Timing Belt Snapped

[grumpy rooster]

I think your comparing apples with oranges. The first graph your comparing it to was before you got the car tuned (ie without CROME). Now your trying to compare the current setup (with CROME tune) to that graph. Without getting it retuned I think the comparison is just confusing. Your comparing 2 different setups with 2 different tunes and trying to tie it down to 1 thing. And, the tune was done on a different dyno which again makes it impossible to compare numbers.

Maybe I'm missing something but to me, until you get it retuned, any comparison with some sort of relevance is not possible.

I'm happy to be proven wrong.

[dsp26]

OK i'm gonna swap out the IM/TB tomorrow morning and get a redyno with both chips...

i know honda's are sensitive to air but not 15wkw sensitive on a mild setup...

also i know my dizzy is somewhat screwed with bearing issues right before belt snap but even then the graphs don't indicate to me any ign issues either

damn IM swap is such a pain in the arse job, so tight and so shit in hot weather......

[delsol9000rpms]

man leave the IM & TB

yu left the cam gears when you took abit more off the head which would mean it would be little bit retarded with the cam timing... the afr's would be one cause of lost power.. howeever i reckon the cam timing could also be aswell as causing the change in chracteristic of the curve as adrian pointed out...

also take in mind if your car was tuned and then yu added the coil pack it could not be functioning properly and therefore not be burning the fuel correctly causing your afr's to be the way they are?? take all of these into consideration... you said yourself when you installed the IM & TB it felt a whole lot faster... so y would it be the problem now??? i rekon it hasnt got anything to do with that soo dnt waste your time pulling it off etc... also the retardation of the cam timing would cause a change in the afr's? could be lots of things

try resetting the cam gears... and also try your stock coil setup.. and get it re tunedd correctly at the correct afr's

[dsp26]

Maybe... I did consider the coil and pulstar plugs but the curve doesn't indicate ignition issues with the usual serrated knife edge look but hopefully i can test a few things on the dyno.....

Cam gears are still fine though... i only had it shaved an additional amount equivalent to going back from 0.5mm to the oem size head gasket... plus the workshop used those cam calipers to reset cam timing properly and then just add the BC3+ +2INT recommendation.

How did you go with your IM/TB?

[ZeForce]

Get it retuned and see how it goes.... dont get caught up with dyno figures as they can vary quite a bit from day to day in my experience

[delsol9000rpms]

i havnt put on my inlet and tb just yet...

[dsp26]

OK i'm going to recap

1) Built engine
2) Belt snaps 5000KMs later
3) Put back together


Setup is exactly the same EXCEPT the following changes from Step 1 to 3...

- Idle Fuel Pressure (Vacuum line on) from 40psi to 34psi
- Dizzy timing from 14* now retarded ALL THE WAY?!?!
- All valves replaced
- Valve seats cut again (Again)
- cyl compression went down from 230psi to 200psi

Now ive seen 2 engines lose power before from having the valve sinking in the seat (a 4age20v and sr20) and i was discounting that memory until recently 2 separate people/workshops reminded me that B-series engines make power in the head and that a sunk seat will lose power... my valve seats were reseated twice and chances are its beyond the Honda limit of 10 thou...

So tell me is the below powerband loss a result of valve seating? Plus the fact that dizzy timing had to be retarded aaaaaaalllll the way....
i'm losing my patience. Had i known this was going to happen I would have just sourced a head from here....

These are the justifications i was given:
*230psi to 200psi cyl pressure drop
- Non oem valve replacements.. "may have a bit more of a dish"...
- Fair enough but 30psi is ****ing huge

* Valves sinking in seat
- "Had to be done"
- Which is fair enough... but Honda specs limit it to 0.010" otherwise needs to get re-seated. and that minute amount won't look "sunk in"

* Different powerband on second pic)
- "The manifoldand throttlebody you put on isn't designed for it, if you take it off you get it (power) back"
- OK I did that.. made less power... was 91wkw but the curve changed back to how it was

Now i'm not ****ing stupid... i'm getting irritated because:
- I refuse to believe a reputable workshop would try to justify these as so...
- "tinkering" the dizzy and fpr to gain 2wkw additional peak doesn't equal the 5-8wkw i've lost from 2000-7000rpm.... and the fact the dizzy had to be retarded all the way is a ****ing huge diference.

[fatboyz39]

why isnt your air/fuel last time was 10:1 ? and now back to where it was?

[TODA AU]

These are the justifications i was given:
*230psi to 200psi cyl pressure drop
- Non oem valve replacements.. "may have a bit more of a dish"...
- Fair enough but 30psi is ****ing huge

* Valves sinking in seat
- "Had to be done"
- Which is fair enough... but Honda specs limit it to 0.010" otherwise needs to get re-seated. and that minute amount won't look "sunk in"

* Different powerband on second pic)
- "The manifoldand throttlebody you put on isn't designed for it, if you take it off you get it (power) back"
- OK I did that.. made less power... was 91wkw but the curve changed back to how it was

Now i'm not ****ing stupid... i'm getting irritated because:
- I refuse to believe a reputable workshop would try to justify these as so...
- "tinkering" the dizzy and fpr to gain 2wkw additional peak doesn't equal the 5-8wkw i've lost from 2000-7000rpm.... and the fact the dizzy had to be retarded all the way is a ****ing huge diference.

You seem to know the answers to your own questions but you’re just not putting it together.
Get back to basics & think of it in simple terms.
You’ve got larger than std cams,
If the cam timing is out,
this affects the dynamic compression of the engine & therefore what it shows on a compression test…
So, check/set the cam timing.

Valve seat sinking,
You know this is an issue…
It may not be perfect but it works.
If you want to fix it, pull it down & use 0.5mm oversize valves.
This will allow you to reclaim the seat.
Worse than sunken valves is core shift…
Hopefully you don’t have that…

Going back to your original intake manifold you can see plain as day…
The cam timing is retarded.
Lack of low end, then coming to life in the last part of the rev range.
Again check/set cam timing.
Once cam timing is sorted together with a good tune, you’ll probably make some decent power.

Dizzy being full whack one way or the other is not right…
Cam manufacturers aren’t complete retards rarely ever machine the distributors drive in the end of the cam, in a position when the timing cannot be effectively set.
If the dizzy is near the middle chances are the cam timing is near right, if it have to go full whack one way or the other.
Mate, you know the answer…
Check/set the cam timing.
Hope that helps

[dsp26]

You seem to know the answers to your own questions but you’re just not putting it together.
Get back to basics & think of it in simple terms.
You’ve got larger than std cams,
If the cam timing is out,
this affects the dynamic compression of the engine & therefore what it shows on a compression test…
So, check/set the cam timing.

Valve seat sinking,
You know this is an issue…
It may not be perfect but it works.
If you want to fix it, pull it down & use 0.5mm oversize valves.
This will allow you to reclaim the seat.
Worse than sunken valves is core shift…
Hopefully you don’t have that…

Going back to your original intake manifold you can see plain as day…
The cam timing is retarded.
Lack of low end, then coming to life in the last part of the rev range.
Again check/set cam timing.
Once cam timing is sorted together with a good tune, you’ll probably make some decent power.

Dizzy being full whack one way or the other is not right…
Cam manufacturers aren’t complete retards rarely ever machine the distributors drive in the end of the cam, in a position when the timing cannot be effectively set.
If the dizzy is near the middle chances are the cam timing is near right, if it have to go full whack one way or the other.
Mate, you know the answer…
Check/set the cam timing.
Hope that helps

Thanks for the details Adrian just wanna clarify some things though...

- I discounted the dynamic CR issue because the BC3+ low lobe wasn't that much bigger than stock.. 30psi difference between first build and now.... sooo.... so your suggesting i loosen LSA on the cams to reclaim some CR?
- Cam timing, you mentioned its retarded, currently setup at +6 +4, each marker on the gears = 2*@crank. i'm guessing the +4 +4 is to account for my head shave to reset to TDC.. the additional +2INT is as per Buddy Clubs recommendation. (those are rough observations btw, they were dialled on a degree wheel/tool)
- Is there any guideline I can use to somewhat gauge P2V clearance while i play with my cam gears with head still on? jack the car up and rotate wheels?
- does the graph indicate to you sunk valve seats? i just know it creates a powerloss due to the shrouding but i don't know the resulting curve characteristic and how much. Does this also mean cam gears have to be adjusted to account for the sunk amount? is this contributing to retard?

- i'm going to estimate that my head is shaved 0.040" / 1.016mm all up. rough guide from research says that every 0.040" removed = roughly +1 on cam gears or 2* crank.
- Written down on one of my papers was LATDC.... INT = 0.93mm/4.5*A + EXH = 1.04mm/1.5*
- so cam gear correction is roughly +2 +1 for head shave
- To loosen LSA is to advance int + retard exhaust? but this decreases V2V clearances right? but since i have sunk valves its less of a risk?
- wouldn't this mean +6 +4 is too far advanced already?
- Should i try +7 +5 to advance them more? or should i +8 +4 to loosen LSA some more? or since the top end is fine now +6 +2??

- relative to TDC (assuming 0 0) does the P2V clearance increase/decrease for the below scenarios:
Adv Int =
Ret Int =
Adv Exh =
Ret Exh =

- can you please explain "Core Shift". Is this something that should be obvious to a builder/head specialist?

- On a side note... how come i'm the only loser that lost power with an ITR (copy, aebs) manifold and 65mm TB?

- How did my AF change between Pic 2 and 3 from leaning FPR (i thought this would cause linear movement) + retarding dizzy all the way?

- Why are there so many drastic/extreme changes just to get me back to similar peak power + nowhere near the same midrange because i snapped a timing belt and had valves replaced?? when the engine was first put together cam gears were in the vicinity of +4 +2 and dizzy timing at 14* and fpr at 40psi??

- With some of the above info (especially cam timing so far advanced and dizzy so far retarded) does this still look like a case of cam timings retarded? or its powerloss from head failure?



But i'll be honest.. i can't afford to screw my own engine a 2nd time... my expense so far has already far exceeded a b18c7 motor :/ Are you able to have a look at it for me and do the fiddling? PM me?

[delsol9000rpms]

adrian speaks the truth...

[Benson]

losing 30psi is heaps!

Probably those cheapo valves you got in it now. Or something isnt sealing right.

Like Dave said the other night, the engine just feels lazy