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Discussion Starter · #1 ·
I blew the head on my b20 after breaking the timing belt. Now, after installing a b21 head, when i hit the gas it struggles to pick up rpm. Once it hits a certain point it feals fine.It also does that random revving shit. It runs a little bit better when i advance the timing all the way. One thing i didn't do that might have something to do with this is change the intake manifold gasket. ANYBODY please help!
 

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the manifold gasket was the problem i had w. the surging idle in my 90....it could be the cause. cant hurt. there only like 15 bucks...u throwing any codes?
 

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Are you sure you aligned the timing belt correctly when you installed the new head? You may have accidentally put the valve timing off a tooth...
 

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diamondsleeper said:
Timing belt off one tooth on exhaust cam caused similar symtoms on mine
x2 Ditto, check your timming belt, the intake cam is most likely one tooth retarded (judging by the fact that when you fully advance the dizzy (which is on the intake cam) it runs better).
 

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check your ignition timing.
also...having the b21 head on the b20 block lowers your compression quite a bit ... 8.8:1 or 8.6:1 IIRC
 

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without proper mods most hybrid block/head setups ive seen all surge idle.

lsvtec, b20vtec, ect. doesnt hurt anything. idk how to fix it off the top of my head but every hybrid ive seen does this if it isnt modded properly
 

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That may be, but this should run pretty much perfectly (aside from less power due to reduced compression), seeing as the B20A/B21A are essentially the same motor, just different bore (and of course, the frm). Doubt it's anything more than off timing or gasket issues.

You did use the B21 head gasket right?
 

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88_2.0L said:
without proper mods most hybrid block/head setups ive seen all surge idle.

lsvtec, b20vtec, ect. doesnt hurt anything. idk how to fix it off the top of my head but every hybrid ive seen does this if it isnt modded properly
this isnt a hybrid...its a bolt on affair...
there's no modding :Rock:

oh...what head gasket did you use?
 

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all 3 have been mentioned, but noone said all 3 in the same post so here it is plain and simple:

1) you better have used a b21 head gasket, if not, you're gonna blow that gasket
2) timing belt is off, go back and remount it, and quadruple check that it is perfectly aligned on all gears.
3) get a timing gun and adjust the ignition timing properly, AFTER you remount the timing belt properly

and the rest is correct, this is not a hybrid setup, it is a simple bolt on. and the reason b21 head on a b20 lowers the compression is not due to the bore differences, but because the head's combustion chamber volume is different. b21 head has more cc's then a b20 head. same reason why b21 bore with b20 head raises compression
 

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motoxxxman said:
and the rest is correct, this is not a hybrid setup, it is a simple bolt on. and the reason b21 head on a b20 lowers the compression is not due to the bore differences, but because the head's combustion chamber volume is different. b21 head has more cc's then a b20 head. same reason why b21 bore with b20 head raises compression
well....if the b20 had an 83mm bore...you'd have the same compression as a b21 with the b21 head on the b20 block...I'd say that the compression is lowered because the bore is different
yes, the b21 head has a larger combustion chamber...but saying "the reason b21 head on a b20 lowers the compression is not due to the bore differences" is like saying "if I bore the cylinders to 85mm and leave the head stock, my compression wont change"
:Rock:
 

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Discussion Starter · #14 ·
well, that means i'm f*cked. I used a b20 head gasket! Whats gonna happen? When i drive it has really low low end power. once it hits 4,ooo rpm, it boosts like a v-tech. On the highway it runs fine.
 

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sorry, was trying to say that the better way to word it was that the reason the compression is different is because of the head's combustion chamber volume.
which is mostly due to the bore, but most people typically dont think of the bore of the head, they think volume size lol
 

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hiddenplague87 said:
well, that means i'm f*cked. I used a b20 head gasket! Whats gonna happen? When i drive it has really low low end power. once it hits 4,ooo rpm, it boosts like a v-tech. On the highway it runs fine.
ya man...check your ignition timing.
you might be fine with the b20 gasket...but who knows for how long




and its freaking VTEC!!!! :wzbigcry: :jehon: :evil smile: :devil: :glare: :wow: :newbie: :flipa: :rocketwhore: :mad: :notify: :uriel: :whatsthat: :camper: :rolleyes:
 
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