56 Mechanical cam with a Hydro... does it work??

EssexAdv

I really need to ask... I have a "56 Mechanical" cam I bought from Clifford in my 54 with Hydro-matic.  I hate the stupid thing.  You can't pull it to an idle without cam related rough idle.  I spoke to a friend of mine, who is much more knowledgeable in these things than am I, and he said the had the same problem with his similar set-up.  He would up degree-ing the cam and found that to get a proper idle he had to retard the cam 4 degrees. 

I have never been a profession engine builder as was he, so I valued his opinion but never did the work on my motor.

So the question is, ahs anybody had a good experience with a Hydro and the 56 cam?

I really am tired of putting the car in natural at every red light and would love to fix it... new cam, degree-ing the cam.. what-ever

Any help will be appreciated

Thanks

Lew

53jetman

Had a similar problem with my '54 Hornet, and found that most of my problem was idle set too high.  Someone had set the idle at 550 RPM, and found the transmission comes down to a proper stop without shifting into neutral with idle set at 450 RPM.

EssexAdv

Thanks Jerry.  I tried that and all it does is make the stupid thing stall.... oh well, another try, another failure.

(I've been at this for a long time, you'd think I would get used to that!)

Lew

Lee ODell

Lew,
The 55-56 engines with a little bigger cam calls for total 7.5 degree vacuum advance (3 3/4 distributor degree). That may help some. Also, with a bigger cam you may need to advance the initial timing about 5 degrees. Then readjust and balance carbs and readjust hydro pressure rod.

Then again you may have already tried that.
Lee O'Dell

EssexAdv

Thanks Lee, the car acts like it has too much advance.  If I get an acceptable, but not smooth idle, it pings on acceleration.  If I get rid of the ping, it is so week it can't pull the hat off my head.   I'm thinking the cam might be to advanced for the motor.  The car has more than enough bore and valve relief to use the cam.   Compression isn't too bad.  It has a stock 308 head with a slight clean up mill on it. Still within specs.

I'll retry your suggestion, reset it to measurable advance and see what happens

Thanks

Lew

Lew

Lee ODell

I reread your initial post and didn't read what grade gas you are using. You may need to be using premium grade gas if it is pinging.

I have not seen a Clifford catalog for many years. But didn't they have several mechanical cams. Cam grinders usually have different grinds for stick shift cars and for automatic cars. Did you order a camshaft for a automatic car?

Camshaft degrees and ignition timing degrees are two different subjects. Each has a different function. Camshaft degrees has to do with when the cam lobes lift and lowers the valves in relation to the position of the crankshaft.
Ignition timing has to do with when the spark plug ignites the fuel in degrees before crankshaft and pistons arrive at top dead center.

Your camshaft may have to much camshaft duration (both intake and exhaust valves are both open to long at the same time). This hurts engine low RPM operation. Or the camshaft may be installed incorrectly causing the valve to be opening and closing at the wrong time.

I would try the highest grade gas and adjust timing where it should be with vacuum advance disconnected and vacuum line taped closed, then readjust carbs. and balance twin H. May have to readjust everything 2 or 3 times before everything is correct. Then adjust carburetor linkage to transmission.

Also, check trouble shooting problems in Hudson Mechanical Procedure Manual or Chilton Manual or Mortor's Manual. The trouble shooting section will give areas to look for other factors that may be contributing to your problem. Such as vacuum leaks, float level, ect. ect... If everything checks out OK and you were happy with previous stop and go driving you will be happier with a lesser performance camshaft., still giving you more performance without and still keeping low end torque performance.

The highest HORSEPOWER PERFORMANCE CAMSHAFT was designed for pedal to the metal and not for stop and go driving.

I wish you good luck. Try premium gas and go from there.
Lee O'Dell

Lee ODell

Lew

I finely found Clifford's 3 camshafts for Hudson. Which one of these camshafts do you have in your engine?

H117 2000 - 4300 power band, 2300 RPM power span
H116 3200 - 4800 power band, 1600 RPM power span
H118 3500 - 5200 power band, 1700 RPM power span

If you put "camshaft comparison" in SEARCH at upper right hand corner of screen, you will find a lot of discussions about camshaft choices. Just remember, the greater the horsepower increases, the greater the off idle and lower RPM performance loss.

I agree Randy Maas would be a good choice for advice.

Lee O'Dell

EssexAdv

to update. I spoke to Randy. We discussed the cam and he came up with a different idea. He says the problem with this cam is the idle fuel mixture on then54 twin-h carbs. He said to re- adjust the idle mixture and if that didn't work, try enlarging the idle jet. I re-adjusted the idle mixture and got it better-still not right. I'll give the re-bore of the jet a shot when I get a chance

BillUSN1

Just to add my .02

A larger cam will need more base timing as mentioned.

The problem as you found is if you just grab the distr and adv the base timing you are also adjusting the entire timing curve.

Then you ping.

So you have 2 options.

1. recurve the distr to limit the mechanical adv the same amount you want to add to the base timing.

That way the total timing will remain the same.

ex:

base 0* + 14*mech = 14* at WOT No vacuum adv at WOT

base 5* + 9*mech = 14* at WOT No vacuum adv at WOT

2. Change from ported vacuum adv to a manifold vacuum adv connection.

Vacuum adv is only used at part throttle to help with driveabilty.

But by using manifold vacuum on the adv it will apply the adv at idle and then drop as the throttle opens and continue to operate exactly the same as when connected to ported vacuum.

Ex: base timing 0* + vacuum adv 6* = 6* at idle

then at WOT there is no vacuum so you only have the 14* mech at WOT.

Now keep in mind that you will need to reset your idle speed once you connect the vacuum adv to manifold vacuum. and may need to adjust the mixture screws.

For me, I have the advantage of being able to custom design my timing curve and fuel table with my EFI conversion.

So I can adapt it and custom tune to each engine it is installed on.

I have found a big difference in how much timing these engine can use just from old tired engines to a new fresh rebuild with good compression

HTH..

maasfhcenturylinknet

Lew,

How many thousands did your bore the idle jets?  You have to feed it before timing it correctly.

Randy

EssexAdv

Randy. Haven't gotten to it yet. But I should be able to this fall/wi tear. As usual, I ran into other more pressing Hudson issues.