Rebuilding Sprint engine...checking what parts to buy

[misterp]

The more I spend looking at the block, the more Im thinking it will give some peace of mine just fitting a new set of mains, big ends and piston rings to me and any future owners.

I need some help deciphering the parts however as I dont seem to be able to find any markings that would indicate a re-bore or oversize.

The mains have 143040 stamped on them (and searching seems to suggest they are standard bearings)..but no 0 or 0.20" )or any other markings. Does this mean standard if there are no other numbers/values of oversize?

The pistons are a 'F' (they have F stamped on the crown) and 17/0 which again, seems to indicate a F grade block, so does that mean simply ordering standard bearings and rings and then gapping them accordingly?

Thanks

Andrew

[tony g]

Yes the lack of numbers on the shells means its standard. Checking the crank diameters will of course tell you what size they are. Big end journals are 1 3/4" std, I cant remember the mains sorry. You wont be spoilt for choice on rings. Grant from the usa do them, as they are the same as tr7's which they had imported. Gapping the rings would be nice if theyre a bit too tight but Ive only seen too large a gap on new ones Ive seen so far. Grade F pistons bores also indicated std size. (one of the std sizes at least)

Tony

[Jon Tilson]

You have standard crank by the look of it. Try and find vandervell or glacier bearings. You may have to search high and low...TR7 and 1850 and early Saab 99's are the same.

Jonners

[misterp]

Thanks for the replies guys. Much appreciated.

Its good to know its a good original engine.

Million dollar question now...I currently have Vandervell bearings (big end and mains) installed. I posted previously what they look like but below are the current installed bearings:




What would you do?

Replace with county brand (I doubt I`ll be able to find Vandervell ones here) or stick with the seemingly good condition ones?

[xvivalve]

I'd say there's life left in those.

[Jon Tilson]

Me too....

Re-use if they are Vandervell...county bearings hmmmmm

Have a VERY good look at oil pump rotors and use an original paper element filter - not a spin on conversion.

Jonners

[misterp]

[quote="Jon Tilson"]
Have a VERY good look at oil pump rotors and use an original paper element filter - not a spin on conversion.
Jonners[/quote]

Thanks both for the advise. Ill stick with the vandervells then.

Can I ask just a few more Q's?..
What to look for on the oil pump rotor/gear..excessive wear and it scuff marks? Or is there a check process with feeler gauges etc?
Why the paper element over spin-on? Surely the newer filters are higher filter grade and better flow..and they have a anti-drain back valve in to stop the pump emptying?
Finally, is it worth changing the rings as there is a little bit if piston wash around the crown on them.?

Cheers guys..much appreciated.

Andrew

[Jon Tilson]

On an earlier thread Jeroen demonstrates how the adaptor reduces flow.

Its not the filters - its the adaptor.

The pump rotors have a set clearance that you can check but look for scuffs and damage.

The current paper filter bowl doesnt drain.

If your rings have some blow by definitely fit new ones and light hone of the bores to break the glaze.

Jonners

[misterp]

Nice one Jonners..thanks

I didn't RTFM as Ive just read the checks to do on the pump so feeler gauges at the ready.

Interesting RE: the adapter fitting. I`ll do a search and find out the post you mention. I have the original can on my 'new' engine, but an adapter on the one thats failed.

edit:- post I think details the restriction is here. viewtopic.php?f=4&t=26428

Just making sure well..by piston wash I mean this (where the carbon ring is washed away by gases escaping past the rings):-



I remember from a while ago when i last rebuilt an engine, the guy I was learning from said this indicated the rings were not sealing/letting by.

Did I remember this correctly as this is the only reason I'm contemplating putting new rings in.

Thanks once again.

Andrew

[SprintMWU773V]

Bearings are an interesting subject. Most new bearings are aluminium and the research I have done suggests that these actually wear quite well as they have a high wear resistance but they do tend to wear the crank more than a tri-metal. It's preferable to fit tri-metal bearings in high performance applications but these can be hard to source. I was able to find Vandervells in the US and fitted them but there will be a time when they are extinct and we'll have no choice but to fit County or other aluminium bearings.

For the vast majority of people in a road car that's used sparingly and sympathetically there's nothing really wrong with the aluminium bearings. The cause of most bearing failures is debris damage. Aluminium bearings are less forgiving than tri-metal ones so you must be prepared to ensure everything is faultlessly clean. I also recommend the use of Graphogen assemble paste which will help you when you start the engine. Oil tends to leak out whereas graphogen is oil suspended in a paste so it doesn't flow off. Lots of 'professional' engine builders use it. A thin coating on the crank journals and bearing faces will be a good thing.