I have a 1970 and a 1977 318, I am going to rebuild one of them and put in my 76 W100. Witch one should I rebuild? The 70 is a higher compression motor than the 77? Right? The 70 crank is not in good shape, the 77 is in good shape, will the 77 crank work in the 70 motor? The 77 has factory pistons, the 70 has different pistons, cylinders look good in both blocks. Was just going to hone the cylinders and go. Any thoughts? Thanks.
318 Difference?
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A38Valiant
Collector Of Rust
Just my two cents, but I would go with the 70. That should be 8.8 compression, floating pins, and rods that are slightly lighter. The crank from the 77 should work with no issues that I know of. Be sure to use the damper that matches your pulley selection, as the crank pulley bolt pattern changed in 72.
txstang84
Well-Known Member
The '70 should be a higher compression engine, but I'm pretty sure the crank casting numbers are different between 70 and 77. Also, take into consideration that just swapping the cranks out-while they will indeed swap each other-if one engine has non-factory pistons, the crank may've been drilled for balancing. I'm a bit weird that way...if pieces parts get swapped in the bottom end, they should be balanced together.
what's wrong with the crank in the 70?
what's wrong with the crank in the 70?
bad440
everything,all the time..
Not a noticable difference in power use the good one
nm9stheham
Well-Known Member
I'd be turning the crank anyway so if the 70 crank is not that bad, I would just have it turned and use the next undersize bearings.
I never have 'just honed' the cylinders since I was a poor college student rebuilding an old F300 292 ci. It too often ends up being a waste of time and you don't get good performance, often have a lot of blow by, and the engine doesn't last that long. So JIMO, no, plan on boring it and put in new pistons. You can do the measurements to check for taper and out-of-roundness to see how good or bad they bores are, but I bet they are all tapered to a degree; that'll wear the rings fast. If you do just hone, make sure the ring ridge is all reamed out or you'll break your nice new top rings.
I never have 'just honed' the cylinders since I was a poor college student rebuilding an old F300 292 ci. It too often ends up being a waste of time and you don't get good performance, often have a lot of blow by, and the engine doesn't last that long. So JIMO, no, plan on boring it and put in new pistons. You can do the measurements to check for taper and out-of-roundness to see how good or bad they bores are, but I bet they are all tapered to a degree; that'll wear the rings fast. If you do just hone, make sure the ring ridge is all reamed out or you'll break your nice new top rings.
amen
The rod and mains are already .10 over, One of the rods was spun, the 70 crank looks bad. Is it wise to go .20 over?
Do you know what the 77 compression would be?
You could raise the compression a bit if you use the early 273 heads with the smaller combustion chambers.
I have a set of 302s I was going to use, what do you think?
Be careful if you go with early 273 heads since I seem to remember they had a different intake bolt pattern on them. As for the crank going .020 under- don't sweat it; I've had them .030 under and not a problem. The gentleman's advice about a hillbilly hone job is not just talk. Don't ask me how I know this, please.
nm9stheham
Well-Known Member
Can't see where it will hurt anything at all.....it is a service undersize. Hardly enough metal removal to weaken anything. If yo uare looking for performance, you should be working over the crank anyway for a variety of things. Kinda depends on if you want a high perf, high reliability engine, or if you just want to throw something together to run for a short while.
I don't know what the 302 casting is without more explaination. How big are the combustion chambers? What year and engine are they originally from.
302's would raise compression because they are close chamber heads. Just let me tell you, the difference between a 8:4 to 1 motor and an 8:9 to 1 motor would not be felt by the seat of your pants. Flow is much more important than compression. In other words, an 8.4 to 1 318 with a 4 bbl, 340 cam, 340 heads and headers will demolish a 9:5 to 1 318 2bbl with single exhaust.
Yes, the 64 and 65 heads have the different angle intake manifold bolts. those are 2465315 and are supposed to have 57 cc chambers.
He could get a set of 66 or 67 heads 2536178 & 2658920 are supposed to have 57 cc chambers.
The next "step" would be the 2843675 that are 68 - 71 and supposed to have 60 cc chambers.
The 77 heads are 4027163 or 4027593 castings are supposed to have 63 cc chambers.
The 67 - 69 piston compression height is 1.759".
The 70 - 71 piston compression height is 1.750".
The 72 - 78 piston compression height is 1.739".
Wow.
Lets start with your first point.
The goal of building an engine is to try to tweak every last bit of power out of it that you can. the "seat of my pants" cannot accurately tell the difference. A dyno or quarter mile slip can more accurately.
If you count your pennies, your dollars will always be accounted for....
Flow AND compression are needed for a good engine. You have to go for BOTH, not one or the other.
Your example with a "8.4 to 1 318 with a 4 bbl, 340 cam, 340 heads and headers will demolish a 9:5 to 1 318 2bbl with single exhaust" is like comparing apples and oranges.
Comparing a single exhaust engine with a dual exhaust engine is not a fair comparison. The single exhaust on a 318 is the bottle neck for the engine. I had a 70 Swinger with a stock 318 2bbl. I did an acceleration test from 70 to 100 MPH and it took a long time to get to 100 MPH with the single exhaust.
I replaced the exhaust with a mandrel bent 2 1/4" dual exhaust with an h-pipe, and the car went from 70 to 100 MPH in almost 1/3 of the distance that it took to do that with a single exhaust.
It is a given to upgrade to a dual exhaust.
We are trying to help him pick the best components for his engine to achieve its best potential and giving him tips for improvement.
Compression is efficiency. The higher compression will have more efficiency, but you don't want to get too high where you have to run premium or racing gas to keep it from knocking/detonating.
Why even go there? Just get some 10:1 flat tops and after that it doesn't matter which engine you go with.
Did you even read the original OP?? He did not say he wanted to go fast. He wants the best engine to rebuild for a Dodge truck. He is focusing on compression when the truth is, once it is in his truck, he won't feel the difference on a half of a point on compression. I went to extreme to prove a point that flow is more important than compression. I did not say compression is not important. He is not trying to build a 10 second 318 pickup. So my advice is to pick the "best" engine that needs the least to be a good motor.
Here's some pictures of what I have and believe to be factory pistons:
68 318 - has eyebrows:
View attachment 68 318 Block A03 B23.jpg
71 318 stock - no eyebrows, flat top:
View attachment 71 318 Block A01 B.jpg
They may not be stock.
If you want the most out of what you have:
Can you compare the two pistons side by side with the wrist pin centers lined up? (Like having the same pin in both pistons) and see which one is the tallest.
Then use that set of pistons if they are ok to use.
If the ones with the eyebrows are taller, then use those. If not, then keep the 77 block, crank, and pistons together and just hone it and give it a "refresh kit" from Mancini Racing:
If you're gonna hone it, put in a new set of rings, & bearings. Here's a kit with cast iron rings, main bearings, rod bearings, and a Fel-Pro rebuild gasket kit for $200:
http://chucker54.stores.yahoo.net/sealpowkitb.html
And here's a nice true roller double roller timing chain set for $62:
http://chucker54.stores.yahoo.net/edelbrock4.html
It's a great chain for the money. I put one in a 318 and went to change it at 125 k and it was fine. I've driven them for over 250,000 miles with no problem on a daily driver.
Much better than the stock 318 timing chain. I've had to replace the crappy stock timing chains at 80,000 miles with lots of stretch and chipped cam gear teeth (and only single row chains).
And a fresh oil pump for $39:
http://chucker54.stores.yahoo.net/318340360.html
... minimum.
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Or if you can spend a little more, you can go with the rebuild kit C which has the main bearings, rod bearings, rings, and Fel-Pro rebuild gasket kit just like the $200 kit PLUS:
Freeze plug and oil galley plug kit, oil pump, cam bearings, and cast pistons for $400.
http://chucker54.stores.yahoo.net/sealpowkitc.html
And then add the $62 timing chain from above and you're ready to go.
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Go with whatever fits your needs. Those are just a couple of minimum options.
If you got the pistons out measure the pin heights.
Here's the tallest cast pistons you can buy that I know of
http://www.summitracing.com/int/sea...-in/3-910-in/compression-distance-in/1-745-in
Those with a .020" cut off the block and heads with a .040" gasket would put you in the 8.8:1 CR range and a .025" gasket will get you 9:1 CR
Here's the tallest cast pistons you can buy that I know of
http://www.summitracing.com/int/sea...-in/3-910-in/compression-distance-in/1-745-in
Those with a .020" cut off the block and heads with a .040" gasket would put you in the 8.8:1 CR range and a .025" gasket will get you 9:1 CR
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