Beat a dead horse......

[jake]

I rebuilt my 383 with a mild cam, I keep advancing it and she keeps taking it. I am getting worried, 21btdc at idle and she just loves it. Vacuum is at 16iwc, no pinging, is this getting dangerous or should I keep going? She is really starting to wake up, I know everyone says 12-18 degrees but........

 

[70NEWYORKER]

Even if it's not pinging I believe too much advance can beat up the rod bearings.

 

[pomonamissel]

did you time in the cam ? some aftermarket cams have advance built in at install . what spec did you go with ?

 

[Newport 66]

My 383 purrs along at abt 12 degrees. mild cam, dual exhaust with cast iron manifolds, electronic ignition and ram induction.

 

[Davea Lux]

did you time in the cam ? some aftermarket cams have advance built in at install . what spec did you go with ?

Your engine is more than maxed out for timing at idle. I would be worried about the vacuum and mechanical advance causing damage when fully deployed. I would look at advancing the cam timing and starting over. Usually with the stated timing number, you would be getting some significant pinging. Have you checked the harmonic balance to be sure the rubber has not deteriorated and giving you a false reading? What is the total advance curve for the aftermarket ignition?

Dave

 

[jake]

did you time in the cam ? some aftermarket cams have advance built in at install . what spec did you go with ?

Your killing me, 383 with stock manifolds(coated) and stock heads with alittle massaging and 1406 edelbrock and electronic ignition with dual exhausts. Cam is this:
21-221-4(Single Bolt) - Xtreme Energy™ Hydraulic Flat Tappet Camshafts

 

[jake]

9.3 to 1 compression

 

[jake]

Your engine is more than maxed out for timing at idle. I would be worried about the vacuum and mechanical advance causing damage when fully deployed. I would look at advancing the cam timing and starting over. Usually with the stated timing number, you would be getting some significant pinging. Have you checked the harmonic balance to be sure the rubber has not deteriorated and giving you a false reading?

Dave

It looks good and the balancer gives constant readings.

 

[jake]

Here is my plugs running at 18 degrees.

 

[Davea Lux]

They look normal. What are you running for fuel?

Dave

 

[jake]

premium, which is still ethanol by me. 10%

 

[pomonamissel]

well i run 14 degs in this hp 383 , 4 degs advance in the cam 470/270 comp . but went from hp manifolds to headers , it was way too lean . but yours is still choked off . like i was in the dart .

 

[jake]

choked off? Stock exhaust maniforlds?

 

[Davea Lux]

choked off? Stock exhaust maniforlds?

The stock log manifolds are not noted for their high flow characteristics. The HP manifolds were a lot better. Headers are better still when the flange gaskets don't blow out.

Dave

 

[pomonamissel]

tried out some new ones on this build ''remflex'' tall money but so far , no leaky !

 

[jake]

For what I have I like my stock manifolds, ceramic coated. Plenty of get up and go, just nervous about dentionation, not looking for a drag car, just something fun to surprise the hondas!!!!

 

[jake]

 

[moper]

Timing is one of those things that may have several solid approaches. You have a low compression engine with big chambers. So more ignition lead will always help. But - you need to limit the total amount of advance. You can't just run 50* total. So if you're going to run 21+. you will need to limit the centrifugal so that your total is maintained around 38* without the vacuum advance hooked up. And I'd then hook up the vacuum to ported source.