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Looking at the different options on the center main cap .......
Have a few steel straps here......also, a 4 bolt cap.
I have never used either application....even on my highest revving Longman 1071's...and my big bore 8 port engine.......never had an issue with the standard cap.
So, are these over kill??? I may be using one of the later solid web 1300 blocks on my next engine.....according to what I hear...these are really strong blocks..
The center main cap is an odd shape.....perhaps that might benefit from a steel strap....but that would necessitate a lot of metal being removed from the cap.
Appreciate experienced feedback.

360gts wrote: ↑Mon Dec 07, 2020 4:14 pm Looking at the different options on the center main cap .......
Have a few steel straps here......also, a 4 bolt cap.
I have never used either application....even on my highest revving Longman 1071's...and my big bore 8 port engine.......never had an issue with the standard cap.
So, are these over kill??? I may be using one of the later solid web 1300 blocks on my next engine.....according to what I hear...these are really strong blocks..
The center main cap is an odd shape.....perhaps that might benefit from a steel strap....but that would necessitate a lot of metal being removed from the cap.
Appreciate experienced feedback.

Dermott, I always used the later solid centre web 1275 blocks with standard centre caps. Never had a problem ever with them, and also found them strong. I think steel straps are an over-kill (never used them in high end race cars) Only my opinion again

Alan

Hi,
The only problem i had with the four bolt steel cap was when the machine shop cut the thrust faces, they managed to get a three thou step on one side. Easily cured by using an over size thrust half. Was it worth it? Probably not. Never had any problems with the standard caps. Looked good if nothing else!
Machining a big chunk off of the standard cap to fit a strap has always seemed a bit odd to me as it could result in slight distortion in the bore of the cap, nessesitating line boring. If line boring then might as well go the whole hog and fit a four bolt.....
Jerry

I have never seen the need in these engines for anything other than the standard caps, unless those get lost.

Fitting straps is a backwards step as material needs to be removed from the Cap (except for S Blocks) to fit them and as they are 2 separate parts in this instance, it's not going to add up to being stronger.

To draw a bit of a parallel here, the flat head Ford V8 Engines have a crank that's a little longer than the A Series, it's made in Cast Iron, similar sized journals and it's only a 3 Main Bearing design The guys modifying these run stock caps up to around the 600 HP mark.

I have seen the centre web of a race engine block crack around the 7/16 outside "extra" bolt holes.
Its never made sense to me to drill such a large stud hole into a rather thin and weak part of the block.
So when I have to fit a 4 bolt main cap, we reduce the size of the outside holes and use a 5/16 cap head bolt. The smaller hole in the centre web reduces any weaknesses while still providing extra support. We do this on our twin cam engines without a single crank or block failure to date.

Machining the top off a cap to then replace with a strap has also been seen as a waste of time, why make something weaker than it already is. In the 60s it was common, but better options are available now.