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Stops pulling on the big end?

M

Mr.Vintage

Active Member
Ok guys the last 1000 rpm or so my car just goes flat until the shift then pulls hard again it does this through the gears?

MODS: Adj reg, 42lb, TT race chip, race gas, test pipe stock turbo with waste gate closed, SM in place

SM #'s look good 810's KO's 3.0 or less around shifts seems like 1st and 2nd gears numbers are more erratic then in 3rd it settles down to 810's and 0 KO's

I have other mods to install but don't want to until everything I currently have is working properly

?'s Do these car run out of cam on big end (with stock turbo full tilt?)

Exhaust: is stock muffler limiting it at full boost? if so what muffler is out there that sounds like stock one but flows more? I DON'T WANT CAR LOUDER THAN STOCK

I want the car to pull all the way through the RPM band without missing a beat!!

Funny story I was out with my Boy's 14 and 12yrs old Saturday night cruising
Mazda speed and evo racing just ahead of us, Light ahead turns red Boy's yelling get next to them (rubs hands together) OK
So here we are 3 cars wide TTA, Speed and Evo the guy in speed is on my right and my oldest says you wanta go? this guy laughs at us and says OK but I have to warn you I'm going to suprise the Hell outta ya this car is fast it's got blah blah blah!!!! (His girls is with him)
(Thinking to myself I'm on MTDR's no way I'm losing to this clown from a dig) opposite light turns Yellow, I'm on the converter car starts pulling through the brakes, Light turns green TTA gone speed and evo somewhere behind us until we hit traffic!! OH YA BABY OLD SCHOOL STYLE THEY DIDN'T KNOW WHAT HIT THEM!!! Boy's are going crazy good times when speed caught up to us he had window rolled up and wouldn't even look at us "SUPRISED" ttarider
 
Great question I have adjusted to shift firm under normal driving conditions.

If I adjust it to be really soft during normal driving which I think is (moving it forward?) will it pull down the shift point down at WOT?
 
I think you need more evidence than that to rule out worn valve springs. If they are original(s),then more than likely they are "sacked out".
My LT1 valve springs probably have less than 10K miles and have been in the engine for a few years and the closed pressure is around 76-85 lbs as measured just 1000 miles ago.And they are sacked out. Now I kept them in so I could break in the flat tappet cam nicely, but they are coming out this winter and new ones are going in. My car flattens out too at the big end but I can't hear them but the car stops RPM-ing and you can see it in my data logs.
 
Interesting......
Mine still RPMs and I've been chasing a slight stumble in the top end, changed plugs gapped to .30 seemed a little better but still flattens out.
I'm losing roughly 800rpm on the top where it should still be pulling hard
Messed with TV cable today after earlier suggestion but didn't correct problem
So would sagging valve springs feel like an ignition problem?
 
At the top it kinda flutters like misfiring and flattens out but its very slight avg joe blow wouldn't know the difference.
So if a TTA flattens out in the last 800 rpm or so on the big end and still has stock springs is that a classic tell tell sign that it time to replace springs?

? any way to lower the shift point at WOT so I can keep it in the power band?

Thanks for all the help:thumbup:
 
Are you absolutely sure it's not detonating...it sure reads like it is. I suppose you could have a failing coil pack or module. But based on what I'm reading I'm still inclined to say valve springs...at best...and head lift at worst.

They are a cheap maintenance item, but somewhat time consuming to install.

What are your trap speeds in the quarter? and this is where a PL file comes in handy.
 
Its on straight TORCO 118 fuel so In my mind there is no way it's detonating...
SM 810's and 0 KO's in third at WOT to 100+
Exhaust?
Lets say it valve springs. What kind do I get, How long does it take for avg mechanic? Is there a hot tip thread somewhere that shows or tells best way to change them?

What about just lowering shift point? any ideas?

BTW: I have alky kit and 340 pump and TT chip to install but wanted to get it running perfect before I added these mods....
 
I guess All TTA's at this point need springs replace regardless of miles but because of age?
What springs did you replace them with and how long did it take?
Seat of pants difference after? Does it pull hard right to the shift point, or redline?
Was it worth the effort?
Kyle
 
Mr.Vintage said:
I guess All TTA's at this point need springs replace regardless of miles but because of age?
What springs did you replace them with and how long did it take?
Seat of pants difference after? Does it pull hard right to the shift point, or redline?
Was it worth the effort?
Kyle
Click to expand...

yes springs are needed if factory ... think abt it they have a load on some of them all the time when the engine is off ....On high lift race engines they take the rockers off during the off season to take the pressue off the springs ... If you replace the springs you might not have that detonation on top end because its putting alot of stress on the ignition but it does sound like a coil or moduel is going bad. I run my spark plugs @ .25 the more boost the tighter the gap
 
Just get some Comp 980's if you have the stock cam. They are around 90 pounds seat pressure at a rocker ratio of 1.700. The LT1's are good for aftermarket cams.

The 980's will take you to redline just fine, with less worry about wiping the cam.

Rich, post a screenshot of your PL for everyone to see. It is so easy to spot on a log it really is incredible. Of course, most with powerloggers race or change parts. I am willing to bet that unless you are a racer that races and is proactive, you need valvesprings. It is WAYYYY overlooked and people buy turbo's instead of springs to gain 3-4 MPH in the 1/4. I have had 3 sets of springs in my car. Two in the GN.

On the street it won't matter...
 
Last edited:
Quiky One said:
Rich, post a screenshot of your PL for everyone to see. It is so easy to spot on a log it really is incredible.
Click to expand...


I'll have to grab one off the laptop,I don't have it here at the house and I don't have any track logs on the home PC.
 
Becareful messing with the TV cable. One bad flare up could smoke the clutches. Push the tab and move the cable toward the firewall as far as it will go, release tab, get in car and push the pedal to the floor. Then leave it alone!

Comp 981 are another good choice. Good luck changing the valve springs. They are fun :chat:.


Joe
 
Black Shepherds & Turbo's said:
Becareful messing with the TV cable. One bad flare up could smoke the clutches. Push the tab and move the cable toward the firewall as far as it will go, release tab, get in car and push the pedal to the floor. Then leave it alone!

Comp 981 are another good choice. Good luck changing the valve springs. They are fun :chat:.


Joe
Click to expand...


This is the way mine is set, I think it is sometimes called having the cable all the way out. Shifts good with it set this way.:cheers:
 
Quiky One said:
For a stock cam??
Click to expand...


Yes, Stock cam and 30 over pistons. That is one thing I asked when I got my car back. How is the TV Cable set? He said it was all the way out.
Seems to do fine. Only had it at WOT a couple of times with no problems.
 
TTA984 said:
Yes, Stock cam and 30 over pistons. That is one thing I asked when I got my car back. How is the TV Cable set? He said it was all the way out.
Seems to do fine. Only had it at WOT a couple of times with no problems.
Click to expand...

I was talking about the comp 981's. Sorry about that!
 
Here's a very typical log snapshot. You'll see I'm still very much in it and it just flattens out and goes no faster and all but quits RPM'ing at around 5350 or so.

This is with a tank of 110 and a relatively conservative tune for race gas AND alcohol.Jason and I kinda came to the conclusion that the small KR at the end is the valve float and probably the harmonics of that event or that it is leaning out individual cylinders with especially weak valves.
screen.jpg
 
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