Miss at 4500 RPM

[David P.]

I need some help. I have a high RPM miss. The car starts well and runs well until I push it to the 4500 RPM range then it starts to studder and miss.
Its a 67 with the factory correct 327 / 350 hp engine. All stock, numbers matching.
What I have done so far:
had carb redone sent off (needed to be done had a leak) Holley Carb
New plugs, wires, points and coil.
Added new gas.
Still have the miss.
Any help is appreciated.

[Duke W.]

Re: Miss at 4500 RPM

When was the last distributor overhaul?

Duke

[David P.]

Re: Miss at 4500 RPM

When was the last distributor overhaul?

Duke

I have never had the distributor over hauled??? Owned since 92 but never driven much.
Could that cause the miss??
Who is some one good to do it? How much?

[Peter J.]

Re: Miss at 4500 RPM

David,
Had the same problem with my 66 L-79 and it was just the points out of adjustment. I filed them and re-set and it ran just fine at the upper range of rpm until I got a new set of points. The old rule of trying the easy stuff first came through for me.
Pete

[Larry M.]

Re: Miss at 4500 RPM

David:

I would start with the distributor. Problems could be point bounce, erratic advance weight operation or excessive end play, worn dist. cam lobes, etc.

Buy/install a DELCO D-112P set of points or buy a #8104 HP set from ACCEL. If these do not solve the problem, pull the distributor and have it checked out on a SUN Distributor Machine and also check for proper end play/shims.

Also install a new set of AC 45 or R45 or R45S spark plugs, or their equivalent gapped at proper setting (0.032 -0.035 inch).

Other things could be weak or broken valve spring, bad distributor cap/rotor, bad coil, or perhaps a bad plug wire(s). Plug wires should be tested for overall resistance.

Carb COULD be a problem, but I would expect more low power or back-fire/mis-fire.

I am sure others will contribute and offer supporting or other opinions.

Larry

[Duke W.]

Re: Miss at 4500 RPM

Do some archive diving. It's been discussed numerous times. As long as the bushings don't need replacement, it's an easy DIY job.

These distributors were indifferently assembled and sloppy when new, and most have never seen a serious inspection and overhaul since new. My SWC ignition broke up at 4500 all the time when new, and it took me a few years to figure out how to "blueprint" the distributor and use the high breaker arm tension points.

Duke

[George J.]

Re: Miss at 4500 RPM

I echo what Larry said. Try changing the points, first, if you don't have the correct type. The same thing happened to me when I changed the points, once. The engine wouldn't rev over 4500. They were the low tension spring type. Changed to the correct type and problem solved.

George

[Clem Z.]

Re: Miss at 4500 RPM

make sure someone did not put the heat riser valve on upside down. have seen this cause your problem

[Doug J.]

Re: Miss at 4500 RPM

Had the same problem with my 71' 454 with stock dist. and stock points.....problem was point bounce...replaced with Accel points....problem solved.

[Jim T.]

Re: Miss at 4500 RPM

Since you are going to be working on the distributor, you could also remove the centrifical weight springs and weights and clean the pivot points. Very lightly lubricate the sliding surfaces and pivot points for the weights. Remove the distributor tack cable, remove the distributor tack gear and lubricate the gear with grease. Keeping the gear teeth intact will save a lot of grief later.
If you feel like doing more, remove the distributor, remove the gear on the bottom. Remove the distributor shaft and clean the upper cavity of the dried out crud and lubricate and install new seal. Good web site for how to rebuild a distributor is www.tispecialty.com

[William C.]

Re: Miss at 4500 RPM

Had the same problem with NAPA heavy duty points breaking up at 4500RPM. Replaced with Accel #110128, 6500 RPM points and it runs to 6000RPM without a problem. I have used NAPA in the past without a problem, but not any more.

[Duke W.]

Re: Miss at 4500 RPM

There's a lot of misinformation on the Web about the actual PART NUMBERS for the current equivalents of the discontinued Delco D112P 28-32 oz. breaker arm tension points. In particular, numerous Web postings f... up the proper number for the NAPA/Echlin set. Here are the proper numbers. All are the EXACT SAME PART manufactured by Standard Motor Products. The only difference is the name on the box.

Echlin: CS89
Borg Warner: A112HP
Niehoff: DR8P
Standard (Blue Streak): DR2371XP

With the above points in a blueprinted Delco single point distributor and a mechanical lifter cam you can rev a 327 high enough to bust one of those weak pre-'66 connecting rods!

Duke

[Clem Z.]

Re: Miss at 4500 RPM

just back up the movable side of the points with a piece of foam rubber.