7.4 Mercruiser Distributor, Ignition, coil

[floating greenhorn]

So new to the group, I bought a serious basket case this spring SMH, you can imagine what I've learned in the process. Motor was in pieces, ended up purchasing another long block so it was correct. new rings, bearings, gaskets ect. Now I'm to the in the boat, make it run phase. I DO NOT have a thunderbolt ignition or module as they were not in the boat when purchased. Question 1, is it needed? Question 2, Do they make a marine distributor for 7.4L that doesn't require it. Question 3, Would I have fried the ignition sensor in the distributor without it? Hooking it up like old school 454. Hoping for some feedback that is helpful. NO SPARK! I have the TB IV I believe, 2 posts on back and ground on bottom

 

[alldodge]

Question 1, is it needed?

Yes, otherwise your going to use a different ignition

2, Do they make a marine distributor for 7.4L that doesn't require it.

Yes, TB, Delco EST, MSD, DUI or old school points

Question 3, Would I have fried the ignition sensor in the distributor without it? Hooking it up like old school 454.

Yes, if you connected the Negative side of the coil to the pick up, its fried

I would suggest buying a Delco EST ignition

 

[alldodge]

If you do have a TB module connected, then run thru the TB module then run thru the troubleshooting guide

 

[achris]

Hello and welcome to iboats.

When you start a new thread it's always helpful to add the engine (or drive if you're asking questions about the drive) serial number and year to the first part. Merc used the GM 454 for many many years, and in many different variants.

One of the best places to start your learning when dealing with new subjects that you haven't worked on before is the 'stickies' section. At the top of the Merc forum you'll find 'MUST HAVE technical section for DYIers'. Click on that and you'll find an index of subjects, including 'MerCruiser information' (I think it's the second option). LOTS of valuable stuff in there...

And as always, if in doubt, ask questions... Before you start a job you haven't done before, it's worth asking. Just recently had a member start a shift cable replacement by cutting the end off the cable, not realising that snookers you for a step down the track... Ask ask ask... No brownie points for messing up a (seemingly) simple job.

Chris...

 

[floating greenhorn]

Hello and welcome to iboats.

When you start a new thread it's always helpful to add the engine (or drive if you're asking questions about the drive) serial number and year to the first part. Merc used the GM 454 for many many years, and in many different variants.

One of the best places to start your learning when dealing with new subjects that you haven't worked on before is the 'stickies' section. At the top of the Merc forum you'll find 'MUST HAVE technical section for DYIers'. Click on that and you'll find an index of subjects, including 'MerCruiser information' (I think it's the second option). LOTS of valuable stuff in there...

And as always, if in doubt, ask questions... Before you start a job you haven't done before, it's worth asking. Just recently had a member start a shift cable replacement by cutting the end off the cable, not realising that snookers you for a step down the track... Ask ask ask... No brownie points for messing up a (seemingly) simple job.

Chris...

Thanks for the input! I tried to look it up on here before I was a member and got lost! Couldn't see some of the diagrams and thought well maybe these guys didn't use one somehow. I didn't even have a distributor when i started. Got lucky and ran into a fella that owns a performance boat shop close to me that has parts thank the gods! This guy also has a boat he runs in Florida on poker runs with twin v12's which was cool he let me drool on for a couple minutes lmao! I picked a really hard project this time and can for sure say I will never purchase another without the boat at least engine completely together even if it does need a rebuild which I also did on this one lol! Learned a lot mostly the hard way lol! Thanks Chris!

 

[floating greenhorn]

Yes, otherwise your going to use a different ignition


Yes, TB, Delco EST, MSD, DUI or old school points


Yes, if you connected the Negative side of the coil to the pick up, its fried

I would suggest buying a Delco EST ignition

Ok, when you say ignition, can you explain please. Are you talking the whole distributor and coil kit or just the sensor in my distributor? I have a round coil which is new, the distributor is an tb IV I believe with posts on the back, I don't have a module so trying to avoid it if possible. Trying to save a little money and make what I have work if possible!

 

[alldodge]

Without the module you don't have a working ignition. The link chris has list parts and how the TB ignition works. Search for Delco EST and it will show what it takes. All ignition except points or petronix or the like require a module

 

[floating greenhorn]

Yes, otherwise your going to use a different ignition


Yes, TB, Delco EST, MSD, DUI or old school points


Yes, if you connected the Negative side of the coil to the pick up, its fried

I would suggest buying a Delco EST ignition

Without the module you don't have a working ignition. The link chris has list parts and how the TB ignition works. Search for Delco EST and it will show what it takes. All ignition except points or petronix or the like require a module

So I found another boat shop close to me that had some parts. The older fella gave me a heck of a deal I believe and got a different distributor with module on it and she fires and started on a shot of fuel into the carb! Now I have to chase down a starter because this one barely whirled it and gave a puff of smoke lmao. Here we go again lmao. Thanks for all the help!

 

[Scott Danforth]

So I found another boat shop close to me that had some parts. The older fella gave me a heck of a deal I believe and got a different distributor with module on it and she fires and started on a shot of fuel into the carb! Now I have to chase down a starter because this one barely whirled it and gave a puff of smoke lmao. Here we go again lmao. Thanks for all the help!

buy a PMGR starter and new battery cables