...and I'm really P.O.'d! graemlins/angry.gif I've been to the track 4 times now, and tried numerous things and my car will not go faster than 99mph through the traps. Jet changes, timing, suspension, and I just had my carb totally re-worked by an expert and nothing changed ( except it's a lot smoother). Here's my set-up:
69' Camaro ~3600lbs(w/ me)
355cid 5.7" rods
10.3:1 c.r.
ported LT1 (old) heads, 2.02/1.60
Perf. RPM Air-Gap
4 hole 1" spacer
Reworked 650HP
1-5/8" super comp headers 2.5" exhaust w/ x-pipe
.485/.485 232/232@.05" (I THINK?!?) :confused:
TH350 3200-3400stall
4.11 posi, McCreary dirt track tires
Cal-tracs, adj. drag shocks all around

I said "I think" on the cam, because the guy that built the engine could've put anything in there. I was told, that this set-up should get me into the 12's(that's what I paid for too), but my best yet is 13.6x with a 1.88 60ft. :mad: After I got the new carb on, and the carb guy tuned it up, the car sounded real lame, and I have enough vacuum for power brakes. It revs, and it's response is great now though. It pulls hard through 1st, but after that it gets more and more lame. I shift at about 6200rpm, and on the high end the car just craps out!

Do I have valve float? Do I need a bigger cam to get into the 12's? Is it the converter? I have no idea where to go from here, any advice would be appreciated before I go crazy.

Sounds like it might be your fuel system . What size line are you running? Maybe your fuel pressure is dropping big time once you get deep into the rpm band. My wifes 01 Stang GT tips the scale at about 3600 with me in it and it traps 99 mph. The car dyno's around 235rwhp. Also what kinda timing are you running. Should be looking for around 34 to 36 degrees total. Good luck with it.

Whenever you change a bunch of things in a combo trying to go faster and nothing helps, there is normally a major choke point in the combo. Like cylinder head flow. If the heads only flow enough for 350 HP then no matter what you do to the rest of the engine you will not likely ever get more than 350 HP.

If the obvious stuff (fuel pressure, ignition curve, carb mixture, etc) is all OK and you are up against a wall then it probably IS a cylinder head flow problem. Have you ever had them flowed? Before or after porting?

PS the cam, converter and gears are all good choices IMO. The only thing I'd change is the 4 hole spacer - either go with a 1" open spacer or ditch the spacer altogether. A spacer is only worth a tenth or two anyway - not at the root of your problem IMO.

Fuel;

agree with the others: fuel

why the 4 hole spacer? (just curious)

ignition? not breaking up?

stall too loose and slipping?

that's not a big cam, but it should have a noticable idle, does it sound right? have you measured the lift @ the valve?
thought of going to 1.6 rockers?
maybe swap springs too (better safe . . . )

toad,
Post a couple of your runs with all the times and the mph.
I have a couple of questions...what size are the tires ? What rpm are you at going through the finish line ? Are you sure of the car weight with you in it...sounds a bit heavy to me for a 69, but I might be wrong.
If you are at 3600 lbs , you are going to need about 340 hp at the rear wheels to go in the 12's. Answer my questions and I will continue my answer.....

6200 rpm shift? Does that give you your best times or have you tried other shift points???

Rod

well, I'm no expert comapred to some of the other guys, but as stated above you are only putting 235hp to the ground which puts your auto at about 290 hp at the crank, your 60 ft is pretty good and your time matches the your hp. I see that you are in AZ, what was the temperature and more importantly what was the corrected altitude, if you were running on a hot day at say 3800 feet, then your time would correct to sea level in the high 12's.

I have a 4-hole 1" spacer because I need a 1" spacer so I can put a vacuum fitting on the manifold for my headlights, tranny, and brakes. Should I use an open spacer?

-I have a Holley mechanical pump and it has 6-7psi.
-I run 36* total timing
-The car is pretty heavy b/c it has A/C,PS,PB,full interior with seat covers floor mats etc.
-Never had the heads flowed.
-My tire is a 265/60/15 which is ~28"
-My best time I shifted at 6200rpm, so that's what I stick with. Here are a few runs:

R/T .949 .581 .580
60' 2.084 2.041 1.885
330' 5.843 5.786 5.601
1/8 8.934@79.34 8.896@79.24 8.720@79.16
1000' 11.618 11.581 11.408
1/4 13.888@99.05 13.859@98.83 13.679@99.20

I've even had runs where I had traction issues and I still ran 14.391@99.0 and 14.261@99.65. I've had jet sizes from 72-74 primary and 73-75 secondary and no real MPH change!
The track altitude is 3075ft, but with the weather it was about 2600ft. I don't know...thanx for the help though!!! graemlins/thumbsup.gif

Sorry my times got all messed up, here they are again: graemlins/clonk.gif
R/T - .949
60' - 2.084
330' - 5.843
1/8 - 8.934@79.34
1000'- 11.618
1/4 - 13.888@99.05

R/T - .581
60' - 2.041
330' - 5.786
1/8 - 8.896@79.24
1000'- 11.581
1/4 - 13.859@98.83

R/T - .580
60' - 1.885
330' - 5.601
1/8 - 8.720@79.16
1000'- 11.408
1/4 - 13.679@99.20

What changed on the 3rd run? What size fuel line? Hi-flow inline fuel filter (not those little bronze in-carb filters)? It also sounds to me like a fuel problem...like you are hitting a wall and it just isn't pulling anymore. Does the engine pull smoothly to 6200? Hydraulic cam, I assume? If that is really what size it is then it ought to have quite a noticeable idle to it, unless it is ground on something like a 114 lobe center.

Toad,
I would still like to know your rpm at the finish line ?
Personally, I think the exhaust might be hurting you more than you think. My 71 Chevelle had almost the same engine in it except for a bit more cam and it ran a best of a 12.52 back in 1978 or so but...that was with slicks and open headers. 3.73 gears and a Muncie 4 speed. If I put the exhaust back on (2 1/2" pipes with Hemi Road Runner mufflers) it would not run a 13.anything.

Thanks guys, I'll try the exhaust next time. I have cut outs on it so I think I'll try that. I kept that as kind of a last resort.

The fuel line is all 3/8" factory, and I have a bronze inline filter but it doesn't connect to the carb.

On the 3rd run, the car just hooked up better, it didn't pull harder or anything. The car doesn't pull smoothly throughout the RPM range. I cross the traps at about 5000rpm in 3rd gear.

The cam does have a noticable idle, but not like other cars out there...that's all I meant by that. It has a 108*LSA too.

Thanx again!!!

I've had jet sizes from 72-74 primary and 73-75 secondary and no real MPH change!
[/QB][/QUOTE]
Should not he have secondary jets about 8 sizes larger than the primary? I know this to be true if running a power valve in the PRI and Not the Sec.

Are you running power valves in the pri and sec?
Or, no power valves at all?

If pri power valve only, an increase in sec jets approx 8 sizes > pri are worth a try!

good luck'
joe c

You are going the wrong way with the jet changes. You are already too rich and just making it richer --- thats why there is no MPH change. At 3000 feet elevation, especially in hot weather you will need to lean out your carb.

The old thumb rule is 1 jet size leaner for every 800' above sea level. What do your plugs look like? Are they black and sooty?

A 1" open spacer will make it a little leaner but you should actually run fastest with jet sizes 3 - 4 sizes smaller than stock all the way around. I would go to a 1" open spacer instead of the 4 hole.

Based on the description of the jet sizes I GUESS you are running a Holley 750 cfm vac secondary? If so that carb comes with #72F/#76R jets (or a metering plate that is equivalent to #76's). At 3000 feet elevation I would start at #69F/#73R jets and work slightly leaner from there. Check the plugs after a change and watch very closely for signs of detonation (little black specs on the plug insulation).

If you are running a different carb than what I describe you can go to the Holley website and see what the stock jet sizes are. Then subtract 3 and go leaner a little at a time like I suggested.

PS. A restrictive exhaust will make it run rich too. Cutouts will make the A/F mix a little leaner . . .

Thanx again for the input. Joe Clance, I think you misunderstood me, I wasn't very clear about the jets. The carb is a 650cfm HP. It came square jetted with 70's. I could only muster a 14.0 w/that jetting, plus it ran real hot. I then changed to 71/72, and my MPH was like 97.X. Next time to the track it started to run hot w/that jetting so I tried 72/73's, that's when I started to run 99.X MPH. My last time out I had the carb re-worked. It flows about 770cfm now, and the carb guru who built it said 72/73's should be real close. My 1st run was exactly the same 13.8@99. Second run my car was at about 210* in staging and was sputtering. I then ran a 14.0@94. I jetted it to 74/75's and I ran a 13.8@99. So I don't know if that's just weather or what? Do you guys think it could be vavle float, due to improper springs? Or maybe converter? I don't think its carb, because the guy who built it was out there, and he does it for a living. Thanx for all the input though guys!!! graemlins/thumbsup.gif

Equall jets (pri and sec) could be perfectly fine if the carb has pri and sec power valves in the pri and sec jet plates. If the power valve is primary only (very common in holley) the pri is much richer under low vacuume, (all throttle), when the jetting in the sec is equal to the pri..

I used to run 1/4 @100 mph w/ a stock 350 and a 600 vac holley pri jetted at 66 and sec metered plate.

With your combo's potential power you should get to 110mph if you can feed it enough fuel (guessing)))).

good luck , i;m sure you'll find the mph soon