Parts it has: Engine-390 (.60 over), comp 268H cam, Performer dual plane int., Holley 750 vac. sec., '67 2 bbl heads (mild work), K&n air filter, comp 110 elec. fuel pump, 3/8 aluminum fuel line, pertronix ignitor ignition, cool can.
car: 4.11 gears, 275/60R15 BFG drag radials
What I have tried: replaced carb with a 600 edelbrock, replaced fuel pump with a new comp110, checked fuel pressure at high RPM's, upgraded valve springs, swapped out different igniton systems.
With all of these changes the car still bogged out at the exact same rpm's. It's like the engine cuts and barely runs for about 5 seconds. once the rpms slow back down it runs like normal right away again but even if I put it in neutral it still takes about 5 seconds of feathering the throttle to get it run smooth again.
The engine went 6000rpm with a much larger cam before I put in the 268H. but it makes a ton more power now and I went from a 14.7 to a 14.3 @95 shifting @ 4900. problem ever since cam swap thanks.
2006-07-14 11:53:08 · 9 answers · asked by me 2 in Cars & Transportation ➔ Maintenance & Repairs
If I was going to wager on this, I'd say that it's either valve float, valve timing or hydraulic lifter problems. The problem kicking in with the new cam is the key, I think.
Check the installed height of the valve springs.
Look for oil flow issues if you're using hydraulic lifters. Could be low flow or cavitation of the oil pump resulting in the lifters collapsing.
Get the cam degreed it.
Also, would be a good idea to have a dyno run with scope. Check the fuel mixture when it cuts out and look for RPM related ignition issues as well.
But my money is on the cam or valve train.
2006-07-14 12:30:59 · answer #1 · answered by Bostonian In MO 7 · 3⤊ 1⤋
I don't drag race but I do know cars. How many runs have you made with this "freshend" motor? It doesn't sound like fuel, it sounds more like an ignition problem, old coil? The one thing I can think about is your valve springs, if they have to much seat pressure than you need for the rpms you plan on turning you could flatten you cam, or if they have too little you would be "floating your valves" , meaning that they never truely close. My best two answers Coil or Valve Springs.
2006-07-14 12:25:29 · answer #2 · answered by Bad Andy 7 2 · 0⤊ 0⤋
I have to agree with Boston, again. All this started with the cam change. Nothing else has helped and it cuts out at exactly the same RPM and it went well with the previous cam. This is the only constant after all your subsequent fixes. Im leaning to suspect cam timing but this cam could also be causing valve train issues. Your going to have to keep trouble shooting, this will probably involve some dismantling of the engine to view the whole valve train.
2006-07-14 16:08:22 · answer #3 · answered by webman 4 · 0⤊ 0⤋
OMG i like your avatar! Racing in Drag? They do it in San Francisco all the time, case in point interior the Bay to Breakers races each 365 days. for sure the platform heels make it extremely puzzling, yet a Vicodin or 2 makes one forget approximately the discomfort.
2016-12-14 08:12:44 · answer #4 · answered by ? 3 · 0⤊ 0⤋
I suggest a longer drip to the intake. A high rise intake and on top of it a 2" spacer beneath the carb. It solved a similiar problem for me. Incidently, your car is rather slow , I have a 66 and I run 9.6
2006-07-14 12:10:22 · answer #5 · answered by Anonymous · 0⤊ 0⤋
Maybe a smaller gap in the plugs or a different heat range.
2006-07-14 11:57:35 · answer #6 · answered by Hillbillies are... 5 · 0⤊ 0⤋
Swap back your regular ignition for starters and see if that improves it. I think your spark is too weak.
2006-07-14 12:38:03 · answer #7 · answered by Anonymous · 0⤊ 0⤋
you need to get a mopar!!!
2006-07-14 11:57:30 · answer #8 · answered by seabee12333@sbcglobal.net 2 · 0⤊ 0⤋
TAKE YOU HEADS BACK AND HAVE THEM CHECKED !!!!!!!!!.......
2006-07-14 12:14:40 · answer #9 · answered by paddlefoot2001 1 · 0⤊ 0⤋