Engine wont rev in the 1/4 mile

[Domobomb]

I see you've upgraded the coil and cap...with an otherwise stock HEI? The module is what keeps the coil saturated with spark. If you're still running the stock ignition module...well they tend to lose a bit of energy above 3800 RPM. Especially done by 5000.

It could also be lack of fuel....and it may very well be a combination of both issues.

Yes, ignition is all stock except the cap and coil which was causing EMI noise on my vette's efi so I put it on my Camaro.

How old are those heads? Probably not, but weak valve springs will cause problems like this with a radical camshaft. Weak fuel supply will sometimes cause the engine to pretty much shut off, then catch, repeat. Lean in the secondaries might actually cause this type of hesitation too, let off the gas just a bit and it runs better sometimes.

I built the heads/valvetrain 2 years ago.

Check the float levels. If they are set to low the engine is going to be starved for fuel at the higher RPM. Check all the basics first before you go crazy. Just my .02 cents

Thanks I'll do that. I did set the float levels properly a few years ago though. Maybe they need adjustment again.

With a 60' of 2.248 I suspect gearing is the issue at hand here . Do you know the rpm you were pulling crossing the stripe at the big end

Well, I can calculate rpm based on trap speed and assuming torque converting isn't slipping much. I get 3560 rpm at my trap speed of 82 mph. It sits at 3600 rpm like it's hitting a rev limiter almost the last 1/3 of the track.

The slow 60' time is more due to the street tires I was running - BFG Sport Comp 2 - 275/40R18, which I grabbed off my vette. Any brake torquing at all and it'll just sit an spin, so I had to launch at idle to control spin.

Man, that car is laying down, only gained 10 mph from the 1/8th to the 1/4. It must be fuel. The 1/8th mile time isn't bad, especially with the slow 60 ft time, but it isn't doing much after that.

You're right. The 18 second truck I was racing picked up more speed in the last 1/8th than I did. It was bracket racing though and the engine would die out the same way every time so I dialed in a 15.25 and won a few races lol.

what is your total timing set at out of curiosity? 36-38? too bad you dont have a visible fuel pressure gage. Is the carb fairly new? Are you shifting manually or letting the tranny shift itself?

Total timing I have not checked. Initial was set to about 12. Carb isn't new but always ran great on the street, very strong down low. But I never really stretched the cars legs on the street like I did on the track.

I have assembled a list of parts based on the feedback in this thread:

 

[77 cruiser]

Check your fuel line front to back. Any kinks? How big is it?
Vent for the tank. Dia.?
Fuel pickup sock in tank.

 

[Mwilson]

I pay more attention to total timing set it around 36 then adjust your initial. Total is where all the power is, thats a huge variable you could be sitting at 22* and making no power.

 

[badazz81z28]

The 60' foot time can just be wheel spin, I'm going to say I would suspect a fuel issue too. Your pump is probably bad and not supplying adequate fuel and pressures at RPM. The bog is tuning and a symptom of not enough fuel

 

[Z73]

Don't buy that distributer we put one in my buddy 81 and had nothing but trouble with it china made. just put a pertronix kit in the Stock GM distributer and like said in prevues post shoot for around 36 degrees total timing!

 

[1980RS]

Hello guys.

I took my car to the strip and made about 7ish passes.

The car seems to bog down/hesitate and wont rev past 3500-4000rpm, at least in third.

I was letting the transmission shift for me which was about 4000rpm in 1st and 2nd.

I thought my plug gaps were too wide at .045", so I dropped them to 0.030" with no change at all.

I'm thinking it's running out of fuel. I don't have an O2 sensor so I cant check AFR.

I was going to try replacing the fuel pump and fuel filter.

What do you guys think?

Here is a typical timeslip with street tires...

60' 2.248
330 6.275
1/8 9.617
MPH 72.30
1000 12.633
1/4 15.308
MPH 82.72

Engine Specs:

Carb: Holley 600
Intake: Edelbrock Performer RPM
Heads: Dart SHP 180 64cc, 2.02/1.6" valves
Cam: Lunati 10120703 - 268/276 duration, Lift .489/.504"
Exhaust: 1 5/8" Long tube headers w/ 2.5" pipes and flow master mufflers
Compression: ~9.5:1
Ignition: Stock HEI with MSD cap and high voltage coil.
Stock GM rotating assembly.
Stock mechanical fuel pump.

Also has a TH350 with 2400 stall and 3.42 rear gear.

Before you get all carried away with this and change too much stuff, which 600 Holley is this? and 1850VS, 80670VS or a 4776 DP?

 

[Damon]

Of all the parts you listed the only one I would buy at this point would be the fuel pressure gauge. And a length of flexible hose to hook it up so you can read fuel pressure WHILE YOU ARE DRIVING. Fuel pressure readings at idle in your driveway are meaningless. You need to see what happens UNDER ACTUAL LOAD. I just duck tape them to the outside of the windshield (temporarily!) to see if I'm holding pressure all the way down the track (or your local deserted back road).

I'd almost guarantee you are just outrunning the fuel system from what you described. Make a run with the fuel pressure gauge taped to the windshield like I said and this will be OBVIOUS if it's happening. Fuel pressure will nose-dive followed shortly thereafter by the motor nosing-over, too.

 

[cadillac_al]

Great advice from Damon. Save your money and get the fuel verified. If it was ignition you would have some misfires or something.

 

[Domobomb]

Thanks for the replies guys.

I replaced the fuel pump, filter, and distributor. (Went with the PerTronix Flame-Thrower HEI)

Also threw and old set of drag radials and 650 double pumper holley carb my dad had.

Shifted at 6500 and it ran 13.5 at 103 mph. Here is the new vs old timeslip:

60' 2.085 2.248
330 5.821 6.275
1/8 8.832 9.617
MPH 82.44 72.30
1000 11.395 12.633
1/4 13.567 15.308
MPH 103.65 82.72

This time seems about right for my setup with 3.42 gears, right? Or do you think I'm still leaving something on the table.

I was going to try a looser converter (Can brake torque to about 1800rpm right now), slicks, and 4.10 gears for next year. Any hope of hitting the 12s with my engine?

Here is video:

 

[muscl car]

More rear gear like 3.73's and a looser converter like a 3500 stall , these two will definitely drop your 60' and also drop your overall ET