Sprint Engine Rebuild

[Mad Mart]

When I bought VHK I also had a spare engine with it. So today I decided to start stripping it down to see what was what & whether it was worth rebuilding.

It's in a bit of a state externally but that's easily dealt with, it's the internals I was anxious to see.













Slight damage on the timing chain cover but I think I have a couple of these spare.




Once I'd got it on the engine stand I took the plugs out & tried to turn it over. It was a bit reluctant at first but soon started to turn with gentle persuasion from a breaker bar. I turned it about 180 degs. & then a piston hit something solid, so I turned it in the opposite direction and eventually the piston hit the same solid bit. I wasn't sure what it was at this stage as the valve timing seemed to be fine. So I carried on stripping the engine.

I removed the rocker cover and all looks pretty good. The top of the head & valve train needs a good clean but I have had worse...



Next I removed the head. I could now see why the crank wasn't turning 360 degs., a bit of muck had gotten into no.1 cylinder...






...the rest of the cylinders look fine. My initial thoughts is that no.1 bore would definitely need either a rebore or new sleeve but after I cleaned it up I'm not so sure. I'll wait to see how it looks after I hone (de-glaze) it.

I then removed the sump & the oil pick-up.



That's as far as I've got.

[Mad Mart]

[xvivalve]

Flyfisherman asked me about the length of the oil pick up/strainer bolt lengths a couple of days ago Mart; do you now have them to hand to measure?

[Mad Mart]

He asked me about the thread size a couple of days ago. I was thinking of him when I removed them yesterday. They're in the bottom of the box so I may be able to get at them fairly easily.

[dursley92]

I am just going to start rebuilding a spare Sprint engine so its interesting to see how someone else is getting on. I will be following this thread to help me avoid mistakes..My engine did run and has been kept dry since so I am hoping its in OK shape. Time will tell.

How have you got the engine mounted on the stand, it looks pretty closely fixed. I was thinking of making an adapter to mount it sideways on one the normal engine mount positions to allow access to the rear adapter plate and crank seal. Anyone else on here done that?

[Mad Mart]

I just bolt the plate directly to the block, I don't use the arms that come with the stand. I keep meaning to make a bracket but just haven't gotten around to it. Hans & Jeroen have mounted them sideways. Here's a link to Hans's website, there's a couple of pics on there.

http://sprint.smugmug.com/Cars/Forum/11 ... 37_d2bNWnP

[soe8m]

Or here:

viewtopic.php?f=3&t=20105&start=45

Jeroen

[Mad Mart]

Thanks Jeroen, I was looking for that thread.

I removed the pistons and crankshaft this evening. Before going any further I wanted to hone out no.1 bore as I needed to know how bad it was...or not. Unfortunately, after 2-3 minutes of honing, it was obvious that I wasn't going to get rid of the gouges in the cylinder wall. So now I need to decide how much money I want to throw at this engine.









A pity really as the other bores look fine. So if you are going to store an engine long term, especially outdoors, make sure you drain the coolant from the block (the 3/4" A/F brass screw on the side below the exhaust ports on a Sprint/1850) and keep it well covered.

I've got another couple of blocks so I may drag those out & check them, I know one is good.

I was asked about the two oil pick-up securing bolts the other day. They are:-

1/4" UNF 7/16" A/F x 1½" long bolt

1/4" UNF 7/16" A/F x 1" long set screw

[SprintMWU773V]

Those marks are a real pain but if you're going to keep the engine they'll be no choice but to bore it out. Still amazes me how much it costs to do, yes it's a skill and you need special equipment but why is it so expensive?

Still it would seem a shame to scrap the engine.

[soe8m]

Those marks are a real pain but if you're going to keep the engine they'll be no choice but to bore it out. Still amazes me how much it costs to do, yes it's a skill and you need special equipment but why is it so expensive?

Still it would seem a shame to scrap the engine.

Because it's an angled engine. And not even flush. My machineshop has a special dolomite slant rig that has a round bar and clamps in the main bore. So after boring the bores are straight to the crankshaft. After skimming the deck all the piston are at the same hight also.

Jeroen

[tinweevil]

Because it's an angled engine. And not even flush. My machineshop has a special dolomite slant rig that has a round bar and clamps in the main bore. So after boring the bores are straight to the crankshaft. After skimming the deck all the piston are at the same hight also.

Got any pictures of that jig? I get how it would give correct alignment in one plane (tilt along the length of the crank) but how is the block aligned and fixed about the centre of rotation of the crank?

[Mad Mart]

I thought I'd make a start on the head today.



It didn't look too promising with one inlet valve being a different height than the other on no. 1 cylinder (remember the state of the bore?).



Once I'd removed the rocker shaft you can see that no.2 inlet is stuck open.






I removed the valve spring and gave the valve stem some lubrication then started to tap the valve in & out a bit at a time. It didn't take much to get it moving & with a bit of twisting it soon came out.


I then polished all the valves...




and finally started to clean-up the head itself, now that everything has been removed.



I'll hopefully finish cleaning the head tomorrow.

[Mad Mart]

Cleaned off the carbon in the inlet & exhaust ports...



...then cleaned the deck up a bit with some wet & dry.

[Mad Mart]

I didn't have anything else to do this afternoon so I spent about 3 hours honing no.1 bore, just to see if I could make any impact on those gouges. This is the result so far...







The worst bits I can just about catch my finger nail on. Maybe do a bit more? What do you reckon?

[Toledo Man]

I reckon you should do a bit more. You're nearly there...