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View Full Version : 92 Prostar 205 Spark Plug Replacement Question


MatthewStokes
06-30-2011, 02:59 PM
Hi, looking for a couple of answers to what I think will be some simple questions.

Background:
I purchased a used 92 Prostar 205 about 1.5 years ago. It's only got 200 hours on it, of which only about 100 are on the motor as it was replaced in 2000 due to incorrect winterization (I have the receipts so it is documented). This is the 351W, not the 351W HO engine. The spark plugs are looking fairly rusty so figured I'd go ahead and replace them, which leads me to my questions.

1. Looks like due to clearance between the spark plugs and the exhaust manifolds that I will have to pull the manifolds to replace the plugs. Does that sound correct?

2. If I have to pull the manifolds I assume I can leave the risers attached?

3. Anyone have the torque specs and tightening pattern for the exhaust manifold bolts?

Thank you

east tx skier
06-30-2011, 03:01 PM
I never had to pull the manifold on mine to get the plugs in. Those back two are a bit tough though. Autolite 24, if I recall correctly, are the correct plugs.

1redTA
06-30-2011, 03:28 PM
I put the autolite 24s on my 351w 240 hp engine, recommended to me by this site, they were real easy to put in with nothing removed. wasn't even a one beer job including checking the gap, neverseize, dielectric grease and changing the plug wires

MatthewStokes
06-30-2011, 03:38 PM
I never had to pull the manifold on mine to get the plugs in. Those back two are a bit tough though. Autolite 24, if I recall correctly, are the correct plugs.

Thank you. It didn't look like enough clearance but I grabbed a 5/8 wrench and was able to get to them. On mine it's the front 3 on each side that are tight to get to, the back one I can use an actual spark plug socket on.

Was good that I pulled one and checked it's gap as it's set at .045" . Skidim says it should be .035.

Thank you

east tx skier
06-30-2011, 03:45 PM
Yeah, I think it might be that the PCM marinized motors are .045 and the Indmar are .035. I know my GT-40 is 0.045, but my old Indmar 351 HO was .035. Not sure what you have in there, but go with what the manufacturer recommends.

MatthewStokes
06-30-2011, 04:31 PM
Yeah, I think it might be that the PCM marinized motors are .045 and the Indmar are .035. I know my GT-40 is 0.045, but my old Indmar 351 HO was .035. Not sure what you have in there, but go with what the manufacturer recommends.

Ah that sheds some light on things. The replacement engine is a 1999 PCM 351W . I'll have to track down PCM documentation I guess. Thank you

MatthewStokes
06-30-2011, 04:53 PM
Here's what I know about the engine in case someone else knows the answer for the spark
plug gap while I searching it out:

PCM 351 LH ( replaced in 1999)
Distributor cap is a Prestolite screw down type cap
No points, it has a breakerless ignition module (which isn't made any more, I think made by Prestolite if I recall)

Any info or pointers would be greatly appreciated.

For now will most likely set the gap to the .045 since that is what they are at currently.

east tx skier
06-30-2011, 05:13 PM
Because it's a PCM, your gap should be 0.045.

Here are the specs of the PCM 351 Carb engines in a 99 CC.

The PCM Engine Manual is in the Tech Section of CCFan (http://correctcraftfan.com/reference/manuals.asp)

As for pointers, this should be top priority: Take a silver paint pen and mark the orientation of your water pump by drawing an arrow upwards with the word "UP" underneath it. Plenty of people have reinstalled these upside-down when changing impellers (it's easy to do and looks identical in either orientation). Sort of defeats the purpose of a new impeller when you use it to pump water out of the engine.

MatthewStokes
06-30-2011, 05:25 PM
Because it's a PCM, your gap should be 0.045.

Here are the specs of the PCM 351 Carb engines in a 99 CC.

The PCM Engine Manual is in the Tech Section of CCFan (http://correctcraftfan.com/reference/manuals.asp)

As for pointers, this should be top priority: Take a silver paint pen and mark the orientation of your water pump by drawing an arrow upwards with the word "UP" underneath it. Plenty of people have reinstalled these upside-down when changing impellers (it's easy to do and looks identical in either orientation). Sort of defeats the purpose of a new impeller when you use it to pump water out of the engine.

Thank you very much. All but 2 are in at this time. Finish tonight and then lake tomorrow.

east tx skier
06-30-2011, 05:32 PM
Do you have to regap?

JMann
07-01-2011, 07:19 PM
while we are talking spark plugs............
I have the same 240 HP Indamar engine. I just did a search for Autolite 24's and it came with with resistor or copper core. Which one do you recommend, is there a difference?

j.mccreight@hotmail.com
07-01-2011, 08:02 PM
No significant difference both will do the job properly, I run the motorcraft sp-215 in mine...

east tx skier
07-01-2011, 09:23 PM
while we are talking spark plugs............
I have the same 240 HP Indamar engine. I just did a search for Autolite 24's and it came with with resistor or copper core. Which one do you recommend, is there a difference?

Copper is what I use. The only other option I saw was "Platinum," which I was told was "too hot" for these engines.

JMann
07-02-2011, 07:10 PM
did you mean Motor Craft SP-415? every motorcraft search I did comes up sp-415 not sp-215.
Thanks

MatthewStokes
07-05-2011, 10:23 AM
Do you have to regap?

East TX Skier,
Hi, unfortunately I was not able to get it out on the lake this weekend and test the .045" gap. While putting the last plug in on the passenger side I looked down at the transmission cooler and found that both of the female ends on my transmission cooler lines were split. There was no leakage of fluid so hopefully caught it in time. I've never seen brass nuts split like that before but guess at 20 years old something is bound to give. So, needless to say I cancelled the plans for the weekend rather than run the risk of them letting go.

Hopefully on the water this Friday.

Thank you for the help so far.

JMann
07-08-2011, 04:04 PM
I pulled one of my plugs and the PO was using NGK UR5 2771 plugs. I took these to NAPA and they cross referenced this to an autolite 23 which they told me is the same as the autolite 24 just a little cooler version.
I went with the autolite 24's in copper. I will gap them to .035 and see how they work.

TxsRiverRat
07-08-2011, 04:44 PM
I put the autolite 24s on my 351w 240 hp engine, recommended to me by this site, they were real easy to put in with nothing removed. wasn't even a one beer job including checking the gap, neverseize, dielectric grease and changing the plug wires

Damn you drink slow!

j.mccreight@hotmail.com
07-08-2011, 04:54 PM
did you mean Motor Craft SP-415? every motorcraft search I did comes up sp-415 not sp-215.
Thanks

yes sp-415 sorry for the typo... ford's other number for the same plug is asf-32c