Geoff 2
Well-Known Member
Yes, EGR was an emissions requirement. The EGR had to go into one of the primary throttle bores, which already had PVA & MVA ports. So I guess some re-arranging was needed......
1965 Belvedere II 318 poly tuning
- Thread starter R. Shackleford
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Once again....using un-named, un-documented sources, as gospel, to try and emphasize your point.......what is/was the source of the underlined references....or just "cherry picked" out or thin air....without any reference to anything relevant. And no mention of anything about the need for vacuum advance for those that don't want or need it......just your biased opinion........and for those of us (me) that NEVER use manifold vacuum as a tuning component. PM to discuss....if you want......
BOB RENTON
Geoff 2
Well-Known Member
Bob,
Nothing to do today? Had an argument with the wife? Forgot to take your medication?
I wouldn't waste my time discussing a weather report with you....
You insult people then 'invite' them to discuss the matter with you.
If you weren't so dumb, you would know that GM used man vacuum as a STANDARD tuning function through the 1960s. Chrys missed the boat on MVA, but with no alternative, was forced to use it in the 1970s...
Excerpt from Pontiac service manual. Other link is self explanatory, even for dumb people...
Nothing to do today? Had an argument with the wife? Forgot to take your medication?
I wouldn't waste my time discussing a weather report with you....
You insult people then 'invite' them to discuss the matter with you.
If you weren't so dumb, you would know that GM used man vacuum as a STANDARD tuning function through the 1960s. Chrys missed the boat on MVA, but with no alternative, was forced to use it in the 1970s...
Excerpt from Pontiac service manual. Other link is self explanatory, even for dumb people...
R. Shackleford
Active Member
Alright come on guys, we don't need to get into a dick measuring contest over this. I very much appreciate everyones advice and opinions on the subject. As far as the manifold vs ported debate I see it as more of a personal preference than a right or wrong way to do it. However if there is a "right way" to do it than whatever the factory setting for that specific motor would be it, from an engineering perspective, but that doesn't necessarily mean that its right for what you want out of your engine. Just my opinion though
R. Shackleford
Active Member
Well there ya have it. What "holy grail" did this come from out of curiosity (I can't stop it)? I am always willing to give it a go if it can help.
UPDATE: I put a Holley 600 and after a little throttle linkage adjustment she running like a champ. Been playing with the timing here are there but settled in at about 13 degrees BTDC. Doesn't kick back on the starter when starting, doesn't diesel when shutting down and fires right up with a bump of the key. I have noticed there is a "chatter" when under load when I put my foot into it. When cruising or light acceleration everything is sooth and sounds great.... But when I put my foot down it gives me a chatter sound. Never did that before so another fun little mystery. Maybe bump the timing around until it stops? Or may this be a valve adjustment issue?
Last edited:
66 Sat
Well-Known Member
That "chatter" sounds like detonation - take a couple of degrees out of the timing and see if it goes away.
Can't go wrong with a Holley...
Geoff 2
Well-Known Member
The info in post #45 came from Lars Grimsrud, a retired GM engineer.
Reduce your initial timing by 5* & see if the noise goes. If noise is gone, you most likely have detonation. The fix would be to have your dist recurved, so that you can use more initial timing but have less timing at WOT.
Reduce your initial timing by 5* & see if the noise goes. If noise is gone, you most likely have detonation. The fix would be to have your dist recurved, so that you can use more initial timing but have less timing at WOT.
R. Shackleford
Active Member
Ok so I have been bumpin the timing around and can't seem to get it to go away completely. Back it off a couple degrees at a time until I got it really close but still there. I was looking into recurving the distributor and went down the rabbit hole of modifications and it got me thinking... Could this possibly have been a modification made on purpose for slowing down the advance? I figured it was worn but maybe done intentionally? It never did this pinging before when I was using this distributor. Any thoughts?
Ps. its only on the one side
Ps. its only on the one side
R. Shackleford
Active Member
And a better comparison
Geoff 2
Well-Known Member
From the pic, the dist looks be in excellent condition. Weights need some lube; springs should be tight, not loose.
With the engine idling, retard the engine 5* & test drive to see if chatter is still there. I maybe wrong [ was wrong in 1974.....& 1981....] that Poly's could suffer from cracked pistons..which cause that noise.
With the engine idling, retard the engine 5* & test drive to see if chatter is still there. I maybe wrong [ was wrong in 1974.....& 1981....] that Poly's could suffer from cracked pistons..which cause that noise.
R. Shackleford
Active Member
Ok update time:
Reassembled original distributor after a good oil bath for the advance. Dropped it in and she fired right up and idled down perfectly. Drove up and down in the heat (92) yesterday and not a single ping or chatter. Slight hesitation off the line so need to adjust the power valve a little. Might bump the timing a little more for some snap but runnin nice again. Tore down the repop distributor and the weight springs are about as light as you can go along with the longest and easiest moving vacuum advance I've ever seen. You just can't beat OG parts. Thank you all for the fantastic advice and tips. Now in search for headers and to figure out why no matter how I adjust it the kick down won't ever actuate.
Reassembled original distributor after a good oil bath for the advance. Dropped it in and she fired right up and idled down perfectly. Drove up and down in the heat (92) yesterday and not a single ping or chatter. Slight hesitation off the line so need to adjust the power valve a little. Might bump the timing a little more for some snap but runnin nice again. Tore down the repop distributor and the weight springs are about as light as you can go along with the longest and easiest moving vacuum advance I've ever seen. You just can't beat OG parts. Thank you all for the fantastic advice and tips. Now in search for headers and to figure out why no matter how I adjust it the kick down won't ever actuate.
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