Homebuilt Mid-Engine Sports Racer

Neil

Supporter
While my engine is out, I thought it would be a good time to upgrade my clutch to give it more torque capability. I have the 240 mm KEP “Ultra Light” aluminum clutch cover and a Sachs organic clutch disk with a KEP adapter mating my small-block Chevy to an inverted Porsche G50 transaxle. The German Sachs disk is rated for a fairly high torque but KEP now offers a 6-pad metallic disk that has even higher torque specs than the Sachs so I placed an order for a disk and a new starter ring gear. I had the new disk within two days. Here is a photo showing the two disks. Both have a spring center but the metallic disk has no “marcel” ( a spring disc between the front & rear friction surface that allows a smooth take-up) so I suppose it is not suitable for the street.

The KEP (Kennedy Engineered Products) website is pretty poor but at least their products and customer service is good.
 

Neil

Supporter
Re-reading back a few posts I see that I've not updated my findings on the engine. First, I found water in the oil and cylinders. This was apparently the result of a heavy rain here just after getting home from Bonneville and before I had the opportunity to unload it off my open trailer. Ordinarily this would not have caused a problem but the top of my air filter acted like a funnel, catching the rain and pouring the water into the intake. I didn't discover this soon enough to prevent light rust from forming in some cylinders and draining past the rings into the oil pan. After discovering the water, I pulled the engine & transaxle out of the chassis and tore it down. I also discovered damage to the rod and main bearings from some debris that had been lurking in oil passages in the block and, most likely, in the crankshaft. Fortunately the crank journals looked OK but I'm having the crank journals polished while the block is at a local machine shop getting the cylinders bored & honed as well as having them install new cam bearings. I hope the cylinders will still allow the re-use of my nice Cosworth pistons.
 

Neil

Supporter
My Donovan aluminum block is now at Gary's Machine Shop here in Tucson. I'm getting the cylinder liners honed/bored, new cam bearings installed, and the crank polished. I had asked Gary to take a few thou' off the deck to clean it up but he noticed something that I had not- the liners are all o-ringed. I had used a usual Fel-Pro head gasket when I built the engine and it seems like if I could have made a good, strong run I might have blown that head gasket. As it was, the gasket survived intact.

Now that I know that the liners are all o-ringed I've ordered a set of Milodon copper head gaskets. The gasket bores are 4.060" so the o-ring will be well into the copper. The thickness is 0.030" while the Fel-Pro was 0.039" so I'll pick up a little bit of compression.
 

Randy V

Admin
Lifetime Supporter
In the few aluminum block SBC’s I have worked on, literally all of them leaked water into the oil from the cylinder sleeves. A rather well known (in our area) engine builder told us about Ceramic Engine sealant and said that we should use it in all aluminum block engines with steel sleeves. He was right. No more seepage.
Perhaps something to think about?
 

Ian Anderson

Lifetime Supporter
Supporter
Neil
When it is apart get them to check that the liners have not moved!

May not be a problem with your make of engine but with the Rover mills over here it is reasonably common for them to “drop” a liner especially if it gets hot or runs lean. Basically the steel and aluminium expand at different rates and the liner can slide down the bore.

Easy to check when apart but a pain to have to pull apart to check later

And yes they use a similar sealant on them as Randy describes.



Ian
 

Neil

Supporter
Thank you, Ian- good suggestions but the Donovan aluminum block uses "dry" liners. The liner is inserted into a hole in the block that is not in direct contact with the coolant, unlike a "wet" liner.
 

Ian Anderson

Lifetime Supporter
Supporter
Thank you, Ian- good suggestions but the Donovan aluminum block uses "dry" liners. The liner is inserted into a hole in the block that is not in direct contact with the coolant, unlike a "wet" liner.
Still worth checking!
The answer normally is top had liners which have a flange around the top, the matching hole being ground into the block.
Cannot go down because of the flange and cannot go up as held in place by the head

Ian
 

Neil

Supporter
Last week I was surprised to find that the top surfaces of the liners contained a stainless steel o-ring. This means that I'll need to switch to a copper head gasket.
 
Last week I was surprised to find that the top surfaces of the liners contained a stainless steel o-ring. This means that I'll need to switch to a copper head gasket.
Usually the liner has the receiver for the ss outing and the heads have the ring in them I think. Rod
 

Neil

Supporter
Rod;

O-rings can be installed either way. When Ford dropped out of racing in the early Seventies, I bought a Boss 302 block from Holman-Moody that was cut for o-rings. There were square grooves in the deck around each cylinder where copper o-rings were placed.
 

Neil

Supporter
It looks like I lucked out. Gary called yesterday and said that my crank polished to much less that 0.001" under standard size so I went ahead and ordered new King XP main & rod bearings in STD size. He had good news on the cylinders, too. Honing them out +0.002" (from 4.030" to 4.032") cleaned up the bad spots. This means that I can still use the Cosworth pistons and the ring gaps will not increase more than one tenth with the slightly larger bore.

The machine shop should have the block & crank cleaned and new cam bearings installed by the end of this week. I also ordered a set of block cleaning brushes so I'll clean the oil passages myself, too.

Regards, Neil Tucson, AZ
 

Neil

Supporter
The set of engine cleaning brushes and the bearings arrived so I cleaned the oil passages in my crankshaft this afternoon. The machine shop did a good job of cleaning it; I did not see any evidence of any remaining debris when I ran a brush through all the passages or when I sprayed them with brake cleaner. I used a lintless fiber cloth to wipe everything down before spraying on a light coat of WD-40 to prevent rust. Now to tackle the block...

This is a 51 lb forged 4340 steel Lunati crankshaft, 3.75" stroke, with knife-edged counterweights. USA steel and USA forged, not Chinese.
 

Attachments

Neil

Supporter
Thank you, Dave. I use a single-pass aluminum radiator made by Howe Racing Enterprises. It is a type that is often used in sprint cars. I added a vent fitting to the top of the header tank to provide a continuous air bleed. https://howeracing.com/
 
Neil, you should find someone with a good chassis dyno and resolve your driveability issues without ever leaving town. It is typically money well spent and you can solve alot of problems in a short period of time-just my 2 cents worth.
 

Neil

Supporter
Mike, I've come to the same conclusion- a dyno test or find a nearby track or little-used stretch of road. :rolleyes:
 
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