Gain extra benefits by becoming a Supporting Member Click here find out how!
Classic Performance Products Classic Parts
American Auto Wire Classic Industries
Chevs of the 40sDanchuk Catalog
Hellwig Products IncPerformance Rod & CustomEcklers AutoMotive
Nu-Relics Power WindowsRain Gear Wiper Systems
Impala Bob's Bob's Chevy Trucks Bob's Chevelle Parts Bob's Classic Chevy





Username Post: Locking out the distributor        (Topic#354219)
79eliminator 
Poster
Posts: 22

Loc: Montana
Reg: 10-25-18
12-04-18 07:54 PM - Post#2753411    

I’m building a 450 horse 454 for my jet boat. I know that a person doesn’t need to run vacuum advance and that you can lock out the dist. I do have the little plastic lock out tab that goes inside the dizzy. Can anyone give me more advice on what else needs to be done. I know enough to set it to get it up and running but good advice is always appreciated. I also have the timing tape to install on the damper pulley cause I heard at around 3500 rpm the timing should be set around 35 degrees.

1979 eliminator speed boat


 




IgnitionMan 
Valued Contributor
Posts: 3509

Reg: 04-15-05
12-04-18 08:17 PM - Post#2753414    
    In response to 79eliminator

Wrong way to go.,the proper mechanical and vacuum curves will allow the engine to run best, but you have given us NOTHING to go with about the engine.



 
acardon 
Ultra Senior Member
Posts: 11103
acardon
Loc: DFW TEXAS
Reg: 03-25-05
12-05-18 05:54 AM - Post#2753452    
    In response to IgnitionMan

A boat is entirely different from a car and a jet boat is different from a prop boat. The pitch of the jet drive and the size and type of boat has to be considered. A flat bottom jet boat won't need as much low end power as a boat that draws a lot of water with a deep pitch prop. Best to go to a marine site.

Don
66 Corvair (driving)
57 2dr HT (driving)
56 2dr HT (waiting to be restored)


 
IgnitionMan 
Valued Contributor
Posts: 3509

Reg: 04-15-05
12-05-18 08:49 AM - Post#2753468    
    In response to acardon

And, of course, in this instance, we know NOTHING about the engine setup, but, we need to go to a jet boat site to tune, or lock out the ignition curves.

I do this for a living, have for over 4 decades, and blindly locking an ignition curve out while knowing no info, simply because an engine "sounds different" is NOT the way to do it.



 
IgnitionMan 
Valued Contributor
Posts: 3509

Reg: 04-15-05
12-05-18 02:18 PM - Post#2753515    
    In response to IgnitionMan

I believe in open posts, not a bunch of PM's, so, from the OP's PM, mild 454, doesn't matter if it is driving a drive shaft, or jet pump.

Initial timing, 12 deg/BTDC

Set vacuum advance pull pin travel to .110 inch, by making a stop plate to stop the pull pin travel. Thus will give 10 crankshaft degrees of vacuum advance. This plate goes between the pin and diaphragm on the vacuum advance mounting bar. Screw it to the bar with two small 6/32 machine screws. Gives 10 crankshaft degrees, connect to full manifold vacuum only. NOT ported.

Use weights marked 41, center plate marked 375, 22 crankshaft degrees for the mechanical advance. Use springs to start mechanical curve 100/150 RPM's over idle speed, stop curve between 2,800 to 3,000 RPM's.

Simple as that.

Lock it out, enjoy looking at destroyed piston decks.



 
65_Impala 
Very Senior Member
Posts: 4139

Reg: 12-29-02
12-05-18 07:25 PM - Post#2753548    
    In response to 79eliminator

Does the boat use some kind of timing retard system when it is engaging/disengaging the drive? If it does, you can't lock it out or use vacuum advance or else that system won't do what it's supposed to.



 
79eliminator 
Poster
Posts: 22

Loc: Montana
Reg: 10-25-18
12-06-18 05:18 AM - Post#2753593    
    In response to 65_Impala

It’s direct drive, there is a small drive shaft that goes directly from the crank to the jet drive. Once it’s started it’s under load.

1979 eliminator speed boat


 
IgnitionMan 
Valued Contributor
Posts: 3509

Reg: 04-15-05
12-06-18 07:26 AM - Post#2753617    
    In response to 79eliminator

All the more reason to have a correct curve setup, with vacuum advance operational.



 
79eliminator 
Poster
Posts: 22

Loc: Montana
Reg: 10-25-18
12-06-18 04:46 PM - Post#2753667    
    In response to IgnitionMan

Not on a jet.

1979 eliminator speed boat


Edited by 79eliminator on 12-06-18 04:47 PM. Reason for edit: No reason given.

 
IgnitionMan 
Valued Contributor
Posts: 3509

Reg: 04-15-05
12-06-18 04:59 PM - Post#2753671    
    In response to 79eliminator

Ok, I've owned 3 jet boats, and all of them ran just fine with curved ignition and vacuum advances.

My blown, injected drag boat didn't like an ignition curve, but it was vastly different than my 3 jets, as was the Mission Possible hydro I built the engines for. Those two were prop type drag boats.

But, then, you know more about low perf big blocks than the rest of us do.



 
79eliminator 
Poster
Posts: 22

Loc: Montana
Reg: 10-25-18
12-06-18 07:16 PM - Post#2753686    
    In response to IgnitionMan



1979 eliminator speed boat


 




Icon Legend Permissions Topic Options
Report Post

Quote Post

Quick Reply

Print Topic

Email Topic

289 Views
FusionBB
FusionBB™ Version 2.1
©2003-2006 InteractivePHP, Inc.
Execution time: 0.079 seconds.   Total Queries: 16   Zlib Compression is on.
All times are (GMT -0800) Pacific. Current time is 10:01 AM
Top