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Re: 440 Compression
[Re: 383man]
#1158836
01/17/12 07:42 PM
01/17/12 07:42 PM
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Joined: Feb 2009
Posts: 583
San Antonio, TX
CurYellowBird
OP
mopar
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OP
mopar
Joined: Feb 2009
Posts: 583
San Antonio, TX
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383Man,
Who's pistons are those and what cc type of head are you running?
I just called my machinist and halted him from going any further. Told him that the CR was going to be too high to use a closed chamber head. He agreed and he also said that it would be better to go with a motor that utilizes quench anyways.
Project War Bird:
1971 Plymouth Roadrunner
383 4 speed with air conditioning
GY3 Curious yellow
All original
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Re: 440 Compression
[Re: dogdays]
#1158839
01/18/12 12:08 AM
01/18/12 12:08 AM
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Joined: Nov 2008
Posts: 671
Wisconsin USA
Bill MeLater
mopar
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mopar
Joined: Nov 2008
Posts: 671
Wisconsin USA
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Quote:
First of all with a B or RB engine the steel shim head gaskets are available so having a piston 0.020" down in the hole is all right. Squish with a closed chamber head will be at the optimum 0.038".
Second, I do not believe the RB deck of 10.725" was changed from 1958 to 1979. But those motors' decks are all over the place and famously not square, tilted front to back or even side to side. So spend the money and get the decks squared and you can set your piston depth at the same time.
Third, the Speed Pros are meant to be a stock weight replacement.
Fourth, the closed chamber heads are better and of the two, 915s are the best. They usually came with 84cc chambers, so a 78cc head has been cut a bit. However, the newest of them is 45 years old and things happen.....
Fifth, you should know that MOPAR engines of that era usually came with real compression ratios about one point lower than the advertised compression. So any 10.5:1 engine was really closer to 9.5:1, etc. If you build an engine to the published compression ratio it will have a hard time on pump gas. So I'd say run an honest 9.5:1 with the closed chamber head, , which means a total of 107.5 cc above the piston. With an 84cc head and 0.039" squish distance that means you remove an additional 5.5 cc from the chamber, probably can be done by unshrouding the intake valves a little. For a 78cc head you take off something like 11.5 cc which I would do by cutting a little off the top of the piston in the non-squish area. If you were to use an open chamber head I'd run no more than a real 9.0:1 so you'd have metal to move in that case as well plus a much worse combustion chamber. There's a reason that the new heads for most every engine everywhere have squish, you need it too.
All in all it's not that bad a situation in which to find oneself.
R.
Agreed, But don't forget to take altitude and cam timing (intake closing) into consideration....It all works together. Also....Make absolutely sure whatever head gaskets you decide to run with that block have the sealing rings for those extra coolant passages, not all of them do.
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Re: 440 Compression
[Re: JohnRR]
#1158840
01/18/12 12:09 AM
01/18/12 12:09 AM
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Joined: Feb 2009
Posts: 583
San Antonio, TX
CurYellowBird
OP
mopar
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OP
mopar
Joined: Feb 2009
Posts: 583
San Antonio, TX
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Appreciate the help and advice guys.
I'm going to model the short block and heads after the factory 440+6. Going to stick with the flat top 2355 pistons and go with a 906 or 452 with larger valves and some good port work.
Project War Bird:
1971 Plymouth Roadrunner
383 4 speed with air conditioning
GY3 Curious yellow
All original
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Re: 440 Compression
[Re: CurYellowBird]
#1158841
01/18/12 12:38 AM
01/18/12 12:38 AM
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Joined: Jan 2007
Posts: 7,664
IN
ahy
master
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master
Joined: Jan 2007
Posts: 7,664
IN
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Quote:
Are big block mopars really that prone to detonation? I know that working on a sbc that I never considered quench into the equation when I was building it and I've only ever heard the term with mopars. Did the factory ever utilize quench in most engine builds? Can you utilize quench without getting into high compressions?
"open chamber" combustion engine (MOPAR, Ford ect.) are prone to detonation. With a moderate cam, 9.0 to 9.5 cr max with iron heads. A big cam reduces detonation sensitivity as does a high stall convertor on an auto which helps the engine get past the points it is most likley to detonate. With a 4 speed, you will likley want to enjoy BB torque and accelerate from lower RPM from time to time so any detonation tendancy will show up. That's no fun.
If you want/need to do this in a single step, suggest shoot for 9:1 CR. You can be confident it will wind up somewhere between 8.5 and 9.5. As several have posted, the nominal 10 or 10.5:1/real 9.5 or 10:1 BB's of the late 60's would not like pump gas available today.
If you have a little time, I'd get the block cleaned up and decked just enough to get it square. Also get your rods measured. Then you will have actual deck height. Also choose your cam and ask Arrowhead cc's they would expect for their various heads. The other question, for you or your machinist, is what would be involved in fitting quench pad pitons? Quench pad pistons give the benefit of quench with open chamber heads... the pad needs to be machined to fit with .040: clearance, however. It is time and/or machining cost vs the benefit of quench. In the end, you will have to decide if the extra half point or so of compression is worth it. Then you can get better recommendations on piston, gasket and CR.
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Re: 440 Compression
[Re: CurYellowBird]
#1158842
01/18/12 01:05 AM
01/18/12 01:05 AM
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Joined: Jan 2003
Posts: 27,421
Balt. Md
383man
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 27,421
Balt. Md
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Quote:
383Man,
Who's pistons are those and what cc type of head are you running?
I just called my machinist and halted him from going any further. Told him that the CR was going to be too high to use a closed chamber head. He agreed and he also said that it would be better to go with a motor that utilizes quench anyways.
These are 440Source pistons with a 24cc dish. I use Indy EZ heads that were cut a tad to 70cc chambers (stock is 75cc) to end up at 10.6 and with good .046 quench. Ron
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Re: 440 Compression
[Re: CurYellowBird]
#1158843
01/18/12 02:22 AM
01/18/12 02:22 AM
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Joined: Jan 2003
Posts: 75,095
A Banana Republic near you.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 75,095
A Banana Republic near you.
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Quote:
Appreciate the help and advice guys.
I'm going to model the short block and heads after the factory 440+6. Going to stick with the flat top 2355 pistons and go with a 906 or 452 with larger valves and some good port work.
If this is your final answer then you better shoot for 9.0 compression or use a cam that will bleed of cylinder pressure , you would be better off with the KB icon piston and a closed chamber head.
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Re: 440 Compression
[Re: JohnRR]
#1158844
01/18/12 08:27 AM
01/18/12 08:27 AM
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Joined: Feb 2005
Posts: 4,321
Prospect, PA
BSB67
master
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master
Joined: Feb 2005
Posts: 4,321
Prospect, PA
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Quote:
Quote:
Appreciate the help and advice guys.
I'm going to model the short block and heads after the factory 440+6. Going to stick with the flat top 2355 pistons and go with a 906 or 452 with larger valves and some good port work.
If this is your final answer then you better shoot for 9.0 compression or use a cam that will bleed of cylinder pressure , you would be better off with the KB icon piston and a closed chamber head.
I agree with you, but there is an up side to his choice. If he builds a zero deck with 2355 or similar piston, 92 cc heads and .051 or thicker gasket he'll be around 9.3. Even at 9.3 he'll need to watch his cam choice/ICL. But, he can easily upgrade to an aluminum head in the future and get in the low to mid 10 CR with quench. I would however recommend some other 2.06 CH piston.
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Re: 440 Compression
[Re: BSB67]
#1158845
01/18/12 11:48 AM
01/18/12 11:48 AM
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Joined: Jan 2003
Posts: 75,095
A Banana Republic near you.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 75,095
A Banana Republic near you.
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Quote:
Quote:
Quote:
Appreciate the help and advice guys.
I'm going to model the short block and heads after the factory 440+6. Going to stick with the flat top 2355 pistons and go with a 906 or 452 with larger valves and some good port work.
If this is your final answer then you better shoot for 9.0 compression or use a cam that will bleed of cylinder pressure , you would be better off with the KB icon piston and a closed chamber head.
I agree with you, but there is an up side to his choice. If he builds a zero deck with 2355 or similar piston, 92 cc heads and .051 or thicker gasket he'll be around 9.3. Even at 9.3 he'll need to watch his cam choice/ICL. But, he can easily upgrade to an aluminum head in the future and get in the low to mid 10 CR with quench. I would however recommend some other 2.06 CH piston.
I'm not a huge fan of KB pistons... especially their hypers ... , but that Icon is probably a better 2.06 piston because of the dish allowing a lower compression ratio and being able to build for quench. I did a quench build with an open chamber head, it was a lot of work and a set of pistons that were almost $800.
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Re: 440 Compression
[Re: JohnRR]
#1158846
01/18/12 12:34 PM
01/18/12 12:34 PM
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Joined: Feb 2009
Posts: 583
San Antonio, TX
CurYellowBird
OP
mopar
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OP
mopar
Joined: Feb 2009
Posts: 583
San Antonio, TX
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My 71' Roadrunner is all numbers matching original. I had a spare 383 block but its missing the #2 and 4 main caps and the machine work alone was going to be more than if I had gone with just the 440.
The plan for now is to just have a good spare running motor while I build the numbers drivetrain up for a later numbers matching restoration. The 440 was complete and I only paid 220 for it out of the local pick-n-pull and picked up the 2355's and forged crank same day for 150. The spare 383 I didn't have a crank, rods, or pistons for, so it made financial and dollar to power ratio sense to simply build the 440.
This car is going to be street driven and will rarely see the the track. So my goal is to have a good torque motor making 425hp or better with stock hi-po manifolds and with the fuel injection.
Project War Bird:
1971 Plymouth Roadrunner
383 4 speed with air conditioning
GY3 Curious yellow
All original
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Re: 440 Compression
[Re: CurYellowBird]
#1158847
01/18/12 01:12 PM
01/18/12 01:12 PM
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Joined: Aug 2007
Posts: 1,271
Vista, California
67Satty
pro stock
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pro stock
Joined: Aug 2007
Posts: 1,271
Vista, California
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If this helps, here's a real world example of what you are talking about doing. I'm running the 2355 TRWs, 452 heads. .039" Felpro head gaskets on a .040 over 440. Pistons are zero deck, compression is about 9.5:1, cam duration is 238 degrees at .050. I'm running a 9.5" Dynamic torque converter that flashes to 4200. FBO distributor curved for my car (3600 pound '67 Satellite) and setup - 15 initial and 34 total. It runs fine with no detonation on 91 octane California swill, idles at 700 rpm, never gets hotter than 180 degrees. Drive it on the street all the time. Seems to pull hard but haven't taken it to the track yet to get an ET. Basic tried-and-true, mild 440 street/strip build that's been done a million times by others over the last 30-40 years.
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Re: 440 Compression
[Re: 67Satty]
#1158848
01/18/12 02:04 PM
01/18/12 02:04 PM
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Joined: Feb 2009
Posts: 583
San Antonio, TX
CurYellowBird
OP
mopar
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OP
mopar
Joined: Feb 2009
Posts: 583
San Antonio, TX
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Thank you 67Satty, that does help. I've got a 4 speed so I don't have to worry about a stall converter.
Project War Bird:
1971 Plymouth Roadrunner
383 4 speed with air conditioning
GY3 Curious yellow
All original
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Re: 440 Compression
[Re: JohnRR]
#1158849
01/18/12 09:11 PM
01/18/12 09:11 PM
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Joined: Feb 2005
Posts: 4,321
Prospect, PA
BSB67
master
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master
Joined: Feb 2005
Posts: 4,321
Prospect, PA
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Quote:
Quote:
Quote:
Quote:
Appreciate the help and advice guys.
I'm going to model the short block and heads after the factory 440+6. Going to stick with the flat top 2355 pistons and go with a 906 or 452 with larger valves and some good port work.
If this is your final answer then you better shoot for 9.0 compression or use a cam that will bleed of cylinder pressure , you would be better off with the KB icon piston and a closed chamber head.
I agree with you, but there is an up side to his choice. If he builds a zero deck with 2355 or similar piston, 92 cc heads and .051 or thicker gasket he'll be around 9.3. Even at 9.3 he'll need to watch his cam choice/ICL. But, he can easily upgrade to an aluminum head in the future and get in the low to mid 10 CR with quench. I would however recommend some other 2.06 CH piston.
I'm not a huge fan of KB pistons... especially their hypers ... , but that Icon is probably a better 2.06 piston because of the dish allowing a lower compression ratio and being able to build for quench. I did a quench build with an open chamber head, it was a lot of work and a set of pistons that were almost $800.
My point was if he builds a quench motor for iron heads today, he'll probably have to switch pistons on any future aluminum head upgrade to have decent CR.
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Re: 440 Compression
[Re: 67Satty]
#1158852
05/09/12 03:59 PM
05/09/12 03:59 PM
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Joined: Oct 2011
Posts: 460
Oklahoma
VoodooCLD
mopar
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mopar
Joined: Oct 2011
Posts: 460
Oklahoma
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Quote:
If this helps, here's a real world example of what you are talking about doing. I'm running the 2355 TRWs, 452 heads. .039" Felpro head gaskets on a .040 over 440. Pistons are zero deck, compression is about 9.5:1, cam duration is 238 degrees at .050. I'm running a 9.5" Dynamic torque converter that flashes to 4200. FBO distributor curved for my car (3600 pound '67 Satellite) and setup - 15 initial and 34 total. It runs fine with no detonation on 91 octane California swill, idles at 700 rpm, never gets hotter than 180 degrees. Drive it on the street all the time. Seems to pull hard but haven't taken it to the track yet to get an ET. Basic tried-and-true, mild 440 street/strip build that's been done a million times by others over the last 30-40 years.
This thread is a little old, but my plan is almost exactly what 67 satellite has. And then when i get the money to buy some aluminum heads it'll bump the compression to about 10.5 and have optimum quench. How is this not as good as it gets for iron heads which will soon be upgraded to aluminum using pump gas?
Satellite you ever get some track times, or dyno numbers?
I'm pumped about my new combo.
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