Boost as fuel screw measure?

[Jgolden]

Does this make sense?

When I removed the lock collar from my fuel screw a while back I had to take out the screw to get the collar off. I counted the turns as I removed it but thats not too scientific.

I turned the screw a full turn past the guesstimated spot and did a test run to Myrtlebeach(Ok, so I'm retired) Max boost 15Lbs. No real egt problems.

Most of the posts I have read, show stock non-intercooled at about 15 lbs boost.

First,is it possible that all I did was get back to the original settings on the screw?

Second,I could use a little more power (ever heard that before?)for hills, and I drive by egt and boost, but I am tempted to leave well enough alone... ..... Is there a down side to more boost if I turn in the screw from here ?

Thanks all opinions

 

[CSchafer]

sounds a little low for a non IC truck, even stock I think they are closer to 20 but if the the fuel screw is messed with at all twenty five should be easy enough to get. Did your idel go up from from when you moved the screw? Just a half turn on my truck moved the idel up noticebly. I would turn it in a turn and see what you get and go from there. Hope this helps.



Cade

 

[dpuckett]

Yeah, I agree with Cade- turn it in a little bit more, and see what you have. If you dont like it, you can put it back. Plus, you drive by the pyro anyway, so you are safe there.



FWIW- when I got my early 91 (since sold), I could make 28psi at 6K ft- stock turbo and sticks. Got here, and had 32-33. New head gasket and PDR HX35- 35. 12cm housing- 40+ in 3rd- and in the red on pyro. Point is, you are low on your boost, and could use more turning. I could turn my screw past the locknut, "bumping" it back so to speak, on some trucks.



Daniel

 

[Jgolden]

Thanks folks. Time to turn it up a little.

 

[Smokey 01]

My stock 1990 had about 18 psi stock and after some tweaking ti put out 35 psi.

 

[Jgolden]

Okay, turned it up and now right about 20lb boost. Does heat up quicker, but not too bad. I'll take a trip in the near future for long run check out.

My guess is I'm just about stock plus a little.

Probably need better exhaust flow. Need to work on egt's.

Thanks for replies.

 

[dpuckett]

Timing can hlep your EGTs, but can also help the need for an updated head gasket. I had 30psi and blew the gasket when I bumped the timing to cut bottom end smoke. Oops. Drove it that way a while before I figured out what the weird noise was under acceleration.



Daniel

 

[Jgolden]

A few upgrades are on my list and headgasket is one. The rig is pretty heavy and with a car on the back it requires a little while to get up to speed, about like a school bus. (Wish I lived closer to Greenleaf)

A little more climbing stregnth with safe egt's and I'll be done.

Thanks

 

[PToombs]

Jgolden, if you want/need some help don't forget I'm not too far away,and love to turn screws! Really though I'd be more than happy to give you a hand if you need it.

 

[Jgolden]

Thanks, for the offer ,have a trip I've got planned then during the winter I hope to gather funds for summer upgrades. I'll give a shout when the time comes.

I know there was some attempts to get a group "get together" going in this/your area. Can use all the help I can get. Thanks again.

 

[Jgolden]

low boost/power answer

Found the problem

I have for a while been asking for and recieving good

advice on how to trouble shoot for low boost/power.

Turning up the fuel screw seemed to have little effect on boost. Did big air filter, changed out fuel filters etc. . each thing helped a little, but still a dog.

The real problem was this. My rig has an electric transfer pump. If I turned the key on, the pump sounded as if it was running. I "assumed" it was running. Actually it was sticking and barely turning. The regular Cummins lift pump could pull enough fuel through the electric pump when on a level, or under light load to run fairly well. Ad a stuck tank vent and getting up a long hill got to be pretty slow.

I replaced the electric pump today and what a difference. 20lb boost, reasonable egt's. Not a rocket, but lots of power and pretty good on hills. maybe now I can turn up the fuel a little or look for a bigger housing to get some top end power additions... ...

Thanks to those who have taken the time to answer my questions and help me eliminate possibilities. Another example of never assume... .



If my wife was a better sport and had agreed to hang under the rig and listen to the transfer pump run, while I climbed some hills, I would have figured it out sooner.

Thanks again.