GreggymacZ28

I finally got to get my car to the track today, and i was expecting to run somewhere around 12.50 or maybe even a little lower. The car was running 12.97 last year.

But since then i switched to a new cam, which now has 236/242 duration, and .520/.540 lift from a .450/.450 lift cam that had something like 198-202 duration? Not too sure.

I also put in some subframe connectors, and went from a 2200 convertor to a 3500 and switched my carb from a quadrajet to a holley 750 with mechanical secondaries. And i have vortec heads with the guides cut and springs.

Anyways, my fastest time was 13.13. But my fastest 60 ft. before all the changes was 1.88 last season. Today i got it down into 1.73. So i was pretty happy with that. But my mph at the end of the track went from 105 last season, to now barely breaking 100 every run. The car takes off like none other and everything feels really smooth, just at the end of the track there is no speed.

Also, my dad put a governor that he had in the transmission(Which is a Turbo350) that would increase the 1-2 shift, but it went way too high as it wouldnt shift till 6800 and i never wanted it at that rpm. But the car ran fine with it. And i'd shift into 3rd on my own at 6400.

The jets that are in the carb right now are 70 primary and 80 secondaries. Also at the end of the day i checked the plugs and they were very white and showed to be running lean. I didnt think that i would be lean with a holley 750 as alot of people hinted that i needed even a 650? So do you guys think i am running lean and should jet it up? And that that could be the main reason why my ET's were almost a full second off of what i was expecting? Also im replacing the governor, as i know i should not be running it to that rpm, which is why i didnt make as many passes as possible.

Any suggestions would be appreciated! Thanks!

GTA matt

iTrader: (1)

Go ahead and jet it up if the plugs are showing lean. Double check your timing as well. Did you degree the cam when you installed it?

As far as the governer goes, get a spring and weight kit for it. Keep in mind, it won't take much to lower it 400 rpm. You just need a slightly heavier set of weights and it will be spot on.

GreggymacZ28

Ok sounds good i was just going to buy the kit that has jet sizes from 66-99 and start off with jetting the secondaries up to 82 or 84's? Not too sure where to go with them.

And no we did not degree the cam when we installed it, we just put it right in. The timing was set at 34 we checked it, and then even raised it some to 38 to see if it changed anything, and it still ran around the same time.

And thanks for the tip on the governor! I will definitely have to do that then!

xpndbl3

iTrader: (5)

fresh plugs in there, one burnout, one pass, shut down at return road and read them. You can't gauge anything if you drove on them several passes.

GreggymacZ28

Yeah, thats a good point, i'm going to do that next time i can get out there. I was thinking i was lean by the loss of power at the end of the track more than the reading of the plugs. I will just check the plugs before i swap in other jets then and see if it helps me. I'm hoping its just running lean, as i dont like to do all the work and be right back to where i was to begin with.

xpndbl3

iTrader: (5)

yes and keep jetting up until mph stops improving

DIGGLER

iTrader: (1)

add some fuel and make another pass. if it speeds up, add some more fuel. if it speeds up, add some more fuel. if it speeds up, add some more fuel. if it speeds up, add some more fuel.
if it goes slower with more fuel, take fuel away until it stops speeding up.

unknown_host

iTrader: (1)

Check your timing, I had this happen with my old motor and it was because the crappy spectre distributor hold down flattened out. Basically was running way too much total timing and lost mph/ran lean. Although I only lost 2-3 mph not 5.

GreggymacZ28

Alright thanks guys i will just purchase the jet kit and add fuel like you guys said and keep jetting it up. Thanks!

And unknown i checked the timing and it was at 34, which is what i set it at, and even raised it to 38 but there was no difference in mph or et.

pancherj

Post up the entire slip. Maybe your 1/8th was strong and you were running out of gas on the top end.

GreggymacZ28

I will when i get home! I know that my 1/8 was the same in my 12.97 run as my 13.27 run that i had once. But i think it was 8.2 in the 1/8 although the mph was already 2 mph off or so at the 1/8. Ill give you the whole slip when i get home tonight. I was going to 6800 rpm's in first and i know vortecs dont flow well there so i think i was losing alot of power by going that high.

Orr89RocZ

iTrader: (20)

750 carb is about what a good running 355 needs with a big cam like that. Its probably lean if you used the same tune as last setup. I'd get new plugs like others suggest, jet up and run again to see the increases. Or take to a dyno and place a wideband o2 in the tail pipes and see what it reads and tune accordingly.

GreggymacZ28

Well, i had a q-jet before with an adapter on it, so i figured a holley 750 without the adapter would help my times. So, i havnt really had a "tune" yet, it was the first time running with a holley carb on the motor. I'm hoping thats why the car was so slow, was just my lack of tuning with it. Should i mess with the primaries at all when at the track, or only swap out the secondaries? Thanks again for all the responses guys!

TB2

iTrader: (1)

These are the best way of doing it. Even though I have a wideband A/F gauge, this is still the way I do it.


Depending on the Q-Jet, some of those can be up to 800cfm. Normally SBC's love a lot of advance. Once you get the carb close you should start adjusting JUST timing and see what it gets you. All of my smallblocks have ended up with the timing locked at 38-40 total adv for my best ET's.

Orr89RocZ

iTrader: (20)

Vortec heads usually like less timing tho. But give it whatever it runs best at and no signs of detonation on the plugs

unknown_host

iTrader: (1)

Agreed mine liked 34-36* total

GreggymacZ28

The q-jet was a 800cfm. And it seemed to do worse when i pushed the timing from 34 to 38, about the same et but slower mph. Ill just have to expirement i guess. My first move is going to be the jets. But im not sure if anyone answered this before and i keep reading about jetting it up, but do i jet up the primaries and the secondaries or only the secondaries?

mw66nova

iTrader: (13)

some great info in here, just wanted to chime in and say follow what these guys say

unknown_host

iTrader: (1)

I just realized something after re-reading your original post, my 82 Vortec Camaro on slicks would lose about 4 mph. It actually ran about the same ET on street tires or on slicks, I think the little bit of tire spin kept it in its powerband better than dead hooking. Probably was an indicator it needed more gear and converter.

Is this scenario possible for your combo now that you are dead hooking?

GreggymacZ28

I've been dead hooking i just thought the car took off a little harder because of it being a little faster, and i put in subframes so i thought maybe that kept the car going straight better. I have drag radials on and the same ones from last year.

I have a 3.73 gear and a 3500 convertor. My cam range is from 2500-6000. I think if anything i was staying out of the vortecs power range for too long, when going all the way to 6800 and 6400. This, and running lean could be my main problem maybe?

I was thinking i was going to put a weighted spring back on the governor to try and get my 1-2 shift back to 5900 or 6000, and then shift from 2nd to 3rd at around 6300. Does that sound about right?

mw66nova

iTrader: (13)

sounds good to me.

what fuel pump are you using?

Orr89RocZ

iTrader: (20)

With that cam it could use abit more converter but for now, just concentrate on getting the air fuel ratio where it needs to be and then work the shift points to find its sweet spot. 6000-6500, anywhere in there it should be leveling off in power if its not floating Cam that big will hang onto power as rpms go up so it may want to be shifted where you were shifting Hard to tell. Could put it on a dyno and see where the power falls off and go from there.

GreggymacZ28

I just replaced my other fuel pump with this one before i took it to the track.

http://www.summitracing.com/parts/SUM-250000-1/

3rdBird

iTrader: (1)

No data log?

What's your AF ratio, 02 correction, when does it lean out?

If you cant look back and see what happened, it's 12 seconds of "what just happened".

Technology is cheap, use it. Buy a RacePack and start seeing the problem and correcting it.

If you can measure it, you can improve it.

GreggymacZ28

I wish it was 12 seconds of "what just happened" if it was i wouldnt have this thread, instead its 13 seconds of "what just happened" haha

And im running a carb, i hardly have any "technology" in my car. I dont have a a/f wideband, and thats not "cheap" by my standards. My dad does things old fashioned and so thats the way im learning it. They seemed to tune cars fine back then.

Also i have a pretty good idea about whats wrong, it says it in alot of the posts above, so i dont think im completely clueless on the run. But you never know what will happen next time i go back with the changes!

pancherj

Still would like to see the incrementals from your slip so we can look at your splits and see if they make sense. I can't say I like the looks of that fuel pump either. It would be marginal at best on a 400HP small block.

Get a fuel pressure gage on there that you can look at while making a run (down the 1/4 mile or on a back road). See if your FP is holding. If it isn't, you can throw all the jets at it you want, and it wont fix the problem.

GreggymacZ28

Ah, i knew i was forgetting something. I'll get that up for you tonight!

Shagwell

A larger carb will be leaner if you don't have the engine to support it. The larger venturis will lessen signal through the carb, thus it won't pull as much fuel if the carb is too big.

Same scenario in reverse - a local swamp buggy class' only engine limitation is to use an out-of the box 390cfm holley 4-barrel(out of the box meaning un-altered main-body). Had a guy put it on a nicely built 496 and ended up with TINY jets in it because the big motor had so much signal through the little carb it was stupid rich. We were down into the low 50's on both ends just trying to get it to run, and that was with the PV plugged.

mw66nova

iTrader: (13)

eh, i dunno man. lets look at a couple things:

his car is an 84, which is carb'd from the factory with a mech pump. so if he wants to utilize an efi setup with data logging capabilities the entire car will need to be re set up.

if you're saying put a stand alone data logger on his current setup, that's still $1k easily to even get into one of those.

i agree with what you're saying overall, but don't forget that people like you and i who are more than general enthusiasts may prioritize these things differently.

Shagwell

^ I'm in the 4's in the 1/8 and don't yet have a data logger, LOL.

Orr89RocZ

iTrader: (20)

Whats there to datalog in 4 seconds? You either have the motor together or it comes apart right?

GreggymacZ28

Alright here are the time slips! Let me know what you guys think now! Thanks again for all the answers!

The pass on the left is the most recent and the one on the right is from last season.

DIGGLER

iTrader: (1)

lol @ a racepak in a 12 sec. car

pancherj

I don't see anything strange with the splits. They are consistently lower now (.060 to .080 seconds) than they were before. I'd start by looking at the timing and the fuel. Throw some bigger jets in to see what happens. Make sure you are getting full throttle (been there before!). Also, with that cam, I would not hesitate to spin it to 6500RPM.

What intake? Any spacer? What is the exhaust setup? Also, what gears?

GreggymacZ28

The only strange thing is that i'm 4 mph slower now. And i have an edelbrock performer rpm intake, and i have a 3.73 gear. There is no spacer. And actually the exhaust is shorty headers with a y pipe and then stock exhaust to the back with a new muffler.

I was thinking first was too far drawn out going to almost 7000 rpm. And also i think it just wasnt jetted enough. Is that what you are thinking too?

Orr89RocZ

iTrader: (20)

You could pick up some with a better exhaust. Single 3" minimum maybe even a 3.5" custom witha good straight thru muffler.

I'd try new jets and keep revs lower for now and see if it picks up. if it does, keep jetting and then go to raise shift points.

GreggymacZ28

Alright thanks guys! Ill try all those things and let you guys know what happens next time im out there. Probably next week.

TB2

iTrader: (1)

That exhaust is killin you. Get that thing to breathe, and then get a fuel pressure gauge and see what your fuel pressure is on the big end. I doubt that pump can keep up.

colehjermstad

I run about the same setup with a demon 750 carb. I've had a lot of people tell me I'm crazy for put that much carb on the motor. But in the right conditions I do notice mine leaning out from time to time. I cant remember what I have in it jets. I have 34 degrees of timing in it. Even as your car sits it runs a bit quicker than mine, so I don't think your too far off.

Orr89RocZ

iTrader: (20)

I dont understand how thats possible.. You have better heads/intake/cam than stock L98's and yet run the same or worse times? Something isnt right

GreggymacZ28

Ok so i think i found what the problem is! We took the car to milan today, but something messed up with their track so we went over to lapeer. I've never been there before, but its nothing like milan, especially in track quality.

Anyways, my 1/8 mile ets actually suffered at this track but that was to be expected, as instead of 1.73 60 foots i was getting 1.89's. But i was going for mph anyway. I changed the governor and it is now shifting at 5600 into 2nd, i need it a little higher i want it at 6000 but oh well ill get there next time.

We also jetted it up alot as mph kept going up. So we ended up getting to around 78 primaries, and 84 secondaries and the mph increased to 102.83. So a 2mph gain. But because of the 1/8 mile loss i still ran 13.15,13.16,13.17. Atleast the cars consistent.

It still seemed like at about the eighth it wasnt getting all that it wanted, so we rigged up my fuel pressure gauge and taped it to the windshield to see what was going on. First run it started at like 8psi and only went down to 6 psi. So i thought theres no problem really there. But then i took it again, and after i shifted into 3rd it dropped to 3.5, then the next run it did it again, and finally it dropped all the way to 2.5.

So im guessing it has to be the fuel pump correct? And throughout all these runs when checking the plugs at the end the plugs still were lean. Im pretty positive at this point im just going to have to put an electric fuel pump on there with a regulator. What do you guys think?

mw66nova

iTrader: (13)

This is exactly what I thought it was, but didn't want to bust on your new pump since I know nothing about them. You're headed in the right direction. Check out the aeromotive pumps.

GreggymacZ28

Yeah i figured that pump was the culprit. But ok ill have to check out aeromotive, ive never heard of it. I was going to do the holley blue pump. the one with a 110 gph and 14psi with a regulator?

mw66nova

iTrader: (13)

The holley blue is barely enough for a stock engine in my opinion. I always go way overkill on my fuel supply though.

xpndbl3

iTrader: (5)

i would go the holley billet hp 150 or whatever it is or larger. Aeromotive makes some nice pumps that are also pretty budget friendly or the best pump choice is magnafuel and you'll pay for it too they're spendy.

mw66nova

iTrader: (13)

magnafuel is definitely the bees knees, but aeromotive makes a quality piece that's not too pricey.

check out this pump:
http://www.summitracing.com/parts/AEI-11203/

and use this regulator:
http://www.summitracing.com/parts/AEI-13301/

GreggymacZ28

Oh ok thanks guys, What is the "recommended" gph for 450 hp anyway? That's what i wasnt sure of, ive read alot of different peoples opinions but not sure of what the real thing is. I'll probably go with aeromotive then since it is the cheaper option and will do the job. I dont want to waste any more money on the wrong fuel pump,aha.

mw66nova

iTrader: (13)

take a look at this pdf
http://aeromotiveinc.com/wp-content/...werPlanner.pdf

mw66nova

iTrader: (13)

more info on the SS pump
http://aeromotiveinc.com/products-pa...l-pump-38-npt/

i've used this SS pump in my car, and am currently running a Tsunami pump. i have also used a bunch of those 13301 regulators on both carb and EFI setups and i love it. it's a very simple setup and it works great

GreggymacZ28

Okay sweet thanks alot! That definitely looks like the path im going to go then. It seems like a good pump! Hopefully i can get it in the next couple of days and have it on there by next weekend!

If i was running lean because of the fuel pump, if i was jetting up the carb, now if im getting the correct psi needed, will i be running too rich with the updated jet sizes i put in?