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Is there any way to tell what's been done to my motor?

2K views 21 replies 7 participants last post by  GAmes 
#1 ·
OK, I realize the title sounds kind of stupid but here's what I'm asking. Do you guys have anyway of knowing what someone has screwed around with on your motor? I've read the beginner thread and KDP is tabbed. The truck blew a crap ton of black smoke with generous throttle application, so I checked the star wheel and it had no tension on the spring at all (seems like the easiest way for some kid to make it 'roll coal') so I fixed that. I'm timing it to 15.5* today and have gauges on it (98 5spd). I'm just wondering if there are any 'give aways' that someone has done other things to the motor/injectors. With the star wheel turned down I get just a haze most of the time when throttling it that the turbo cleans up pretty quick. RPM wise the truck seems to pull strong past 2500rpm which it sounds like isn't really what a stock one does? Keep in mind I'm not out hammering down on it just to drive around ( I drive exactly the opposite) but I would like to know if there is a 3gsk in it or not. Any way to tell these things with out tearing each of those parts down to see?
The timing on it seemed to be close to stock according to JD's plunger lift chart, for a 13.5* 215hp motor it should be .200 lift and mine was .197, or just a little over 13* probably.
 
#3 ·
OK, I'll check closer, of course now there is some on from me. What about the non tampering bolts I've read about on the AFC? What do they look like?
 
#4 ·
Sometimes tamper proof bolts are replaced with the same bolt or another tamper proof.
Makes it hard to tell if they've been messed with.
If the AFC spring was loose you can pretty much assume the plate has been slid all the way forward too.
Your have to remove the plate to see if it's been altered.
 
#5 ·
My PO replaced all the bolts with tamper proof ones. I was real surprised.
 
#6 ·
Being able to get fueling to 2900-3000 rpm does not mean you have a 3k gsk. Both my original p-pump and one I tested for about 5000 miles from a '96 would and neither have a gsk. One member's theory is that 215 pumps do not defuel at lower RPMs that pumps from automatic equipped trucks do. With the stock springs and time on a flow bench mine will now fuel to 3200+.
 
#8 ·
On my 97 215, fueling fell off at 2500rpms before I put my 4k's in.
Sorta pokes a hole in his theory then. It doesn't change the fact that stock springs can be adjusted to fuel past 3200.
 
#9 ·
Same story as pyro690, my 215 fueling would fall off @ 2500. Now with the 4gsk, different story. 2ed half of the theory still stands though.
 
#10 ·
Thanks for the reply's guys. I'll check the fueling drop off point. So in neutral if I rev it I should only see 2800 or so? if stock. And under a load down the road it will/may fall on it's face a little over 2500rpm? My timing ended up being at 16* give or take a little on my new dampner mark. Took a little trip already and doesn't seem to be a huge difference, turbo seems to spool a little quicker/sooner, egt's are basically the same, mpg are unknown exactly yet but seem like they may be a little better. I could swear by 'feeling out' the truck that it got it's best mpg at about 62-63mph (I guess 50mph would be better, but there are limits......) and know from my 300mile road trip and fixating on the fuel/egt/boost that it gets better gas mileage at 70mph than at 60-62? Anyone else found this to be true? I meant to set the timing at 15-15.5* but with my misinterpretation of how the gear lash would affect it, it ended up right at 16* according to the plunger lift chart from JD's.
 
#11 ·
Well it looks like I don't have any kind of a GSK in it. It pulls hard and fast and will rev all the way to 3000rpm but the boost really starts falling off at 2500rpm. Any point in a 3k GSK for someone who tries to keep it below 2000rpm 95% of the time? Will it help towing noticably?
 
#12 ·
it may free rev to 3,000 rpm but when under load it will fall on its face at a lower rpm. because the gsk defuels as you get closer to the governed RPM. In another word, the engine do not need lot of fuel to free rev to 3,000 RPM but will need much more fuel with a load to reach 3,000 RPM.

This is why most people get GSK so the engine will give much more broad, useful RPM range, such as being able to reach 3,000 RPM without defueling before upshifting.

I love my 4KGSK, worth the money :thumbsup:

Just like in the sticky "beginners thread", where 12VEG said:

Bang for Buck value = High!
 
#13 ·
Yes, go with the 4. I will gladly sell you my 3 if you want to go for that.
 
#14 ·
Thanks, that'll probably be in the future sometime. (3 or 4 GSK???) So anyway, I pulled off the AFC housing and discovered a few things. A PO put a fuel plate in it, the style that just has a triangular/j hook at the bottom. Apparently they just did what I guess a lot of people do with these trucks and I consider the lazy power gain setup. It looked like they just put in the plate and then slid the plate and AFC forward and called it a day after they backed off the star wheel to make it smoke alot. They never modded the AFC washers and it looks like they never adjusted the smoke screw either judging by the tamper bolts.
So on to the beginning of my tuning, I ground the lip off the washer and then flipped the washers too. I removed the cap for the smoke screw and adjusted it 1 turn in (I think) from where it was. Is there any problem with leaving the cap off of the smoke screw so I can adjust it as I drive it tomorrow? Is there a need to grind off .100 from the foot? If you don't and the fuel plate is slid all the way forward will the governor never get to the fuel plate?
What is the best gear to tune in? (5spd) On the way home today I did a couple of 5th gear stomps at about 1300rpm, the truck would pause for about 3 sec before boost started coming on and the truck really took off with no real noticeable smoke. (That is why I turned in the smoke screw to start off with and I'll go from there) It was pretty chilly this morning when I did that (just above freezing). I tried a 3rd gear stomp and it went through the usable rpms (2500) a lot faster but also seemed to smoke a little more in 3rd gear. weird??? I assume 4th gear would probably be ideal to tune in.
 
#15 ·
Look up this thread "Which to adjust first… Star wheel or smoke screw?" There is a huge discussion on it, some very good information. Take your time, read through it all, you will learn a lot.
 
#16 ·
I did read that and more, but thanks for the tip. I'm pretty confident that the preboost/smoke screw could use a little turn due to no smoke when first getting on it with no boost, and the laggy response.
I'll never plan on taking the engine past 3000rpm, or even up to it for that matter. At 2500rpm will there be a difference in the 4k vs the 3k springs? What do you want for your 3k springs?
 
#17 ·
I have 4K's in mine and I've never seen 4K.

Most I'll let it go is 3500 before I back off.
 
#21 ·
GAmes,
I've read many posts where people reference your 'magic' pump, no offense from me. So if I remember the posts correctly does yours 'pull' to 2900? and free rev to 3200? Mine will rev into the 3's but a hard roll on throttle on the highway definitely shows a start of defueling at 2500rpm. Think I will try going up a click or two, it's free except for the tool I'll make to get at it.
 
#22 ·
I don't free rev to 3200, I don't even like to free rev to 2500 to check fuel pressure. Totally stock and unmolested I could pull with my original pump up to 2900 and could also with a pump from a '96 that I test drove for about 5000 miles. After getting an oil leak fixed at a Bosch shop the original pump was benched and now pulls to, and probably past 3200. I don't go that high while driving, but got off the throttle at 3200 while on the dyno. Peak HP/TQ was 313/752 at the wheels, rpm was around 2250 rpm, at 3000 it was 240/400, 3200 rpm 200/340 which is about what the engine is rated at stock (215/440 at the flywheel). Not real high numbers, but not bad for stock injectors and turbo. I never dynoed with this plate and the 3k gsk I once had, so I can't give you a comparison..
 
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