sprint eng rebuild

[NFXdynomite]

Could i get on that list mate? just building up me spare engine may need to experiment

[trackerjack]

If you going to fit a girdle plate (ladder??) you need to make spacers to go between the top of the main bearing cap and the plate. We have had studs made to fit into the block that are long enough to pass through the bearing cap and through the plate.

The cap is bolted down using nuts on the studs, spacers are machined to fill the gap between the top of nut and plate and then nut is used to secure the plate to the bearing cap stud. We also dowel and screw the plate to the block (sump edge) face. We don't rely on the sump bolts to secure the plate, as you can't tighten them enough as you damage (crush) the sump gasket. Gasket is only used between sump and plate, plate can be sealed to block edge using Loctite Master gasket, Hylomar or silicon.

To prepare a plate and set a block up for the first time is a VERY time consuming job.

Mark

Thank you so much for this information Mark.
Most interesting is the fitting side, as you say the correct fitting to the block is crucial, I have a block in front of me and assume that Triumphs dowel holes are used for locating the engine for machining purposes, would I be right in using these as location points?

I have been busy sifting through my old Sprint stuff and come up with a picture of the assembly.
The ladder brace would consist an 8mm alloy plate the same size as the block sump on each main journal there would sit an alloy block that would space to the exact level of the ladder frame, the main bolts would go through this lot sandwiching it all together.

It all seems very doable but I will measure everything and get back with the details (I have 4 blocks here to compare to see if Triumph kept reasonable tolerances

[Neil907]

John do you not think it may be worth going up to 10mm ally, bearing in mind that the stiffness will go up by the cube of thickness so another 2mm will will almost double the stiffness of it.

[trackerjack]

John do you not think it may be worth going up to 10mm ally, bearing in mind that the stiffness will go up by the cube of thickness so another 2mm will will almost double the stiffness of it.

To be honest Neil I think as you 10 alloy or 8 ground steel and I favour the steel as once I have a drawing done I can get them burn out and ground just like my brake brackets but use alloy blocks to space it to the journals.

I will get my block up on the CNC to log the exact positions of everything and wahey we will be in business.

[Neil907]

Good stuff Jon. if you were to go ally you could allways get it lasered out, If there is enough of us it should cost to much. Would burning it out not risk casuing some distortion over that size?

[trackerjack]

Good stuff Jon. if you were to go ally you could allways get it lasered out, If there is enough of us it should cost to much. Would burning it out not risk casuing some distortion over that size?

No cos it gets plough ground afterwards.
The works cars could rev to 8300 using this mod but I will go no more than 7000 it should be quite solid.

[Mad Mart]

Wish I could get mine to rev to 7000. it doesn't seem to want to rev passed 6250?

[DF]

I have seen a few of these plates at Kens place (Dolly racer 33)
He may do a deal on a production run ?

[rich]

daz ,sure you were producing 155 hp at the wheels with your sprint engine, did you ever suffer from bottom end damage at any time, i know you had steel crank and rods but this didn't make the block any stronger.

rich

[DF]

daz ,sure you were producing 155 hp at the wheels with your sprint engine, did you ever suffer from bottom end damage at any time, i know you had steel crank and rods but this didn't make the block any stronger.

rich

No bottom end damage on mine
If i had gone up the revs and done a lot more track days i would have had a plate.

[trackerjack]

Here is just one journal showing the crack (23&4 were all like this)


And this is the waterpump that is considered reliable cos it has Zeyphr stamped on it as you can see.

[trackerjack]

Got all my balancing stuff back from the engineers and my nice new block all bored out to start the back to power build

What did occur to me is the fact that the blocks were known to crack when used hard, why didn't the factory beef up that part?
If the engine was Japanese or German they would have. now we know why there are no Triumphs being made any more.

[newguy]

As you have pointed this out Jon i think people will be more aware when looking for damage if driving their engine hard.

You wouldn't be able to post some engine building Pics?
Ohhh how i love them.

[Sprint36]

Just thought of something else to add to your list Jon:

ARP big end bolts.

David

[xvivalve]

ARP big end bolts

Off the shelf with Mr Clark...Ken that is