250 tune up advice needed

[old cool]

Here's the question: I have the correct 250 block for multiple years, but all of my bolt-ons are mid 60 parts. My block, on the other hand is a 1976 (dated 9-24-75). Hence, manual choke Rochester monojet is exact match to 64-66 carb. Distributor is old school; not HEI. Exhaust and intake manifolds were used from 1963 to 1971.
With all of that said, do I tune up using 1966 specs. I believe timing is 4 degrees btc, plugs are gapped at .350. And I assume since it is a 75 head, I don't have to worry about led additives. Oops, the head may not be '75. Guess ill need to pull valve cover.
I think im answering my own question; especially since i have points and not HEI. Plug choice, gap, timing, etc would be mid 60's?????
While I think of it, were engines built for 1976 all integrated heads? Mine is definately a non-integrated.

[D13]

ignore the casting dates. Treat the engine like your carb and ignition want. From your description the engine thinks it's a 66 so treat it that way.
Not all the 76's were integral. In fact the 292's were never integral, and they ran into the 90's in some countries. My 77 is integral with the 1bbl, my 81 is integral with the 2bbl.
All the heads physically interchange, as long as the correct manifolding for the head is used.
Best 'hop up' you can do is replace the distributor with an HEI and add the performance spring kit to improve the advance curve. But if it runs and works be happy!

[old cool]

Thank ya D13. I appreciate the wisdom (common sense). The block wouldn't dictate air, fuel, and fire as would distributor, carb, plugs, etc.
I am really hoping for 1975-76 head. Then I can disregard led additives.

Wonder why all 75-76 250's wouldn't be integral. Must have had a bunch of non-integral heads and manifolds to use up back here in Pontiac.

As a footnote, did the mid 70's 250 come with more or less internally? ie, in the way of bearings,etc. Were rope seals still being used? (gotta leaking rear main seal)

THANK YOU AGAIN!

[D13]

Cars and trucks went integral head at a different time, I suspect the cars had to meet emissions first and the EGR was the key. The seperate manifold head did not have a reasonable way to incorporate EGR.
The only significant difference internally is cam bearing size, one of the bores is different on the early motors. Externally there was a belt package change somewhere in the 70's and the groove spacing on the harmonic balancer is different, and I belive the timing pointer moved. this may be conincedent with the introduction of th integral head.
Wouldn't bother with lead additives. By time the valvetrain has issues with that it's time for major valve job and hardened seats can be installed.
Pretty much every one leaks at the rear main. There is a lot of whip in the long crank, which seems to scrub. Seals are molded (at least all of mine are) and most replacement seals have the lip slightly offset to get to a clean surface. My 77 leaks like crazy, anhe motor I'm rebuilding has a very definite groove from th seal. Too deep to polish out, next time it gets rebuilt (another 200K or so) it wil have to be welded and ground.

Piece of amusement - bought the 82 body out of Rochester Hills, ex-Califonia truck that was a theft recovery,

[Big Port Jimmy 6]

Originally Posted by D13

. Seals are molded (at least all of mine are) and most replacement seals have the lip slightly offset to get to a clean surface. My 77 leaks like crazy, anhe motor I'm rebuilding has a very definite groove from th seal. Too deep to polish out, next time it gets rebuilt (another 200K or so) it wil have to be welded and ground.,

Get a Speedi Sleeve for the end of the crank. bought my last one at NAPA,
http://www.skf.com/us/products/seals...eve/index.html

Jay

[old cool]

Hey Jason,
I have read and heard enough on HEI distributor. I will definately take you up on your offer.
How to go about getting it to me and paying for shipping is the question. Please advise.
Thanks. OC (teo)

[Jaysonb]

Originally Posted by old cool

Hey Jason,
I have read and heard enough on HEI distributor. I will definately take you up on your offer.
How to go about getting it to me and paying for shipping is the question. Please advise.
Thanks. OC (teo)

Just send me a private message with your address.

[D13]

Originally Posted by Big Port Jimmy 6

Get a Speedi Sleeve for the end of the crank. bought my last one at NAPA,
http://www.skf.com/us/products/seals...eve/index.html

Jay

Can't speedi sleeve the rear main.
Never a rope seal on the modern(ish) inlines.
'sealer treatment's swell the rubber. it may seal that a bit but ultimately the grooved crank will continue to leak. The other wuation is what else is swelling?
The cam bearing change was so that the bores became common in the block. Not sure why they didn't start out that way.
The whip is a harmonic and probably not your issue. More likely motor mounts or trans mounts. The sixes run very smooth.

[Jaysonb]

I have a couple of 6 banger hei distributors kicking around the shop. Let me know if you need one.

[old cool]

THANKS AGAIN FOR REPLIES
As you all know, some responses will lead to other questions. lol. Soooo:

-My balancer looks like one on a 64-66 250 (no certain bolt). Pulley size, not sure if mine is diff than 75-76

-Were the cam bearings on 75-76 an improvement?

-From response, I take it the 65 - up did not use a rope seal?

-Would blue devil rear main treatment help? hurt?

-When I rev engine lightly in neutral, the steering wheel has shimmering effect. Would that be based on crank whip? I know my throw-out and clutch are not perfect....

-I have heard others say don't bother with led additives. SURE do push them at parts store..

-Jason i will keep this post, and if the time comes I get back. Currently have a Pertronix. NOTE: not sure if the coil is a flamethrower which may explain the shimmering in steering wheel when engine slightly reved. That is, not enough juice supplied if a common coil. May I ask what you charge for HEI are they in excellent cond.? Never bought anything via forum..

APPRECIATE HELP... Great forum!!

[Jaysonb]

I pulled a good running 250 out of the stepside that I'm working on, and the truck also came with a spare 250. I just pulled parts off the spare, as it had a cracked intigral head. The hei would be yours for the price of shipping if you need it.

[tucsonjwt]

X2 on HEI upgrade - well worth the $$, and I would stick with GM, not aftermarket - not much more if you by OEM from the online OEM suppliers (maybe cheaper.)