Carb/Trans/head issue after repair.

[rwcstang 201]

Hey everyone, 

 

So got my car back a few days ago and I noticed for some issues with my c4. When cold, it doesn't want to upshift when in Drive. It does go in reverse and 1-2 are fine when shifting manually, but when I go into drive it over revs, or seems like it goes back to 1st.

 

When the car is all warmed up the car can shift through all 3 gears, the shift points are much wider now as I assume they adjusted the shift points but they are denying they didn't touch anything. When Cold, I check the fluid level and it shows little to no fluid, when warm the fluid is at level. 

 

the thing shifted great before I dropped it off, I spoke with the owner of the shop to look into this.

 

I checked vacuum on the modulator, and I am getting pressure. Any suggestions? could it be incorrect fluid? or stuck relief valve? Its push-in modulator and trans was built by Performance automatic a few years back. 

 

Thanks, 

[Rcodenewf 44]

Just curious. What did you  take the car in for?

 

John

[rwcstang 201]

Just curious. What did you  take the car in for?

 

John

 

the car was smoking from the exhaust, We though the engine went bye bye, but it was actually the heads, the valve guides were installed incorrectly which cause wearing on the guides and valves which caused my Intermittent smoking issues. Spoke with the shop, the Tech the worked on my car adjusted the vacuum modulator so the car shifts are wider than what I'm used to. 

[1969_Mach1 333]

I would first check and adjust as needed the kick down linkage where it attaches to the carb.  Then readjust the vacuum modulator if needed.

 

I am curious, was your car smoking because the vacuum modulator started leaking and small amounts of trans fluid were being sucked into the intake manifold?  And after all the cylinder head work was done they thought, oops and replaced the vacuum modulator?  If the vacuum modulator was okay before, most tech's would not tweak on it after rebuilding the cylinder heads.  Just saying, the story as it is so far sounds a little sketchy.    

[rwcstang 201]

I would first check and adjust as needed the kick down linkage where it attaches to the carb.  Then readjust the vacuum modulator if needed.

 

I am curious, was your car smoking because the vacuum modulator started leaking and small amounts of trans fluid were being sucked into the intake manifold?  And after all the cylinder head work was done they thought, oops and replaced the vacuum modulator?  If the vacuum modulator was okay before, most tech's would not tweak on it after rebuilding the cylinder heads.  Just saying, the story as it is so far sounds a little sketchy.    

 

Modulator wasn't leaking or replaced prior, he wanted to adjust the shift points because he said the trans shift too quickly. I did see the old valve guides and they were F**Ked beyond repair. Told Him Im taking it back so he can revert it back to the old shift points. 

[barnett468 418]

I checked vacuum on the modulator, and I am getting pressure.

and just exactly how did you do this?

 

remove the modulator vacuum hose from the engine and suck on it or blow into it or put a vacuum gauge on it . if it passes air, the modulator is bad or the hose going to it is bad or is not connected.

[rwcstang 201]

and just exactly how did you do this?

 

remove the modulator vacuum hose from the engine and suck on it or blow into it or put a vacuum gauge on it . if it passes air, the modulator is bad or the hose going to it is bad or is not connected.

I used a hand vacuum pump gauge, was holding pressure 

[rwcstang 201]

so update, after weeks and weeks of back n fourth the car is still not shifting when cold. Now before I start off this rant, Im going to say what was done to the motor when I first had it in there:

 

They rebuilt the heads, they said the valve guides were crooked and were installed incorrectly, which caused my smoking issue (this was resolved). The tech also offered to port & Polish my heads, saying he needed to bring down my compression, he said it was at 12:1 and even with 91 octane my car kept pinging. I gave the greenlight on this, pinging issue is gone now but this is when issues started to arise.

 

also, hey wanted to also change my holley's main body and wanted to tune it better, only thing that would be gone is the electric choke. I okayed this aswell..he also said he re-curved the distributor...I didn't okay that but he said it was necessary.. at this point, I was getting concerned that he was doing things with out my approval here..so I am wondering what else he did without my approval here.

 

at first, when the tech re-installed everything back he told me the trans wasn't working and didn't want to go into any gear and further diagnosis the front pump failed and he let the owner of the shop know and it wasn't going to cost a cent to me. I gave the green light and he changed the front trans pump. After this is when sh*t starting to really hit the fan...

 

when I picked up the car the thing wouldn't shift, this is when the gears were shifting at a wider band aswell, I didn't like it and told him to go back to the way it was cuz I did not okay to widening the shifts and he shouldn't have touched this in the first place, he kept saying it's my linkage and I didn't believe that was the issue. Took it back to the shop again and it was there for roughly a month and they said changed the vacuum modulator, when I picked up the car it would shift fine but the car was warm when I picked it up. I asked if it would shift in cold the tech said yes... so I told them I would leave the car overnight and pick it up in the morning.

 

Next Morning - I discovered quite a few issues here.

 

1. Issue persist when cold - not shifting until the car is warm, I would manually shift to 1-2 and it would shift but when I shifted to 3rd it would over rev so I took the car back and told them to work on it- during the whole month of back n forth they said they took the car to the transmission shop and they said mechanically the trans is fine..( I don't believe this) as there is something wrong and saw no paper work. He kept saying it was the shift linkage, I said that was false, cuz it shifted fine before when I brought it to him.

 

2. also, During Cold start up I kept getting a popping noise in the exhaust it would happen once in a while.. then would go away when warm. Tech said it was the "valves"

 

3. Also, The brakes are rock hard I didn't notice this when cruising but when I speed up and tried stopping I felt I was riding on manual drums. The brakes wouldn't grab like they use to, I almost shat myself. I also looked at my brake fluid and noticed my Master Cylinder rubber gasket is slightly swollen and herd a slight whistle or wheezing when I put my foot on the brake pedal really hard.

 

When I brought the car back I told the tech my concerns, The Tech Didn't like what Im saying this to him, and he says he feels the brakes are fine.. and transmission is fine and he wasn't going to put in free work until more money involved. he said I had to adjust to these new "settings" I said no, and that's b.s, told them they ripped me off and I would be calling BAR on him and taking this into a legal matter.

 

While in the Heat of the argument, he tells me that it could possibly be a bad brake booster or due to the porting of the heads and Manifold Vacuum is lower and it could possibly be why my trans is not shifting and brakes are rock hard. he said to get a Vacuum Canister for the brakes to compensate...at this point i was pist.

 

Tech Refused to work on the car from here on out, I called the owner of the shop as we worked with him before for many years. In the end the owner said he would fix the transmission issue but taking it for an inspection and rebuild, I told him to write it that on the invoice which he did, he apologized about what I was getting into and didn't know what was going on...to an extent. Only thing he told me that he will fix is the Transmission and if I wanted to revert back to the holley carb i had but as for the brakes he said that was going to cost me.

 

I took the car back home and told them, that I will be getting a second opinion.. at this point I am truly dissatisfied. The week after, this the owner calls me to see if I took the car to another shop yet, I told them no but I will be taking it when I am on vacationion break starting next week.

 

Help Guys, Im Lost at this point Im already getting the paper work and making this into a legal matter.

 

so is it true that porting heads will lower manifold vacuum? I used a vac gauge and measured my manifold vacuum and saw I was getting 12-14lbs of pressure. I found another shop but this point, I exhausted almost all my funds Im actually wanting to take the car to a new shop and fit the other shop the bill. Though the owner is willing to work things out it seems he only wants to fix the Transmission issue and carb issue but not the brakes. should I go foward with this?

 

end rant... sorry if this is confusing to anyone it's late, I working right from home right now.. need to catch some z's.

[barnett468 418]

yes, porting heads can lower vacuum and so does lowering compression . this will have some affect on the brakes and trans but its hard to say how dramatic this affect will be . i would call performance automatic but it sounds like your trans is nearly trash . it is not a fluid type/brand problem but type f will make it shift firmer than dexron/mercon .

[1969_Mach1 333]

Did they actually port the heads?  Their claim was to stop detonation, so did they only debur/polish the combustion chambers.

 

Did they installed an HP style main body?  If so, there is now no choke assembly.  The popping out the exhaust when cold can be lean misfires.  If it were my car, I would first put the carb back to its original condition.  In the process make certain the kick down linkage is properly adjusted.

 

Could be coincidence, but I find it suspicious the trans worked fine before this work was done.

 

This job snowballed into a mess.  Probably to cover mistakes.  Time to find a new shop. 

[rwcstang 201]

Thanks for Response. I figured this the build hit the wall.. I wish I can do this myself just don't have the time for it due to work and have no garage work under and its super cold right now.. lol 

 

yes, porting heads can lower vacuum and so does lowering compression . this will have some affect on the brakes and trans but its hard to say how dramatic this affect will be . i would call performance automatic but it sounds like your trans is nearly trash . it is not a fluid type/brand problem but type f will make it shift firmer than dexron/mercon .

Thanks Barnett for the Clarification I will give them a call today and try to figure the trans issue, but sounds like vacuum is the culprit here. Question, If I were to buy new heads, will this resolve my issue? I assume I will need to revert back to the old style type heads or pick a new type of head here..I feel like these heads gave me so much grief..

 

Did they actually port the heads?  Their claim was to stop detonation, so did they only debur/polish the combustion chambers.

 

Did they installed an HP style main body?  If so, there is now no choke assembly.  The popping out the exhaust when cold can be lean misfires.  If it were my car, I would first put the carb back to its original condition.  In the process make certain the kick down linkage is properly adjusted.

 

Could be coincidence, but I find it suspicious the trans worked fine before this work was done.

 

This job snowballed into a mess.  Probably to cover mistakes.  Time to find a new shop. 

I came in to see the heads when they were off, he was already starting to grind the combustion chambers before even asking me. they just told me this will lower compression. Kinda got f*cked on that one and he didn't tell about that I will lose compression.

 

Im looking at a new shp right now so hopefully someone can help me out... sucks. 

[1969_Mach1 333]

Yeah, I'll bet next time you won't let that happen.  Since the heads needed valve guide work as well, maybe other cylinder heads with larger combustion chambers would have been a viable option.  When I was younger I worked at both an independent shop and a GM dealer for a  8 or 9 years.  Neither place would take initiatives like that without informing the customer first and getting approval.

[barnett468 418]

ok, no, just bolting on new heads will not cure your problem . you really need to start from the beginning and give us ALL your specs for any of us to be of much help, however, doing a drive test with a vacuum gauge and calling perf auto with the info is something i would do . i know engines but i don't know much about trannies but if you have a huge cam, you probably should install a full manual valve body . it sounds like you have incompatible parts.

 

if you want much more vacuum, buy a much smaller cam . that is the answer.

[rwcstang 201]

Hey Barnett, 

 

Thanks for the tip, I do have the build sheet, but the only thing that I cannot find is the Cam Specs.. 

 

 

 

 

 

[barnett468 418]

cant help ya without all the cam specs and cylinder head info.

[1969_Mach1 333]

Plus, there just isn't the right information within all those spesc to determine anything.  No specs for the heads, combustion chamber volumes, intake and exhaust port volumes.  No valve relief volume for the pistons.  No head gasket bore diameter.  Not enough info needed to calculate just the static compression ratio.  No cam specs, not even a mfg and part number.  Why are they so secretive?

[DocWok 30]

I may be able to assist with one of your issues, the one with popping noise from exhaust during cold start up then goes away when warm.

 

I had the same issue a couple of weeks ago, turned out the idle mixture was too rich, guess the extra fuel was still occasionally burning out through the exhaust when the engine was cold, but after the engine warmed up it disappeared.

 

Anyway it turned out to be a simple fix, adjusted the idle mixtures as lean as they could go before the rpm's started to drop and that solved the problem, no more popping out the exhaust on cold starts.

[rwcstang 201]

cant help ya without all the cam specs and cylinder head info.

 

 

Plus, there just isn't the right information within all those spesc to determine anything.  No specs for the heads, combustion chamber volumes, intake and exhaust port volumes.  No valve relief volume for the pistons.  No head gasket bore diameter.  Not enough info needed to calculate just the static compression ratio.  No cam specs, not even a mfg and part number.  Why are they so secretive?

I understand, I will try to call FPS this week and find the info needed. It seems from what I am understanding, I need to start from scratch. 

 

In terms of re-building a streetable 393w, can my bottom end be salvaged? if so what info do you specs do you guys require? I assume from what 1969_Mach1 specified the piston spec & valve reliefs. When I first got this motor I was told it should run about 450hpw 420tq I had no problem of course when the engine was installed, minus the intermittent smoking, but I had no issue with braking or shifting until I went to this guy.

 

Can I build a 393w but still be achieved the hp without sacrificing vacuum? just trying to wrap my head around this if it can be built it not, I'm willing to sacrifice the hp/tq I wanted achieve and to have something streetable.

 

I may be able to assist with one of your issues, the one with popping noise from exhaust during cold start up then goes away when warm.

 

I had the same issue a couple of weeks ago, turned out the idle mixture was too rich, guess the extra fuel was still occasionally burning out through the exhaust when the engine was cold, but after the engine warmed up it disappeared.

 

Anyway it turned out to be a simple fix, adjusted the idle mixtures as lean as they could go before the rpm's started to drop and that solved the problem, no more popping out the exhaust on cold starts.

That's awesome, I will try to figure this out as soon as I find out what I really have in terms of parts, i.e heads, cam, pistons. 

[barnett468 418]

we have no idea if you will be sacrificing any power or need to start from scratch until we have the cam and head specs.

 

you can make "decent" power with a 393 and automatic shifting trans

 

do you even know what heads are on it?

 

you also need to post your goals

 

rough or smooth idle

 

torque monster or 8,000 rpm revver

 

how much freeway driving do you do

 

do you want an automatic shifting trans or a fully manual valve body

 

gear ratio

 

tire size

 

favorite brand of beer

 

your ol' lady's vital statistics

 

etc

[1969_Mach1 333]

Lean misfires when cold creating a popping sound in the exhaust are more common than too rich causing popping.  If it is that rich the motor will be running terrible at the same time.  Does the carb have a choke anymore after the main body was replaced?  A simple check if there is no choke, when the motor is cold and running, cover the carb with your hand and see if the issue gets worse or better.

 

I have seen too rich when cold to the point a muffler exploded.  But the motor ran terrible at this time as well. 

[barnett468 418]

the fuel mixture screws should always be set when the engine is up to operating temperature because this is where it will be operating at 99.999% of the time . adjusting them when the engine is cold serves zero purpose.

[rwcstang 201]

we have no idea if you will be sacrificing any power or need to start from scratch until we have the cam and head specs.

 

you can make "decent" power with a 393 and automatic shifting trans

 

do you even know what heads are on it?

- As of right now, no but I looked at the Avenger Head Catalog and found two heads that may match my set up. I think they its either the 205 head or 215CC head on my receipt it says "SBF 2.08 1.6 195cc" but, I dont see the 195CC in the catalog. So it might be one of these two. I also found the part number to my Pistons from AutoTech/RaceTech pistons which I will attach on the bottom. Unfortunately, I called the engine shop that built this engine, spoke with someone and they tried helping but couldn't get info on the heads or cam specs, only thing it says it has a hydrualic roller conersion. they said that they will give my name and number to the owner as he may have a better understanding, as it looked like it was built by him. Haven't gotten a call yet..so I think I just hit a wall on that one. 

 

-Also found the p/n of my piston, They are RaceTech/AutoTech ATP-1000446

 

you also need to post your goals 

-Original Goals was to make as streetable stroker with 400-450

 

rough or smooth idle

-I do like the mild rough idle, enough to be noticed.

 

torque monster or 8,000 rpm revver

-This will only see street, I doubt it will rarely see a track. Currently running a hughes 2500 stall Convertor

 

how much freeway driving do you do

-actually I do alot of freeway driving, most of the shows Im going to are 20miles+ Away, I will convert to manual but due to these issues, I see Manual put in the back burner as an idea

 

do you want an automatic shifting trans or a fully manual valve body

- I want an auto shifting trans, just put it in drive n go, I want the luxuries of able to drive the thing and go, thats how I originally had it. 

 

gear ratio

-Currently Im running 3:00 open 8" I want to go 8" Track lok since 9 is super pricey. It wont have slicks, just street tires and some tough axles

 

tire size

rear tire size is 275/40/18 BFG sportcomp2

 

favorite brand of beer

Stella & Cusquena

 

your ol' lady's vital statistics

alive and not ditzey. lol

 

etc

[barnett468 418]

ok i will get back to you later today . i need to leave for a few hours . others will have good ideas as well.

 

do you want a torquey engine with power off the bottom?

 

will you be happy if it only revs to around 5600 rpm?

 

can you take a compression test on at least 2 cylinders . oreilly and auto zone loan testers.

 

without deciphering everything yet, my guess at the moment is that you might need a cam similar to the one below . this cam with 1.72 rocker arms would also work well and would guarantee you plenty of vacuum.

 

http://www.lunatipower.com/Product.aspx?id=1668&gid=289

[rwcstang 201]

ok i will get back to you later today . i need to leave for a few hours . others will have good ideas as well.

 

do you want a torquey engine with power off the bottom?

- I would like both but for street a little bit of nice torque would be nice.

 

will you be happy if it only revs to around 5600 rpm?

- if it revs, and doesnt take manifold vac, I'd be so happy lol.

 

can you take a compression test on at least 2 cylinders . oreilly and auto zone loan testers.

-will try this out this weekend, I was low on gas when I was looking at the car, gonna fill her and warm it up so I can run compression test.

 

without deciphering everything yet, my guess at the moment is that you might need a cam similar to the one below or slightly smaller.

 

http://www.lunatipower.com/Product.aspx?id=1669&gid=289

 

 

this cam with 1.72 rocker arms would also work well and would guarantee you plenty of vacuum.

 

http://www.lunatipower.com/Product.aspx?id=1668&gid=289

Thanks for the recommendations, will look into these after work.

[barnett468 418]

i don't understand your answer to my rpm question but if you want to rev more than around 5600 rpm you need to change your gear ratio so you can use a bigger cam and have less vacuum.

 

if you want to accelerate more quickly you also need to change it .