Walbro 255 fuel pump?

[HAWAIIZR-1]

Pete,

I'm all ears and have SGC Stage I cams too, but I don't know about any issues yet and very pleased with the way it runs. I have not flattened out at 7,200 rpms but only took it up that high once since I just broke it in and working to get pass emissions with different tune. Having said that, I'll know when I give up (fail) or pass emissions and put the headers back on with X pipe and some dynomax etc. and get it dyno tuned. I'll post the results and what issues I ran into.

I believe you if you said it about the exhaust cams as evidence by everything you have done so far and proven. Not all the tuners for the LT5 agree with each other, in fact they all seem to believe differently about certain things so understood. We all take the risks with who we believe or trusted at one time. Get me once, but you won't get me twice. Thanks for your honesty and sharing the truth.

Craig

[HAWAIIZR-1]

Originally Posted by Tony Davila

Pete I like your honesty. If there is something to be learned I am all ears.
I have Stage 1 cams installed that are my reground stock ones. Aaron Scott did mine for me back last April. I ported my own heads (saved in cost but almost had a heart attack), Aaron's machine shop put my tapperd valve guides in and did the standard 3 angle valve job. Aaron also timed my cams for me and I did the rest of the reassembly to get it running.

I am running 1 .75 Watson headers not the 2" from SW. I didn't think my 350 needed 2" headers and I was trying to keep my bottom end torque; I think it worked, I noticed no loss in bottom end but a re-dyno run will confirm. I am not smart enough to know if my exhaust cams are too big but I believe you, I just can't do anything about it now or would know the difference. Now you just made me feel better about having smaller headers then the norm.

My tune is from Aaron with secondaries removed....just to get it running until I can re-dyno it for proper tune. It is very close (A/F) though and it runs awesome.

Back to my original post about the Walbro FP, it was just a question to see if somebody has done it already. I based my FP issues off of my assessment and diagnosis of my FP pressure being 48psi on my secondary fuel pump and that it is over 20yrs........ I haven't had any issues with it until just recently. Thanks

The finished product......
Tony D.

Glad to hear you have been having good luck with Aaron Scott. I'm still waiting for my receipts for over 2 years now and my car barely ran with his tuned chip; but I did not even bother to go back to resolve and gave up.

[XfireZ51]

Tony,

BTW, I have 1.75" Watsons on my car. Frankly, I don't think the extra .25" makes any difference. Marc H. Has agreed whenever we have discussed it. Certainly not on a 5.7L motor. My opinion is that if you suspect a fuel pump,
then replace w the stock Suburban pumps. That's what I use. Replace the pump filter socks as well. However, I wouldn't conclude that the stock pumps don't flow enough unless there's a problem w them. Any chance you have a copy of the calibration currently being used? PM me if you 'd like.

[Demps]

I also have an SGC stg I cam'd 350. Runs like a scalded dog below ~6,800rpms. Pete and I have talked extensively about over-cam'd exhaust. I'm going to leave mine alone, mechanically at least. The car has an open loop chip--runs rich and gets poor gas mileage but has instantaneous throttle response. The FBI prom lessons learned don't/haven't translated to my '95.

When Aaron was interested in LT5s, there was none better. This was supposedly his first 4-bolt cam'd 350. Jim Smith went open loop as the cam tuning proved troublesome.

Ted

[Paul Workman]

Just following along here...

After scratching my head after all static indicators didn't turn up anything, taping the pressure gauge to the windshield and making a few WOT pulls reveiled issues with one of my pumps.



Adding insult to injury, the replacement pump (an Airtec, BTW) had a bad check valve, as it turned out, which introduced another round robin troubleshooting stint. However, in both cases, the fault was detected by this gauge taped to the windshield - dynamic - test.

Hope this helps someone.

P.

[Pete]

Originally Posted by HAWAIIZR-1

Pete,

I'm all ears and have SGC Stage I cams too, but I don't know about any issues yet and very pleased with the way it runs. I have not flattened out at 7,200 rpms but only took it up that high once since I just broke it in and working to get pass emissions with different tune. Having said that, I'll know when I give up (fail) or pass emissions and put the headers back on with X pipe and some dynomax etc. and get it dyno tuned. I'll post the results and what issues I ran into.

I believe you if you said it about the exhaust cams as evidence by everything you have done so far and proven. Not all the tuners for the LT5 agree with each other, in fact they all seem to believe differently about certain things so understood. We all take the risks with who we believe or trusted at one time. Get me once, but you won't get me twice. Thanks for your honesty and sharing the truth.

Craig

Ok,you guys asked for it LOL
I will get flack for this,oh well no guts no glory.
Let me say that any cams passed thru my hands have been checked/spec'd.

If a good tuner done some,not a whole lot just some and knows anything about performance 101 they would know that 75-80% Intake/Exhaust ratio is very good to perfect.
If they took the time and flowed LT5 heads either stock or ported they would find out I/E ratio is way above and beyond 80%.
LPE has done research on this and it shows on his LT5 cam specs he was selling.
So question is if I/E ratio is 90% do we need more exhaust especially on small cube motors.

If you guys went with Stage III intakes & Stage I exhausts with some extensive porting,i would say ok.
The issue i see with Stage I intake cams they are not much bigger if any over stock intake cams so it's like putting in big exhaust cams with stock intake cams.

The other issue is tuning it could be made to run ok but no matter what you do you'll get fumes at idle,overlap.

At this time i'm testing Stage III intake with .224 exhaust,i don't know if i went overboard with the cams for 350ci,we'll find out or will i have to go back to the smaller .236in .220ex

Need more proof i had Stage II .237 .440 cams on a 415 car made good power tuning was a mother, she ran ok but idle fumes were forget bout it.
Anyway we changed to .224 exhaust cams that was the only change we made, picked up 25-30 accross the whole RPM range tunability/driveability was way way better.
Need more proof Ted's 415 peak #'s are as good or better but look below that and forgetboutit.


Pete

[DaveK]

Thanks for explaining, Pete. Much appreciated even I'm not going there anytime soon
Always good to be informed though - never know when the lottery win might come!

[Demps]

Originally Posted by Pete

The other issue is tuning it could be made to run ok but no matter what you do you'll get fumes at idle,overlap.

At this time i'm testing Stage III intake with .224 exhaust,i don't know if i went overboard with the cams for 350ci,we'll find out or will i have to go back to the smaller .236in .220ex

Need more proof i had Stage II .237 .440 cams on a 415 car made good power tuning was a mother, she ran ok but idle fumes were forget bout it.
Anyway we changed to .224 exhaust cams that was the only change we made, picked up 25-30 accross the whole RPM range tunability/driveability was way way better.
Need more proof Ted's 415 peak #'s are as good or better but look below that and forgetboutit.


Pete

My 415 is good. Tune could use a slight tweak down low ~2,000-2,800rpms for drive ability purposes. Running LPE B cams:

The intakes are 239 degrees and .448 lift.
The exhausts are 221 degrees and .399 lift.

Ted

[HAWAIIZR-1]

Originally Posted by Pete

Ok,you guys asked for it LOL
I will get flack for this,oh well no guts no glory.
Let me say that any cams passed thru my hands have been checked/spec'd.

If a good tuner done some,not a whole lot just some and knows anything about performance 101 they would know that 75-80% Intake/Exhaust ratio is very good to perfect.
If they took the time and flowed LT5 heads either stock or ported they would find out I/E ratio is way above and beyond 80%.
LPE has done research on this and it shows on his LT5 cam specs he was selling.
So question is if I/E ratio is 90% do we need more exhaust especially on small cube motors.

If you guys went with Stage III intakes & Stage I exhausts with some extensive porting,i would say ok.
The issue i see with Stage I intake cams they are not much bigger if any over stock intake cams so it's like putting in big exhaust cams with stock intake cams.

The other issue is tuning it could be made to run ok but no matter what you do you'll get fumes at idle,overlap.

At this time i'm testing Stage III intake with .224 exhaust,i don't know if i went overboard with the cams for 350ci,we'll find out or will i have to go back to the smaller .236in .220ex

Need more proof i had Stage II .237 .440 cams on a 415 car made good power tuning was a mother, she ran ok but idle fumes were forget bout it.
Anyway we changed to .224 exhaust cams that was the only change we made, picked up 25-30 accross the whole RPM range tunability/driveability was way way better.
Need more proof Ted's 415 peak #'s are as good or better but look below that and forgetboutit.


Pete

Pete,

Thanks for sharing all your knowledge and experience with this topic about Stage I cams. Very valuable information and very curious how it runs in the end once dyno'd and fine tuned. Maybe someone like myself won't see or know the difference, but proven by your testing. I am very please with them and could have saved $800 based on your findings to have not replaced the exhaust cams and just the intakes. Now I am even more curious to see what is laid down to the rear wheels when all the tuning is done. I may never be able to drive my car like you do, but I sure do enjoy it none the less. Like many others, I'm not getting into learning how to tune these cars myself as I find mail order tuning only goes so far. Right now my car is running rich in all areas and conditions so it is being addressed too. Thanks again!!

Craig

[Tony Davila]

Originally Posted by HAWAIIZR-1

Glad to hear you have been having good luck with Aaron Scott. I'm still waiting for my receipts for over 2 years now and my car barely ran with his tuned chip; but I did not even bother to go back to resolve and gave up.

I understand you and you are not alone on that issue. I have heard it before.

Pete,

Thanks for sharing all your knowledge and experience with this topic about Stage I cams. Very valuable information and very curious how it runs in the end once dyno'd and fine tuned. Maybe someone like myself won't see or know the difference, but proven by your testing. I am very please with them and could have saved $800 based on your findings to have not replaced the exhaust cams and just the intakes. Now I am even more curious to see what is laid down to the rear wheels when all the tuning is done. I may never be able to drive my car like you do, but I sure do enjoy it none the less. Like many others, I'm not getting into learning how to tune these cars myself as I find mail order tuning only goes so far. Right now my car is running rich in all areas and conditions so it is being addressed too. Thanks again!!

Craig

Pete I agree with Craig, thanks....I could have saved $800. My tune I got from Aaron is pretty close, not perfect, it has its quirks but Jim Smith might have gotten the tune a lot tighter than before. I might still get a Haibec chip because I hear they are better with their tune.

Tony

Originally Posted by Pete

If they took the time and flowed LT5 heads either stock or ported they would find out I/E ratio is way above and beyond 80%.
LPE has done research on this and it shows on his LT5 cam specs he was selling.
So question is if I/E ratio is 90% do we need more exhaust especially on small cube motors.

Pete, I see and understand your point on what you said above. I might not have an issue with my exhaust cams being too big or I might have accidentally compensated for them being too big when I ported the exhaust side. I only cleaned up and improved the flow but did not hog then out. The port size is still smaller than the gasket opening. My goal was to port my heads for improved velocity both intake and exhaust hence my smaller header size. She runs awesome, I might have done something right and not know it.

Tony