OT For the pros engine question

[Ross]

A friends Olds V-8 has me puzzled with it's behavior.
This odyssey begins at purchase. A '70 442 convertible very pretty with a rough running motor, seemed a bit like an BAD ignition miss.
The seller said it was the W-30 camshaft making it rough, BS for sure. My friend has the hots for it and money burning a hole in his pocket so pays up.
Immediately trouble starts as when shut off the thing boils over. It seems to be running very hot all the time, the exhaust is like a blowtorch out the pipes and it reeks of preignition.

I started with an ignition tune-up and compression check, all semmed well but no improvement. At this point I began suspecting valvetrain trouble like a flat cam lobe so removed the rocker covers for a look. All the valves were opening, no measurements made. Next the timing gears were checked for alingment and wear, the marks were where they should be and the chain was fine. There was no # on the end of the cam to see what it is.

Another friend suggested a blown head gasket so the heads were removed and sure enough there was an area between two cylinders that was suspect and one valve showed evidence of coolant in that cyl. The compression check gave no clue to this. The heads were pressure checked and done at great expense with stellite seats and reinstalled this past weekend. The car runs exactly as before!!

Carburation is not an issue as the carb has been properly overhauled with the throttle rod bores bushed.The tune- up is right on and there are no vaccuum leaks.

This thing runs hot, shakes like a plug wire is undone, smells of preignition, blows coolant out the overflow when it heatsoaks and the exhaust is very very hot.

The head gasket seemed to make sense even though the car acted more like valvetrain problems. The hot exhaust could be attributed to steam, the smell perhaps from burning coolant and the "boiling" was maybe only the cooling system being pressurized.

This is one bitch of a car to take apart the top end on as it has a full load of accessories in the way. I'm getting disgusted and need some suggestions, my friend is counting on me and I don't want to just start throwing parts at it or take this fkr apart any more.

My latest suspicion is a wrong or poorly manufactured cam or timing set.
In thirty something years of amateur mechanics on
stuff from beaters to Formula 1 I've nver seen this. Somehow the sellers comment about the so called W-30 cam (the hot factory offering) leads me back to the valvetrain. I'll bet he installed some cam had these problems and is still pinching himself over the good fortune of selling this headache to my pal.

I'm out of ideas guys, so before I go and rip this monstous iron turd apart again someone please save me with an obvious simple solution I've overlooked.

I'm going to pressurize the cooling system on the off chance a head gasket is not sealing, and another comp. check. The plugs weren't run long enough to tell anything.

Ross

[Ausmpower]

If it's burning coolant the exhaust will smell 'sweet'.

Could it be a cracked bore?

Poorly reground cam?

Water pump or thermostat u/s?

Cam timing way retarded?

Distributor centrifugal/ vacuum advance locked fully advanced?

heads shaved too much or block decked too low?

What's the C/R ?

Pre-ignition has a smell?

[632 Regal]

Ross,

firing order? maybe the cam is ground wrong as you say. you can get BB chevy cams with the 4-7 swap that makes a few extra horsies.

with that smell I would have to say firing order or cross firing. Whats the timing at at an idle and at 3000 or so rpms? Plug gap? Weak ignition? Wires?

I know you have gone over the firing order a million times but that is suspect to me, this will cause it to get hot as hell.

mystery cams suck.

[Ross]

Thanks,ausmpower
Don't say cracked bore, that awful thought crossed my mind. Removing the heads from this pig is a serious pain in the ass, replacing them means putting a few of the pushrods in along with each head as the a/c evap. housing is in the way on one side and the brake booster on the other.
Preignition has a terrible smell that burns your eyes and nose, it's unmistakeable.
The cooling system is okay, I'm not sure how hot it gets as there isn't a guage just the generals idiot lights.
As far as the CR it's sixties typical 10 or 10 1/2:1 the block didn't appear to have been decked and the heads got only a minimal cut to make them flat.
The cam or it's position seem to be all that's left, I should have had him buy that last time I was in there.
Have you seen a motor act like this??

[Ross]

Thanks Jeff,
I'll check the order again to be sure but that would mean I've put it together wrong half a dozen times. If that's the case please disregard ANYTHING I ever post here.
The mystery cam or the position of it seem most likely. I've read about the 4/7 swap cams. I wonder if there is such a thing for the big Olds, or if the same concept would apply to this motor. I wondered if a marine cam intended for reverse rotation could do this?
This last time I never even put a timing light on it, it was apparent thing were F'ed.
Have you ever heard of such a thing before??
It's really a shame as this is a REALLY nice car otherwise, one of those I always wanted to own one day. Now I just hate the thing.
When I get to the bottom of i
this my buddy has agreed to let me beat the living **** out of it for a day. That and pride are my only motivation to finish it.
Wish me luck.
Anyone else ever see this???

[632 Regal]

throw that cam away and get a reputable one like a comp cam 270H if it can take .501 lift and has dual valve springs. I like to go a bit hot on cams with higher compression engines to prevent spark knock. 224 dur @ .050 should be perfect.

are you sure there isnt a bad lobe or 2 on the cam? To properly break in a cam isnt for the faint of heart. People hire me to break their cams in for them, last one was a chevy 350 and the dude wiped out the cam in less than 10 minutes while attempting to break it in.

270H Magnum™ is a great cam for high performance driving in street machines. The 270H has a rough idle in small blocks and a noticeable idle in big blocks. This is the largest cam you can use with a stock torque converter. The 270H will not affect power accessories, but should be used with headers and a 4 BBL. carburetor. This is the perfect cam for cruising.