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Re: Raising compression in a 400?
[Re: MoparforLife]
#303071
04/29/09 04:14 PM
04/29/09 04:14 PM
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Joined: Jul 2003
Posts: 4,770
Holland MI Ottawa
2boltmain
master
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master
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Posts: 4,770
Holland MI Ottawa
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Something to ponder- the costs to machine the block and heads are not cheap. With my smogger 360 the cost of new KB107s at under $200 a set is cheaper than all the machining of a block and 2 head surfaces. I dont know what a set of 400 B pistons costs but a psiton change is better than milling to get comp.
Keep old mopars alive.
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Re: Raising compression in a 400?
[Re: 2boltmain]
#303073
04/29/09 04:28 PM
04/29/09 04:28 PM
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Joined: Jan 2003
Posts: 25,200
Upper Midwest
MoparforLife
Too Many Posts
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Posts: 25,200
Upper Midwest
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Quote:
Something to ponder- the costs to machine the block and heads are not cheap. With my smogger 360 the cost of new KB107s at under $200 a set is cheaper than all the machining of a block and 2 head surfaces. I dont know what a set of 400 B pistons costs but a psiton change is better than milling to get comp.
Granted it is better but not less $$$. Would you put a set of new pistons in a marginal bore??? Plus rings and bearings, + machine work to press the old pistons on and either press the new pistons on or float the rods. Not cheap or right either way but----
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Re: Raising compression in a 400?
[Re: JohnRR]
#303075
04/29/09 05:37 PM
04/29/09 05:37 PM
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Joined: Aug 2007
Posts: 6,095
Valencia, España
NachoRT74
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master
Joined: Aug 2007
Posts: 6,095
Valencia, España
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its aaaaaaall in the pistons.
We got 9.5 to 10 compresion Rate with same heads volume on earlier years BB and RBs
Pistons and you are done... $400-500 rate.
then mill and porting heads for extra, but main win is on the pistons.
With a Charger born in Chrysler assembly plant in Valencia, Venezuela
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Re: Raising compression in a 400?
[Re: JohnRR]
#303076
04/29/09 06:35 PM
04/29/09 06:35 PM
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Joined: Jan 2003
Posts: 25,200
Upper Midwest
MoparforLife
Too Many Posts
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Upper Midwest
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Quote:
Milling the block and the heads to raise compression in this particular case is just silly. it's going to cost more to do all that machining and in the end you end up with parts that will fit nothing else .
Just throw it together and run it till you have the money and equipment to do it RIGHT ...
Machining the heads the right way does not make them parts that will fit nothing else. Done right they are interchangable between engines. I agree that the gain will be minimal and that pistons is the right way to go but as I stated but would you put pistons in a marginal or high mileage block without boring & fitting?? I wouldn't. Nor would I put new pistons and a bore job into the engine without having the heads reconditioned and the crankshaft checked out and trued if needed. But what do I know I am just a shadetree mechanic. Right Johnahah??
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Re: Raising compression in a 400?
[Re: MoparforLife]
#303078
04/29/09 07:46 PM
04/29/09 07:46 PM
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Joined: Jan 2003
Posts: 75,020
U.S.S.A.
JohnRR
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Quote:
Quote:
Milling the block and the heads to raise compression in this particular case is just silly. it's going to cost more to do all that machining and in the end you end up with parts that will fit nothing else .
Just throw it together and run it till you have the money and equipment to do it RIGHT ...
Machining the heads the right way does not make them parts that will fit nothing else. Done right they are interchangable between engines. I agree that the gain will be minimal and that pistons is the right way to go but as I stated but would you put pistons in a marginal or high mileage block without boring & fitting?? I wouldn't. Nor would I put new pistons and a bore job into the engine without having the heads reconditioned and the crankshaft checked out and trued if needed. But what do I know I am just a shadetree mechanic. Right Johnahah??
Lighten up Francis , Don my post was not directed at anything you said, the OP has been asking this question 30 different ways and is not getting the answer he WANTS to hear.
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Re: Raising compression in a 400?
[Re: polkat]
#303079
04/29/09 07:50 PM
04/29/09 07:50 PM
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Joined: Jan 2003
Posts: 75,020
U.S.S.A.
JohnRR
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Quote:
If one mills the heads .060", must something be done about the pushrods? I remember in the old days people talking about shimming the rocker shafts to make up for milling. I believe some companies made these shims. Seems to me they could be homemade from .060" stock. Right?
By the way, is there a way to tell if big block heads have already been milled?
Shimming the rocker shaft is the HACK way to make up for aggressive head and/or block milling , shims are to CORRECT for INCORRECT rocker to valve geometry.
Measure the outer row of head bolts , under the exhaust flange , stock heads would be 1.000 plus or minus a couple of thou.
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Re: Raising compression in a 400?
[Re: polkat]
#303082
04/30/09 12:37 AM
04/30/09 12:37 AM
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Anonymous
Unregistered
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Anonymous
Unregistered
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You use the "Lighten up Francis" ALMOST as much as you use the "Outside the box thing" Think up some new ones or crawl back under your rock PLEASE!!!!!!!
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Re: Raising compression in a 400?
#303084
04/30/09 12:52 AM
04/30/09 12:52 AM
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Joined: Aug 2007
Posts: 6,095
Valencia, España
NachoRT74
master
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master
Joined: Aug 2007
Posts: 6,095
Valencia, España
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as I told... PISTONS is all you need to get the old good numbers from BBs. EVERYBODY will say you diff opinions mostly of them are not on budget just on performance, but PISTONS is the only real difference between a 330 HP from 383 and 260 HP from 400. THEN you can get some more points extra with some milling, porting and cam... or simply headers and intake, you choose. I bet you can get same 330-350 HP from a 400 than a 383 with JUST THE PISTONS and the basic resto MP HP camshaft, because IS ALL THAT 383 GOT !. CRANKSHAFT was different to, because 383 HP were mostly forged and 400 are casted, BUT a casted crank can handle it without problem. we have a "cheap" solution using KB240 pistons what are same kind of stock pistons ( casted, not forged ) but hypereutic technology/design. I woudl say is the only "cheap" solution for 400s we have out of the shelf KB can get you some forged pistons too, but a little bit more expensive than the KB240. Then you have Ross, Diamond what gives you teh option for custom built But PISTONS and yu are done. I can't think somebody wouldn't be agreed on this, being the DIRECT relation with CR, being THE REST of engine is the same than earliers. 2 advantages of 400 beside a 383... stock manifold is already SPREADBORE design, and more displacement... so who can say you can't get 330-350 HP from a 400 with just that piston change ? anyway I dunno if a KB240 could give you those 330-350 HP rate, because even they are higher than stock 400s, don't know how much they really are againts 383 ones with OEM/Stock 9.5 CR. I'm not an expert on this, just being LOGICAL.  
With a Charger born in Chrysler assembly plant in Valencia, Venezuela
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Re: Raising compression in a 400?
[Re: polkat]
#303085
04/30/09 01:01 AM
04/30/09 01:01 AM
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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Snce the block CANNOT come out I'd get some (std bore I'm assuming) KB quench dome pistons of the correct CR & mill them(& the open chambered recess's) to get quench & pull your old pistons & weigh them & hope that they are close to the KB's(if heavier lighten them) & put it together w the block in place! Your piston/bore clearance might be not perfect but this will satisfy your parameters. I'd do it in a second.
live every 24 hour block of time like it's your last day on earth
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Re: Raising compression in a 400?
[Re: hemigod426]
#303091
04/30/09 03:02 AM
04/30/09 03:02 AM
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Anonymous
Unregistered
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Anonymous
Unregistered
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Doesn't the low compression 440 pistons in a 400 bring it up to 10.1? You may have to cut valve reliefs but..... 
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Re: Raising compression in a 400?
[Re: hemigod426]
#303094
04/30/09 04:04 AM
04/30/09 04:04 AM
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Joined: Feb 2003
Posts: 21,318
Manitoba, Canada
DaytonaTurbo
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Manitoba, Canada
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Quote:
Quote:
516 might spec at 74cc but unless it's already been milled they typically measure 84cc....
And that 8.5 C/R estimate is pretty optimistic as well...
i just milled my 906 heads 40 and there are now 74cc and those are open chambers, 516 are same chamber as 915 closed there 74-5 ccs now unmilled. you can have a 8.2 to 1 400 seen many with taller than factory deck like plus 20-25 thou. got my 906 head soo tight by also putting in 2.14/1.88 monster farera nontulup valves 
I don't remember the formula off hand, but I really don't think cutting .040 is going to bring a 90cc 906 head down to 74cc.
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Re: Raising compression in a 400?
#303096
04/30/09 08:31 AM
04/30/09 08:31 AM
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Joined: Jan 2004
Posts: 640
AZ
FM370RR
mopar addict
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mopar addict
Joined: Jan 2004
Posts: 640
AZ
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Re: Raising compression in a 400?
#303097
04/30/09 09:26 AM
04/30/09 09:26 AM
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Joined: Jan 2003
Posts: 75,020
U.S.S.A.
JohnRR
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Quote:
You use the "Lighten up Francis" ALMOST as much as you use the "Outside the box thing" Think up some new ones or crawl back under your rock PLEASE!!!!!!!
Do you actually have anything constructive to add , if not go back under your BRIDGE ... PLEASE ...
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Re: Raising compression in a 400?
[Re: hemigod426]
#303098
04/30/09 09:32 AM
04/30/09 09:32 AM
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Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
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Quote:
Quote:
Doesn't the low compression 440 pistons in a 400 bring it up to 10.1? You may have to cut valve reliefs but.....
you cant put 440 pistons in 400, 440 has 4.32 bore 400 has 4.34 bore and 440 has 6.76 long rod for raised block 400 is low deck with monster bore
you can get .020 over 440 pistons at 4.34" or .030 over at 4.35". 0 deck on a 400 block should be a compression height of ~ 1.932". federal mogul stock replacement pistons are 1.813" CH, so I'd imagine the stock pistons would be ~.120" in the hole. low comp 440 replacement pistons are 1.912" CH, so they'd be ~.020 in the hole if the deck is at blueprint spec.
assuming blueprint deck height on 9.98", .020" steel shim head gaskets, 90cc open chamber heads, and .020 in the hole low comp 440 pistons, you're looking at 9.12:1 compression by the math.
1976 Spinnaker White Plymouth Duster, /6 A833OD
1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!***
2011 Toxic Orange Dodge Charger R/T
2017 Grand Cherokee Overland
2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
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Re: Raising compression in a 400?
[Re: hemigod426]
#303099
04/30/09 09:35 AM
04/30/09 09:35 AM
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Joined: Jan 2003
Posts: 75,020
U.S.S.A.
JohnRR
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Quote:
Quote:
516 might spec at 74cc but unless it's already been milled they typically measure 84cc....
And that 8.5 C/R estimate is pretty optimistic as well...
i just milled my 906 heads 40 and there are now 74cc and those are open chambers, 516 are same chamber as 915 closed there 74-5 ccs now unmilled.
Someone must have milled those 906's then because out of the factory it will usually measure 90 cc. typically every .005 is 1 cc so with .040 off you only pulled out 8cc . the specs you are quoting for the 915 is NHRA I'm guessing which is alot smaller than ACTUAL .
As far as everyone telling him to change to a taller CH piston with it the way it is another post brought up a valid point ... CYLINDER RIDGE , unless he removes the ridge he will BREAK the new rings and from the sounds of it , NO ENGINE HOIST and he says he has NO CAR the block isn't coming out of whatever it's in anytime soon .
Buy hemigod's 516's and thats the best you will do with the constraints you have to work around for the short term fix .
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Re: Raising compression in a 400?
[Re: 64Post]
#303102
04/30/09 11:10 AM
04/30/09 11:10 AM
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Joined: Jan 2003
Posts: 75,020
U.S.S.A.
JohnRR
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Quote:
I'm sure a head change will yield some increase in compression, but with worn bores and rings I gotta think blowby is going to be increased greatly. So, how much additional compression is he really going to get?
Judging by where and how this is bouncing all over the place you are just adding more facts that are confusing the issue and I don't think it really matters, if I'm reading this right getting any work done outside of just bolting on parts to the shortblock as is is the only course of action ?
There isn't a piston that will swap directly in that's not going to cause havoc with the rings and the current ridge, that's an issue being ignored.
One thing that is been glossed over is no 440 piston is going to fit a standard bore 400 because the standard bore of a 400 is 4.342 , thats .022 oversize .
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Re: Raising compression in a 400?
[Re: JohnRR]
#303103
04/30/09 11:32 AM
04/30/09 11:32 AM
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Joined: Aug 2003
Posts: 8,716
Baltimore/Denver
64Post
master
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master
Joined: Aug 2003
Posts: 8,716
Baltimore/Denver
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Quote:
Quote:
I'm sure a head change will yield some increase in compression, but with worn bores and rings I gotta think blowby is going to be increased greatly. So, how much additional compression is he really going to get?
Judging by where and how this is bouncing all over the place you are just adding more facts that are confusing the issue and I don't think it really matters, if I'm reading this right getting any work done outside of just bolting on parts to the shortblock as is is the only course of action ?
Yeah, that's why I was trying to stay out of it. But it's like a train wreck... 
Quote:
One thing that is been glossed over is no 440 piston is going to fit a standard bore 400 because the standard bore of a 400 is 4.342 , thats .022 oversize .
Nothing that a piston stretcher or some aggressive knurling won't fix... 
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Re: Raising compression in a 400?
[Re: JohnRR]
#303104
04/30/09 11:37 AM
04/30/09 11:37 AM
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Joined: Dec 2006
Posts: 3,533
Indiana
Fury Fan
master
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master
Joined: Dec 2006
Posts: 3,533
Indiana
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Quote:
As far as everyone telling him to change to a taller CH piston with it the way it is another post brought up a valid point ... CYLINDER RIDGE , unless he removes the ridge he will BREAK the new rings and from the sounds of it , NO ENGINE HOIST and he says he has NO CAR the block isn't coming out of whatever it's in anytime soon .
Buy hemigod's 516's and thats the best you will do with the constraints you have to work around for the short term fix .
 Don't buy new pistons to put in an old, worn block. You're gonna spend $200-300 on pistons and rings but what kinda ring seal will you have???
If you want some ideas on low-compression fixes, read this one:
https://board.moparts.org/ubbthreads/show...rue#Post5195287
Aside from that, I have to be harsh here:
If you have no daily driver, no engine hoist, etc, you are lacking some of the basic resources to do this job properly. 
By 'properly', I'm not even referring to a high-HP engine, I'm just talking about an engine that will last for a few years.
If you're not planning for this engine to be used for a few years when you get it running, just skip this activity altogether and plan for the next step - either getting a good used engine or a well-planned rebuild. 
Parts I seek:
driver doorpanel, 65 Sport Fury, prefer black, needs to be 7-8 on 10 scale, might buy set
16" x 6" Dodge truck wheel(s), from early 70s?, takes 9" dogdish - need for a research job so cheaper is better.
69-73 C-body caliper brackets and/or splashields
Send a PM.
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Re: Raising compression in a 400?
[Re: Fury Fan]
#303105
04/30/09 12:03 PM
04/30/09 12:03 PM
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Joined: Jan 2003
Posts: 25,200
Upper Midwest
MoparforLife
Too Many Posts
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Too Many Posts
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Posts: 25,200
Upper Midwest
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Quote:
Quote:
Don't buy new pistons to put in an old, worn block. You're gonna spend $200-300 on pistons and rings but what kinda ring seal will you have???
Exactly what I said way back when. But nobody seemed to agree and kept on with the new piston thing. 
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Re: Raising compression in a 400?
[Re: MoparforLife]
#303108
04/30/09 01:53 PM
04/30/09 01:53 PM
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Joined: Jan 2003
Posts: 75,020
U.S.S.A.
JohnRR
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Quote:
Rings just plain aren't going to make up for an out of round cylinder but do what you want. If you go with the tight clearance KB pistons be prepared for some piston slap too. If you are going to spend the money for new pistons do it right. For about 125 bucks you can have it bored and the pistons fit right.
Putting rings in this engine as is is just silly , the cylinder needs the proper hone finish to get the rings to seal, I don't think gapless rings come in plain cast iron as that's probably the only thing that will even remotely seal , plus now people are expecting him to breakdown the short block while it's still in the vehicle ?
Don , I wish I could get a V8 bored and honed for that cheap, around here is $300 ...
Train wreck , that's what this has been for me .... 
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Re: Raising compression in a 400?
[Re: 69dart]
#303111
01/06/12 11:14 AM
01/06/12 11:14 AM
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Joined: Jan 2003
Posts: 75,020
U.S.S.A.
JohnRR
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Quote:
Typically changing pistons will require the engine to balanced as well. Otherwise its going to shake itself apart. Also the factory head gaskets were .020 and felpros are typically .042 so milling .040 off the heads only nets a .020 gain.
I think your money would be better spent on a performer intake, carb and camshaft.
Did you notice the date before dragging this CF back from the dead ?
2009 ...
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Re: Raising compression in a 400?
[Re: JohnRR]
#303112
01/06/12 11:33 AM
01/06/12 11:33 AM
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Joined: Feb 2004
Posts: 1,839
Sault Ste. Marie, Ontario, Can...
moparmike1
top fuel
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top fuel
Joined: Feb 2004
Posts: 1,839
Sault Ste. Marie, Ontario, Can...
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Quote:
Quote:
You use the "Lighten up Francis" ALMOST as much as you use the "Outside the box thing" Think up some new ones or crawl back under your rock PLEASE!!!!!!!
Do you actually have anything constructive to add , if not go back under your BRIDGE ... PLEASE ...
I really have to laugh at this, 'constructive to add'. Funny thing is, when I said the same thing your response was something along the lines of 'people not blowing sunshine and rainbows up your backside'.
Pot meet kettle x2.
This was an interesting thread that I didn't mind reading through. So what if someone brought it back from 2009? What's your point?
Mike.
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