354 Hemi adapted to a 727

Long story short, work was done on my car some time back and the shop installed the 354 hemi with a hot heads adaptor to a 727. I just did some wiring on it to try to get it started. The new starter spins and engages the flywheel but the motor won't turn. Sounds like the flywheel is not attached to the flexplate. Now I'm about as sharp as a bowling ball on this but I thought I should just ask. Do I need to drop the ****** to fix this?

 

Check the flywheel to flex plate bolts or nuts to see if they were installed. If so try cranking the engine with starter and visually look for flexplate to be turning.

 

The flex plate seems to be bolted to the crank. The flywheel turns freely and independent of the flex plate. There are nuts between the engine and the flex plate that are near the inside cir***frence of the flex plate that I think secure it to an extension off the crank shaft. The flex plate has a series of holes (maybe a dozen or so equally spaced) about 2" from the outside edge of the flex plate. I'm not sure if these holes are for joining the flex plate and flywheel.

 

Here are some pics. The difference between the two is you can see through one of the holes where I've moved the flywheel behind the flex plate.

 

I don't know about your adapter, but a stock 727 has a flexplate bolted to the crankshaft, then the converter bolts to the plate. The ring gear is on the converter. Sounds like there are no bolts joining the converter to the flexplate.

 

That would make a lot more sense. I've been digging around and it seems that having my ***umption of a flexplate and flywheel attached to the torque converter was wrong.

So it looks like I need to bolt the flexplate to the torque converter. I think the only way to do this is with the ****** still attached by turning the flexplate and the converter to get the holes to line up.

Guess I need to find the right hardware now. What's the torque specs? Do you put loc***e on the bolts?

 

I have your set up except mine is on the 331 extended bellhousing. I can tell you that on mine, the converter is attached to the flexplate. The starter actually engages the teeth on the flexplate not the converter. At least that's my set up. There are four small grade 8 bolts that I used to attach the converter to the flexplate. Make sure they're not too long so as to cause an obstruction. I think mine were only about 3/4 or 1 inch long.

 

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are you kidding me

 

Hard to believe any builder would not bolt the flex plate to the converter. I suppose it is something that could be overlooked however in the midst of all kinds of other tasks.

 

There is a long story about the builder that did the engine and transmission that I won't get into but not bolting the flexplate to the converter would fit into my expectation.

Thanks for all the feedback everyone!

 

Getting the 4 bolts to line up with the 4 holes can be a task. Get the bolts @ a ****** shop.

 

There are four bolts holding the converter on. Just to make things interesting, one hole is offset a bit. That was done to ensure proper installation on externally-balanced applications, but it makes it harder to ***emble. Put one bolt in snug, then turn the engine over and check that the other three holes line up. Only then, put the rest of them in.

 

Remember: Use some "Blue" semi-permanent Loc***e on the bolts into the torque converter, or they will back out over a short time......

 

What R Pope says!!! Will save you a lot of time.
Good luck with it.

 

Great advice! Thanks!

 

Thanks for the advice on getting the bolts holes to line up. A few more questions before I finish this up:

1.) With the bolts loosely in place there is a little play (about 1/16") between the flex plate and the converter. I know when I tighten them up the play will go away, but I am concerned that the torque from the engine could be enough to make these slip and even shear. Should there be any play between the flex plate and the torque converter?

2.) I bought four grade 8 steel bolts (5/16"-24 0.5 UHL) at the hardware store to do this. This is the spec that I've seen at Summit for these type bolts. the car is for street use so I think this should be fine. Should I use something stronger?

3.)I'll use the blue loc***e but what is the torque specs for a 354 Hemi to a 727? I've seen values range from about 22 ft/lbs to over 100.

 

The converter should fit snug against the flex plate. If not, it could be one of two reasons. 1: The converter register is not seated all the way into the crank hub adapter.
2: The mechanic used regular bolts to secure the flex plate to the crankshaft, and the heads are hitting the converter.

 

The play is rotational in the converter because the holes in the flex plate are just a bit wider than the bolts that join them. My concern is that little bit of play could cause the flex plate to slip relative to the converter and shear the bolts.

 

I don't trust hardware grade 8 (chinese ****) find a trusted source

 

Two thoughts, and Tom is spot-on with the first: verify that the bolts holding the flexplate to the crank have a short head that does not contact the converter. The larger,'normal' bolt head will push the converter back and create a gap at the flexplate. A 426 Hemi converter will clear std bolts but a 'standard' converter has a different involute. The wrong bolt head can actually puncture the converter!

Second, if you are using an oem 426 Hemi flexplate then you will need to redrill and tap the converter lugs for the larger 426 fasteners. Short of that you will need a shoulder bolt made for the existing dimensions.
Most aftermarket 426H flexplates have a pair of bolt holes but some only use the original pattern.

And like Jim suggests, when you get the issue figure out buy some fasteners from a trusted supplier, like your Mopar dealer.

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