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| Differences 8 valve vs 12 valve head http://4g61t.org/forum/viewtopic.php?f=17&t=5147 |
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| Author: | socrateez [ Thu Sep 11, 2003 6:28 am ] |
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[quote= BTW has anyone noticed drivability issues when reatarding the cam 5 degrees?[/quote] You only lose a few ft. lbs. of torque on the bottom end. the gain in Hp and shifting of the powerband is more than worth it IMHO. The onl thing ive noticed is that i had to get used to shifting a little higher rpm. Power doesnt drop off at high rpm now. All the power and torque sits in the mid rpm range and extends all the way to redline.  Try it, you can always set it back! |
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| Author: | The Ethereal [ Thu Sep 11, 2003 6:41 am ] |
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Sounds great! Will it work on a 12V engine also? I'm afraid of smashing pistons into valves, as it is not yet certain if the 12V head is also non-interference. |
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| Author: | pumaproton [ Thu Sep 11, 2003 8:22 am ] |
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Its well worth doing. I don't think I have much torque down low anyway, because I have a crack in my manifold. It's amazing, the power is up higher but there is no noticable lack of power down at the bottom. Yesterday I forgot I was in 3rd gear, doing 65mph because I'm getting used to driving a lot higher up on the power. Its great, I can put my foot down and it instantly pulls hard. |
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| Author: | Guest [ Thu Sep 11, 2003 8:52 am ] |
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I haven't followed this thread too closely, but when you guys are done discussing this, someone post a new thread with a summary of the differences so that I can move it to the 4g15 Archives. |
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| Author: | pumaproton [ Thu Sep 11, 2003 8:58 am ] |
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I'm collecting information on it all. I still think we need to find out about interefenerce or not on the 4g15s. I tried to work it out on a dead 12v injection, but couldn't turn the crank over by hand. |
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| Author: | The Ethereal [ Thu Sep 11, 2003 3:37 pm ] |
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Quote: I'm collecting information on it all. I still think we need to find out about interefenerce or not on the 4g15s. I tried to work it out on a dead 12v injection, but couldn't turn the crank over by hand.
Uh... did you remove the plugs before turning? Turning an engine against it's compression is for bodybuilders only. 
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| Author: | HondaHunter [ Thu Sep 11, 2003 3:46 pm ] |
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seriously...a gerbil can hand cranck a 4g15 
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| Author: | The Ethereal [ Thu Sep 11, 2003 3:48 pm ] |
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OK guys, let's get it on! The 8V EFI is reportedly non-interference. How about the 12V EFI, 12V carby and 8V jet-valve heads? Will a 8V EFI cam pulley fit a 12V EFI? Jason, as the initiator of this thread I think it's my job to post a summary. Oh I should u/l the updated 4G15.html file.... |
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| Author: | The Ethereal [ Thu Sep 11, 2003 4:01 pm ] |
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Quote: The 8v carby 4G15 block uses flat-top pistons and the head has hemispherical combustion chambers. The EFI 8v 4G15 block has dished pistons, the head combustion chambers are smaller and kidney shaped - the combination of which maintains the same CR as the carby engine.
(emphasis added)Oh sh... I got the table wrong!  I'll fix that soon!
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| Author: | pumaproton [ Thu Sep 11, 2003 6:05 pm ] |
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Yeah, I did remove plugs,first thing I did! Having nothing to lever one didn't help, flywheel I've had, and I was trying to pull on the end of the cam belt  Ethereal, would it be worth including some of the info I gave you? I can't believe there are differences between UK Colts and German Colts... Base timing with out vacuum advance-EFIs don't have vacuum advance on the dissy. |
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| Author: | The Ethereal [ Fri Sep 12, 2003 8:21 am ] |
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Quote: Yeah, I did remove plugs,first thing I did! Having nothing to lever one didn't help, flywheel I've had, and I was trying to pull on the end of the cam belt
Huh, that's strange. It should rotate really easily that way. If the engine still in a car, putting in the highest gear and turning one wheel should do it. Quote:
Ethereal, would it be worth including some of the info I gave you? I can't believe there are differences between UK Colts and German Colts...
Sure it's worth! Thanks for the info again! I have to apologize for not including it yet. I'll do a full update soon, promised!Quote:
Base timing with out vacuum advance-EFIs don't have vacuum advance on the dissy.
OUCH!  Stupid me!
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| Author: | The Ethereal [ Tue Sep 16, 2003 8:12 am ] |
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Guys, there's so much information here I decided to write up a 4G15 FAQ. Please be patient, I'm currently working on this. |
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| Author: | T__K__A [ Tue Sep 16, 2003 3:01 pm ] |
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I bent a valve on my 4g15 |
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| Author: | The Ethereal [ Tue Sep 16, 2003 3:25 pm ] |
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OH F***! How did you do that? Did you retard the cam and it didn't work out or what? Or did the timing belt break? do you have a 8V or 12V engine? |
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| Author: | mikbik [ Wed Jul 17, 2019 7:43 pm ] |
| Post subject: | Re: Differences 8 valve vs 12 valve head |
any update on this planning to swap a 8v carby head over a 12v carb head?? anyone tried doing this? |
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