R8 G 1700 upgrade

[Bustamif]

The existing 1647 842/841 engine has many road miles on it plus a few racing miles so I am building a fresh engine.
I previously started a thread when considering a 1796 cc engine. During the time since that thread was hijacked in October last year, a few parts have arrived despite COVID related supply and shipping delays. This new thread picks up the progress of the new engine build.

Salv Sacco helped out with a set of 80 mm liners he had on the shelf and some nice new forged pistons. I plan on running about 10.5 - 10.8 :1 CR so that I don’t have to chase fuel availability problems.
A cam is at Clive Cams and will be ground in the new year. We are still working on a suitable grind profile. Always a compromise for road and track. I currently run an old, mild Cosworth/Waggot grind. Can’t remember the specs.

The block needs a lot of work to repair some corrosion around the seal area at the bottom of the liners to make sure there is reliability. The block corrosion is part of the reason I have gone for 1700 not 1796.
A lot of work is being done on the 807 head to change the water flow to the opposite end. The head will need a lot more work to fit the pistons and big valves.

I will post some pics of the progress of head mods so the water pump inlet is at the rear of the car, not under the back window.

The new H beam rods arrived, I have 3 cranks to choose from, I will select the best one after crack testing and a polish of the journals to work out bearing size.

Still waiting on Alpine 110 engine parts from Jean-Yves in Belgium. I believe he has a problem getting some bits from France.

 

[schlitzaugen]

How do you work out the bearing size? I mean how do you measure the inside diameter of the conrods/tunnel bore?

 

[J-man]

You have my attention Busta
That looks like some serious rubber you have under the back! Looks mean

 

[COL]

You have my attention Busta
That looks like some serious rubber you have under the back! Looks mean

And mine too, looking forward to the progress of the build

 

[Bustamif]

How do you work out the bearing size? I mean how do you measure the inside diameter of the conrods/tunnel bore?

The three cranks will be sent for crack testing first then the journals checked. They are all standard size and none have been ground as yet. If they need to be ground or lightly polished the finished diameters will tell me if I need bearings for undersize journals. Fingers crossed as I have a couple of new sets of standard bearings on the shelf.

I have another spare 842/841 block with no main bearing caps. If I need to use that block I will have to install some caps from an 807, which I have a few sets of, then tunnel bore.

 

[Bowie]

That is such a nice photo of you scooting back onto the main straight

 

[Bustamif]

Bowie, it was only due to your enthusiasm for things Renault that prompted me and a few other Aussie froggers, including first timer on a race track Baldrick, to run in that event.

 

[Bowie]

Ah you didn't need that much encouragement. Looking forward to seeing this engine put back together, such a cool R8.

 

[schlitzaugen]

The three cranks will be sent for crack testing first then the journals checked. They are all standard size and none have been ground as yet. If they need to be ground or lightly polished the finished diameters will tell me if I need bearings for undersize journals. Fingers crossed as I have a couple of new sets of standard bearings on the shelf.

I have another spare 842/841 block with no main bearing caps. If I need to use that block I will have to install some caps from an 807, which I have a few sets of, then tunnel bore.

I was just curious if you use an internal micrometer or some such to measure the bore. I have seen quite a few three point internal mikes come up in various auctions.

 

[Bustamif]

Wheel sizes are 7 x 13 rear and 5.5 x 13 front.

The mock up for the new water flow was set up on my spare head. The material used on the current head in the car is tried and proven, Belzona 1111. It works fine in the harsh environment of a water cooled cylinder head.

The first pic shows the end of the head with standard bung removed. The rust and residue must be cleaned off all the aluminium and the surface roughed up so the Belzona gets a good surface.

The ally tube is then shaped to neatly fit into the water chamber to direct flow through the head into the block.
This tube and its buddy are glued in, not welded.

There is an electric water pump on this engine, no need to mount a mechanical pump, just make a suitable plate to cover the end of the head after the tubes are glued in, parted off flush with the head wnd more glue to tidy it up.

 

[Bustamif]

The 80 mm forged pistons are good quality. The rods seem to be OK, at least they have AP rod bolts.

A lot of work to do on the block, corrosion has done some damage but it is repairable.

The block does look cool from the outside

 

[Frans]

Hi Bustamif, This will be an interesting thread.

That rust won't be a problem. The 807 engines I built had similar corrosion and I cleaned it out and made it slightly deeper with a Dremel Tool. I made it deeper so that the hole to be filled in with epoxy had a wall right around it. That then prevented the epoxy to slide out sideways if the sleeve gets torqued down. We from South Africa believe in an epoxy called Pratley Putty and that is what I used.

Do you know about the 807 eating cams? I have experienced it with an 1800 motor that I built for a customer and eventually sorted it. I'm not sure about your way of doing things but this motor destroyed itself on the Targa NZ and that happened over a period of about 700 km of special stages. After the mod, we could get 2 Targas with one engine. That is equal to about 1600 racing kms.

as the lobe and follower were destroying each other the rocker clearance got so big that there where no "lead in" on the lobe and everytime the valve opened the clearance was so big that it was like a hammer hitting the the valve and eventually the head broke off. There is other members on AF that experienced the same problem as me.

Regards, Frans.

 

[Bustamif]

Thanks Frans, I have seen a cam spit a follower out the side of the block on an 807 engine. That one used to go to 8,000 easily until that day. I recall there was a fix using followers with a wider diameter where it touches the cam, not the stem diameter. The modification used old followers from a Porsche 912 4 cyl engines. I actually have a set of those Porsche followers somewhere, they are pretty rare now.

Clive at Clive Cams asked me to send a set of followers to him as he was aware there was some issues in that department. I will be talking to Clive about followers and cam specs when he is back after the Christmas break.

This engine will not have a big cam. I used to have a Cosworth A6 grind on the Lotus back in the day, there is probably better grinds for a road car used on occasional track days.

The block repair is coming along nicely, I have been giving the Dremel a workout. It reminds me of the dentist drilling out cavities and putting fillings in.

 

[Aln]

The 912 cam followers are available new from various suppliers particularly in the US. About $25USD ea. I have considered whether our 807 cam problems are the material of cam or the follower failing taking the other one out. I did look at whether the cam follower head was too small with large cams causing the cam lobe to go too close to edge when the flank starts to move the follower, starting the failure process. The Porsche follower does look larger in the head, but also possibly longer (I have no specs) and so would require further work. Porsche follower link below.

https://www.ebay.com/itm/3124930311...D%3D|ampid:PL_CLK|clp:2047675&epid=1732978515

 

[jaahn]

Hmm re the cam follower failures. I had some experience back in the day with this on another motor, and it was sorted by two steps with advice from the cam grinder. The short life was resolved.
The followers were replaced with larger diameter ones so the cam did not lift close to the edge.
The follower faces were radius ground to promote turning for even wear. Even new followers were reground correctly before use.
Use that information as you see fit in this situation.
jaahn

 

[Frans]

Hmm re the cam follower failures.
The followers were replaced with larger diameter ones so the cam did not lift close to the edge.
The follower faces were radius ground to promote turning for even wear. Even new followers were reground correctly before use.
jaahn

Our experience. After the failure, our A110's co-driver, with a bit of French language and a few VIP contacts on his side phoned the mechanic that kept the 8 x 1800 Eric Comas Alpines going. https://www.autotitre.com/forum/Dis...mas-Historic-Racing-Alpine-inside-90644p1.htm These were or still are rental cars that you can rent for classic rallies. Very clear instructions from this guy were "do not radius grind the followers or camshaft, they will destroy each other". They have to be flat. No reason was given and normally a Kiwi with only school French can't have a casual long conversation. From that info, I made up my own story/reason.

1) If you fit the head loose without followers and look down into the guides you will note that the guides and the center of the cam lobe are not in line. The offset creates the rotation of the followers.

2) I ground spiral grooves in the followers to take oil in as they rotate for better lubrication. Take note that the spirals should match the rotation to assist oil intake.

3) With the wild cam we used I noticed that the grind at the bottom of the lobe was so deep that it went even with the cast of the shaft because normally the most metal is taken away at the bottom to induce more lift. They do not weld the nose of the cam as I have heard people say. So I reckoned that if the rotation and lift are started by the offset of the lobes it is stopped again when the cam has done one rotation and the follower's head reaches this wide base/bottom. So I put the cam in my lathe and turn a deeper groove in the cam right next to the lobe base so that the follower doesn't touch a wide base and the rotation stops.

Which one of these points solved the problem, I do not know. It can be any of the 3 or maybe a combination of the 3.

These are the spiral grooves that I grind in the follower. Easy with a cutting disc in a small angle grinder.

The cam with the grind going into the base that I think stops the rotation and the follower needs to start its rotation again all over.

After my mod where I removed some of the base to give it a uniform width.

There you have my solution and how I did it and had success with these mods. Just a sideline mention, this engine was my pride and joy as I achieved a higher hp output than what the factory got with theirs. Taking into consideration the differences between Dynos, this engine peaked at 195hp at I think 8200rpm. From there I de-tuned it by retarding the timing a fraction and set the rev limiter to 7500 because of the 800 km special stages however, after the second Targa we had to replace the crank, it became the weakest link. The same for the next 2 Targas.

Regards Frans.

Frans.

 

[Frans]

For some porn...this is the car.

 

[GavinT]

Many moons ago I purchased an 807 from a Sydney fellow out of an F2 car.
He told me he'd blown up that engine more times than I'd had hot dinners. I asked him "why" and he said it was trying to keep up with the Golfs!

Here's pics of the cam.
The cam lands have been turned down mostly similar to Frans's example but note the witness marks where the followers appears to have contacted the dizzy drive gear on both sides.
I'd need to check if they were OEM followers or of larger diameter.

 

[Bustamif]

That guy who raced the Renault powered F2 is Mike Stack. I used to visit his workshop in Crown Street Sydney quite often to discuss occasional engine failures. They were really pushing the limits to compete against Golf and Toyota engines back then. They were running well over 8000, after sorting valve gear issues the last hurdle was trying to stop the cam from leaping out of the cam bearings due to harmonics at very high revs.

 

[jaahn]

Hi Frans and other interested bods, I add this for discussion only on a problem area, not to be argumentitive.
The cams in the older engines were always offset from the lifter holes to promote lifter turning. The cam grinders always recommended radius grinding and told us to just put one lifter side on the face of another to check them. If you could see through the center then never put them back without grinding. Hmm I was just a young fella and never forgot that advice from an expert.

The cams were certainly welded up in those days. We had an R8 cam converted to an R8G cam by grinding off half the lobes and the cam man welding them up pointing correctly. Worked OK for a reasonable time as did other brand/type cams done likewise. You allmost had to weld up the lobes because the cam lobes were small in those days. Note I am no expert here.

I had the 'pleasure' of adjusting the tappets on some old motors, Grey Holdens, that were done hot and idling with the tappet cover off. You did need to be a bit dextrous sliding the long feeler strip in to the tappet and holding it while adjusting the self locking adjuster with a ring spanner in the other hand, while they both went up and down Lets see what OHandS says about that procedure. If you do not rev it up the oil does not spray over you. It was interesting to watch the push rods and lifters rotating at varying speeds but you would check if any were not turning properly and free them up.

If our cam man saw those hollow lifter faces he would say when they get to that stage the cam will shortly fail for sure. Frans know that. But the hollow concentrates the pressure into uneven edge loads on the cam face. IMHO Just commenting. Frans found an answer that solved his motor problems.
Jaahn