Engine stumbles slightly at start of throttle opening up

[gnonyx]

Correction,
When the longer threaded studs of M8x1.25x50mm comes in I will replace all of the plenum bolts to threaded studs with nuts and torque them them down to 30 ft-lbs

[Steve Wood]

Wait! I thought you were talking about the intake! I don't know what the plenum torque is. Look it up!

[~JM~]

http://www.gnttype.org/techarea/misc/torque.html

Plenum fasteners not listed.

Throttle body to intake listed as 20 Ft.Lbs.

Water pump to timing cover listed as 115 INCH Lbs.

I'm guessing somewhere in that range might be good.

[Steve Wood]

I don't know what the factory specs are.  Given the size of the bolt/stud and the fact that at least one hole is going to be short on threads, I would probably stay under 144 inch pounds and I would use some locktite on the damaged set of threads to try to keep the stud from pulling out.

I always just snug them by feel using a 1/4" drive ratchet....  the gasket is not going to compress measurably and all you want is a nice clamp between the doghouse and the intake....  either it is flat, or it is not.

[Shimy87]

Thats why I like silicone 🤣🤣

[Steve Wood]

Yep! Silicone solves a lot of problems as long as the coat is paper thin. Use it thin and let it sit for 20-30 minutes to skim over before bolting it down.  Makes it easier to get off.  Silicone is a heckuva glue when put together immediately.

[gnonyx]

Hi Steve,
I know I haven't been on board, but the normal summer stuffs, cut glass edging, chopping trees, branches, and a hole lots of other crap landscaping brings.

Anyway, I tapped the plenum and used the arrival threaded studs of M8x1.25x50mm; used no RTV torque everything down, and did a smoke test, to which all was good, no vacuum leak.

I also did an exhaust smoke leak test, and also no leak except some smoke coming out of the turbo linkage where the wastegate rod connects to. Is this okay to have some smoke leak or is this part of the pre turbo exhaust leaks?

I'm also going to remove the fuel injectors and have them professionally clean and tested

[Steve Wood]

I believe that is above the O2 sensor so it should be fine.  

You are a busy man.  You do almost as much as I think about doing LOL

[gnonyx]

Hi Steve,
I didn't want to intervene the other thread so I will continue on mine.

1st, Thanks for the info on the valve spring replacement comment:

When your car does not want to rev up to the rpm it used to...

In other words, if it used to run up to 4800 rpm and shift out of second into third, but, now it gets to 4400 rpm and does not want to increase...it's time.

Most of the cars when new, had a spring life of about 40-50,000 miles if you were lucky.

I guess I will found out if I need to do the replacement once I put the car on the road, and finally drive it around now that I found the culprit of the engine having a slight miss.
The photo shows the control module epoxy had a major crack, and once the engine runs hot is when the miss started to happen.
I also replaced the new Delphi AF10056 - 3-1/2" MAF ( scanmaster #'s all over the place) to an old style AC 3" MAF type
MAF Translator setting:
MODE SW: ON, ON, ON, OFF
MAF BASE: 3
Here are the final scanmaster #'s
02- 519-675
AF - 05-06
LB - 38
BAT - 13.4
INT - 128-129
BL - 117-120
NPH - 0
CLT - 173
ATS - 112
R - 825-850
TPS - .42
IAC - 34-36
CC - 148-249
NAL - 0

OIL PRESS - 23
VAC - 16.5
A/F - 15.1-15.6

[gnonyx]

Personally, I think UR4 is getting pretty hot.  I would go UR-5, myself.

I see many people are going to very tight gaps.  I have never had a problem running 25 psi on 0.035" but I often set them at 0.032".  For normal boost, I don't think you will have any problem.

If you want to read what Earl statement on his Ebay item:
This heat range is correct for stock cars with minor upgrades to modded cars with basic bolt-ons.  If you're serious about tuning and getting every last little bit out of car that runs a little hotter than usual, the UR5's might be worth trying.(NGKs heat range is 'backwards'. Higher numerically = colder on a scale of 1-10)

I don't know about these spark plugs other than reading and hearing about them

https://www.ebay.com/itm/163122170495?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649

Hi Steve,
You were right about the NGK UR4 are hotter, I kept thinking about these spark plugs and found this NGK chart from Summit, and the NGK UR4 are hotter as the NGK UR5 are a bit cooler.
As I mention before I don't know much between a hotter or cooler plugs and how critical would it make a difference for our engine.
I finally got the right 3"GM MAF and the scanmaster readings on my last post above this post and can you please tell your opinion of it.
Thanks

[Steve Wood]

The O2s are slightly leaner than I would have guessed.  I would drive the car and if it feels good, I would stop worrying about stuff and enjoy it.  It looks fine to me

[gnonyx]

The O2s are slightly leaner than I would have guessed.  I would drive the car and if it feels good, I would stop worrying about stuff and enjoy it.  It looks fine to me

Thanks for the fast reply Steve, and enjoy the weekend