Thread: Bad Miss

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I HAVE A 355 SMALL BLOCK CHEVY. IN A 80 MALIBU AT ABOUT 4000 RPM TO 6500 IT HAS A BAD MIS IT HAS A MALLORY UNILITE DIST AND A PROMASTER COIL.A HOLLEY 750 CARB.I NEED HELP

Originally posted by 80BU
I HAVE A 355 SMALL BLOCK CHEVY. IN A 80 MALIBU AT ABOUT 4000 RPM TO 6500 IT HAS A BAD MIS IT HAS A MALLORY UNILITE DIST AND A PROMASTER COIL.A HOLLEY 750 CARB.I NEED HELP

Got a little more information for us to go on?

Like ..........

When's the last time it had a tune-up?
What kind of shape are the plug wires in?
When's the last time the carb. was looked at?
Is the fuel filter new?
Does it do it when it's cold/hot?
Did it just start doing this or is it a new engine or a rebuild?

All else fails ............... keep it under 4000 RPM.

Originally posted by pro70z28
Got a little more information for us to go on?

Like ..........

When's the last time it had a tune-up?
What kind of shape are the plug wires in?
When's the last time the carb. was looked at?
Is the fuel filter new?
Does it do it when it's cold/hot?
Did it just start doing this or is it a new engine or a rebuild?

All else fails ............... keep it under 4000 RPM.

Or above 6500!

Originally posted by pro60chevy
Or above 6500!

Originally posted by Streets
or use a taller gear so ya nevah see 4G's..

I woulda said valve springs but it wuz already taken...

I'll say valve springs Ann E. Way .......... It sounds kinda' kewl.

A 355 is an awesome motor .What do you want to pull for a max r.p.m. I used to run 6,000 in my 355 . If your missing at 4-6500 it means your motor is either running out of spark or fuel . Check ignition system Plugs, wire's, cap , rotor. and check your fuel supply hoses , filters, pump. If you had a bad valve you would know it . It would smoke and go through a lot of oil. Also check your choke and make sure it is opening all the way for high r.p.m's

I'll side with Tech and Streets on the valve springs, but that sure is a lot of carb for that size engine.

I'll have to throw in my lot tech streets and ntfday and conclude valve springs, just a thought, though, that holley 750 is it a double pumper or a vacume secondary ?

I'd go with either valve springs like everyone else sez, but also i saw in your first post, a mallory dist. sorry to break this to you, but mallory's are pieces of junk, I've owned a lot and never have had luck with any of them. try slapping a stock distributor in if you have one... your problems might dissappear.... if they do... just add a pertronix ignitor to your distributor and you'll be set

Darn, I thought BAD MISS was about women gone wrong.

I'm going to say no on the valve springs, not because I know better but thought I would be the devils advicate.

I'd check the ignition system.

has it allways had a bad miss?did you do anything to the motor before it started missing sounds electric or carb related what sort of cam you running,how much vacumn at the carb,hot or cold when it happens????

almost sounds like guide seals, but more likely valve springs.

other ideas:
Fuel pump?
Is it running rich? lean
pull each of the plugs to see which, if any, one is fouled. If there is a fouled plug how it is fouled might help figger out why there is a miss