New to me - inline 6 250 service info needed.

[Hansome]

Hi all,

Happy New Year from the UK.

I hope to start 2015 in good form by finally servicing my c10 engine. Had the truck only 3 months and trying to work out what I need to do first.

There are no threads on basic servicing etc so I have a few questions that maybe you could help me with

C10 1966 250 inline 6 with HEI dizzy and single barrel carb.

So my plan is to...

Change oil for new
Change spark plugs
Compression test
Set the timing on the HEI
Set carb

Can you tell me what new spark plugs I should be looking for ? NKG? bosch ? Etc
What should I be setting the timing at with the HEI 10° BTDC? Or any other recommendations happy sought.
Once I have set the timing roughly what RPM should I be setting idle at? 500/600?

It seems to be running a bit rough is why I wanted to do thE service and this way I also get to learn something new about my (currently unfamiliar ) engine.

Thank you In advance

H

[Lugnutz65]

Originally Posted by Hansome

Hi all,

Happy New Year from the UK.

I hope to start 2015 in good form by finally servicing my c10 engine. Had the truck only 3 months and trying to work out what I need to do first.

There are no threads on basic servicing etc so I have a few questions that maybe you could help me with

C10 1966 250 inline 6 with HEI dizzy and single barrel carb.

So my plan is to...

Change oil for new
Change spark plugs
Compression test
Set the timing on the HEI
Set carb

Can you tell me what new spark plugs I should be looking for ? NKG? bosch ? Etc
What should I be setting the timing at with the HEI 10° BTDC? Or any other recommendations happy sought.
Once I have set the timing roughly what RPM should I be setting idle at? 500/600?

It seems to be running a bit rough is why I wanted to do thE service and this way I also get to learn something new about my (currently unfamiliar ) engine.

Thank you In advance

H

Hello from this side of the pond!
I have a 250ci with HEI in my 1965 C10. My 250ci is from a 1971 truck. 1965 trucks came with a 230ci but they look identical and I'm not gonna tell.

I bought my HEI dizzy from Tom Langdon Here's his website.

He recommends Champion plugs. Make sure you check what hex size is correct for your head. My 230ci plugs will not fit in my 250ci.

A compression test is a great idea. If the compression is bad somewhere, then I think you will be wasting money until you solve that problem first.

I have my timing set at about 10 degrees BTDC but I used a vacuum gauge to determine what seemed best. I hooked the vacuum gauge to a port on the intake manifold. Once you have the idle RPMs down around 700-800 you can adjust the timing to get the best vacuum. It makes sense that the engine is making the most power at a certain RPM if you also have a stronger vacuum.

As far as tuning the engine and carb, I think a Factory Service Manual is about the best investment you can make. There are so many things that the average guy can do with simple tools

The one barrel carb is easy to rebuild.

I hope this info helps. Also, be sure to look at the FAQ section for lots of info that people have taken time to post to help folks like you and me.

[TJ's Chevy]

NGK plugs work fine. BR6ES is what I run on mine. Set timing to 8-10 degree at idle without vacuum...20-25 with vacuum at idle....no more than 36 at full advance.