Author Topic: 1937 346 basic tests  (Read 335 times)

Offline Steve Rinaldo

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1937 346 basic tests
« on: June 18, 2017, 08:01:25 AM »
I have been doing some engine tests on my 1937-60 and I would like to get have some opinions on the results So here goes.

1. Compression test- I did a compression test on a warm engine and here's what I got. Dry all were around 90 and the wet test showed 95. The shop manual spec. is 100-105. I don't think this is an issue. Thoughts?

2. Vacuum test- At hot idle the gauge shows about 15 inches. The wiper hose was pinched off. I can get the reading to increase to 18 by advancing the ignition timing. Thoughts?

ignition timing- When using a timing light should I still us the IGA mark with the engine a slow idle and the distributor advance line pinched off?  I had a Chevy that the damper ring with the timing marks slipped causing weird timing readings. Does this happen on these engines?

Thanks, Steve

Offline Steve Passmore

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Re: 1937 346 basic tests
« Reply #1 on: June 18, 2017, 03:31:47 PM »
That's not bad if it's still the original engine. I think it's more important to have them all within 10%  I have engines running well on 90psi

You should still work to the timing marks IGN

I have never heard of a problem with the crank pulley marks on these engines.
Steve

Offline Steve Rinaldo

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Re: 1937 346 basic tests
« Reply #2 on: June 18, 2017, 03:48:29 PM »
Thanks

Offline Brad Ipsen CLC #737

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Re: 1937 346 basic tests
« Reply #3 on: June 18, 2017, 04:01:49 PM »
There is no rubber in the vibration damper.  All is metal to metal so very unlikely that the marks would ever move in relation to the keyway.
Brad Ipsen
1940 Cadillac 60S
1938 Cadillac 9039
1940 Cadillac 6267
1940 LaSalle 5227
1949 Cadillac 6237X

Offline Carl Fielding

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Re: 1937 346 basic tests
« Reply #4 on: June 18, 2017, 09:29:35 PM »
"...................distributor advance line pinched off.." ? I am wrong about something almost every day. Are you referring to vacuum advance ? I do need to know if I am wrong , but I didn't think vac. adv. came in until '40 for Cadillac. What year is your 1937 346 engine ? Thank you , Carl

Offline Steve Rinaldo

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Re: 1937 346 basic tests
« Reply #5 on: June 19, 2017, 06:07:06 AM »
It is the matching engine. This is the distributor that was on the car when I got it about 15 years ago. If it is a later distributor should the vacuum advance hose be connected to manifold vacuum? the fitting on the carb. shows 2 at base idle which leads me to believe it is ported vacuum. What do you think?

Offline Steve Passmore

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Re: 1937 346 basic tests
« Reply #6 on: June 19, 2017, 09:59:44 AM »
Someone fitted a later distributor. Happens a lot but you need the later carb base. It attaches just below the idle screws Steve.
Steve

Offline jackworstell

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Re: 1937 346 basic tests
« Reply #7 on: June 19, 2017, 12:06:04 PM »
Steve P

If a vacuum advance type distributor has been substituted....is it  OK to simpiy use straight intake manifold vacuum for it....ie  tee-off of the vacuum fitting  which goes  the fuel pump and then onto the vacuum wipers ?

Jack Worstell      #7558      jlwmaster@aol.com

Offline Steve Passmore

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Re: 1937 346 basic tests
« Reply #8 on: June 19, 2017, 01:19:06 PM »
I honestly don't know Jack. Never seen it done and don't know why anyone would want to. The pipe and fittings are tiny compared to the wiper pipes so that would be an issue. Easier to pipe it where it should go.
Steve

Offline Steve Rinaldo

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Re: 1937 346 basic tests
« Reply #9 on: June 20, 2017, 11:28:04 AM »
Here is a follow-up to my post. I teed into the line that went to Wipers which is manifold vacuum and ran a line to the vac. advance. I removed the distributor and reset the points to .015 and bench checked that the mechanical and vacuum advance operation. They are working fine. I retimed the engine using the IGN marks at very slow idle with the vac. advance removed.   I checked both the vac. and Mech. advance while running they are working fine. I checked the amount of vacuum at the advance hose and was reading about 19 inches. This proves to me that port on the carb is a ported vacuum pickup.

The engine starts very easy both hot and cold. It also idles very smooth with a setting of about 500 rpm.

So I learned some things in this exercise and I hope this helps some other guys. Steve

Offline DaveZ

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Re: 1937 346 basic tests
« Reply #10 on: June 20, 2017, 04:35:52 PM »
Steves:-)
I know you guys will know this....
Where does the positive ground bolt to on the 37's? Is it a cable or ground strap? Many thanks, Dave Z
Regards,
David Zitzmann
1932 345B
1940 5219

Offline jackworstell

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Re: 1937 346 basic tests
« Reply #11 on: June 20, 2017, 05:10:10 PM »
Steve R     pls clarify...why do you think the carb port     is ported vacuum and not straight manifold vacuum ??

Jack Worstell

Offline Steve Passmore

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Re: 1937 346 basic tests
« Reply #12 on: June 20, 2017, 05:12:06 PM »
Mine was a ground strap straight to the chassis, but who knows if it was original?
Steve

Offline Steve Rinaldo

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Re: 1937 346 basic tests
« Reply #13 on: June 20, 2017, 07:35:43 PM »
Manifold Vac. is below the throttle blades at idle and reads about 18-21 inches. Ported vacuum is above the throttle at idle and strength is directly related to the port position in the carburetor bore. It generally reads about 5-15 inches, again related to the throttle blade position. The is one more named venturi vacuum and it is picked up at the restriction in the carb bore. It is strongest at wide open throttle and only reaches about 5 inches Steve.

Offline Brad Ipsen CLC #737

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Re: 1937 346 basic tests
« Reply #14 on: June 20, 2017, 09:48:20 PM »
Without going into all of the exact engineering that goes into the port location for vacuum advance which I may not know completely correctly the easy answer is not to question Cadillac engineers.  It took a lot more cost and effort on their part to locate that port exactly right in the carb than just tapping into the intake manifold.  There must be a good reason for it to be where it is. 
Brad Ipsen
1940 Cadillac 60S
1938 Cadillac 9039
1940 Cadillac 6267
1940 LaSalle 5227
1949 Cadillac 6237X

Offline Steve Passmore

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Re: 1937 346 basic tests
« Reply #15 on: June 21, 2017, 06:35:34 AM »
Without going into all of the exact engineering that goes into the port location for vacuum advance which I may not know completely correctly the easy answer is not to question Cadillac engineers.  It took a lot more cost and effort on their part to locate that port exactly right in the carb than just tapping into the intake manifold.  There must be a good reason for it to be where it is.

Agreed. otherwise, why would they bother?
Steve