2366cc FAT Performance T4 Questions

[Bugged1303]

Hi all,

My name is Zach, I've had a thread going on Germanlook.net for years on my slow 1303 progress. I'll get a thread going here soon to share my build, but for now I have a few questions as I'm trying to get the last bits of the car buttoned up. Here's a quick pic of the Super and a link to my germanlook build.



https://www.germanlook.net/forums/showt ... hp?t=11037

Germanlook.net Bugged Build Thread


OK, here's my issue. Let's start it off with a few videos to get ya interested.

Here is cylinder 1, I notice a lot of black build up that doesn't seem like carbon build up. It's soft because when the bore scope touched the piston, it easily scraped the goop off. There is also that brownish color, which I'm not sure if it is left over gas from a leaking weber carb or if it is oil from something more heinous. All four cylinders seem to have this issue.
https://photos.app.goo.gl/fjfug9VzwpnVKwQSA

Also cylinder 1, I notice some oil wiping as the piston descends to BDC and also some light vertical scratches.
https://photos.app.goo.gl/TBK41uBKfDFx6XxWA

Background:
-Motor built by FAT performance in 1995, was bench dyno'd, and then was never installed in a car until I bought it in 2013. It lived in an airconditioned garage in Arizona, covered and periodically turned over. It's a 2366cc (103mm pistons). I have all the original build documentation and can get any more info desired, but I'll start here.

-I've put maybe 100 miles on this motor, but haven't done extended drives because I was trying to solve overheating and would stop the car before the oil temps got over 220F. I relocated my external oil cooler to the front and am hoping it will give me enough cooling to keep the motor under 210F.

-I've also had issues with the carbs. I've had issues where the carbs leak gas and I have to block off the fuel line from the pump and then run the carbs dry, otherwise the garage smells strong like gas. I've rebuilt the carbs twice, but I continue to have issues with these carbs.

My Thoughts:
-The black goop is either gas from carbs leaking into the cylinders or it is oil getting wiped onto the cylinder walls and getting gunked all over the piston top, valves, and cylinder head chamber. I'm hoping it is just a simple fix, but am concerned I may have a valve and/or a piston ring issue.

-I'm also seeing some vertical scoring on the cylinders and would like to address it, as it currently seems pretty minor

My Questions:
-What do you think this issue is?
-What next steps should I do to trouble shoot?

I plan to do a compression and leak down test on the motor to figure if I have intake or exhaust valve leaks.

[Bugged1303]

Any takers?

I performed a cylinder leak down test and all 4 cylinders are perfect. Almost too perfect. 100/100psi on all 4. I used a stethoscope to listen to intake and exhaust valves and could maybe hear a tiny leak, but hard to tell with the noise of air in the crankcase (thru the rings). Here are a few more pictures and a link to all the videos.

https://photos.app.goo.gl/eF847UvQnQjpPdar7



How concerned about the vertical scoring of the cylinder walls. Do the rings just need to break in? I only have a few hours on the motor.





The backside of the intake valves. Does this suggest a fueling issue, a valve seat issue, or a ring issue?

[Bruce.m]

Your comments that leak down is 100% and you can hear the wind sound in the crankcase, don’t seem consistent.

A leak down tool has a pressure gauge after a 1mm restriction bore, which limits the air flow to the measuring gauge. So if the rings leak move than the flow capacity of that tiny hole, then It’s less than 100% (psi)

[Bugged1303]

Yeah, I was a little suspicious myself and was trying to get my hands on another leak down tester. I would think that even a perfect motor would register <100% unless they have total seal rings.

I did a test to see if the tester worked by turning the crank until a valve started to open, and the gauge registered the leak.

Either the leak past the rings is so small that the gauge doesn't detect it or the gauge is not sensitive enough to detect a moderate leak.

[Bugged1303]

Leak down test video demonstrating the gauge works when I open the exhaust valve slightly.

https://photos.app.goo.gl/76iHvyYNuMGzqUAE9

[Bugged1303]

I have more information, would be awesome if someone had some insight.

I got the new pushrod tubes installed (leaking) and the motor back in. I performed a compression test (cold motor) and all cylinders are reading 85-90PSI. This seems a bit low, but I do live at 7000ft elevation. The recorded compression ratio of the build sheet was 8.2:1, I don't know what the overlap of the cam is (FAT FC443 - 290 degree duration, .507" lift).

I'm a bit confused because the leak down test showed 100/100psi, but I could hear air leaking into the crankcase. I looked at the build sheet and the motor does have Total Seal Rings so that could explain the perfect leak down numbers. I don't know why I would have low compression numbers, but good leak down numbers.

I plan to get the motor running and get it hot so I can do a compression test when the motor is up to temp.

[Bruce.m]

Compression gauge is working based on that test. Maybe not accurate to +/-?% but clearly you have decent seal.

Have you got a decent oil cooler set up & all the little important air seals & tinwear around the engine? Spark plug holes for example need sealing with the large rubber washers on the HT leads, plus well sealing tin & rubber seal around the edges.

103 cylinders used to get a bad rep for going oval & having leak down, but that doesn’t seem to be your situation.

[raygreenwood]

I have more information, would be awesome if someone had some insight.

I got the new pushrod tubes installed (leaking) and the motor back in. I performed a compression test (cold motor) and all cylinders are reading 85-90PSI. This seems a bit low, but I do live at 7000ft elevation. The recorded compression ratio of the build sheet was 8.2:1, I don't know what the overlap of the cam is (FAT FC443 - 290 degree duration, .507" lift).

I'm a bit confused because the leak down test showed 100/100psi, but I could hear air leaking into the crankcase. I looked at the build sheet and the motor does have Total Seal Rings so that could explain the perfect leak down numbers. I don't know why I would have low compression numbers, but good leak down numbers.

I plan to get the motor running and get it hot so I can do a compression test when the motor is up to temp.

So....you live at 7000 feet elevation. I found a chart online (actually have found several and they are all close or identical) that shows "a version" of an air density offset chart for compression at variou elevations.

So for 7000 feet ~0.81 is the offset. This means only 81%...19% lower than 100%.
This means that if you tinker around with the math....your "real" compression that is being offset by the thinner air at 7000 feet...is approximately 124 psi.

This is about right for an 8.2:1 compression engine....that is NOT completely broken in.

Of course this does not yet get into overlap issues with the cam etc. etc..... but I have worked on a lot of type 4's that were 8.2:1 compression and after complete break-in down at not far above sea level ...like Dallas Tx at ~420 feet above sea level...which gives ~98.16% of being right at sea level....you could typically expect about 130-135 psi....when TOTALLY broken in....which really takes about 3000 miles give or take.

With only 100 miles on hard rings like total seal....I would say you are not yet broken in all the way. The differences in compression gauge and leak down test could just be the accuracy of gauge, the temperature...and of course with a leak down test you are adding oil to the cylinder ?...further indicating not yet all sealed up. Ray

[Bugged1303]

https://photos.app.goo.gl/18V83Qzuh8z3NEG67

Compression gauge is working based on that test. Maybe not accurate to +/-?% but clearly you have decent seal.

Have you got a decent oil cooler set up & all the little important air seals & tinwear around the engine? Spark plug holes for example need sealing with the large rubber washers on the HT leads, plus well sealing tin & rubber seal around the edges.

103 cylinders used to get a bad rep for going oval & having leak down, but that doesn’t seem to be your situation.

I do have a decent oil cooler set up, I hope. The DTM cooling shroud doesn't have a spot for the internal doghouse cooler, so I have made an effort to maximize my external oil cooler efficiency. I am using this cooler, front mounted, using AN10 lines plumbed along the floorpan channel. I'm using a remote oil filter mounted in the rear driver's wheel well, using a MOCAL sandwich thermostat. Not currently using an electric fan set up, but have the inline Setrab switch and a fan if I decide I need it. Oil temps are pretty good, I haven't gotten the car over 200F even when I'm on the gas for extended periods. Warm up does seem to take a while, but the sandwich plate seems to be stopping flow to the cooler during warm up.

https://www.summitracing.com/parts/csf-8119

As far as engine tin and sealing goes, it is a work in progress. The DTM aluminum kit leaves a lot to be desired in my opinion. There is a gap between the rear apron (fiberglass) and the rear tin which allows heat from the exhaust to seep into the upper engine compartment. Working on a solution, I may have my own tin cut out in aluminum that enables addition of rubber seals. I have the spark plug rubber sealing washers, but they are little dry so I have some new ones on the way.

[Bugged1303]

Also I'm seeing that some of my images aren't displaying in previous posts. Can anyone confirm if they cannot see the pictures?

[Ol'fogasaurus]

You get a small pix then Google cuts in and wants the person to join.

Lee

[Piledriver]

Beautiful car.

There is a foam rubber seal for late VW busses that has an "H" cross section, works wonders for sealing an engine with simple tinwork (I built a Cali conversion ages ago for my son for his `71 Super)

Its kinda expensive but it works and can take the heat well.
(actually much cheaper than I remember, fits 72-79 Busses in US)
Absolute must to keep the hot air from getting recirculated.

Make sure any holes in your tinwork are sealed off somehow.

It appears your engine is simply not broken in.

As to your Webers...

There are several things that can cause similar symptoms...

If the fuel pressure is much over 1.5 PSI to Webers, they tend to continuously pee fuel into the bowls.
You cannot tune the ANYTHING like that (or with ~any of the following issues)
Note: Malpassi sells a very good low pressure/high volume fuel regulator for Webers and Dells..

The idle jets on Weber IDFs like to collect dirt that gets through oiled gauze "air filters".
Get the extended jets if you don't have them already. (idles and mains)

I use the term "filter" loosely: Oiled gauze air filters stop coarse sand. Usually. Don't expect long ring/bore life using them.
At least use them with oiled foam outerwears. I always found large bits of dirt got by at the air filter base and lid if thebase/filter and lid were not RTV'd together as a unit. Google silica fines and ring wear. Oil analysis will show it very clearly.

The aftermarket needle valves like to stick. They are ~=garbage.
Try to get a set of the real Weber ones if correct fuel pressure does not help issue..

...also if the linkage being used vibrates and "works" the throttles so fuel is constantly being added from the accel pumps... forget tuning the idle at least.

I fought that... tore my great looking new CB hexbar off after a month or so... and fabricated a cable pull setup from used bicycle brake cables and an old pushrod that worked ~infinitely better for many years and a few hundred K miles (my old 914 was a daily long distance commute driver)

(sync-link throttle linkage is an excellent fix, costs as much as a nice set of cuff links... far more useful)

A super rich mix from stuck fuel needles etc... can cause break in issues...
Running at a full load for about 30 seconds a dozen times usually seats the rings just fine, yours may need more.
A dyno is idea (chassis dyno or engine) but a series of on ramps to a highway work fine... hills even better.

If you don't have a wideband O2 setup you are always guessing, reading plugs stopped working about 30 years ago when they stopped making real gasoline. Reading plugs didn't work that well back then. If the exhaust smells like gas you already lost.
All of these fuel issues can make for an untunable engine.