Ok heres the scenario. Took out my car for the first time after some upgrades and here what i ran. (My first time to the strip). I'll list the times, then ill give you the story. 3 slips, best to worse.


1/4 mile ET: 15.684
1/4 mile MPH: 89.319
1000 ft ET: 10.073
1000 ft MPH: 67.805
1/8 mile ET: 6.744
60ft ET: 2.073

RT: .939

Before i go any further, this is something you should know. The track i go to, lists the time as follows.

Dial in:
Reaction:
I1:
I2:
I3:
MPH (I3):
I4:

ET:
MPH:

WIN...

I think I1 = 60ft, I2 = 1/8 mile, I3 = 1000 ft, I4 = 1/4 mile. I will call the track and confirm this.

Slip 2:

1/4 mile ET: 15.746
1/4 mile MPH: 90.663
1000 ft ET: 10.229
1000 ft MPH: ?
1/8 mile ET: 7.009
60ft ET: 2.323

RT: 1.201


Slip 3:

1/4 mile ET: 15.851
1/4 mile MPH: 88.699
1000 ft ET: 10.210
1000 ft MPH: 69.571
1/8 mile ET: 6.941
60ft ET: 2.289

RT: .884



Track: Luskville Dragway, Aylmer Quebec, in Canada.
Temp: 15*C or 59*F.
Humidity: Moderate.
Elevation: Not sure, but not that high.

Heres the story. the engine is a 1975 355, with about 9.5:1 compression. 11:1 TRW pistons, 4bolt main,a nd nice bottom end, 1969 74cc heads, ported polished, RPM Air gap intake, with a 750 cfm DP Holley carb. #71 jets all around, rest is out of the box holley. Choke style, with the choke fully open. Stock mechanical fuel pump, getting about 5-7 psi at idle. 94 octane fuel, with lead substitute. Headers, to a 3" y-pipe, UNCORKED! All in all, nice tight running engine, pulls hard.

My holley isnt tuned well yet. ie: It pulls harder at 3/4 throttle, than at full throttle.

3.73 open rear end. 235/60R15 M+S tires, REAL sticky. When i launched, i didnt have to worry about spin, i just burried the throttle, and because of the soft springs, i left the line with a THUMP from my bump stops.

Problem: MY TRANSMISSION!

Stock 1987 700R4, with stock converter. Was slipping when i got it, but only hgappened at WOT. After the upgrades, it happens ALL the time.

Basically, i cant shift past 5000rpm. So goin down the strip. i have to play with the throttle. Lifting, and pressing, trying to get it to shift. My buds recorded a video of the run, you can hear the tranny slipping and me missing shifts. Sorry its oldschool VHS, ill see if i can find a way to post it.


Based on the time slips, and taking into account that my 0-60 ft times are fairly accurate, what SHOULD i be running in the 1/4?

The guy i bought the car from had a tunnel ram setup on it. But downgraded to a stock intake and q-jet. So the car was very tired feeling when i bought it. But the RPM and the 750 holley, woke it up. It just doesnt stop pulling. Judging the speed by what my freind 69 cutlass felt like, its alot quicker. So i was very surprised i only scored 16.00 ET.

WHAT SHOULD I RUN?

(sorry for the long read).

Forgot to mention a very important point:

I weigh 130 lbs, the car is a 1987 firebird formula. Flat hood, with a small portion cut out. Basic hatch, no spoiler. Aluminum factory Z28 wheels (82-85), and the rest of the car is stock trim. No AC, but i had some extra junk in the trunk. Camera bag, 4L of tranny fluid, timing light, a couple of water bottles, and some clothes.

So maybe a 3000lb car, 3130 with driver? Not sure how heavy these cars were from factory.

Your MPH matches your ET. 60' times suck so you're probably spinning off the line.

Don't kid yourself, third gens are heavy. Your race weight is probably closer to 3500 pounds.

Put an exhaust system back on it. You don't have the engine to run with no back pressure. Loud doesn't make you faster.

Does the carb have powervalves installed? How old is the carb? I've seen people buy old carbs thinking they got a good deal and never have any luck with them. Buy a new carb if it's old.

Change the fuel filter. Find out how much fuel pressure you have while going down the track.

What camshaft is in the engine?

If the axle hit the bumpstops when you launched, soft springs have nothing to do with it. Buy some new shocks.

What should you run? Exactly what you did run.

how are u running 6.7-6.9 1/8 mile times and 15 second 1/4 mils..u sure thats not 330' times? those 1/8 miles should be good for mid-high 10's

double post.

Stephen:

Yup youre right, i punched in the numbers i got into some of the wallace racing calculators on google, and thats exactly what they came up with. However, the news gets worse, heres what the drag strip owner e-mailed me with:

"send me your times, I1 is 60 feet, I2 is 330 eightmile and quarter we dont give out the 1000 feet."

WHEELSUP: So im running much worse than i had thought. What i thought was 1000 ft, is actually the 1/8 mile, and the 1/8 mile is actually 330'.

I had made 8 passes in total, first 2 with full exhaust, last 6 with it uncorked. I dont see how back pressure would matter with a carbed car. It didnt feel like a difference either way to be honest. For the holley carb, i bought it off a credible member on this board. Its definately not an old carb, #4779, 6150 series. I was told the only difference is in the jets, #71 all around. Theres a vaccuum leak in it though, i need to track that down.

I was told the engine has a 284H cam. Its really hard to time. I think you guys helped me out with that issue, its running at 34* total without vacuum. Idles like crap, hard to start at this setting. Stock distributor, need to ad springs, etc...

Fuel filter is new, only has about 80 miles on it. Im probably around 5 psi while goin down the track, or less.



My question basically is, if i get the holley tuned, and the transmission shifting, and starting with a stall? will i do much better?

Im launching from idle basically (700rpm), and missed atleast 1 shift on every run. I could see the oponent gain a car length every time while i shifted. Also, what would i need to do to the power valve if i pull harder at 3/4 throttle, than WOT.

Thanks for all the help guys.

The 4779 carb is a 4150 series. Is there a -1, -2, after that list number?

The straight 4779 should have #75 jets in the primary and #76 in the secondary. The power valves should be 6.5. The squirters should be .025.

If the carb is a -1 or -2, the jets should be #70 primary and #80 secondary.

The 284H is an old grind. You need a 2000-2500 converter to make that cam work. A stock converter has too low of a stall speed.

Distributor timing. What's the initial timing? Is the 34* at full advance by 3000 rpm. If it's a stock distributor, I have to assume it's not locked out. For a street driven car, you should have a distributor with a timing curve, vacuum advance etc.

i would say once the carb is tuned a lot more and the slipping tranny is fixed you could expect much better times, and dependin on how for off the tune is or how hurt the tranny is, it coould be up to a full second or more

Stephen, sorry, wasnt thinking straight at 8am on a monday morning goin off of memory. Its a 4779-6 holley 750. yes its a 4150 not 6150. So should i step up the power valve or reduce it? The throttle is smooth all the way through, from idle to WOT, no bog. But when i hit the floor, the RPMS rise SLOWLY, and if i back off to about 1/4 throttle, it pull NOTICEABLY harder, and the RPMS just rise like crazy. Its nothing to do with the power band, this was always noticed between 4000-6000 rpm. Im not sure why this is, too rich, too lean?

Im aware the stock converter is complete crap :agree: a new transmission is in order. (winter project, still debating if i should spend the $$$ on a race 700R4 or a T56, i love the overdrive so i would really like a T56.

The distributor's total timing (i think its called), with the vacuum advance disconnected and plugged, at 3000rpm is 34*. However it does have a vacuum leak bad enough to sound like a supercharger whine, so its probably off a little. The rest of the distributor is stock, i need to get it recurved. Also another winter project. No time with school.

The tune of the carb is not that far off, i need to fine tune the jets a bit, but its developed a vacuum leak that i need to track down.

And the transmission is REAL slippy. Like i said, i miss every shift, it takes a good couple seconds to shift, the engine kinda over revs it, and it sounds like the next speed isnt catching.


Another question for you guys. What is a typical 60 ft MPH for a thirdgen running a 1.9-2.1 60ft ET?

I was a little full of adrenalin to notice what speed i was at, but i shift from first to second at about 40 km/h around 5500rpm so (about 30MPH). If the MPH at 60ft is higher than 30MPH, then i made it past the 60ft mark in the 1-2 shift, which would basically make my time slip useless to gauge anything.

However, i still have some hope, because my worst time slip read as follows.

Reaction, 0.805
60ft: 2.433
330 ft: 7.2
1/8: 10.654 @ 64.968 MPH
1/4: 16.440 @ 87.795

According to wallace racing, with a 2.433 60ft, i should have run a 17.5 sec 1/4 mile @ 75MPH, but i was close to 88MPH. SO i think there is some hope yet.

Once again, thank you both for your insight. I really appreciate it.

4779-6 should have #71 in the front and #80 in the rear.

Power valve opens when the vacuum signal drops below the rated number. Yours should have 6.5. The power valve allows more fuel into the engine during a WOT lean condition. From the sounds of it, you're getting too much fuel at WOT and when you back off a bit, it's leaning back out. First suggestion would be to change the power valves to #4.5 so they won't open above 4.5 inches of vacuum and put #80 jets back into the rear. The secondaries are too lean if the carb has been squared to #71's.

Where is the vacuum leak? An audible vacuum leak makes the engine go very lean. At WOT it's going even more lean and changing the vacuum signal to the carb.

The 700R4 isn't a very good race tranny to begin with. Since it's still a street tranny, it will never get good firm shifts. A shift kit can help but won't fix a worn out transmission.

You've got a lot of conflicting problems. Fix them one at a time and get more track time after changes are made. Nobody can guess what you might run when the entire package has problems.

the trans would be top priority on my list....its pointless to beat on a wore out trans and expect to run anything faster than you currently do. also it sounds like you have the stock converter, which will make it take ff like a dog with that 284H cam

Yea its definately a dog, and its definately the stock converter. Its a stock 700R4 through and through, on its death bed behind this mill, and the worse part is you can FEEL it. Ive never been able to "feel" what the auto tranny was doing until now.

However, my take on it is, since i dont race the car primarily (its used more as a cruiser, or street driving), i can "afford" to leave the tranny till last.

2 things to keep in mind, is ofcourse budget is a HUGE issue here, and the tranny is the only real expense. Also the car will be parked for the winter, so it doesnt matter where i start. Id prefer to get the engine in tune, because if the tranny doesnt happen this winter, i can still drive it come spring.

My budget is at its end for this year, so T56 shopping starts around x-mas time .
----------
Stephen

4779-6 should have #71 in the front and #80 in the rear.



Power valve opens when the vacuum signal drops below the rated number. Yours should have 6.5. The power valve allows more fuel into the engine during a WOT lean condition. From the sounds of it, you're getting too much fuel at WOT and when you back off a bit, it's leaning back out. First suggestion would be to change the power valves to #4.5 so they won't open above 4.5 inches of vacuum and put #80 jets back into the rear. The secondaries are too lean if the carb has been squared to #71's.

Ok ill try that.



Where is the vacuum leak? An audible vacuum leak makes the engine go very lean. At WOT it's going even more lean and changing the vacuum signal to the carb.

The vacuum leak sounds like its coming from inside the carb. WHen you cover the choke horn over the primaries with you hands, you can hear the whine getting muffled. Same test doesnt affect the whine while covering the secondaries.

The 700R4 isn't a very good race tranny to begin with. Since it's still a street tranny, it will never get good firm shifts. A shift kit can help but won't fix a worn out transmission.

If i go for the 700R4, i would ONLY be using mine as a core, all new internals, and a heavy duty shift kit with stall converter (atleast 2500 lockup). But because of the formentioned probs, im leaning towards the T56. The only down side i can think of for the T56 is ill need to relearn how to do a burnout .

You've got a lot of conflicting problems. Fix them one at a time and get more track time after changes are made. Nobody can guess what you might run when the entire package has problems

I posted all this yesterday but forgot to delete the "quotes" so it didnt show up.

Problem 1 is on its way to being addressed, but not solved yet.

Problem: Vacuum leak. From the carb to manifold gasket. I went for a 15 minute drive, warmed the car up. Now that its getting colder, the noise only seems to appear when the car is warmed up. I pulled the carb off after the drive when the noise was at its worse. @ 800rpm idle, the vacuum reads 9-11 in-Hg fluctuating with no real pattern. Upon removal of the carb, there is a mostly clear residue on the carb surface, the manifold surface and the gasket surface. It evaporates after a few minutes, obviously gasoline.

The carb is a square bore holley 750, the manifold is an edelbrock RPM air gap and the gasket is a 1in thick holley gasket (installed new in June with around 100 miles on it). Kind of like the stock q-jet ones. The carb wont fit on the manifold without atleast a 1in rise, because of the double pumper plunger in the rear float bowl hitting the vacuum hose fitting.

I cleaned all surfaces with brake cleaner, used a sharp blade to very lightly scrape away any excess gasket. I sanded down both metal surfaces with emery paper to a very smooth texture. The carb was easy to do, but the machine marks on the manifold are very coarse, so you can see the emery paper sandings get stuck in the machine grooves. I got it as smooth as possible. Brake cleaned surfaces again, wiped away any dust. Brake cleaned again and let dry.

Reinstalled. Engine still fairly warm. The idle seemed MUCH smoother, the vacuum reading is now glued around 12-13 in-Hg vacuum around 900rpm. At low idle, around 600 or so the "whine" from the vacuum leak is still there.Not anywhere near as bad, but u can still hear it. Obviously the gasket isnt working.

Should i get another 1" thick gasket from holley? Or should i get a 1" spacer and two thin gaskets? Clearance is not an issue. I just want a proper seal. Please help.

EDIT: Not sure if its 1" thick, but heres the link.
http://store.summitracing.com/partde...5&autoview=sku

do you have a bottle of propane? You can try moving it around the carb base unlit to see if the idle speed changes. I'd want to be sure it's the gasket.
Then i'd probably try gooping it with RTV and see if that helped any.

I'd just get another stock 700R4 from the wreckers, then put in a shift kit and bigger convertor for now. Leave any "beefing up" for down the line.

Point the propane torch at the carb or the gasket? Isn't this dangerous cuz its full of fuel?

Also i was thinking of RTV, but i shyed away from it, because if its NOT the problem, id need a new gasket. It also makes it hard if you need to remove the carb for any reason.

Not gonna bother with junk 700R4. Im only driving it a couple more times, and insurance is coming off at the end of october. THe tranny is good enough to cruise, and im not driving it hard or anything. T56 over the winter hopefully.

Junk 700R4 + shift kit, will still run me in around the neighbourhood of $300-400, and i just dont have that $$ to put into "temporary" items.

Point the torch at where ever you think it's leaking.
Gasket most likely. (unlit torch!). If the idle speed changes at all, then it's pulling in the fuel there, so you know it's leaking.

RTV wouldn't make it very hard to replace the carb. It won't "glue" it down like with the intake manifold or something.

Oh i thought you wanted me to LIGHT the torch!. Thank god i didnt do that.

hold on a minute, step away from the torch......First you said the noise is comming from the carb, and you cover the primairys and it stops? some noise will be present due to idle air going through small opening in the throttle blades, so if it is inside the carb, stop dont worry about it. secont you said your idle vac was 12 to 13, the basic formula that most use for power valves, is , half of the idle vac minus 1 (some say 1.5) so about 5 inch power valve would be ok or the 4.5 previously reccommended you could also go with a two stage power valve but that gets more confusing. by the way a 700r4 is overdriven in high gear and has a lockup converter , and can be made to handle alot more power than you have, just pointing that out, since this is a street car. also it is over carbed but , well you have it and money is obviously tight (otherwise you would be in the i got a new camaro forums whenever they release it lol) i dont know how much a t56 swap would cost so i dont know if it is more or less money. also is that a spreadbore intake? if it is is the spacer an adaptor? the idle vac sounds about right for that type of cam so i dont think there is a leak, and the carb sounds like it is too rich when you floor it so putting the big jets in it will not help but unless you happen to have an air fuel ratio gauge in you pocket you could either dyno it or do plug checks and that is hard to do, cuse they arent easy to get to with hot exhaust there. confused yet?

1) ok so a little whine is ok? The only reason this stood out to me, is, when i first installed the carb it seemed to run fine ( i didnt notice the whine). But the high pitched whine REALLy started bugging me. Obviously it got pretty bad. I could hear it over my subs. After i cleaned the surfaces, its only audible outside the car near the hood....

2) I absolutely LOVE the overdrive. Ive driven 2+ hours once in this car, on a hot summer day and it was absolutely amazing. So i really dont wanna lose the over drive. However, my tranny guy quoted me $1200 to fully rebuild it with quality parts, made to handle about 600hp. Hes not into too many performance builds, but hes been doing this pretty well since these trannys FIRST came out, so i trust him. He said he'd do it for $350-400 if i supplied the parts. So i might save like 300-400 if i buy used (unopened) parts. but that requires time. Im aiming for $1500 for a T56, i think if i look in the right places i can do it. Its more expensive than the 700, but much more fun.

3) Overcarbed? Yes and no... I did alot of research before selecting the 750. Main reason being, its possible to get a 750 just right, but the 650 is sometimes not enough. Love the carb, im stickin with it. Its bolted on, and was running on a 383. So definately needs tuning. And i agree it is running too rich. my car starts as if it is fuel injected with a wide open choke. Fires almost immediately. Cold, no pump.

4) As for jet selection, there is a pretty good thread on here about "tuning a holley". Gonna work off of that. I might dyno it in the summer.

5) Its the RPM air-gap manifold. So its a square bore. I would run the thin gasket, but the DP wont fit on this intake with the vacuum hose fitting behind it. I dont wanna tap a new hole in it, so thats out of the question.

Im a student, and it was a busy summer, so i bolted on a bunch of new stuff, and it runs like ****. So need to fix the leaks etc.. before i can tune it.


Thanks for the help.

there are also some good books on the subject, and i would reccomend one. most of them have the same info, dave emanual wrote one that i have, and i have thumbed through a few others that have some of the info, they all do a pretty good job of explaining how it works too that will help you. dave emanuels book also goes in depth about some mods that i havent looked for in other books ( the guy is kinda technical at times and get way too far down some roads, but you do learn what hes saying). start with the basics and you probably will be ok, i do not think you will need any major changes, but most of the time gaskets are not reuseable on the carbs they always seem to leak. holley, quick fuel and others make gaskets for holleys to replace the bowl and meatering block gaskets, and power valves should be redily available, i would do that first by the way, if the one in there is opening at the wrong value it wont help tuning, they arent too much money either. good luck with the tuneing

Any idea where i could get the book?

Im thinking of installing a quick change jet kit, and then sealing the carb and gasket with RTV.

you should be able to get the book at a book store or online from summit or someone. DO NOT use silicone on the carb there are lots of small passages to clog and gas will break down the siicone. quick change jets are helpfull (adjust a jets rock, but the aircleaner probably wont fit and its like 200 bucks) i think there is a quick change kit for the secondarys that comes with jet extensions get that one. once you get the right powervalve and then with the qc jets you wont need to pull the bowls off for awhile, so gaskets will not be needed once its together. that would be a great thing to do as far as tuning, plus later if you change or modify something, just change and go. oh and the saturn is 1.9 litre lol

Ok, so no RTV.

How do i get a proper seal? Or do i just have to live with it?

do you even have a leak? there isnt much torque reguired on those bolts that hold the carb down. you could also use carb cleaner to spray around carb to check for vacume leaks, bu i dont think you have any. raise the idle or lower it , see if the noise changes or goes away, if it is comming from inside the carb, its normal, just a whistle created by the air entering throgh the throttle plate to allow the engine to idle. if it goes away with the throttle open a little to like 1500 rpm then thats all it is. also not related to the noise did you ever check your timing at idle and where is your distributor vacume supply connected?

Just an update on this. Ill post as i fix the probs you guys helped me trace out, and maybe ill be off to a good start come spring.

The other day i was out with my car cuz its the last day i had insurance on the car. Got stuck in traffic unexpectedly, and usually its not too bad in traffic, but i got stuck in stand still traffic, bumper to bumper for 20 minutes, just idling. It heated up to about 220*, but the only real problem i ran into (or so i thought) was, the wire used for the fan got too hot, and melted the inline fuse housing i have on it, so my fan died. i had to bypass the fuse. I later found that the car was idling at almost no fuel pressure. The gauge read like 1-3 psi, but the car seemed to idle ok, and drive fine ok, but crapped out when accelerating hard.

Just to make sure the gauge was not goin bad on me, i took off the hose for the fuel pump, and sure enough it squirted a bit out, prolly just enough to run the car.

Ive had the car off the road for about a week now. Had it out for a wash yesterday, and the gauge read 5-7 psi, flickering back and forth like it usually does.

So i thnk the fuel pump is going bad. I have a holley blue electric lined up for it, so i will definately be installing this, and two new gauges to monito the situation.

I think Stephen you were correct in assuming, the bog i get at WOT is due to low fuel PSI. A rich running carb would bog, but it feels alot like its going to stall. So i think more than the rich mixture, the fuel pump is the culprit.

2 probs down, a few more to go.

Car_fixer, in response to you, yes you are correct. I compared what im hearing (after i fixed it) my carb, with my freinds holley 650 DP on his cutlass, and he has a similar noise. Audible outside, but not inside, and seems to go away (might just be the exhaust drowning it out though). So ill leave it at that for the carb "seal", my timing is kind of retarded, i think it reads 12* with vacuum disconnected. Keep in mind its not recurved for the cam, its on my to do list. I timed it to 34* total at 3k rpm, so for now im going with the "crappy idle" but good top end performance, comprimise. The vacuum advance is connected at the timed port on the holley, frontpassenger side, near the top of the carb.

However, it was DEFINATELY leaking before, as i mentioned before, when i pulled it off, the gasket was soaked in fuel on the mating surfaces. The noise was there all the time before, faster the engine roared, the louder the noise got, and it changed pitch too, from high to low notes. Was definately audible inside before too, but its much better now.

Just wanted to revive this thread. Took the car out a year after the original post. It was a nice 20*C day, all blue sky. I got there late, so i only got two runs in, and i didnt get my second time slip (best time).

The car is basically the same as it was last year, with two differences.
- I borrowed my freind 650 DP carb mech secondaries, because it is tuned fairly well on his olds 350. The carb felt "smooth" but not as "explosive" with power as my 750DP. However, i WAS able to go full throttle this time, so i thought it was ok.
- The T56 has been installed.

Reaction: 1.401
I1 - 60ft - 2.542
I2 - 330ft - 6.757
I3 - 1/8mi - 9.674
I3(mph) - 76.355mph
I4 - 1/4 - 14.760
MPH - 97.416 mph


VERSUS last year's best

60ft ET: 2.073
330 ft ET: 6.744
1/8mi ET: 10.073
1/8mi MPH: 67.805
1/4 mile ET: 15.684
1/4 mile MPH: 89.319

RT: .939

My second run was with the cutout open, it was a 14.6** (nearly 14.6 flat). I launched a little faster and shifted a little later. Also a 97.***mph but it felt quicker than the first. Car stalled because the choke decided to shut itself??? So i didnt get the slip.

When we got home, we decided to run the olds 350 (69 cutlass) with my 750DP carb, since it was sitting there. And it ran with IDENTICAL problems. SO the probs are in the carb. I need help figuring out whats causing them.

Problems: (noted on both cars with same carb)
1) There is a whistling noise (like a vacuum leak). Fairly loud. It had gone away for a long time, but got quite a bit louder recently.
2) There is an off idle "bog" that goes away. ie: bog then acceleration
3) There is a full throttle bog that doesnt go away. ie: you mash the pedal, it bogs, but the rpm stay there and power goes away. Like a flat spot but worse.

I think the bogs can be fixed with tuning and jets, etc... but WHATS THE WHISTLING NOISE??? It gets quieter if you cover the choke horn.

Also, i still cant swallow that this is a nearly 15 second car!!! The new factory clutch was slipping between shifts (i couldnt powershift), and i didnt want to launch hard. It was a nice rolling start (hence the 60ft time). Any ideas what i SHOULD run?

with 97mph, it will go 13's all day long with traction and good driving.