5.7l Chevy pinging/ ignition issue

Hey, we bought a boat roughly two years ago and since then have had a pinging over 3200 rpm's. obvious and probable cause is timing, i understand that. what i dont understand, and my main problem being and have researched and got no where is why isnt the vacuum hooked up on my distributor? its the type of dstrburt that has the coild built into the top (fyi). My initial thought to fix "the ping" is to check the timing correctly (i have all the proper tools to do so) but i cant get passed this whole vacuum issue, the peice to hook the vacuum is on the distributor but is just not hooked up. The engien has power, we have been using it for two years now and the pinging is starting at 3000 rpms now... so we are looking into it. The engine was supposedly replaced about 4 years back, no way to verify exactly what the engine is but the block casting number reads that of a 95-00 zz4 chevy 5.7l 350. ANY help would be greatly appreciated as the tuna are coming soon and we are looking to get out there reliably! Thanks for your time!!!!!!!

Re: 5.7l Chevy pinging/ ignition issue

is it ok for the vacuum advance to not be hooked up? will it operate normally under this "condition"?????

Re: 5.7l Chevy pinging/ ignition issue

one more thing, sorry. If you do know the answer maybe you would know the correct way to go about timing this so i dont get lost in a sea of ignition timing procedures that have nothing to do with my (in my mind) wierd distributor?

Re: 5.7l Chevy pinging/ ignition issue

download the manual that should give you all the info you need. adult only at the top of this forum go to site an download it. Not a answer id like but i think it o be the best then if you dont understand repost.

Re: 5.7l Chevy pinging/ ignition issue

Sounds like someone replaced the engine with a 355HP crate motor from Chevrolet. It would have come with that distributor, and an advance curve unsuitable for your application. You are running premium fuel I hope, as it has more compression than the marine engine it replaced. Do you have a timing light? If not get one and it will have to be one with a dial so that you can check more than is on the balancer. Or you will need some timing tape for the balacer, sold by a company called Mr Gasket. What I would do, take the boat out, run it, and little by little retard the distributor until the pinging stops, it might have trouble idling but what you want is a total advance that keeps it from pinging, probably be around 28 or so and I'd bet that right now at rpm its up around 36 or 38 (you will have to watch while it's revved up under load so it will take one person to drive the boat and another to look. Then reset it so you get a good idle and it's easy to start, and record that number, probably 8-12 degrees. Then find a competent machine shop preferable one that does HP stuff and tell them you want the distributor curved, tell them you are going to set whatever initial (idle) timing and that you want no more than the highest number you came up with (total advance). If you don't want to go to that much trouble you can go to Kragen or somoe other parts house and see if they have an advance kit for an HEI distributor, they aren't expensive, get it and put the heaviest springs in the kit in the distributor and back the timing down a touch and see if that helps. Do not hook up the vacuum advance. A lot of info, but pinging tends to ruin parts.

Re: 5.7l Chevy pinging/ ignition issue

You need to replace the distributor with a marine one.

Re: 5.7l Chevy pinging/ ignition issue

Need to know all the info on the motor. What yr, carb, tbi etc....
Without that who knows. The block number could just mean its a roller block. It could be a vortec, standard who knows. I would think thats electronic ignition and the advance is built into the module. Without all the info everyone is shooting in the dark.

Re: 5.7l Chevy pinging/ ignition issue

Also are you sure the vacuum port isn't just a vent?

Re: 5.7l Chevy pinging/ ignition issue

I know a marine engine does not use a vacuum advance. That being said there is no reason the distrubutor that is in there now wont work if it is properly curved, it does after all have a mechanical advance mechanism in it, however whats in it now will have a curve set for an automobile. The curve is easy to adjust if you know how. The vacuum advance portion can remain attached, just dont hook it up, that's all I was saying.