HKS 264/272 combo, lost 70 miles to a tank of gas. inconsistant idle. ok?

[Korndogg]

hey guys
About a month ago I installed the 264/272 combo. It certainly gave me a lot more power, especially around 4k rpm. It also gave me a pretty crappy idle. the idle would fluctuate a lot. I raised the idle RPM with the BISS and it smoothed out a lot after a bit of time. now it mostly fluctuates only while the engine is cold.

anyway, I have also lost about 70 miles to a tank of gas, especially when not doing highway driving, though that is affected quite a bit also. I was just curious if this is to be expected with these cams? or does this seem unusal to anyone?

I would think that this was normal (more air, more gas), however I was unable to find anyone else complaining of the same thing after a cam install, so I thought that that was fairly unusual. This is the only reason I ask.

Thanks for the info

 

[alexg1323]

you have probably lost some static compression, try adjusting your cam timing manually or degreeing your camshafts with adjustable gears

 

[Korndogg]

you have probably lost some static compression, try adjusting your cam timing manually or degreeing your camshafts with adjustable gears

and this would help both the idle and the mileage? or just one? also, how would I know where the sweet spot was with adjustable cam gears? and by manually I assume you're referring to shifting timing a tooth, yes? my 95 does not have an adjustable CAS


thanks

 

[1stGenRocks]

on dsm's 1 tooth = about 7 degrees so thats a big no no. yes you need adjustable cam gears to properly degree the cams. getting them set right will definately help your gas mileage and idle.

 

[Korndogg]

on dsm's 1 tooth = about 7 degrees so thats a big no no. yes you need adjustable cam gears to properly degree the cams. getting them set right will definately help your gas mileage and idle.

oh, my bad.. one of the big dsm shop sites (i'll be damned if i can remember the name of the site) tells that it is fairly common to change a cam by a tooth...

but anyway, if i buy adjustable cam gears, how do i go about degreeing them in? any write ups?
thanks

 

[sweet97]

Sounds like a lot of loss, 70 miles to a tank. My 1G holds about 12 gallons so that would be like 5 MPG less. I have straight 272's but I am in boost quite a bit but still can squeeze about 16-17 per gallon in mixed driving, much better on the interstate.
You can't degree cams without a dyno to truly see what is giving you the best power. I always thought static compression was just that, static-not changing. If you have 8.5:1 it's still 8.5:1. Please correct me if I am wrong. Mark

 

[Korndogg]

hey, thanks for the reply
i've been searching around on the topic and see now that it really needs to be done on the dyno..
however i've been reading that the hks's are very good at being right at 0º, so i don't see why i would be having these problems.. and when people reply saying that it soudns like i need to degree my cams to fix my idle/mpg, in what way do they think my timing should be adjusted? because if this really would fix my idle, perhaps i wouldn't need to go to the dyno for that.
still searching, but i'm not finding answers to that of course

 

[sweet97]

hey, thanks for the reply
i've been searching around on the topic and see now that it really needs to be done on the dyno..
however i've been reading that the hks's are very good at being right at 0º, so i don't see why i would be having these problems.. and when people reply saying that it soudns like i need to degree my cams to fix my idle/mpg, in what way do they think my timing should be adjusted? because if this really would fix my idle, perhaps i wouldn't need to go to the dyno for that.
still searching, but i'm not finding answers to that of course

GOOD MORNING AND MERRY christMAS! STAY UP LATE OR GET UP EARLY? i JSUT GOT WOKEN BY THE CAT SO IT'S BACK TO SLEEP SOON. MY 272'S ARE STRAIGHT UP AS MOST HKS CAMS ARE. I GOT MY IDLE DECENT WITH ADJUSTING MY IDLE WITH THE maf-tRANSLATOR i HAVE. ADDING FUEL OR TAKING AWAY WILL ADJUST THE IDLE. iF YOURS IS SEARCHING YOU MAY HAVE A VACUUM LEAK. cHECK FOR THAT WITH SOME STARTING FLUID, JUST SPRAY ON THE PIPING couplers AND SUCH AFTER THE MAS OR maf. Sorry about the mess, typing looking at the keys! Are you sure yours got installed straight up to start with? I don't believe adjusting the cams with adjustable gears will affect the idle. NOT the searching idle, I mean. Mark
PS: I'd be careful changing cam timing to get a good idle and risk having valves hitting pistons at high revs! Can you describe the idle furthur? www.VFAQ.com has instructiuons for setting the BISS/idle. Mark

 

[sleepyvr4]

changing the timing and you may risk the valves hitting pistons at high revs? If a valve is going to hit a piston it will do it at any rpm. If timing skips a couple teeth there's a good possibility that a valve will hit a piston, but "high revs" isn't like a danger zone or anything. Yeah you can float some valves at +9,000 rpms, but if your t-belt stays together you're not going to hit anything.

You can degree a stock cam one tooth off, it is no big deal. My friends and I have seen +/-5 degree difference in base timing via 1 tooth.

 

[Korndogg]

sweet97:
stayin up late

I did do a boost leak test and that came up negative. and the problem started when I put the cams in anyway, so i'm sure that that is not the problem. yes, it does sort of seem like it is searching when it is cold.. the idle will come down and the car will shake a lot (motor mount inserts really show that), then the idle jumps back up for a while. it has not been doing this lately while warm since i raised the idle via BISS.

i'm not 100% sure what you mean when you say "are you sure yours got installed straight up to start with?". i put my stock cam gears on, which were lined up with the dowel/pin. i then timed the belt like you normall would. all of the marks are lined up perfectly. i was very careful with that.

thanks

 

[WatchItExplode]

are you sure that your loss in gas mileage isn't just due to your lead foot enjoying the increased power? What I mean is, are you sure you're maintaining the same driving characteristics as you did before the cams, making it a fair comparison?

My gas mileage always decreases after installing a new mod

 

[Korndogg]

are you sure that your loss in gas mileage isn't just due to your lead foot enjoying the increased power? What I mean is, are you sure you're maintaining the same driving characteristics as you did before the cams, making it a fair comparison?

My gas mileage always decreases after installing a new mod

I hear you, but yes, I am sure. In fact, I am driving with a lighter foot now that I have winter tires on (which like to just spin after 4k).

I am only getting 200-220(TOPS!)MPT wheras I was getting 280-310 before the cam install, depending on percentage of highway miles