Runs good but still low comp

[hondamanlxi]

After my last thread(massive efi problems) we got my car running good. Its fast enough to outrun stuff it couldnt before but..... the cylinders still only have 90-110 psi! I screwed with the valve timing and found out if i retard the v. timing the comp goes down. When we advanced the timing two teeth we got the comp to 150psi(this motor isnt stock). Of course, it ran like shit, but it still ran. Im starting to wonder if something is wrong with the crower stage 1 cam?! Any thoughts on this? I know this motor should run harder...


ps: we spun the motor over by hand b/f starting it up to make sure we didnt f up the valves.


***COMP NUMBERS EDITED TO SHOW TRUE COMPRESSION****
i had a freind of mine come over run another check and apparently i was doing something wrong

[Oldblueaccord]

After my last thread(massive efi problems) we got my car running good. Its fast enough to outrun stuff it couldnt before but..... the cylinders still only have 90-110 psi! I screwed with the valve timing and found out if i retard the v. timing the comp goes down. When we advanced the timing two teeth we got the comp to 200psi(this motor isnt stock). Of course, it ran like shit, but it still ran. Im starting to wonder if something is wrong with the crower stage 1 cam?! Any thoughts on this? I know this motor should run harder...


ps: we spun the motor over by hand b/f starting it up to make sure we didnt f up the valves.


Maybe its your cam. Big overlap gives you lower compression readings sometimes.

Can you give me some more info on your setup I remember part of it from the old thread. Cam , head work, pistons.

Did you use the formulas to see what your compression is susposed to be?

Vacuum reading at idle would be nice too it tells you alot on whats going on with the motor.


wp

[hondamanlxi]

-b16a Power-Plus mani
-65mm ford t/b
-header/2.5 piping
-fuel sys upgraded (pump/fpr/teg rail)
-msd 6al/blaster 2 coil
-nx wet (not used on new motor)
-p&p/port match/flow bench/rebuilt head
-crower stg 1 cam (260)
-completely rebuild bottom end (machine/race shop assembled-good warranty;) )
-not pistons, shaving... .07 worth! .05 off the head and .02 off the block. That should of roughly put me at 10/1.

everythings sealed up tight! no smoke and no leak/seepage on the comp gauge

[Oldblueaccord]

-b16a Power-Plus mani
-65mm ford t/b
-header/2.5 piping
-fuel sys upgraded (pump/fpr/teg rail)
-msd 6al/blaster 2 coil
-nx wet (not used on new motor)
-p&p/port match/flow bench/rebuilt head
-crower stg 1 cam (260)
-completely rebuild bottom end (machine/race shop assembled-good warranty;) )
-not pistons, shaving... .07 worth! .05 off the head and .02 off the block. That should of roughly put me at 10/1.

everythings sealed up tight! no smoke and no leak/seepage on the comp gauge


OK well I was thinking that you said the pistons were over the deck some and you had messed with the CC of the head or something I'm getting confused.

Still could be the cam maybe it is ground wrong. I think stock our cars should have a bout 150 psi cranking compression. You cranking the motor over 3-4 times too for the reading?

Thats a good idea if you can do a leak down test maybe the valves arn't seating correctly. If you put air into the cylinder and your valves leak it will seep out the oil cap or the intake you should be able to hear it. Rings it will come out the tail pipe.


wp

[Oldblueaccord]

BTW

What did your head flow before and after I'm knida interested?
I assume its the A20 FI head.


wp

[shepherd79]

on a healthy motor the compression should be 179-180 psi. what it looks like to me, is that when you shaved the head and block, now you have timing issues. you should get adjustible cam gear.

[hondamanlxi]

an adjustable cam gear isnt gonna do shit.
One whole tooth retarded=90psi,
One whole tooth advance=120psi
Two whole teeth advance=150psi

[system-f]

an adjustable cam gear isnt gonna do shit.


it might just let you adjust the timing without taking the belt off and give you finner incriments of adjustment

[guaynabo89]

After my last thread(massive efi problems) we got my car running good. Its fast enough to outrun stuff it couldnt before but..... the cylinders still only have 90-110 psi! I screwed with the valve timing and found out if i retard the v. timing the comp goes down. When we advanced the timing two teeth we got the comp to 200psi(this motor isnt stock). Of course, it ran like shit, but it still ran. Im starting to wonder if something is wrong with the crower stage 1 cam?! Any thoughts on this? I know this motor should run harder...


ps: we spun the motor over by hand b/f starting it up to make sure we didnt f up the valves.


I have a crower 26something degree cam and really didnt do much except open up top end and lose a little low end tourqe

[hondamanlxi]

see, i DONT need fine adjustment, i need major adjustment...2 teeth=160psi

[Oldblueaccord]

see, i DONT need fine adjustment, i need major adjustment...2 teeth=200psi


http://falconperformance.sundog.net/compcalculator.asp

Ok well I am really trying to figure some stuff out so bear with me. Link above is to a compresion calculator program.

I put in

Bore: 82.71mm= 3.256 inches
Stroke 91.mm=3.583 inches

I also put in 0.00 as you deck height just to start

Headgasket bore dia 3.300

I left the RPM at 1000 close to cranking as I could get it

I took a guessa as the CC of the heads chamber as 52 and i got 9.8.


I went with flat top pistons no relief ( 0)


NOW what I am trying to get at is move those numbers around just a little and see what happens to the CR. A CC of 60 on your head does what??

Yeah puts it in the toilet. I tried to get this point accross on the othere P+P head thread. A little goes a long way as far as metal removel in the chamber.
Whats this all mean. Well to me its means we need the numbers your motor builder used to create this monster otherwise your in uncharted territiory and prolly will never find a good answer.


wp

another link to a calc that takes differant deck hieghts
http://www.kb-silvolite.com/calc.php?action=comp

[shepherd79]

you can always put EFI cam back on and see if it is crawer cam. put stock EFI cam back on. set the timing to TDC and see if it will fix the problem.

[rjudgey]

hmm sounds like some kinda cam profile or and timing? as the others said if the crower is only 260 i'd go with putting in a A20A4 cam in from Ajusa or anything else you can find, try and use valve train from something else otherwise you'll damage your new rockers. Then adjust the stock pulley like i suggested but with the amount you shaved off you shouldn't be more than 4-5 degrees retarded which will only give you better top end. Sounds to me like crap cam, get a colt one or Delta or maybe Gude.

[hondamanlxi]

well if its a crap cam, a certain mod owes me $120;) Im pulling the cam tonight

[hondamanlxi]

ok the stock cam is in! My compression is over 210 a cylinder but... its not a fast as it was before(crower cam/100psi)

[hondamanlxi]

it was the cam! Its ground wrong on the backside of the lobes...it drops off at almost a 90 degree angle:( Ill post pics tommarow

w/o the cam or spray it runs a 9.8 in the 1/8, not bad at all;)

[Oldblueaccord]

it was the cam! Its ground wrong on the backside of the lobes...it drops off at almost a 90 degree angle:( Ill post pics tommarow

w/o the cam or spray it runs a 9.8 in the 1/8, not bad at all;)


alright sweet its running good. glad you found whats up.


wp

[Vanilla Sky]

i wanna see pics...

[hondamanlxi]

here ya go...

i know these suck, but try see the lack of a wear pattern on the lobes(esp the back). i was the 4th owner of this cam! All pics but the LAST ONE are for the cam gear side. Ive got 5 more pics after these

[hondamanlxi]

http://i2.photobucket.com/albums/y39/hondamanlxi/947db1f5.jpg
http://i2.photobucket.com/albums/y39/hondamanlxi/8f80d48b.jpghttp://i2.photobucket.com/albums/y39/hondamanlxi/db98f0d2.jpghttp://i2.photobucket.com/albums/y39/hondamanlxi/0e084dbc.jpghttp://i2.photobucket.com/albums/y39/hondamanlxi/S2010030.jpg

i hope you can see something in these! Like my freind said, "buying cams and carbs useds is dangerous, because they took em out for a reason!" Oh well :sad2:

[rjudgey]

hmmm,
doesn't look too bad, the reason for the steep drop off is to have a quicker time in closing the valves, somethings obviously off though as the compression sucks, also using a 2nd hand cam is bad for wear and also bad for rocker fingers, when you get another cam, you'll need new rockers or re-condition the old ones if not badly marked, i used various grades of wet and dry a 100% flat surface i.e marble top or glass top thick perspex sheet etc. then with a oscialtaing movement rubbed the rocker pads over varying grades of wet and dry till the surface was nice a smooth with a round contour, then polished them up with really fine wet and dry like 1500 grade or 2000. I'd go with a well known grind for yours, Delta is cheap basic grind, colt is interesting with it's tri grinds, can work in some engines and a lot of people have them and like, but their are a few of us tech buffs that fail to see what benefit it would have to a A20 head? But i believe it is good as the best way of finding a good product is to actually go by people who have tried it!! If you go for the mid range one that should do, the race one will probably be a bit too mad!! but something in the range of 270-280 with 9.5-10.5mm lift should be good, 260 i think with your mods is to little!!

[hondamanlxi]

whats weird is this cam has NO wear marks at all (except its groove "bearings" on the head. Their is light marks on the front sides of the lobes

[rjudgey]

it's not the wear thats the problem, it's just the way that crower grind their profiles, looks similar to my Pipercams profile but mine have more duration and lift, it might be that the profile just isn't that good. If you get stuck Pipercams do a wicked 272 duration grind with 10mm lift but i reckon go with what everyone has tried and tested as being good which i belive is mainly the colt cams tri flows.