GT350 Engine Refresh Time!

[honeybadger]

Anyway, moving on, does the service manual also give specs for ring gaps?

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[bauern]

^^beat me to it lol

 

[bauern]

If you still have your heads handy, would you measure the exhaust port opening for me please?

It's about 1.523" but not perfectly round. A little narrower top to bottom.

 

[bauern]

Had a chance to finish the engine tear down tonight. Everything looks fairly good me thinks. There is some light scoring on the cylinder walls, but nothing the fingernail can catch. Thinking of a quick honing, new piston rings, new main and rod bearings, a deep wash and I should be good. Am looking around a bit at pistons. @AceOne are there pistons that are OEM replacements worthwhile looking at?

These are the J&E pistons, stock diameter and compression ratio. Part #345870 View attachment 331103

 

[AceOne]

Do you know if this change was made for all MY18 cars or was it a rolling change that depends on build date? (Owning a 2018, I'm hoping you'll say this change started on a hard date.)

Unfortunately, I wasn't told if it was a rolling change or not and I don't have a hard date of the changes either. Sorry. I own a 2016 GT350R myself along with my 2016 GTPP car. It is only at 1,600 miles but i haven't noticed high oil consumption but at only 1600 or 1700 miles it may just be too soon to tell. It ran great at COTA though during an Optima Event.

 

[TDC]

Great info here badger, keep it coming and thanks from all of us who have less guts than you do to tackle a project like this!

 

[honeybadger]

These are the J&E pistons, stock diameter and compression ratio. Part #345870 View attachment 331103

Thanks, @bauern Any insight into the differences between the J&E pistons vs. OEM? Benefits? Risks?

 

[AceOne]

@honeybadger I was looking at the JE 834871 to get a little higher compression. @bauern Could you post a pic of the top of piston and best angle you can get of the dome? I'm still concerned if more dome will hurt the combustion flame front. Could you also mic the piston diameter and post it. Thanks in advance.

Manley 3.7 NHRA 3.701 piston has a 7.5 cc dome.

@honeybadger If your planning on tracking it mostly then you are better off with Manley H beam rods. They make one that fits the OEM pistons. OEM piston pin is 21mm and normal pins are 22 mm. Also as you can see the the trapzoidal small end on the OEM Rods...Manley has one that fits like that small end.

Mahle pistons... still waiting on more info from them.

Daimond pistons would be custom made .

 

[AceOne]

Thanks, @bauern Any insight into the differences between the J&E pistons vs. OEM? Benefits? Risks?

That JE piston is looking real nice. Pretty similar to the Mahle OEM ones. The valve reliefs edges look a bit sharp but the ring groove and pin area look very good. Did you get weight of pistons?? Are they as advertised? How the rib supports on the underside look? Was there a "good" spot somewhere on the piston to lighten it if needed for balancing. They should be pretty good out of the box. The Ford OEMs were pretty good but one was a bit off but I couldn't find a spot I was comfortable trying to drill a little to lighten it. I can't even remember what I did...I think I used my lightest pin it that piston.

 

[bauern]

Thanks, @bauern Any insight into the differences between the J&E pistons vs. OEM? Benefits? Risks?

J&E are slightly heavier, rings are thicker 1.0-1.2-2.8mm and they specify wider gaps, especially the top ring. The coating is designed to conform to the cylinder as it wears in so no slap, piston rock better ring control (so they say).

 

[AceOne]

That JE piston is looking real nice. Pretty similar to the Mahle OEM ones. The valve reliefs edges look a bit sharp but the ring groove and pin area look very good. Did you get weight of pistons?? Are they as advertised? How the rib supports on the underside look? Was there a "good" spot somewhere on the piston to lighten it if needed for balancing. They should be pretty good out of the box. The Ford OEMs were pretty good but one was a bit off but I couldn't find a spot I was comfortable trying to drill a little to lighten it. I can't even remember what I did...I think I used my lightest pin it that piston.

Had a chance to finish the engine tear down tonight. Everything looks fairly good me thinks. There is some light scoring on the cylinder walls, but nothing the fingernail can catch. Thinking of a quick honing, new piston rings, new main and rod bearings, a deep wash and I should be good. Am looking around a bit at pistons. @AceOne are there pistons that are OEM replacements worthwhile looking at?

Pics below:

All your surface wear looks very normal even the rear cam journal. I think mine even showed a little on the rear iirc. Getting new rod OEM bolts might be costly. Hopefully Ford lowered the price. I would mic the pistons and record the diameter then consider switching to the new OEM pistons and ring pack and use your rods unless you are thing about really tracking it hard and upping the HP much. If that is the case I would recommend Manley H beam rods at least....ARP bolts are available for them. It's just cost effective to switch now since you have it apart.

 

[bauern]

That JE piston is looking real nice. Pretty similar to the Mahle OEM ones. The valve reliefs edges look a bit sharp but the ring groove and pin area look very good. Did you get weight of pistons?? Are they as advertised? How the rib supports on the underside look? Was there a "good" spot somewhere on the piston to lighten it if needed for balancing. They should be pretty good out of the box. The Ford OEMs were pretty good but one was a bit off but I couldn't find a spot I was comfortable trying to drill a little to lighten it. I can't even remember what I did...I think I used my lightest pin it that piston.

I weighed them before I sent everything to be balanced on the 5.2 CPC. I got 400g on each of them. The underside does not require the tapered small end on the rod (but they are assembled onto the Manley rods). The crank required two pieces of mallory to balance. It weighed 51 lbs. when I delivered it and 51.4 lbs when I got it back.

The piston dia. is 3.6982" at the bare spot in the coating and 3.7008 across the coating.

 

[AceOne]

I weighed them before I sent everything to be balanced on the 5.2 CPC. I got 400g on each of them. The underside does not require the tapered small end on the rod (but they are assembled onto the Manley rods). The crank required two pieces of mallory to balance. It weighed 51 lbs. when I delivered it and 51.4 lbs when I got it back.

The piston dia. is 3.6982" at the bare spot in the coating and 3.7008 across the coating.

Thanks. I will see if JE will send me pics of the 8,9 cc domed ones to compare to your pics. Dimensions looks good new max cylinder with the plasma coating is 3.7013. if I calculated right you have 3 thousands to work with for honing it.

Was this a new unbalance crank? We took weight off the front and rear of mine. My OEM pistons varied from 388.1 to 389.6 grams. My bobweight was 1696gm using 51%.

 

[honeybadger]

So I just found something as @oldbmwfan reminded me about the PTWA coating on the cylinder bores. http://www.mustangandfords.com/how-to/engine/1601-shelby-block-tech-fords-plasma-transfer-wire-arc/

From the article: "If you haven’t failed a piston and/or gauged things up, the bore is suitable for rebuild just the way it is. It is a thin coating, so if you fail a piston and score the cylinder wall, you will want to start fresh with a new block."

Sounds like Ford doesn't recommend a honing when rebuilding unless things are pretty messed up?

 

[bauern]

Was this a new unbalance crank? We took weight off the front and rear of mine. My OEM pistons varied from 388.1 to 389.6 grams. My bobweight was 1696gm using 51%.

Yes. New unbalanced. I don't have the numbers from the machinist, I'll have to get them. The front weight took a small amount of mallory the rear a larger one. This is the weight card for the rods:

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