Go Back  Offshoreonly.com > Technical > General Q & A
Mercruiser Thunderbolt IV Ignition Module >

Mercruiser Thunderbolt IV Ignition Module

Notices

Mercruiser Thunderbolt IV Ignition Module

Thread Tools
 
Old 12-10-2019 | 07:49 AM
  #11  
Registered
10 Year Member
 
Joined: Apr 2014
Posts: 2,345
Likes: 191
Default

[QUOTE=Griff;4717862
IMO, the V8-HP modules have the best timing curve for most performance apps, but they are getting hard to find.[/QUOTE]
So would the V8-24 be choice #2?
GLENAMY 242SS is offline  
Reply
Old 12-10-2019 | 08:03 AM
  #12  
F-2 Speedy's Avatar
Platinum Member
Community Builder
10 Year Member
Platinum Member
 
Joined: May 2012
Posts: 11,431
Likes: 3,957
From: Midwest & T-Rock
Default

Originally Posted by GLENAMY 242SS
So would the V8-24 be choice #2?
I like this module, ran it on a couple carbed 502's..........set base timing @ 8* all in @ 32*
F-2 Speedy is offline  
Reply
Old 12-10-2019 | 12:50 PM
  #13  
Griff's Avatar
Charter Member # 55
25 Year Member
Charter Member
Super Moderators
 
Joined: Oct 2000
Posts: 20,247
Likes: 2,496
From: Omaha/LOTO
Default

Originally Posted by GLENAMY 242SS
So would the V8-24 be choice #2?
The V8-22(second column) would be my second choice and then V8-24 closely behind it.
Its nice to be able to run a little more initial timing to smooth out idle.
The V8-24 will still work fine in most cases though and was probably used the most by Merc.
Griff is offline  
Reply
Old 12-10-2019 | 01:47 PM
  #14  
SB
Registered
20 Year Member
 
Joined: Nov 2004
Posts: 14,104
Likes: 3,692
From: On A Dirt Floor
Default

Absolutely surprising what just an extra 2*-4* of idle can make on some motors with a little extra cam and/or aluminum heads have, especially for cold start. Typically makes non choked carbs start easy too.
SB is offline  
Reply
Old 12-10-2019 | 02:34 PM
  #15  
Registered
 
Joined: Mar 2010
Posts: 458
Likes: 0
From: Las Vegas, NV
Default

PM sent to OP. I'm using the V6 modules on a pair of bored out 454's with 250's on them. I'm getting a total of 8* advance and all in at around 2500rpm
ramos45 is offline  
Reply
Old 12-10-2019 | 04:48 PM
  #16  
Registered
10 Year Member
 
Joined: Apr 2014
Posts: 2,345
Likes: 191
Default

I'm thinking of V8-24 for my 502 w/731 cam and air gap intake 800 holly stainless Gen III exhaust (all else stock). Any thoughts?
GLENAMY 242SS is offline  
Reply
Old 12-10-2019 | 05:45 PM
  #17  
Registered
15 Year Member
 
Joined: Dec 2010
Posts: 724
Likes: 75
From: longisland ny
Default

I have a v8 hp module...if ur intrested
park35 is online now  
Reply
Old 12-11-2019 | 01:14 AM
  #18  
Griff's Avatar
Charter Member # 55
25 Year Member
Charter Member
Super Moderators
 
Joined: Oct 2000
Posts: 20,247
Likes: 2,496
From: Omaha/LOTO
Default

Originally Posted by GLENAMY 242SS
I'm thinking of V8-24 for my 502 w/731 cam and air gap intake 800 holly stainless Gen III exhaust (all else stock). Any thoughts?
I would use a V8-HP. You're building an engine very similar to an HP500 and they used the V8-HP
Griff is offline  
Reply
Old 12-12-2019 | 09:44 AM
  #19  
Thread Starter
Registered
Active Streak: 30 Days
25 Year Member
 
Joined: Oct 2000
Posts: 1,511
Likes: 598
From: Lake Ozark, MO USA
Default

Sorry, I have not been keeping up with my own post. Been busy fixing house issues, hot water tanks and humidifier. Hot water tanks done for now and parts on order for the Humidifier. Here are my thought on the timing for my particular set up. Engines are bone stock 502Mags with QJ Carbs. I am running 34 degree total timing with the stock 20 degree modules. Issue I see is that these are not full in until 5000RPM. Original thinking by Mercruiser back in the day was these engines have to run everywhere and good gas was sparce and engine life could be reduced with crappy gas and tooo much timing. I am not concerned with the gas issue. I run clean gas with no alcohol and usually higher than 87 octane. Never had issues with fuel, so that is out of the equation. I have so much initial advance, that engines crank hard and slow when warmed up. I also am wanting to see how engines will work with all in advance at a lower RPM.
Helmwurst is offline  
Reply
Old 12-12-2019 | 10:09 AM
  #20  
Knot 4 Me's Avatar
Registered
20 Year Member
 
Joined: Jun 2005
Posts: 8,407
Likes: 797
From: Central IL
Default

What is your normal cruise RPM now? Would be curious to see what your EGT's are currently at normal cruise speed. Since you are bone stock the 24's should work out well for you with taking some initial timing back out.
Knot 4 Me is offline  
Reply


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2026 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.