C6 Auto (79 F250 400CID)
84 460CID(did have a Manual 4S on it)

I purchased my C6 from the Salvage Yard, and rebuilt it before installing. I know I put it together right, but I have a couple of really odd things I have not come across before.

The Flexplate I purchased was just one they had in the pile. It was marked 460, and that was all it had on it. It bolted up fine for both the Crank and the Torque Convertor. I am aware of the Balance weight, and considering my engine is internal balance, I got one without the weight.

After starting the truck, the problems were very obvious. First the Starter will work and spin fast enough, but it grinds as it does like the Bendix is hitting the base against the Ring Gear. Also I am getting ATF from behind the Torqe Convertor, looks like the main input shaft as I can not see up in there to well. But after I turn it off, it will leak out around two quarts, then stop.

I am assuming that the Dish, or offset of the Flexplate is wrong. Thus to far forward for the starter, and for the Torqe Convertor, it holds it out too far, and the seal is riding on the indent for the Pump Gear.

Question is, am I right in thinking it is the Offset or Dish of the Flexplate, and what Flexplates is there for a C6 and 460 matchup.

 

Your '84 460 is externally balanced, so you'll need to get the correct one.
THe 460 was externally balanced '80 and later.

The leak could be caused by a torn input seal. Hopefully, not by anything worse.
When you mated the transmission to the block, did you have to use bolts to draw the bellhousing up tight?
If so, it is entirely possible you cracked the transmission housing. Hopefully that's not the case, but since you have to replace the flexplate anyway, this will be a good time to inspect it.

 

They mated right up, no stress involved.

I could have sworn it was Internal Balance, but it has been a while since I was looking at that. Back in March or April when I bought it. I will have to check it out.To be honest, I am not sure if it is a 84, or a 82 460 if it makes any difference.

What does concern me is the offset of the Flexplate. If they made two or three different offset's on the Flexplate, then I need to find out what one will go with my setup.

I am very picky with how my trucks run, and am very un-happy with the performance of the Engine. I will be pulling it out soon, and rebuilding it. I picked it up with the understanding it only had 2000 miles on it, but after working on it and hearing it run, it has something wrong with it. Loaded with Carbon, oil is back as a moonless night, and the oil pressure comes and goes. He did have a Holley 4bl Carb on it that was in terrible condition, and I think he washed out the new rings. Either that, or the Engine Shop that assembled the engine screwed up big time. Regardless, it is getting new bearing, rings and a RV Cam, or what ever else it needs as I find it. When completed, this will be pulling my Boat and or Camper, and no way do I want to have problems on the road. Chevies breakdown, not Fords.

 

Are you shure the torqconverter fully ingaged in the trans properly? Seen many a trans shop screw it up.

 

I rebuilt the Trans, and as far as I know, it is in, but that is an IF the Flexplate offset is correct. That is what I am trying to find out is if there is more then one offset to the Flexplate.

I just checked on Jegs, and Checker Auto Parts, and they only list a Flexplate for a 460 starting in 83, and only one part number, no choices.

I am really starting to wonder now if what BanjoPicker said about the Balance may not be the problem. If I had put a Weight-less Flexplate in place of one that should have one, then maybe the offset is different between the two. (weighted and non-weighted)

I need to get my Ranger Project completed, then pull the 460 again. With the Gas prices the way they are, I picked up a 89 Ranger, and hating 4X2 the way I do, I picked up a long bed 4X4 Frame, and put my body on it. I have the motor in, and am starting on extending the Cab 8 inches, and when that is done, the 78 F150 goes back in the shop. I am just trying to get prepared for when it does go back in the shop.

I know, I tend to rattle on a lot. Comes from to many hours in the shop after work each day.

 

Not shure if there different offsets. Due know I thought about replacing my twin small block Chevies in my boat with 351Ws or 460s mated to my powerglide transmissions and found adapter kits require either engine to be internaly ballanced.<--now thats rattling on

 

If the engine is badly out of balance it will ruin the front seal on the C6-hopefully nothing else.

 

Sorry for not being here to follow up on this, been real busy with all I have to accomplish.

My Ranger conversion to 4X4 is coming along nice. I had to rebuild the Toyo Trans, and had a heck of a time finding a Bell housing to fit a 4cly for that trans. Ended up going from a center loaded throw out bearing to the older Arm Pivot type, but it works. I have the Cab split, and will start welding it back together tonight.

Anyway, back on topic, the Flexplate as near as I can tell does have a different offset. I was sorting through the stack of flex plates at the local salvage yard the other day, and was doing some comparing. In the end, I think I got my hands on one that was mis-labeled. This is why it does not work. I believe the one I put in was from a 400, and not a 460 like it was labeled. The ones I found that were labeled, the 400's had about a 1/8 offset, and the 460's had a 1/4 offset. 1/8 of an inch does not sound like much, but when it comes to the seal and where it rides, this just as well be a football field. I wish I would have thought when I was there to find a 460 and a 400 and measure how far out the crank is from the flat of the engine.

 

This is the Ford OEM part number for the externally balanced flexplate. You can buy cheap from online OEM parts suppliers.

D9TZ 6375 A

79 was the first year for externally balanced 460's. And this same part number was used until they quit making the 460's.

In my experience the aftermarket flexplates sound like crap when you start the engine. Grind and crunch. Sounded like an old Chevy that needed the starter shimmed.

The real pi$$er was I bought a new OEM flexplate from a Ford dealer for $20.00 less than I gave for an aftermarket one from a big transmission shop locally. It was $50.00 some dollars shipped to my door. And it was nice and quite after. I compared the teeth. The OEM teeth were cut deeper and a little wider and had more taper where the bendix met the ring gear.

I realize you have the oil leak issue still. But just wanted to throw this out there.

 

You can tell if it's internal or external by checking in the back of the harmonic balancer. External balance engines have a small counterweight that enters the front timing cover seal. The internal engine has a smooth non-counterweighted sleeve like piece that enters the timing cover seal. Other items to look for is the engine casting numbers, external balance engines normally come with the D9 (D=1970's, 9 =9, 1979 )

 

Good answers, I will be pulling this engine real soon, and I will check the balancer and casting numbers.

Also ordering the Flexplate from a dealer is a good option for me. I have a friend that is a Service Manager at a Ford Dealership.

 

look right above the starter for the casting number if it is anything but D9TE-## then it's an early block that probably is internal balanced, but if it's the D9TE then it is externally balanced engine. The reason I said it's PROBABLY internal balance on the earlier blocks is you can fit an externally balanced rotating assembly in the earlier blocks but you can't fit the earlier internally balanced cranks into the D9 blocks so if you have that later casting number you will know that you are going to need the externally balanced flexplate with no worries.
I agree with getting the factory flexplate, the costs aren't that much to justify taking a chance with a used one from a wrecking yard, and unless your racing it and need a certified one those will work really good. Even the SFI certified ones aren't that expensive but with the factory unit you know it was designed for your engine. If your racing it like I do then you have to run SFI certied pieces thats another issue but you don't have to worry about it.

 

Racing is out of the question for this one. Mostly I am building it for self satisfaction, and to pull my Boat and Camper with. I have a 91 F150 with a 302, but it is so gutless, it can hardly pull it's self let alone my boat. I live in Utah, and all the best camping and boating is on top the mountain.

When completed, the 78(460) will be a gas guzzler, but it is well worth it. Also I have a 89 Ranger I just converted to 4X4, and stretched the cab on, so the 91 F150 will be sold soon, and I can drive my gas sipping Ranger when not towing.

As a foot note here, if anyone is thinking of extending a cab on a ranger, don't. The metal is so thin, it is a nightmare to work with. I was able to do it, but it is a lot of work, and I had to back each weld seam with a strip of 1/8X1/2 strip steel to be able to even spot weld them back together. I run so many spot welds(thousands) that my welder relay toasted it's self twice. I know cheap welder, but all the same, it was a headache. Tonight, I lay on the magic putty to smooth it all down.

 

Maybe I'm not clear on the terminology here, but my '76 460 has a harmonic balancer on the front of it, doesn't that mean it's not internally balanced?
-kit

 

Actually that is a harmonic dampner not balancer. the balance of the engine is seperate issue, some dampners on some engines are part of the balance (not 385 series engines though) but that is on externally balanced engines only. On external balanced 460s there is a hatched weight spacer behind the dampner that is the balance.