Inliners International Forums General Discussion Bench racing looking for an inline guru in eastern pa

i am having trouble tuning my 250 inline and i cant seem to find someone who knows what they are doing to tune it for me. i know who built the motors but he didnt really build to many and didnt do some thing that should have been done. i live near allentown pa and about 45 minutes from philly. thanks for the help

What's wrong with it?
What have you done to it?

By PA TNPK you are about 2.5 hours from the upcoming,Aug.14, Mid-Atlantic Chapter Inliners event at the Eastern Museum of Auto Racing in Latimore,PA. http://www.emmr.org
Look into the Events Forum for Mid-Atlantic and contact Steve Orrison. Not only will you get more info then you need, but you'll meet other Inliners as well. In any case Steve may be able to give you a contact in the Allentown area.

thanks for the info. well the motor has alot done to it i bought it used so i dont know everything but it was built for short track racing in a late model car. it has 12.5:1 compression by the ay it idles i would say it has a big cam 4 barrel 600cfm carb clifford intake and custom headers. but i cant seem to get it to run right i might be expecting to much from it but doesnt feel as strong as it should i just want to make sure everything is set right.

You're not going to fix it until you know what the cam is, both to set the lash and estimate the power range.
Where is the spark set now?
600 is a Holley 4150, yes? What list number? Has primary PV?
"get it to run right", meaning what? Doesn't start? Doesn't idle? Fouls plugs? Overheats?
Compression test shows what?
Leak-down test?

Carb is an edelbrock, set as it came out of the box except i adjusted the mixture a bit i know the valve lash is supposed to be .020 intake and .022 exhaust it has a solid lifter cam. it runs ok untill it hits like 2200 rpm right before the water meth injection kicks in now i do most of my driving at 1500 rpm or less because i have the stock 6cyl gears in the back. it has been fouling out plugs but they are too cold i was told it had a ar133 i bumped up the heat range to a 134. it runs a little hot like 210 215 i will do a compression test tonight and a leak down test too. thanks for the input.

set as it came out of the box?
It isn't set for anything like your engine. You probably don't have enough vacuum to hold the metering rods down.

Is there a way to adjust the carb so the little bit of vaccum I have would be enought to hold the metering rods down. This is my first non stock engine so I'm trying to figure things out as I go thanks for the help

First, you have to sort the spark advance out. What distributor, what initial, does it have vacuum?

right now i have a stock hei with a msd 6al controlling it and it has no advance. when i git it i was told the driver ran it at 36* locked timing as of today i am running 32* it runs a little better. but im guessing a vacuum advance would be better? i checked my compression and 1 had 100psi across the oard +/- 2psi but it went to zero pretty quick (valve overlap?)like i said before i really dont know much about performance tuning.

Edelbrock sells a complete tuning kit for there carbs.
http://www.jegs.com/p/Edelbrock/Edelbrock-Carburetor-Calibration-Kits/743615/10002/-1
You most likely need lighter springs for the metering rods.

The kit comes w/different metering rods,jets etc,,it's a nice kit!

When the springs are too stiff (engine does not make enough vacuum),you can actually hear the metering pistons hit the top of the access plates,(if your engine is quiet enough.)

You can also cut off some of the springs(make them shorter),but dont get carried away w/the shortning of the springs.

Your meth injection,,,how is it controlled as far as ,,is it progressive,or does it just turn on & pump & spray the same @ all RPMs?

Is this a drag car the engine is in?
What trans,manual,automatic,,torque converter,rear axle ratio etc?


MBHD

Your meth injection,,,how is it controlled as far as ,,is it progressive,or does it just turn on & pump & spray the same @ all RPMs?

Is this a drag car the engine is in?
What trans,manual,automatic,,torque converter,rear axle ratio etc?
this motor is in a street car which has recently become a daily driver ( due to a deer hit in my other car) it has a th350 trans with a shift kit and a 1800 stall converter( i know i need more stall) i dont know the rear gear raito it is a stock 67 chevy ii 6 cylinder rear (probally wont last long) as for the water/meth injection it has a progressive controller it kicks in at 2300 rpm and 4 vacuum and the spray gets stronger untill 1 vacuum. i looked in my owners manual for my carb and i cant read that chart to pick my jets and rods. i feel like i should know this stuff.

W/out having a wideband O2 reader/logger,it would be really hard to know what your A/F ratios are during WOT,or just cruiseing around..

What make is the meth inj kit?

I would guess the gear ratio is 308-355 range.
My friend had put a lot of abuse to his stock,but added posi unit to his 8.2" 66 Nova rear axle & had engines from 327- 406 SBC's making from 250 HP about 500 HP running a best of 11.8 ET

The metering rods are easy to take out & just look @ them to see the size/number stamped on them.

MBHD

i was thinking about getting a a/f guage. the meth imj. kit is made by a company called snow performance its the stage 2 kit its a nice kit

100 psi with 12.5:1 CR?
Something is wrong.
Either:
1. the cam is way, wayyyy too big (not likely)
2. the cam is 10° or more retarded on purpose (not likely)
3. the cam is timed wrong (#2 or 3 might have bent some exhaust valves)
4. you have no rings left
5. the compression isn't nearly 12.5

[quote=panic]100 psi with 12.5:1 CR?
Something is wrong.
3. thne cam is timed wrong.....is there a way to check this?
4. you have no rings left
i should be able to check if my rings are shot by putting a little oil down the cylinders then checking the compression again right? could the low compression also be a head gasket or is that not lkely because of how even the cylinders are?

Right - a head gasket is typically low between adjacent cylinders.
Oil will tell you something.
This is cranking with all plugs out, yes?
With the valve cover off, put #1 cylinder on TDC until both valves are partially open. Rock it a bit both ways. If the exhaust valve is doing more than the intake (farther and longer), it's retarded. If it's about the same, the overlap is close to split, which means the cam is probably timed OK (it may be a bad choice, but not a mistake or damage).
My guess is that someone just made up "12.5:1", or that they were changed before you got it.
You should be able to see a dome that big with a bore scope through the plug hole @ TDC

with the plugs out i can see the piston almost touches the threads for the plug. but i will check the cam timing tomorrow thank you

I know it's hard o see, but does it look like a dome? No dome = 10:1 or less.
A 12.5:1 motor, even if the cam is too big, should show at least 150 psi.
You can start on the jetting before you get the ignition done, but you must have the initial advance tied down so you know where your throttle disc is at idle. Unfortunately, this will also change if you replace your converter.
As suggested, the Edelbrock vacuum piston spring set will be needed in any case; for now, go at least 1 step weaker on the spring.
Let us know what jets and metering rods are in it now.
This is an AFB clone (counter-weighted secondary air valve), or AVS clone (spring-loaded secondary air valve, like a QuadraJet)?

IT REALLY IS HARD TO SEE BUT IT DOES LOOK LIKE IT MIGHT HAVE A SMALL DOME BUT I COULD BE WRONG. I THINK I WASTOLD THE HEAD WAS SHAVED DOWN TOO BUT ILL HAVE TO TRACK DOWN THE BUILDER TO SEE IF HE REMEMBERS. AS FOR THE JETS I HAVE TO WAIT TILL THIS WEEKEND TO PULL THE CARB APART

I had 12:1 compression w/flat tops & 4 valve reliefs.
I used a shaved down 194 head & the engine had 220-230 cranking compression,w/a cam having 236-238 in /exhaust duration @ .050

The pistons came out of the block .002-.004" Thats called a positive deck height,just like the stock LS GM engine have.

Talk about throttle response! Of course 3 DCOE Weber carbs helped also.
I have said it before,,,w/the 3 DCOE's & 12:1 compression,the engine was a torque monster,it was the best combo I ever had normally aspirated,,,& this was w/the 194 cylinder head

MBHD

Greetings . . .

Hey MBHD - you may have had pistons rated at 12:1 - but with those kind of cylinder pressures your static C/R was more like (220/14.7) ~15:1 at sea level.

Static C/R is simple arithmetic (PSI/Atmosphere). The pressure of one atmosphere depends on elevation - Atmospheric Pressure at Altitude.

Wikipedia says Telford PA is 425 feet above sea level - so 115psi/14.5 is 8:1 compression.

chevyiigul, you indicated that the car runs great until the meth injection kicks in. This could be richening the mixture to the point that the plugs resist sparking. Are the plugs black with carbon? This could be an indication of low spark voltage (cold plug? wires? cap? coil?).

Meth injection is typically used to overcome detonation by quenching. With the cylinder pressure readings you've measured this seems unlikely. Have you tried running it with the meth injection disconnected?

regards,
stock49

Hey stock49,
my pistons were not rated for 12:1,they were approx 10:1 flat tops,but I see what your saying.;-)
That explains why my combo made so--------much torque !15:1!!!! LOL
HMMMMMMMMMMMMMMMM torque!

Twisted6 has used the 12:1 pop-up pistons,but,,do not know what his cranking compression was.

MBHD

As you see, I'm making the same mistake again.

the plugs are black but i was told the heat range of the plug was too cold it was a ar133 autolight plug i switched to a ar134 and they are still black but not nearly as bad i am trying a 135 today. and i will try with out the meth inj thanks for the tips

Hi Panic . . .

"True, but 115psi/14.5 is 8:1 compression isn't." It is in fact a measure of static compression.

You are correct that effective C/R can be a hard thing to get ones arms around. And my original response was perhaps an over simplification.

C/R is a measure of volumes V@BDC/V@TDC - as the article you mention points out this is really a drawing-board measure - which is impacted by a lot of factors. Static compression is measure of pressures P@TDC/P@BDC.

I zeroed in on static compression or the overall-pressure-ratio because it can be very revealing about what is going on in the engine: Wiki Atricle on OPR

There is a table in the Wiki article which shows C/R versus OPR.
Because compression adds heat the pressure ratio is considerably higher than the C/R and grows faster as C/R increase. At a C/R of 10:1 the rise in pressure is 22:1. At sea level that is 14.7 X 22 or ~323 PSI.

I had a 327 V-thing that measured 12:1 compression by volumes. The cylinder pressures where just shy of 270 PSI. But that is way short of the theoretical pressure ratio of 10:1 C/R.

So a reading of 115 PSI at 425 feet of above sea level is just not indicative of a 12:1 C/R engine.

These two articles discuss the practical relationships between PSI readings and underlying C/R:
Van Ness
Andrews

regards,
stock49

Huh?

No worries panic . . .

Your original post was spot on. Not sure why you edited it away:


My post confused two fundamental concepts 'compression ratio' and 'static compression'. And perhaps over simplified.

Thanks for the fact-check.

BTW Great article.

regards,
stock49

Ok I changed my plugs again this time to ar135 one heat range up I also shortened my metering rod springs by one coil it seems to run better but it has no low end toruqe it it really sluggish off the line I guess that could be the gearing too? But my biggest issue now is the motor loads up at idle and I rev it up to clear it out and there is lots of black smoke from the exhaust (fuel) but it also keeps running after I shut the ignition off it sounds like a broken diesel running on three cylinders.

Unless you get rid of the cam, the rear axle, or the converter you're never going to have any low speed torque.
You don't have anything like 1800 stall.
Locked timing has to be fixed before you do anything else.

I have a stock distributor what would I have to change to run it on a higher horse motor?

Remove the locked timing, and time it.

Iits locked by removing everything in the dristributor... so just putting a stock one in will be ok even with only 5# of vaccum?

Hey chevyiiguy . . .

I am with panic. A locked distributor is for the strip where an engine is tuned to run wide-open-throttle for a few seconds.

For the street you need mech-advance and vac-advance. Switch to the stock dizzy - time and tune from there.

regards,
stock49

This is true,,,,,,but I would run a higher initial timing & less mechanical advance,,if you can get away w/a higher initial timing & not ping/detonate.

I did this w/my 250,throttle response was better & accelerated quicker & better mileage for my street car.


MBHD

X2 - because of the cam and low cranking compression more initial lead will probably be better, with the same total.

Where would be a good place to start with timing and how do you set total timing? All I have ever set is initial with the vaccum adv plugged.

You're trying to master skills that take most people 20 years (40 for me).
It's simply not practical to answer one question at a time from a remote distance, which then only provokes another question.
You were right the first time: you need to find someone to do this for you.

Patience! The purpose of the forum is to share the knowledge you possess and allow others to learn. Thankfully I'm still learning.

im not trying to master skills just learn them. im sure 40 years ago someone was there to help you and show you how to do things and im sure you improved on those basics to come to the skill level you have today. i do not have anyone in my life who deals with cars at all i have no one to show me how to get started, so i searched the internet and found the biggest pool of knowledge i could and asked questions. some people have shops they can hang out in and watch and learn this is my "shop". i thank you for all the help you have given me so far and i understand if you dont want to answer anymore. i had given up trying to work on this car and this site and this thread gave me the push i needed to do it myself, and now you are basically telling me that i cant. i might ask very basic questions but i want to learn as much as possible. sorry this was asuch a long post thank you for all the help i was not trying to be rude in any way.

Keep asking, I do.