breaking up at 4g rpm ?

[mr mctavish]

would you look at carb, or ingnition first?

engine is new 2500 mi [383]

JET stage 2 q jet

timing set at 34* advance.

engine runs fine until it gets up high.


Thanks

 

[406shark]

My quess would be ignition system.

What ignition are you using? Stock HEI?

Jeff

 

[Ol Blue]

Mr Mctavish

A few weeks ago I pulled my 65 out of storage and had a similar problem with it. It just wouldn't rev, it bogged down like it was running out of gas. I tried everything, including changing carbs, plugs, plug wires, distributor cap, points and condenser. Finally changed the coil. That fixed the problem.
Ol Blue

 

[Jack]

Ignition module inside HEI dist often shows failure around 4K to 5K rpm ... often breakup is more pronounced the hotter the temps are. HEI Ig Mod is cheap, quick & easy to replace ... while you're in there pull the coil out of cap and ensure no moisture under coil and all connections bright & tight. If that don't do it ... look for a new coil. Also check rotor real close ... look at plastic beneath & around where center is ... sometimes burns through ... hole starts off VERY tiny. G'luck.
JACK:gap

 

[wishuwerehere82]

Jack,

Isn't 36-38 degrees the proper advance for the timing?

 

[cruzer99]

Check your fuel filters.

 

[mr mctavish]

thanks everyone

hei dist/coil new in june

34* was set by builder

still pings a little under a little struggle 9.8 CR

 

[78SilvAnniv]

:eek What a striking color...I LIKE IT! What is it called?...Candy something?
Heidi

 

[mr mctavish]

Heidi Thank you, color is stock. code [79]-- Maroon metallic.

with 1980 oyster int.

 

[Jack]

Jack,

Isn't 36-38 degrees the proper advance for the timing?

Yep ... but can range lower or higher depending on many variables ... temps, CR, fuel grade etc.
JACK:gap

 

[Jack]

hei dist/coil new in june ... still pings a little under a little struggle 9.8 CR

Even a new distributor can have a problem.

Is it breaking up in upper range (as first posted)? ... or is it pinging? ... Or Both?

How has your builder addressed this issue?
JACK:gap

 

[mr mctavish]

Jack------- I most likely will bring it back to builder. At this time he is extremely busy with other customers. I fear it would sit at his shop for a few days. If its something I can learn/do myself, I want to. as far as the pinging or should I say "knocking" like from a lower octane fuel developed gradualy. as I posted regular driving is fine.
But when I went to "nail" it, with the original 2.87 rear, I got the rpm's up and just no go after 4000. so , I tried it out on a major interstate, I brought It up to 4000 gradualy.. same thing...... breaking up.
Thanks for you interest.

 

[cruzer99]

Sounds like they put an RV cam in it (dies at 4K).....and the lifters are not set correctly (too tight).

 

[mr mctavish]

comp xe 262

eng. was installed early june ran great up until tue.s

 

[55OHNO]

It's a BEAUTY !!!!!
What type of polish/wax are you using ?
It's definetly ding the job !!

 

[55OHNO]

Definetly doing the job !!

 

[mr mctavish]

55OHNO -------I feel guilty ---- It must have been a trick of the light. It's just a good pic.
Its was polished a week earlier than the pic. was actualy dirty at the time.

I use the easy mcgiures spray on. I felt I must confess.

 

[curtis]

xe262 is the same cam I am running. Most likely stock HEI won't fire hot enough spark to set off combustion at the higher speed when your cylinder pressures are up. That cam makes makes maximum torque right near 4000 rpm so your cylinder pressures will be maximized at that point. My ACCEL module and coil works fine on my 355. Also that cam is good to 5600 rpm if the manifold will support it. I run a Performer intake. One possibility could be you are leaning out too much at the higher rpm, such as high speed air bleeds wrong size, or maybe main jetting should be a little bigger. The main jets too lean will affect the mixture all across the rpm band and could cause the preignition and high heat as well a stumbling or sputtering on the high side. Inspect your spark plugs with a magnifiying glass. If you see little specks on the porcelain you have severe preigniton. The specks are aluminum from the top of the pistons. Hope this helps.

 

[mr mctavish]

curtis ------- thanks. I'll look at plugs. I have the performer intake also.