The Stovebolt Site Forums The Shop Area Engine Shop New 235 overheats

Hi my name is Frank, I live in Germany and I´m new to this forum.

Here is my question.

I have a fresh overhauled 235 (1959) with dual Offy intake, Holley/Weber carbs, Split exhaust, a mild 3/4 cam and a major heat problem.

Strange thing is: I can idle it for 2 hours in a traffic jam and have no heat problem, I can drive down town with stop and go and have no heat problem, but if I drive more than 60 mph it gets hot in a minute.

I think it is not a fan/air problem at this speed.

I checked radiator(flushed), hoses (new), cleaned out the gunk in head and block when I rebuilded the engine, tested 2 thermostats and even tried without thermostat, ignition is set right.

I have 2 suspects:

1. The Holley/Weber carbs may get to lean when I rev it high.
What jets do you guys use?

2. I have a Mallory dual distributer with what Patrick calls a "tailored curve" in his catalog.
It has no vacuum advance and I´m afraid I can not convert it.

But I saw there are different springs aviable to modify the curve.
Has anyone found a good combination of springs for a mild 235?

The Mallory factory setting stops at 24 degrees advance. As far as i know the 235 needs more.

I also have a vintage water injection that sucks water from a jar in the ports of the carbs where usualy the vacuum advance goes. That helps to cool a bit but not enough.

Thanks and many greetings from sunny southern Germany, Frank

I don't know about the carb set up but I am sure someone will post to that. However my first thought when you said that it would over heat at speed was that the Water Pump is Cavitating (sp) or basically not moving water when you get it up to 60. I may be wrong.

By the way Welcome to the Bolt!

Water pump cavitation is a definite possibility. Patricks has information on this, must be in his print catalog. Go to the links section to his website and e-mail him. What this involves is using a largeer pulley on the pump, slowing it down.

Another issue on water pump cavitation that I have learned from the V8 world. GM pumps have too much gap between the impeller and the block. A solution for this is to rivet a plate to the impeller, narrowing the gap, not allowing the water to get sucked underneath the impeller, resulting in cavitation.

Another possibility is valve adjustment. I went with the M4F cam from Patrick's, had it adjusted per the cam card. Patrick recommended different numbers, which lowered my temp at highway speed from 190 to 180*F, but you are far beyond those numbers.

The waterpump I got is the short shaft (for swapping a 235 in a 216 car) pump incl. the bigger pulley from Patrick`s ( also got the m4f cam and most of the parts from him).

When the pump arrived the impeller looked different from everything I ever saw. It is not the cast material It looks like the little fan/impeller of the generator. But it came from Patricks that way and I thought he knows what he`s doing so I bolted it in.

Fred, would you please post the correct valve lashes for the m4f?

Thanks,
Frank

If I recall, set the valves at .008 & .016, but I lost the message when my hard drive crashed.

Patrick definitely knows what he is doing. Since he sold you the parts, contact him about this and get his opinion. It will certainly be of more value than mine.

Here's a good thread on the subject of valve lash.
http://www.stovebolt.com/bboard/cgi-bin//ultimatebb.cgi?ubb=get_topic;f=2;t=003304#000003

I was on the dynotester today to see if the carbs getting lean at higher rpms. It has 3% CO at higher speed. The mechanic don`t know what the old engines supposed to have.

Has one of you guys experience with that?

Also I need some advance figures.

Right now it has 35 total at 3500 rpm.
Im still searching for the right spring combination for the Mallory dual point distributor.

Thanks, Frank

32-34 degrees total advance at 3000-3500 rpm is fine. Your overheating seems to be a radiator problem. You are sure it's running warm, not a inaccurate gauge?The pumps Patrick's uses generally have the sheetmetal impeller as the cast iron ones are not all that common for rebuilding.
235's have a poor combustion chamber design, they require richer jetting than other engines of similar power output.The Holley-Webers with factory jetting should be close enough for high speed running.Does the engine respond normally when accelerating, no hesitation "soft spots"?

I would double check timing curve. Too far advanced or retarded timing will cause overheating. I recently re-timed my Pontiac 350 in my GTO clone. Went from 38 to 32 degrees at 3,000. Engine temps dropped 20 degrees!!

What termostat, fan, and radiator are you using? Sounds like the engine is building heat at high speed. What is your cylinder overbore? .030" .060"??

chip

The Howard M4F cam settings are .014 & .016 hot. Appears that the exhaust is set ok however reset the intake to .014.

One degree over-advanced drops as much horsepower as 5 degrees late, once the best advance is reached. It also raises the temperature drastically above the best-HP advance point. Try retarding the timing a degree or two, and watch the temp gauge. If the dyno can register top horsepower, time it to that point, and then retard about a degree or so if necessary.
Jerry

head gasket may be in backwards partly blocking a water hole mayby

Sounds like a circulation problem to me. try a digital laser thermoter and look for hot spots in the head, possible gasket problem. Another probability is a partially plugged radaitor, mid 80's to mid 90's F***'s were very BAD about this with the exact symptems you described. look for COLD spots primarly around the bottom 1/3 of radaitor core. It will do just fine at idle & low speeds, but highway is a volcano waiting to happen. ALWAYS change the thermostat whenever you have a cooling system problem they will also stick partially open allowing insuffecent flow.
Hope this helps
Brad

Thanks for all the good ideas fellows.

I was throwing out the Mallory dual point and put the stock distributor with tha vacuum advance back in. Just to eleminate any advance curve problems.
No help at all, it was even runing bader.

Got the second new thermostat but it runs cooler without any.

Im starting to belive it is the radiator. But I never had a problem with the old 216 - the needle never tuched the 200 even on hot summer days, I can`t belive the 235 is getting that much hotter.

I have the 41 flywheel so the timing mark is maybe not correct for a 1959 235?

BOOOO HOOOOO! Tomorrow is the race and I sit here and have a water boiler.

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

Got a spring inside the lower radiator hose? Without it, it can suck flat at speed and give the symptoms you describe.

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

Frank,
Glad you got your overheat problem fixed.
I dig the Hot Heads East! I need guys like you for my Kustoms-and-Sleds group. I'd be pleased if you'd join (and tell others!) and help impart the traditional gospel of rods and kustoms.

Kustoms-and-Sleds