Slop in original timing chain on 78k 430

I've been racin' my Riv. since new.
Of course it didn't see above 5400RPM's then or now.
If you really want to get nick picky about it a "Nail" chain could be changed at every tune up because it will stretch that much.

Tom T.

 

So I took her through some paces this evening. Very responsive now and lights up the tires off the line but detonation is terrible especially 2nd and third gear throughout the rpm range. I retarded timing to 4 initial and 27 total mechanical advance. It was better but still noticeable. Took it down to 0 initial and 23 total and it is almost gone but it isn’t nearly as responsive as it was of course. I always use premium gas but don't really want to blend racing gas with it. Im thinking stiffer springs now to slow mechanical advance to 3000rpm instead of 2650. It probably has a lot of carbon buildup over the years. It is much more responsive now than it was though and doesn't stumble off the line now that vacuum advance is working properly.

 

How.much advance is the vaccum advance giving you? You may want to limit it

 

9* i did limit it.

 

Chain stretch. I had to replace the front crank Rope seal with TA's neoprene seal. Bought a new TA timing chain cover.
When we inspected the timing chain it was stretched where we had to replace it. It only had 3,500 miles on it. I had a Buick engine builder tell me BBB are bad about stretching timing chains. I guess it might pay well to go with a double roller chain?? VET

 

Is the limited advance bushing in place?

 

My vacuum advance has the bushing and is limited but I will check mechanical advance bushing. Maybe 23* of total mechanical advance is too much?

 

Yes I can double check that again.
Did my distributor come with a mechanical advance stop bushing? Is the hei mechanical advance bushings compatible with a points type distributor?

 

Thanks so much Larry. I will get one and check spring varieties. Do you think it would be worth trying manifold vacuum instead of ported on my vacuum advance?

 

Wow 30-34 seems like way too much. I will definitely confirm it isn't getting that high by installing lightest springs and try manifold vacuum. Thanks again.

 

Original stop pushing is still there looks only slightly worn. It seems like someone should make an egg shaped one

 

Installed new bushing. Thinking of modifications to the extra weights in the kit limit total advance? Just to try it?

 

My older brother told me again today that it pinged since the day my grandma bought it in 69. Tune ups never helped. Always had premium. Only way to stop it was to retard it WAY down.

 

Today I put my stiffest springs on and tested her. Timing initial set at -2 and all in around 26 now at about 3000. Almost no detonation noticeable but so sluggish and even sputtering when I punch it while moderately accelerating.
Then I changed vacuum advance source from ported to manifold vacuum and WHAT a difference! Timing still the same but very responsive and even chirped the tires at second gear! I think I'll leave it alone for a while now and enjoy it
Thanks everyone