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Discussion Starter · #1 ·
Anyone know how much the head on a 1.9l can be shaved untill the valves knock on the pistons? I am looking for about 10:1 and I was wondering if I could also put a mild cam in too, without bending a valve. Any help is appreciated...

Jeremy

lowered '94 Tracer wagon

http://www.cardomain.com/id/hiney
 

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Discussion Starter · #3 ·
let me clarify... casue the exhaust valve is open as the piston comes up, with stock duration how far can you shave the head before it results in a tick. In other words, what is the clearance of the exhast valve to the piston btdc?

Jeremy

lowered '94 tracer wagon

http://www.cardomain.com/id/hiney
 

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Non Interference head, hell ya could have the thing shaved (resonablly), and then throw a timing belt, and still not hear a "Tick" from your valves hitting... what you might hear though is detonation! (to high of compression to little fuel)
 

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This is nothing a little bit of clay couldn't solve. Yank the head, put some modeling clay on the top of the piston, and use a breaker bar to turn it over twice. cut the clay with a razor and measure it. problem solved.
 

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birddog said:
This is nothing a little bit of clay couldn't solve. Yank the head, put some modeling clay on the top of the piston, and use a breaker bar to turn it over twice. cut the clay with a razor and measure it. problem solved.
great comment, my dad does that to all the race motorcycle motors he builds.
 

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it still wouldnt be really worth it. thats the wonder ful design behind our motors. the non interfearance allows you to brake a timing belt at max rpm and have your motor live. thats why i dont use hondas. if you brake theirs your looking at a new motor. i wouldnt worry about it. just make sure you torque it down right.
 

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i have the head shaved and the blocked decked on my 1.9 in my wifes car and there are no ticks although im not possitive the compression. but i also have a gude cam. all is good.
 

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Discussion Starter · #11 ·
well yes dotonation is a problem with high compression... but i wasn't planning on going any more then 11:1. I figure 11:1, if you wanted to risk it with 87 octane you can... but i will probably be running 91 or so... also have a set of 280 injectors waiting for seals. I think those will take care of my fuel problem (with a 5.0 FPR)

on to my next question... cam duration and lift maximums and good street/strip cams for the 1.9's. i am estimating 150hp at the fly wheel with P&P, 11:1 CR, header, full 2.25 exhaust, 280's, and cam (i love messing around with dyno 2000 :p)

Jeremy

lowered '94 tracer wagon

http://www.cardomain.com/id/hiney

Edit: also... do the walls of the combustion chamber (on the head that is) travel on a parallel to the block for at least .08 inch? i know how much shaving needs to be done to reach 11:1ish (or at least how many cc's i needed to take off). if not i need to recalculate for how much the head tapers towards the valves, thanks...
 

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Well.. if you've ever tried this, you'll find out the hard way that a shaved head results in decreased CTC from the crankshaft pulley to the timing gear(s), so the stock belt just won't do...
 

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Discussion Starter · #13 ·
i don't think a .08 inch shave will affect it very much, and what ever it does change the tensioner should take car of most of it... (just gotta keep an eye on it after around 4,000 miles, it might stretch enough that the tensioner won't be able to keep it tight!!)
 

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You'll find that it's really not the tensioner that "solves" the problem, because the problem isn't length. It's the distance from tooth to tooth, and CTC. It really only applies to significant modification, but it's just something to be aware of. Chances are the belt will have enough flex to not have trouble, but if I were you, I'd leave the timing belt cover off to monitor tooth wear to make sure it doesn't fail prematurely.
 

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i had .050 taken off of mine with no issues. i did need an adj. cam gear to get it back lined up though.

i dont think many ppl know what the actual stock valve to piston clearance is. if anyone finds out, that right there will tell you how much you can shave off the head.
 

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its sposed to be about 9.5:1, but i think its a litter higher than that.

my engine builder didnt tell me what the CR was when it was done, but i did read somewhere that mentioned how many thousanths equals so much increase in CR.
 

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computer simulations and "ideal virtual dyno" testing by my engine builder estimates flywheel hp to be for all intents and purposes 140.

what do i mean by that? i mean the engine hasnt been on a real dyno and all power figures were tossed into an expensive computer program (NOT desktop dyno 2000), and then the fancy schmancy computer figured out how much power the engine should be producing.
 
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