Here is the next problem with the rebuild 235.

I have a split exhaust (splited stock header, 2 pipes straight to the rearend with a crossover yust bevore the glaspacks) and a dual Offenhauser Holley/Weber setup.

As I started the engine the first time I realized that from the exhaust pipe that comes from the front header portion is only delivering almost cold fresh air.

After a compression check we found cylinder 2 and 3 have 100 the rest has around 120.

A check with a glass sparkplug shows that the plugs are fiering but there seems only a view ignitions.

I also checked the idle jets on the holley/webers tey both say 50.

The carbs are both overhauled by factory.

Sorry for the long post,

thanks, Frank

You may be lean on the one end. Try swapping the carbs around and see if it changes.

Yeah, I go and check that first. I let you know tomorrow.

Frank

It sounds like you need to sychronise the carbs for flow, the front one is probably closed down too far. This is a classic problem of multicarb engines. Also make sure the float levels are exactly the same.

Dear Frank;


Solve the oil problem first.

One or more plugs could be fouled because of excess oil all over the place.

Then you could check for a vacume leak between the manifold/head.

Good luck, John M......

PS: That compression is normal for a new engine.

As John suggested,sure sounds like a leaking intake manifold gasket.Did you happen to forget the spilt rings that are go between the intake manifold and head?If you used them,check to see if the intake is up against the head. Paul

O.K. I solved the oil problem so far.

Then I swapped the carbs - no difference.
Checked the plugs, looked o.k.

Cheked for leaks - no leaks. And yes I have the rings in there.

Still get almost fresh cold air and moisture from the front exhaust - the pipe at the rear end is not even getting hot after a 20 minute ride.

I also tried to idle it only with the front carb, it is possible so the carb seems not to be the problem.

Glas sparkplug again. Ignits fine at 1-4-5-6 almost no ignition on 2 and 3 where I got less compression. All spark plugs fire good.

Runs like **** drinks gas like a hole

O-boy am I frustrated!

No fire at 2 & 3 acounts for the cold pipe. check the distbitor lobes and make sure the points are opening ( sparking ) 6 times. Then put a spark plug or glass tester directly into each of the dist. cap terminations one at time--this will let you know if the cap is good. Then check you wires--- I have purchased new ones that were bad right of the box.I do not think the low compression on those cylinders is low enough to cause a cold pipe. I think the problem is in the ignition. Paul

Dear Frank;

Paul is probably right, check out the ignition.

After that, check the valve adjustment on 2 & 3 as it may account for the lower compression and eliminate another possibility.

Good luck, John M........

I'm sure you won't like to here this but you might have a burnt head gasket between two and three.

Gael

@Chevyman - I had this problem when I fired her up the first time. I thought it is a Valve problem ( becaus of verry low compression on 2 and 3) and pulled the head. The gasket was fine. I let the machine shop regrind the 2 valve seats and put the head back on with a new gasket.

@ all others: thanks for the help but:

Checked for vacuum leaks and ignition failure - even used a new set of sparkplugs and cables, distributor is new. 2 and 3 have still only a view ignitions (glas sparkplug shows the plugs fire fine but there seems not much to ignite) Carbs work good.

But it is even geting more strange.

As I said, the cold pipe is the one that comes from the front part of the split exhaust - the one with 2 and 3 with less compression (maybe because the valve seats are way deep in the head now - but not sure how much that makes)

As soon as I rev her more than 2500 when driving the temp gauge goes to the red.

I head her on the lift yesterday. Both pipes get equaly hot up to the glaspacks. The left (cold) pipe was even so hot that the pipe turned totaly blue. Because some sort of magic the gases seems to get cold wehen they pass the glaspack.


I have a crossover pipe 4 inches bevore the glaspacks.

Is it possible that the exhaust gases go back and forth in a strange way and instead of getting sucked out of the engine, while the exhaust valve on 2 and 3 is open, they get forced in, so I don`t get enough fresh gas in.

(oh I feel I run out of my english to explain this - I hope you guys know what I mean) does this make any sense or did I just get to much exhaust fumes?)

Thanks, Frank

Dear Frank;

Not at all, there could be a restriction in the right side of your dual system. That would be the rear header. Possible something got in there while the whole thing was apart.

Hard to analize this W/O being there etc.

Pull the system & leave the headers on & see.

Things "turning blue" is not a normal 'break in' thing. Engine is probably okay.

Good luck, John M......

SOLVED! (almost)

The new coil was labeld wrong (+ and - tags swapped)

I then retuned the carbs and the ignition with professional equipment (Osciloscope/Co2 Meter), and set the valvelash again (was still to tight when hot). Now it purrs like a cat in the creamery and I have equal compression on all cylinders.

The Exhaust tube comming from the front header is still a bit cooler but who cares, she runns like hell and I get good milage.

It has so much torque that I can drive around in town in third gear like an automatic almost without shifting. The exhaust sounds nothing but sweet and I would get even better milage if I stop reving it all the time yust to hear that exhaust note ;-)

With the help of the forum I also solved the oil problem.

She is going now much faster than you want to drive with this tires and suspension.

In 2 weeks there is the anual prewar quatermile race. Let`s see if I can winn a price.

The only thing left is that the engine is getting hot when I go more the 75 mph.

The cooling system is in good shape, I stuck in a traffic jam for 2 hours yesterday - no temp problem. Only at high speed.

I think it is a timing/advance problem.

I got a Malory distributor without the vacuum advance. It has what Patrick`s call a "tailored curve" in his catalog. Has anybod ever found a good spring combination for this?

Thanks a lot for all the help, Frank

Good detective work Frank!

Is the distributor a Mallory Unilite? It should have come with a little tool for changing the advance curve. If your overheating is due to timing, you probably need more advance at higher RPM. I would try that first before changing springs.

I would suggest, though, that it's probably lack of cooling airflow at speed - your web site doesn't show a fan shroud - What about the fan itself? Original 4-blade fans don't move a lot of air. These are pretty easy items to fix.

Gotta love that Autobahn for high speed tuning runs!

No Jack I have 6 Volts so I have a Malory dual distributor that triggers a Thyristor ignition box made by a Porsche ignition engineer for me. It is similar to those MSD or Jacobs devices but for 6 volt.

The Malory manual says there are different colored springs with different tensions aviable to change the curve, but I have no clue wich combination to use.

The heating problem ocures only hat high speed, it should get enough cold air even without a fan at this speed.

The fan is not the original, it came with the engine and it looks like a more "advanced design" (smooth curved blades) and pushes a lot of air.

Yeah Autobahn is fun almost no speed limits, but lot`s of guys drive like hell in the Mercedes and Porsches.

Frank

OK, the anual quatermile race is over and it was great but I have to let my car at home.

Today I took her to the radiator shop to get a new core. Let`s hope it helps. I let you guys know.

Thanks, Frank

Frank,Hope you'll be able to post some "Head Banging Drags" pics on Hot Heads and how about some drag numbers here.Were you able to solve more of your 235 problems and run?

GOTCHA!!

Got the radiator back from the rad-shop today and bolted it in. She is finaly cool now. The needle reads a steady 180 no mather what I do.

First I never thought it can be the radiator. It never gave me trouble before plus I had it cleand and roddet out 2 times.

When they took the core out I could see how bad it was.

Now they welded in a modern core with more than twice of the cooling performance.

Thanks for all the good information and brainwork.

All the best from sunny southern Germany, Frank

Nice to know that someone over there has a chevy. I was over there a month ago and only saw one chevy. That was for over a month. How close to munich and landshut are you? JT

Verry close to Munic - 38 miles to the Ulm/Stuttgart direction.

If you ever come back, we meet every Sunday afternoon at an old filling station close to Munic.

Frank