Bolt Location--Old Model vs New Model

[splashlog]

I am swapping out an old model A4 with a new model A4. The bores on the old model are smaller than the new model. Can anyone tell me if the locations will be the same? Can I just supersize the mounting studs and be confident that the new engine will be located exactly the same as the old one?

Any reccomended sizes for the stud/bolt diameter for the new model. Do I want something that gives me a little wiggle room, or do we want something that's a close fit?

Anyone ever have to do the same procedure?

[Al Schober]

The mounting holes in the oil pan may be smaller on the older engine just due to corrosion. As I recall, the mounting studs are what are called hanger bolts. Lower end is like a lag screw (go into wood timbers) while the upper end is threaded for a nut. I believe they're 3/8". Of course if you have resilient mounts, this is different.
Consider the process of aligning the engine to the coupling. You need to move the front/back of the engine up/down so the gaps at the top and bottom are equal. It's EQUALLY AS IMPORTANT to have the gaps on the two sides equal! The only way to do this is to move the front/back of the engine left/right, and this requires that there be some clearance between the studs and the holes in the oil pan.
My technique is to do the vertical alignment first by putting shims or washers between the engine bed and the oil pan. Washers are fine back aft, while shims (made from old plastic playing cards) give better control at the front end. When vertical alignment is good, I'll address side to side. Hopefully the studs don't go metal to metal with the oil pan before things are good. When side to side is good, I'll mix up some Bondo and put it between the stud and the oil pan. This will keep the alignment from changing when you're heeled over. Finally, the studs get the upper washers and nuts installed.

[Sam]

I can give a little feedback but suggest you double check. I have a 1966 Morgan 34 w/original A4- ie "early model" Back in my youthful days about 30yrs ago I bought a rebuilt short block A4. I did not know early model from late model, Moyer, forum et - just a driveway mechanic. When I received the engine crate at the boat yard [it is considered the most capable if not expensive sailboat yard on the great lakes] it was a late model and I asked the chief mechanic how much the swap out would be. His response was about $2k. When i asked why so much - his response was the bolt pattern does not match and the mounting would need to be rebuilt/modified. I'd check a little further??

[splashlog]

So what now?

Thanks for the info. Inner fear confirmed.
So the question now is what is the procedure to locate the new studs/hangers for the newer model oil pan. I am not too excited about using the new engine as way of locating, that is to say go through the trouble of trying to get it in the correct position realative to the shaft/coupler, making some marks, removing the engine, installing the new studs/bolts/hangars/mods and then moving the engine back into it's final placement.

If I knew what the offsets from the original studs are that would be much easier I think.

I guess a question worth putting out there is; would the old model oil pan fit the new model block and transmission unit by any chance and, if so would that line everything up the same way with only minimal alignment being required....?

[jcwright]

Hello Splashdog.

I'm not sure it will help with your situation, but below is a link to drawings that show the locations of the mounting holes for a late model A4. I've highlighted the hole centers and their diameter. To transfer the locations to the engine bed, I made a plywood template with pre-drilled mounting holes.

Here is the link to the file:

https://drive.google.com/file/d/11ZbrQH1neqbRaNI8PZAttn0izAkdhVOa/view?usp=sharing

Hope this helps some.

Jack

[splashlog]

Hey Jack/JCWRIGHT, that's exactly what I need. Thank you very much!