Engine/Transmission (1994 - 1998) Is this normal or not?

[Johnstra]

I've posted about this in other threads, but I think it's worth a thread of its own. I'm trying to determine if my engine is normal or not. When I give lots of throttle, especially if I'm climbing a steep grade, my engine sounds and feels rough (at least it does to me). I have good power and normal boost for a #10 plate (little over 30 psi). Once the RPMs get up to 2k or so the engine smoothes out again. It's just at peak torque it feels to me like it's rougher than it should be. My fuel pressure runs pretty constant at about 22 psi. When I floor it it pulls down to about 17, maybe as low as 15.



So first off, is this normal for a 12V?



Second, if it's not normal, where should I begin looking?



I thought I'd start with my injectors. Pull them and have them tested. The only other thing that I can think is maybe head or valves. I don't have any particular reason to suspect a problem, just a hunch.



Any other input suggested are much appreciated.



Thanks,

-john

 

[Matthug]

Are you sure it's the engine and not the drivetrain? That sounds normal, you are putting over 700 ft/lbs of torque through your drivetrain now and it gets a little stressed LOL. I think it's mostly the transmission, mine is anyway. After I ground my plate and added the injectors I started having this noise too under 2000 RPM, the transmission doesn't particularly like so much low end torque and it kinda grunts back at ya.

 

[tp0d]

Well, what matt said definetly could be an issue. Mebe check your carrier bearing on your driveshaft for any play.



My question tho is, what is your timing set at? With that #10, you should be up around 16degrees for smooth running. Stock timing could cause a problem there... I may be wrong, who knows heh



also, whats the condition of your fuel feed lines? If you have any cracks/etc introducing air into the fuel, especially under high draw, that will cause rough running.



good luck



-j

 

[Johnstra]

Thanks fellas. My timing is set at 15* right now. I think I'll go ahead and bump it up to 16 just to rule it out. I have considered the fuel lines, so I'm going to go ahead and replace them with new to rule them out too. My fuel pressure is a little lower than I think it should be and I have a new lift pump and OF valve. As for whether I think this might be transmission/drivetrain... I wish I knew for sure, but it sounds to me like it's the engine.



I guess the main thing I'd like to hear from others is whether what I'm describing sounds normal. Like Matt said, is it normal from it grunt a little bit?



Thanks for the replies!



-john

 

[Howard Durand]

I think your fuel pressure is considerably lower than it should be.

 

[DJWyckoff]

I have had trans issues since before having trans issces was cool. and they've never been cool. I put a V-body in my auto like a band aid and procided to grind my own #10 plate wile the plate was out I drove the truck to work 1 day stock timing and no plate = noises rattels and bangs that were scarry o and so much smoke that if the guy behind you threw out his ciggaret he would shurly be incinerated. I have not yet fully adressed my trans but working here in MS will pay for my trans mods and more.

good luck

 

[DESL PWR]

John, in your sig, I didnt notice any upgraded clutch. With your mods, a heavy foot will cook that stock clutch easy. I am still waiting on the loan from the bank (my wife) to get a new clutch myself. I get that same growl and shake when my disk is giving up from a lead foot.

 

[Johnstra]

My stock clutch doesn't flat-out slip, but I can buy what you're saying that it's not happy with the power. A new SB OFE is on my list. I'll be working on this incrementally, so hopefully I can isolate exactly what's causing the noise/vibe and get her smoothed out.



First, I'll try to get my fuel pressure up. I'm replacing my rubber fuel lines today.



After that, I'll bump my timing to 16* to see what effect that has.



And then I'll probably be ready to get the new clutch.



-john

 

[Matthug]

If your timing is already at 15 I seriously doubt it's that.

 

[HPetrat]

Johnstra:

Same truck and almost the same set-up on the mods.

I just set my timing to 16*, after driving for 7 months with the timimng at 14. 5*. I can pretty much assure you that the timing change will not eliminate the sound or roughness you are experiancing.

Before installing my SBC Con OFE 13" clutch I could easily get alot of noise out of the old clutch (the luk gold clutch did not like torque :-laf ).

The other source of noise is the transmission. If you pour the coal to it from 1100 - 1200 RPM in fourth or fifth gear the gears will produce a chattering howl or groan (it's quite load too) that feels like the engine is running somewhat rough.

This is very hard on the transmission and should be avoided, as it will eventually eat-up the bushings and bearings in the trans.

Hope this adds some insite, it's just been my experiance.

Best of luck with it,

HP.

 

[Johnstra]

I appreciate everyone's input. Sounds like my truck is pretty 'normal', so I'll quit worrying I'm still going to make the changes I list above and see what difference they make. If nothing else, the clutch upgrade will serve me well.

-john