The Stovebolt Site Forums The Shop Area Engine Shop 250 cid timing

could anybody give me some timing tips for my 67 chevy 250 cid? seems to be a little rough or a slight miss,maybe a little hesitation when revved...vacuum advance seems fine... checked for fouled plugs,for points breaking/gap ect...inside distributor...
just put on a new head and did my first attempt at valve adjustment...they sound decent maybe a hair loud...not sure if this may be a part of it...

it fires up very easy tho and idles fine...

I know many variables...

I'm scratching my head...

Your 250 should have hydraulic lifters and the tappets shouldn't make any noise at all...

I would have to check my shop manual, but I believe the correct valve adjustment is "one turn beyond zero-lash".

I have a '72 C-10 with a 250 (unknown vintage). I've never been able to get the timing quite right, but my original Mono-jet carb and "Transmission-Controlled Spark" were removed and replaced with a mid-'60s Rochester BV carb. I installed a rebuilt distributor for s '67 Chevy last year; that helped a bit.

I have trouble with the points closing-up and burning; the rubbing block on the contact arm seems to keep wearing down. (These are the points that came with the rebuilt dizzy (A-1 Cardone); I'm going to try a set of Blue Streak Lubri-points next tune-up)

What carb are your running on your '67 ?

Also what plugs and plug gap? Too wide a gap can cause missing at high speeds...

I had the head rebuilt at 96,000 miles; truck now has 119,000 miles on it. Head's great - now the rings and bearings are shot !

Hey Frank...I thought about going with an electronic igition too...a few years back I had it on a 250 that was in a 68 GMC step I had and it ran like a swiss watch...

I still have some smoking after replacing the head I think my rings may be gone too...this thing has been a nightmare from the get go..

the carb is a one barrel I'm not sure exactly what it is...

plugs are champion .035 gap...that was what I was told by the autozone guy...


the points seem to be closing ok and actually the miss/hesitation seemed better before replacing the head... it will start easy and idle well the revving is where I see problems...I'm wondering if the new heads better valve efficeincy may be calling for a timing or carb or whatever adjustment...

I have had a bunch of these 60's and 70's trucks and for whatever reason this one has been a bear with one problem after another...I am almost tempted to roll it off the river bank...

Sometimes too much spark advance can cause a rough running at 2-3 thousand rpm with no load. Try disconnecting the vacuum advance & see if it still does it. You may have to change the vacuum advance chamber or put a limiter on it or set the timing back a little.

I haven't drove it to put a load on the eng yet since I put the new head on...I was thinking about taking it down the road this eve..If I do and the load makes a difference I'll letcha know...I was thinking of getting my hands on a timing light and checking it... what is the basic starting point? when I put on a new water pump I cleaned off the gunk on the marker by the harm. balancer so you could read it again and get a light on it...also which plug for checking? I was thinking it was the #1 cylinder...

thanks I appreciate you letting me needle you with questions

Mike