Chilsam
Well-Known Member
That's where I read it !!
77 440 vs 70 440
- Thread starter Davidrad
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Davidrad
Well-Known Member
I got my answer. Toss the lean burn, replace pistons, and boom mo power.
66Satellite47
Well-Known Member
Interesting, if the main webs were thicker. I never noticed that. As far as I could tell the cylinder wall thickness got thinner starting in 1973 or so with the 440. I sonic checked numerous 440 blocks and found the later blocks about .025 to .040 thinner than the earlier blocks. Main webs don't know.
metaldad
Well-Known Member
you know meat!
Davidrad
Well-Known Member
Ah and probably a hotter cam, because duh
66Satellite47
Well-Known Member
Ya, lean burn no good. A little more CR is a help. Modern camshaft will help a lot.
miller
Well-Known Member
If the bore size on that block is okay, it's a good start for a good motor. And, who knows, considering it's a ex-police pursuit...well, they got the good parts!
Chilsam
Well-Known Member
Heads have xtra cooling passages...
66Satellite47
Well-Known Member
In my opinion the 906 or 915 heads are the best stock iron heads. Stage V sure look like the best except for a Stage III Max Wedge. The later versions with the flat floor can be made to work. Not sure what the cooling passages really did, considering they were on low compression motors.
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Imo, they all had a fair amount of nickel in them. If you've ever been in a machine shop where one was being bored, you can tell by the sound of the cutter how hard a metal is and the Chrysler blocks all sounded about the same to me. Throw up a Chevy block and the cutter made way less noise indicating softer cast iron. Trust me, I've cut a ton of cast iron during my days as a machinist and you can really tell what's happening by the sound of the tool. The first time I heard a big block Ford being machined, it surprised me at the sounds the cutter made. It was very inconsistent indicating hard and soft spots throughout the metal. Don't know if that was a common thing with them because it was the only Ford block I've ever been around while being cut but I've been around a bunch of Mopar and Chevy stuff. Btw, the Ford turned out good and I never heard any complaints from the owner.
66Satellite47
Well-Known Member
I went to the 2.14 / 1.81 DC valves when they became available. The bigger valves & a lot of porting does make more power. But the pocket porting alone on a 906 head makes a very significant increase in power.
Chilsam
Well-Known Member
same valve size as mine...I think anything that improves heat transfer is a great thing...
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minnesota guy
Well-Known Member
Better block in the later block. Pistons sit half way down the hole in 1977. That is the reason they have no power. Police motor should have the same cam as 69 RR. Heads are fine. Same as 69 type 906 head but better ports and hardened seats. Put a 6 pack piston in it and bring the piston to deck level, with open heads and fel pro gasket and you can run 91 octane no problem. I put one together for my 87 Dodge P/U 4x4 to tow.
Garys1969RR
Well-Known Member
I have built alot of 440s, and have researched this stuff for 40 plus years. I currently have a 1970 440 with 906 heads, and the pistons only come to about .080" below the deck. With the 906 heads at 88 cc, this would give a C/Ratio of 9.03 to 1. Chrysler claimed 9.5 to 1 on those motors in the 70 Roadrunners, I believe. You can use a 440 six pack piston with a Compression height of 2.067 such as the KB 237, that will get you to about .015" below deck. Then using an 80 CC head, .020 head gasket, you will get about 11 to 1 C/R. So in answer to your question, Chrysler reduced C/R mainly by lowering the deck height, and in the late 70s, (1977 and after) , they lowered the piston to .140 or more below deck, and also put in a dished piston. Then were talking 7.5 to 1! I took the ported 906 heads and 509 cam out of that motor and put them on a 451 with 14 cc dome pistons, and that thing was a screamer at 12.5 to 1 C/R! Next step was 915 heads on the 451 which took it to 13 to 1, and that was REALLY a screamer! We're talking low 12s in a 3600 lb Roadrunner.
Garys1969RR
Well-Known Member
On the same note, I now have a 69 RR, 440 6 pack. I'm using the flat top pistons at .010" below deck, Edelbrock Performer RPM heads, OOTB with a touch up valve job, .020 steel shim head gaskets, 80cc chambers. This 11 to 1 C/R 440 powered RR runs just a couple tenths quicker than the 451 RR did. The 451 had the 915 heads, 509 cam, and single 4 barrel, but it had 13 to 1 C/R.
drobertson
Well-Known Member
Oh it isn't a myth, go take a look through a few late 70's blocks. They are improved in a few areas like others have mentioned.
66Satellite47
Well-Known Member
Never had any problems with the '67 - 70 blocks. My '72 451 low deck broke the #5 main cap, but I was running 7400 RPM. Not a good plan with a stock steel crank. Keep the RPM well below 7000 & parts will live. Outside block rib seems like very good idea. My early '65 426W block cracked between the freeze plugs.
Chilsam
Well-Known Member
What was the cast date on your 400 ?..I'm told the mid to late 71's are the best.Never heard a word about diff in main caps?...My 400 has a cast date of 8-31-71 and a set of D.C Nodular Iron caps...I'm going to run a steel 383 crank in it tho for the rev's...
66Satellite47
Well-Known Member
So you have '72 year block. I built two low deck strokers with cut down 440 cranks. The first I used low deck rods & 13.5 CR pistons. I ran that motor at very high RPM's, 7300 - 7400. Took it apart at the end of the drag race season, and #5 main cap was broken in half. Motor still was running fine. 7400 is too much for a stock 440 crank. Second low deck used a '74 400 block and 440 LY rods. 12.5 CR. The first low deck with short rods sure seemed to get up quicker. In those days valve springs were a problem above 7000 RPM. Tried numerous brands. Crower orange stripes worked well. Modern stuff should be a lot better.
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