engine cutting out down track after in 3rd gear!

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moparmatt19

moparmatt19

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ok spec on setup. 360 .030 kb pistons 10.2to1 comp. run 93/110 oct 50/50 mix J heads ported with 2.02/1.60 hughes engines cam HTL4852s solid cam. 248 252 @ .050 .563/.572 106 lsa. air gap intake,Hooker super comp headers, carter race mec. fuel pump, holley street avenger 770 carb , pertonics flame thrower 3 bilet dizzy with rev limiter set at 6800 , TF727 race built with 3500 stall, 3.92 sure grip 28/10.5/15 MT slicks. problem I am having is after I shift into 3rd gear going down the 1/4 it starts to sputter, pop and stop pulling... dad said it looked like I lifted at end of track. not sure whats going on! looking for imput on what you all think. I found that the vac adv was pulling the timing up really high and that my fuel pressure was only at 6psi. I plugged the vac port on carb and unhooked the vac advance. recurved the dist to 34deg max. haven't changed the fuel pressure bc I need another regulator. could these things cause this? I haven't been able to get back to the track yet. and don't know when I will be able to. this is my daily driver lol. only ran 12.7@103 in a 67 notch cuda race weight 3300. what do yall think? im sure this combo should get me high 11's when running right and little better traction.
 
when you say cutting out do you mean the motor quits pulling or that it start to pop at the top end?
 
Post ALL incrementals off your timeslip.

That set up should be WAY faster than it's running.
 
sounds like its running out of fuel but would need more info, fuel pump type and pressure? carb?
 
I would start with fuel, I have never had any luck with a mechanical pump. My last 340 combo was similar to yours with less cam, went from 13.3 to 12.8 after going from hv carter mechanical to a holley electric pump and regulator.
 

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Original fuel tank? Check your strainer in the tank. Just my 2 cents.
 
RT. .083
60ft. 1.814
330ft 5.199
1/8. 8.075 @ 84.94 mph
1000Ft. 10.596
1/4 12.757. @ 103.63 mph
 
Motor cuts out kinda like rev limiter. .. sorta...popping and not gaining rpm or speed.
New fuel tank , 3/8 sending unit and 3/8 line all the way. Carter high volume pump. Thinking 120gpm. And 14psi I think if I recall correctly. Haven't hooked my fuel pressure tester and ran it yet to see if fuel pressure drops. I forgot that I had a piece of junk Mr gasket regulator on it that only went to 6psi. Until I was at the track. When I went to break the engine in I could not find my Holley reg. I've got to buy One.
And yes this car should be a lot quicker! I had traction problems also. Couldn't hook. One run it was still breaking lose 40 ft down the track.
 
The timeslip is close/right in line with most incrementals.

What is the initial timing. That's one of the first places to look for why it's slow down low. Total timing is one piece, what it has at idle is REALLY important. It would likely need at least 20* timing at idle.

Regulator have small inlet? smaller than 3/8" pipe?

It's at least 10mph slow from what I'd guess it should run, but it's soggy from the get go as well. There's a bunch missing everywhere. Get to tuning it up.

Fuel delivery, ignition and valve springs would be the three things I'd be looking at for potential issues.
 
Idles. At 1400rpm. Only had base timing@ 14deg.. I set it right at 22deg tonight and total is looking to be around 36 now. It idles better in gear now.
 
Did you get a chance to try any jetting changes? Before I swapped fuel pumps I was attempting to tune with jets, the plugs looked a little lean but not bad, and jetting up netted no change in et. Mine car didn't drop off or pop, but it just felt lazy on top end. After I went to an electric fuel pump and regulator I saw change in et with jetting changes.
 

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I had the exact same problem with my Carter high flow mechanical fuel pump. 1 & 2 pulled great, but as it shifted to 3rd, the sustained RPM's overdrove the fuel pump, which raised the pressure enough to overcome the float pressure on the needle valves in the carb, and the engine would flood. The Air/Fuel ration just kept getting richer until is suddenly went to 0, which is 100% fuel, LOL.

I put on a good quality regulator, and keep the pressure around 5 psi, and problem solved. I am running a Thermoquad, which is a little more sensitive to fuel pressure that the Holley.
 
Fuel pressure/volume, fuel line to close to headers,(needs isolating),High resistance in ign wires ( if they are not Quality wires, i would be getting the ohms meter out and finding the bad one or two wires)

My Carter mechanical pump work grate! But i have a electric pump at the fuel tank pushing 3 psi at the suction side of mechanical pump.

A full loop system would work better, with the regulator at the carb, but it work.
 
Like I said I drive this car everyday. Check the plugs often. On the street they stay a light grey with the race fuel mix. But I did notice when I checked the plugs at the track after a run the showed rich. I do get into it on the street also hehe. But not like on the track. So I am wondering if it was flooding out at the sustained higher rpms. ...
 
Has new moroso spiro race wires. Everything is brand new on this setup. But I know that doesn't always mean is working right. I will check resistant on The wires tomorrow.
 
If you drive this on the streets...and then go to the track....I would have a set of spark plugs that I would use only at the track...remove them went you drive home..
 
I haven't thought about having plugs for the track. Good idea! I'm thinking of running the autolight. Platinum 65's in it. I have crappy. Copper 63 in it now. Could be part of the issue also. I wasn't sure on what heat range to run in it so I ran the colder 63. What's your all's suggestions. On spark plugs I should be running? I was worried about the comp. And the pump gas with the 10.2 comp and iron heads. The chambers are polished though. My cranking pressure right after I broke the cam in was 180 psi to 185psi. I haven't checked it since I've put a few miles on it. Probably has 1k miles on it now. The exhaust is so loud right now I can't hear for spark knock. That's why I check my plugs a lot.
 
moparmatt19 said:
I haven't thought about having plugs for the track. Good idea! I'm thinking of running the autolight. Platinum 65's in it. I have crappy. Copper 63 in it now. Could be part of the issue also. I wasn't sure on what heat range to run in it so I ran the colder 63. What's your all's suggestions. On spark plugs I should be running? I was worried about the comp. And the pump gas with the 10.2 comp and iron heads. The chambers are polished though. My cranking pressure right after I broke the cam in was 180 psi to 185psi. I haven't checked it since I've put a few miles on it. Probably has 1k miles on it now. The exhaust is so loud right now I can't hear for spark knock. That's why I check my plugs a lot.
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opinions will differ, but I personally wouldn't run an Autolite in my lawn mower. My vehicles all have NGK v-power. I'm unsure of the particular heat range that will be best for your engine, but someone will chime in with the proper info. I've had the NGK's in the 225, 318, and my 360 with great success. If I recall correctly, 63morepar has a 340 setup real close to your 360. You might shoot him a message to ask. Can't hurt right?
 
Lots of good advice given so far. Something no one has mentioned yet, is to try a doublepumper carb. Some times vacuum sec carbs just aren't happy on engines with bigger cams.
 
fuel cell or stock tank? The pickup tube under hard acceleration and less then half tank of fuel can suck dry after 5-8 seconds of your run so check that sometimes its so simple you over think it lol. My 70 runner did this because I was thinking to go faster save weight with less fuel in tank! Duh! JMO
 
You HAVE to have the fuel pressure gauge located where you can read it going down the track. On the cowl or hood, or inside the car if using an isolator.
 
Ok question guys... will the vac advance work at WOT? Reason I'm asking is bc when I raced it I only had 14 deg at idle. And when I pulled my vac hose off the dizzy it was only pulling 20 max with the limiters I had in it. I think I was going all the way down the track with only 20 deg timing.
 
crackedback said:
Fuel delivery, ignition and valve springs.
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When you are pretty sure the basics are covered never forget the valve springs and proper installed height!!!!!! To many shops get sloppy here.
 
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