measured. Since I got almost the same answer twice in row, I have to trust it in favor of my previous measurement.

I also cc'd the cylinder head for chamber #1. This number did not change and since my previous measurement was done twice with good agreement, that makes three measurements tightly clustered around 60.4cc.

So it looks like cylinder 1 is still out of line with the highest compression. I'm thinking I need to grind 1.5 cc's out of chamber #1. This would put cylinder 1 right into the middle of the pack.
 

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Given the variability of the measurements and how easy it is to measure incorrectly, I decided to go back and re-measure the three remaining cylinders that had only been measured once. Everything else had at least two measurements. The new numbers were within 1 cc or the old numbers so I averaged the old and new measurements. I also re-measured the depth of those pistons in their holes.
View attachment CR6.jpg
I like that the dome volume numbers have tightened up with a new average of 10.2 cc's.

I still think the next step is to remove some material from the chamber for cylinder 1. If I remove 1.7 cc's, for a new chamber volume of 62.1 it would put cylinder 1 right at the average CR of the other 7 cylinders at 9.24:1.

I'm also thinking once I have a tighter tolerance on my CR I will step up to the .028 head gaskets which will move the average CR to 9.55:1 with a peak value of 9.62:1 in cylinder 8.
 
Before grinding, I thought it might be worth a try to swap valves between the smallest chamber and a larger chamber. So I swapped the valves between chambers 1 & 3. It helped!

Just to be safe, also cc'ed every chamber again. If there was significant disagreement with my earlier measurement, I cc'ed those chambers twice. I am now very confident in my chamber volumes.

Here are the latest numbers.
View attachment CR7.jpg
 
I swapped more valves around. Cylinder #1 got a tiny bit worse, but I did tighten up the grouping on #3 and #6. B
View attachment CR8.jpg
There's no getting around the need to do some grinding in the chamber for cylinder 1#. If I remove 1cc, it will put cylinder 1 right in the middle of the pack at 9.26:1.
 
I did some grinding on the chamber for cylinder #1. My approach was to use a pair of old valves from another head to protect the seats and keep the filings out of the ports. I put the old valves in the head. Then I wrapped the head with cellophane shipping wrap. I cut a square hole in the plastic above chamber 1 and taped the plastic to the head. Then I cc'ed the chamber with the old valves before I started grinding. That way I could cc the chamber and gauge my progress without swapping the valves.

View attachment 20140507_215242_resized.jpg

It took three tries to achieve the desired increase in volume. 1 cc required a lot more grinding than I expected. Once I thought I had removed enough material, I put the new valves back in the head and cc'ed it two more times. It was dead-on at my target of 62cc's. Here is the finished chamber. It looks shiny in the picture, but I used a 2" 40 grit fiber resin disk so there are plenty of deep scratches.

View attachment 20140507_224206_resized.jpg
 
You ,know your sh*t.... Patience, makes it right. Damn, nice work.
 
Here are the final numbers with the .039" FelPro head gasket.
View attachment CR9.jpg
With the Isky E-4 cam, dynamic CR for this combo in the highest cylinder, #7, works out to 8.25:1.

Here are the final numbers with the .028" Mr Gasket head gasket.
View attachment CR10.jpg
Dynamic CR for this combo in the highest cylinder, #7, works out to 8.54:1.

So which head gaskets should I order? Asked another way, what octane would I need to run for each combo? Car is an automatic.
 
Wow! Awesome work man--pretty sure you're going to be utterly pleased with your results.
 
I've been making progress on engine assembly after some delay with trying to figure out the AC brackets.

I got the oil pump installed, the heads torqued down and the valve trained on and adjusted. Those are the Mr Gasket 1121G head gaskets with .028" compressed thickness. Too bad the bores are so huge.
 

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Looking very good. You will be happy with the results. tmm
 
I'm concerned that I'm at the limit of the valve adjustment. The cups on the top of the pushrods are awfully close to the bottom of the rockers when the cam is on the base circle.

I don't have a big enough set of calipers to measure accurately, but using a tape measure, the pushrods are pretty close to 7.5 overall length. They are the pushrods that came out of the engine and I believe they are stock. I actually have two complete sets that are the same length.

Summit Racing is selling a set of pushrods from Comp Cams that are 7.389" overall length. If my math is correct, that would let me turn the adjuster screws in 2 1/2 turns.
http://www.summitracing.com/parts/cca-7821-16/overview/

Do I need them, or should I just run the original push rods?
 

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I've been searching around for advice on the proper orientation for the rocker shafts.

The 65 Factory Service Manual says to install them with the notches pointing toward the centerline of the engine. This points the oil holes toward the adjuster screws which would give the most oil to the pushrods.

But everything I'm reading here on FABO says to point the notches, and the oil holes, down and toward the valve springs. This gives the most oil to the part of the rocker with the most load, which makes a lot of sense to me.

I guess I'm leaning toward trusting the Factory Service manual but would welcome advice and opinions.
 
Re rocker shaft orientation, I recall a picture on here how to orient the oil holes, but can't find in my local files. Perhaps I am thinking of a slant engine. Anyway, my recollection is that the oil hole should be near the applied force location, i.e. on the bottom and equi-distant from pushrod "line of action" and valve spring.

On the slant, they fixed it by changing to a smaller diameter bolt at the rear so only one way to install the rocker shaft (~1976). Some mistakenly thought that coincided with the change to hydraulic lifters (different oiling), but it was 1 yr before. They might have done the same on the small blocks, but perhaps good they didn't since finding special bolts can be a pain (ex. K-H wheel studs).
 
Here's the assembled engine all prepped for paint. The only parts that weren't sand blasted are the block and heads. I spent several hours scrubbing those with a small wire brush and some acetone. Even the bolt heads were sand blasted.
 

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