Vaccume Advance source..?

[frustratedboater]

Greetings all,
Boat info: 85' Mastercraft American Skier, chevy 350, Holley Carb 4BBL, vaccume secondaries..

I just switched over from breaker point system to an HEI distributor. The timing is set around 8-9 degrees before TDC and runs good (there is no vacuume hose hooked up to the distributor). I had noticed a significant diffrence in the sound as soon as I started it. I even took it out for a spin and could not notice much diffrence in performance. The engine backed down real fast from full throttle... thought that was strange...

Q- My friend who teaches engine tech, at school, installed it and said that I would need to obtain a port-side vaccume..? He said the the vaccume should be off the front-side of the carb.? I may have got that mixed up, but there was not a vaccume source for that. I tried to find numbers off the carb, but I am going off memory. 3600, or 3900... there is one capped tube towards the upper choke side, but he said that wouldn't work.

any suggestions on the vaccume source?

 

[Alpheus]

Re: Vaccume Advance source..?

Marine distributer with a vacuum advance, no such thing. You should not run an automobile distributer in a boat. It is against all that is holy including the USCG rules & regs...

 

[Don S]

Re: Vaccume Advance source..?

The automotive distributors not only are not ignition protected (aka spark protected to prevent ignition of gas vapors) but the advance characteristics are completely wrong for a marine engine, and can do more damage to your engine than good.

My friend who teaches engine tech, at school,

Probably not your best source of information for marine engines. Way to many automotive guys think marine is the same............. It's not.

 

[Aloysius]

Re: Vaccume Advance source..?

Listen to Alpheus. As tempting as it is to the naive boater, critical non-marine parts like this are downright foolish.

 

[HT32BSX115]

Re: Vaccume Advance source..?

In addition to all of the above, automotive vacuum advance doesn't work well (at all) on a marine engine.

Marine distributor advance is ALL centrifugal.

Using a non ignition protected distributor is just asking to hurt someone.

 

[dubs283]

Re: Vaccume Advance source..?

Marine distributor advance is ALL centrifugal.

on conventional (points) ignitions

the OP stated that there is now HEI (electronic) ignition on the engine now

in any case, the information provided is lacking and in no way am i defending or condoning the setup the OP is attempting to run - just don't want the fella to be any more confused than he already is

 

[Aloysius]

Re: Vaccume Advance source..?

There are NO vacuum advance marine distributors. There are no vacuum ports on marine carbs, especially ported vacuum, which is what a vacuum advance uses.

 

[rodbolt]

Re: Vaccume Advance source..?

the DELCO HEI distributor was NEVER EVER marinized.
heck we couldnt keep the advance from rusting on automotive apps.
so it means the distributer, if HEI, is NOT marine rated for ign protection.
what an ing protected device means is it will not BE a source of ign. has noting to do with engine ignition systems.
most boats tend to run at or near WOT its also why most ran no PVC valve. at or near WOT intake vacum kinda dissapears.
however some of the early 153 CID mercs tried a vacum advance.
the delco EST was marinized and is still in use and uses a fully electronic timing advance.

 

[cr2k]

Re: Vaccume Advance source..?

The key to your dilemma is " My friend who teaches engine tech, at school..."

Your friend knows not of Marine equipment and should stick to what he knows to prevent needless loss of human life.

 

[fossill]

Re: Vaccume Advance source..?

You can get a brand new marinized electronic ignition distributor from an aftermarket supplier for a reasonable price.

 

[frustratedboater]

Re: Vaccume Advance source..?

Welllllllll... Every day is a lesson learned! I guess I'll have to pull it and ebay the 'brand new hei" Ruuuur.. It's alright.

Forgive me for asking, but are there options to get rid of the points, or is that just the way it is?

 

[rodbolt]

Re: Vaccume Advance source..?

most EST distributers already have the flame arresting screen vent, all they lack is the correct 5.7 marine ICM module.
or look around and you can find them all over, volvo,merc,crusader and some aftermarket suppliers used them.
the difference between the automotive HEI and the delco EST systems is the EST has a vent with a flame arresting screen.
this not only allows fuel vapors to exit the cap area but in the event it did manage a flame under the cap the flame can be vented and broken up, similar to how a flame arrestor on the carb works.
not the first distributer cap I have ever seen blown off due to fuel vapors.

 

[fossill]

Re: Vaccume Advance source..?

Welllllllll... Every day is a lesson learned! I guess I'll have to pull it and ebay the 'brand new hei" Ruuuur.. It's alright.

Forgive me for asking, but are there options to get rid of the points, or is that just the way it is?

Here's a few ideas, I'm sure there are many others out there.

http://www.summitracing.com/search/...r-Conversion-Kits/?keyword=marine+distributor

http://www.summitracing.com/parts/MSD-8560/

http://www.michiganmotorz.com/delco-voyager-marine-electronic-distributor-p-119.html

 

[dan t.]

Re: Vaccume Advance source..?

The Delco Voyager marine dist and the Chev 350 or 305 tbi dist from a 87 to 95 truck engine are identical in every detail, same screened venting ,same cap and rotor,same module. pick one up at the local wreckers, Oh and also same part number stamped into the housing

 

[GLENN M]

Re: Vaccume Advance source..?

or you could buy a petronix module that replaces your points and is a direct bolt in,

 

[Aloysius]

Re: Vaccume Advance source..?

The Pertronix stuff is bulletproof WHEN installed correctly.

 

[frustratedboater]

Re: Vaccume Advance source..?

thanks for the info and all the options. I'll have to determine what is the best step to take (after I yank it all out). For now, I'll go with the previous setup, but would like to go eletronic all the way! The idle sold me! Well, for a few hours of glory.......

 

[zbnutcase]

Re: Vaccume Advance source..?

The Delco Voyager marine dist and the Chev 350 or 305 tbi dist from a 87 to 95 truck engine are identical in every detail, same screened venting ,same cap and rotor,same module. pick one up at the local wreckers, Oh and also same part number stamped into the housing

Module IS NOT the same, truck one interfaces with ECM, at least in USA, Canada may be different, EST is a stand alone unit, they are however, physically identical, and its easy to assume...

 

[rodbolt]

Re: Vaccume Advance source..?

modules will physically fit each other, however the marine module is not the same as the EFI auto module.
the carbed module has some differences from an EFI one.

 

[dan t.]

Re: Vaccume Advance source..?

Hey Rodbolt if the automotive module is different I sure would like to know where? They both have 22 degrees advance, all in by about 2800 to 3000. On page 189 of Dennis Moores book Small block chev marine performance it states that they are identical. This mirrors my own findings in that I can find no differences at all