BritishEngineering

My son and I bought a 71 442 a few years back for a father son project that came with the original 455 completely rebuilt - we finally got around to getting it started and running - they put a Mondello JM20-22 - probably about 5 or 6 years old - cam in it and I "believe" 1.6 ratio rockers. We don't like it - what we want is a stock smooth (relatively) idle - this cam is only one step above a stock cam and we don't know that much about cam specs - Thought the cam being only one step above stock would be OK but so far not. What is the professional opinion out there - should this run smooth with this cam or do need to put in a stock cam for what we want. Also the motor is getting too hot - everything, and I mean everything is new - timing spot on, new radiator etc etc etc, 180 stat.......but that's another thing we have to figure out - would have preferred to rebuild the motor ourselves but it is what it is ....Thank you in advance ......Richard::confused

coppercutlass

Good tunning will make a lumpy idle relatively smooth relatively speaking . What are you looking for in idle quality ??? By spot on timing what do you mean ???

BritishEngineering

Thanks coppercutlass - right - the thing is tuned correctly - not a tuning issue - I meant the timing is set to factory specs - am an old fart with no desire for a lumpy idle at all the red lights - just like smooth and quiet - runs perfect off idle - responsive - idle just sounds - and feels - like something at the local drag starting line.......that's not me anymore.

coppercutlass

Sometimes bumping the idle will smooth out the lump. As the rpm goes up the idle will smooth out. I also think stock timing specs are not desirable even for stock builds. Even the mildest of engines I have ran like 12 to 14 initial minimum.

BritishEngineering

Right - it's set at 12 initial......really appreciate your input.....

oldcutlass

What distributor is in the car? What temp is it running?

Lee_A

Agree. A slight increase in idle rpm SHOULD make it a bit smoother. I would also try different timing settings, to find where it idles the smoothest - you can utilize a vacuum gauge to find the highest reading (adjust for idle speed, so that you are measuring vacuum at the same rpm).


Using manifold vacuum advance will allow you to back off the idle speed screw, and should also smooth it out some.


Have an oxygen sensor bung welded into the exhaust, and use a wide-band to adjust your idle mixture to around 14.0 (test for yourself, to find the best setting).


If that still doesn't provide satisfactory idle, then consider getting a custom cam. Send me a PM if you wish, I might be able to help you on that.

83hurstguy

that's a pretty mild cam that works well in a lot of 455's. You can also try switching the vacuum advance from ported to manifold and see if that helps (as mentioned above, will give you more idle timing which should smooth it out, may increase the idle speed as a result that can be backed down on the carb). It's worth trying before going through a cam swap.

Running hot can be several issues, most of which people love to guess at on the internet. Is it running hot at idle? going down the road? all the time?

oldsmobiledave

That cam is a ***** cat. The problem is not the cam.

Firewalker

Using the vac port off the intake to the vac advance, as suggested will help, including temps usually. Raising the idle speed a few hundred RPMs may also be needed.

You didn't mention the carb and intake used.

That cam is far above "a factory cam", or a normal one.

http://tech.oldsgmail.com/olds_cams.php

But the lope can be tamed

BritishEngineering

Mallory electronic - 200 degrees on idle

BritishEngineering

Carb and intake are stock

Firewalker

OK, so it should be fine.

And 200 degrees is not that hot normally. Just make sure the mix on the water, in the radiator, does not exceed a 50/50 mix with the antifreeze.

oldcutlass

Which Mallory Electronic and what timing settings did you use? 200 degrees with a 180 thermostat idling for an extended period is normal. What is the temp at speed?

rtanner

dude pull it out, put a stock cam in it, no need fighting it, bottom line you want stock, go stock

Firewalker

I would say wrong advice, since no one knows what the compression is on that motor. I also think he is a little nervous, since it it is a new motor and not quite what he imagined and he doesn't want anything to go wrong with it.

That cam's idle can be tamed down some, by just a few easy changes on the timing and idling rpms. Much easier and safer than trying to find the right cam and change it out.

BritishEngineering

Correct - thanks all for the input so far - engine has no time on it but unfortunately someone else built it and I don't know exactly what they did - but from what I am hearing, this cam should idle relatively smooth and I agree so am going to go through the valve adjusting process in the next day or two - hopefully they are too tight and that would mess up the idle too - will see what happens after that and keep you informed -

coppercutlass

For what its worth. I have a decently big cam in my small block. It has a pretty lopey idle and prior to this summer it had its shake and shimmy with that idle. I knew i had pushrods that where too long and i went from a roller tipped rocker arm to a full roller as well. once i got it all dialed in and the geometry was right and pushrod length was right . It still had the lopey idle but the engine idle super smooth No more jump in rpm at idle. Also fine tunning the idle mixture helped it . I dont run a vacuum adv.

olds 307 and 403

If it is the Mallory Breakerless, you can set as much or as little mechanical advance as you want as well as any curve. Set the mechanical advance with the 16 degree keys. Then set your initial around 20-22 degrees. I believe they are set up with 24 degrees of mechanical out of the box. Joe's suggestions are good as always, manifold vacuum advance may also help.

ELY442

I have the same cam in my 455 and it doesnt have a lumpy idle. I have the 1.6 full roller rockers from Mondello. My idle is set at 800 rpm with an HEI.

BritishEngineering

Sorry for the delay - it is a Mallory Unilite - and the valves were set at one full turn in from zero lash - probably not tight enough to make the difference - have not started it back up yet.....checking a few other things....

oldcutlass

The Unilite needs to run off a ballast resistor or the cars original resistance wire. It also has 24* of mechanical advance as stated above which means your initial advance timing is probably set to 12* and that cam will hate that. You need to change your mechanical advance to around 16-18 and then you can set your initial to 18-20* btdc. I know the directions say to connect your vacuum to ported but as others have said try manifold also. This will make your idle quality more tolerable.

You may need this kit to change your rate, but page 4 tells you how to adjust your advance stop.
http://static.summitracing.com/globa..._kit_29014.pdf

coppercutlass

1 full turn from zero is too much. 1/2 turn is .040 lifter preload 3/4 is 60. I run about .050 so that's 1/2 plus a 1/4 turn.

matt69olds

Thats a girlie-man cam, it should idle pretty smoothly if its tuned right. Are you sure the cam is timed installed right? If the trans has been rebuilt, what are the odds the wrong converter was installed? Maybe the converter has a stall speed too low? Are the advance weights in the distributor free to move? What kind of valvetrain was installed? If the valvetrain hasnt been converted to an adjustable setup, maybe lifter preload is screwed up? Lots of things to check before removing a good performing cam.

olds 307 and 403

Looks like the Unlite uses the same advance set up. The keys are needed or I can measure one or maybe send you an extra 14 degree key. That would give 22 timing at idle with 36 total.

distributorguy

I whole heartedly agree with those timing specs, and that's what I do all day, every day.
I also believe your lifters are set wrong. 1/2 turn will do.

More advance, a little more fuel at idle, a little faster, manifold vac to the distributor. The more advance it gets, the smoother it will be and the cooler it will run. Heat comes from lean mixture and low timing. Keep advancing the timing until you find where it runs best. If the cam is not properly degreed, you may need to run significantly more base timing to balance out improper valve timing. Could be at 30+ at idle, but this number is insignificant. Baseline will be wherever it needs to be at idle especially since you don't know if TDC is correct or where the cam is installed. Keep advancing the timing!

costpenn

X2 on this! I've had two experiences with this having engines run hot and poorly trying to hold to the factory base timing numbers - too many things "moving around" on a reman 50 year old engine. Give it all she'll take without clattering or kicking back when starting

BritishEngineering

We removed the Engle/Mondello cam and installed a Howards cam with very close to factory specs - engine runs perfect now - actually better response than the Mondello cam - idles buttery smooth - no overheating on idle - perfect in every way - thanks to all who gave advise......really appreciate it - the Mondello cam/lifters will be going on ebay soon - probably about 10 minutes run time.

oldsmobiledave

Did you index the lifters to the cam so that they can be put back on the same lobes?

Firewalker

The simplest and cheapest solution to most Olds guys needs are found here, for the 400+ cube motors.

http://highperformanceolds.com/phpbb...php?f=3&t=5201

This cam is sold by many companies, and is a $30-$40 whitebox cam under Mellings or Elgin and others. Smooth idle, high vacuum, and great power.

oldsmobiledave

That cam was in a 455 that I had briefly in my 80 GMC & is now in a friends 1970 442. It works well for street driven cars. The thing is a beast to 5500 even with only 9.25:1 compression.

Firewalker

I think it is ultimate cam, for the average BBO off the shelf. Even racing its good into the 11s, with some other work. And we like "Beasts", and if its a tame one, for me, its all the better. Cake and eat it too.

BritishEngineering

Absolutely - all marked and put in the boxes that the Howard cam came in.

Rocketbrian

For future reference, could you supply the part number of the Howard cam you purchased? What brand of lifters did you use? You must have roller rockers, based on your describing the adjusting procedures. Are they roller tip or full rollers? Brand? Did you stick with ported vacuum or go to manifold? Thanks. Brian.

BritishEngineering

Right - Howard cam part number is CL510011-12. Got it as a kit with Howards lifters. We adjusted the lash between 1/8 and 1/4 turn. We have roller tip rockers - forget the brand - will ask my son. Using ported vacuum. Carburetor never responded to adjustments with the Mondello cam - responds perfectly now - am so happy - the engine runs so strong and smooth. Thanks again for everyones help. Rich

Rocketbrian

That's great you are so happy now. Good to hear.
A final question, do you hear the roller tip rockers? I tried them on my 71 SX and the engine sounded like a sewing machine so I went back to the stock set up. Just curious on your findings.
Thanks for the info. I would be interested in the brand of roller tips when you get a chance. Cheers.

BritishEngineering

Found the paperwork - Comp 455 #1442 Rocker kit is what is installed - hope that helps - this engine is so quiet it is scary - must be something wrong. Am stunned it is so quiet and responsive.

TripDeuces

There are some inaccuracies in this thread I wanted to address.

If your studs are 3/8x16 on the adjustment end (which they most likely are) each full turn is .063 of an inch, 100/16 = .0625. So turning them one full turn of preload puts the plunger .063 down in the lifter.

Go with what the manufacture suggests for preload. Preload is designed to stop the lifter from pumping up so that the plunger doesn't hit the retaining ring and possibly lead to a lifter coming apart and puking out it's guts into your engine.

joe_padavano

No, actually it doesn't.

Assuming 1.6:1 rocker arms, one full turn of preload on the stud moves the rocker pivot point down 0.063". Since the valve end of the rocker is fixed, the pushrod end of the rocker moves down approx 0.102".

If we are talking about 5/16-18 threads then one full turn moves the pushrod end of the rocker down 0.090"

TripDeuces

You're not moving the valve end Joe.