[NoMoCEO]

I aquired a car with a '76/77 Y4 block motor. I'm not sure the application but 6X heads would indicate not a Trans Am.

Can anyone help with timing specs and plug gap?

I was surprised to not be able to find this on-line anywhere.

Thanks in advance!

[77 Canamman]

Factory specs were 18 degrees BTDC and .060" gap. The .060" gap was later lowered to .045" to keep the ignition parts alive longer.

BTW, 6X heads were used on Trans Ams along with any other Pontiac car of the period equipped with a 350 or 400 engine.

[Ron Landis]

I've never even seen an EARLY pointer go past 12. I always found 9-12 to work best....and that's higher compression and hotter cam. Initial at 18..then add mechanical and vacuum @ 12 each...you are at @ 42 total...SBC territory. I thought they dialed back the timing to @ 4 or 6 initial in the late '70's. ...... Anyway...this is what I found in a quick search..... Spark plug gap is .035 timing is 10deg BTDC. 700 rpms in a auto trans . spark plug type in a 2 bbl is R46TS Spark plug gap and timing is the same for the 4bbl except the spark plug is the R45TS for the 4 bbl and timing is set at 600 rpms for the std trans and 700rpms for the auto. trans. Point gap is .016 for both and the dwell angle deg. is 30 . Firing order is 18436572. Disconnect the vacuum line or hose at the distributor and plug it so idle speed will not be affected
Source(s):
Motors Manual 36th Ed ,250W 55th St. New York ,NY 10019

I opened up the spark gap to .045 for HEI but typically backed off the timing to @ 6 degrees for a stock smogger engine...but that's just me. Put 18 initial in her...better have some 93 octain in the tank. All I'm sayin'. End up with 34-38 degrees total...you should be golden! Also...are the 6X heads stamped "4" or "8" on the boss? The W-72 cars {chrome valve covers} used the 350 heads[4's]. If you shave the "8's" @ .020...you'll have the same cc's as the "4's". Good luck. Ron

[77 Canamman]

Originally Posted by Ron Landis

I've never even seen an EARLY pointer go past 12. I always found 9-12 to work best....and that's higher compression and hotter cam. Initial at 18..then add mechanical and vacuum @ 12 each...you are at @ 42 total...SBC territory. I thought they dialed back the timing to @ 4 or 6 initial in the late '70's. ...... Anyway...this is what I found in a quick search..... Spark plug gap is .035 timing is 10deg BTDC. 700 rpms in a auto trans . spark plug type in a 2 bbl is R46TS Spark plug gap and timing is the same for the 4bbl except the spark plug is the R45TS for the 4 bbl and timing is set at 600 rpms for the std trans and 700rpms for the auto. trans. Point gap is .016 for both and the dwell angle deg. is 30 . Firing order is 18436572. Disconnect the vacuum line or hose at the distributor and plug it so idle speed will not be affected
Source(s):
Motors Manual 36th Ed ,250W 55th St. New York ,NY 10019

I opened up the spark gap to .045 for HEI but typically backed off the timing to @ 6 degrees for a stock smogger engine...but that's just me. Put 18 initial in her...better have some 93 octain in the tank. All I'm sayin'. End up with 34-38 degrees total...you should be golden! Also...are the 6X heads stamped "4" or "8" on the boss? The W-72 cars {chrome valve covers} used the 350 heads[4's]. If you shave the "8's" @ .020...you'll have the same cc's as the "4's". Good luck. Ron

It's obvious you haven't spent a lot of time around this era Pontiac 400. Here is an emissions decal from a 1979 T/A 6.6 4 speed engine. Note the timing spec and plug gap..........

[NoMoCEO]

Thanks guys.

I believe they are 6X - 4 heads. I haven't looked at them in awhile. I remember it wasn't the heads that were used on Trans Ams. Passenger car heads.

No smog equipment left on this motor. Stock Electronic ignition.

[77 Canamman]

The 6X-4's are either 350 heads or W72 400 heads, commonly found in Trans Ams 1977-79.

Here is a 1977 decal. Note the 18 degree BTDC timing spec and the .060" plug gap

[77 Canamman]

This 527292 timing cover reads to 20 degree BTDC..

[Mark C.]

Factory timing on my 76 455 is 16.