Technical Chevy 181 4 Banger - Timing Info

Hey Everyone. I've got a new (for me) Chevy 181 in a '28 Model A roadster. I'm trying to track down timing information for it. It also has Clifford Intake 6=8.

Can someone give me timing?
How about manifold vacuum (approx 20"?)

One more question... I'd like to mount an oil gauge. Does anyone know where the tap off the engine is for this? Thanks!

Image by dicer2000 posted Jul 6, 2016 at 9:59 AM

Image by dicer2000 posted Jul 6, 2016 at 9:59 AM

 

Vacuum should be the same as anything else when judging where it should be. In sure there's some variation but it's overall a standard measurement across the board.

No help on the vague timing question. Is it running funny?

 

^^^^^ To further add. OE spec's are only good to ball park anymore. Timing today on older engines is by the ear and vacuum basically. Then make road adjustments in + or - 2* until best performance is achieved.

 

To answer your question directly > https://www.perfprotech.com/blog/articles/mercruiser-30l-engine-specifications#

 

Thanks Tim. Yes, it's running very rough. To give you an idea, when I remove spark plug wires (one at a time) while running, I don't see much appreciable change in how it's running. However, I think all four are firing (I'm getting a strong spark).

I've seen online it's supposed to be at 1 deg BTDC, 8 BTDC, and also 2 ATDC. So, I don't know what is right. It runs terrible at 1 and better at 8.

However, timing isn't the only problem, I believe. It has a Weber carb that wasn't ran for a while that I think needs a rebuild. Also, there is a cracked vent hole gasket that leads to the vacuum port. I think it's probably letting in a lot of air.

Anything else you recommend me checking?

 

Oil pressure outlet is just a couple of inches behind the distributor. Only one that I know of.

 

Points or electronic? If points when was the last time you changed or adjusted them?

If electronic could be wires as much as timing. No reason that one would loose time. Usually running rough is not timing.

 

Ok 3Q - I think I see what you are talking about. Is this it on the left? Note the distributor on the right. Thanks!

Image by dicer2000 posted Jul 6, 2016 at 11:15 AM

 

Yeah a vacuum leak you can't see will play he'll let alone one you can visibly see. Get that sealed up even if it's in a way that's temporary.

 

It is electronic. Will add the wires to check onto my list. Thanks.

 

What are the characteristics of it running outside of "rough"

Here are some questions you can answer to help speed up the trouble shooting process.

How does it start? Cold and hot
How does it idle?
How does it run just cruising at 25?
How does it run at higher speeds?
How does it run under heavy exceleration?
How does it run when climbing a hill?
Does it run hot or over heat?

Answer these discriptivly not just "bad"

Also if it will run and idle long enough you can try spraying some starting fluid or other combustible spray lightly around the intake manifold and carb to help find additional vacuum leaks even a lose carb base bolt will leak enough to get you scratching your head. It's as good of place to start as any.

 

Saw your post, had with them back in the 1970s and 1980, for street and drag racing, the motor you got is the Mecruiser 140, 181ci in boats and industrial only. There's also the Mercuiser 120 which is 153ci that was in early novas, boats and industrial stuffs. They were fun little motors with some power in them. Here's some info i had saved. The 181ci timing at idle should be at 6 degree (600-800 rpm) with vacuum line disconnected. Good luck.

 

Guess the outlet is more like a foot back from dist.

 

If you know the brand you can find the OHM value of the wires. Pretty easy to pull them and check resistance with an OHM meter.

 

Ok, Porkn - I had a conference call and was able to measure resistance of the wires while everyone else was talking... Taylor Spiro Pro 8mm @ 350 Ohms/ft. All tested very well. So, that's off the list. Thanks

 

How does it start? Cold and hot
Starts great both hot & cold. I have to keep my foot on it while it's cold. The choke must not be working right. Once it's warm, it will idle, but not well.

How does it idle?
Idles extremely rough - I'll try to attach a video. It won't idle until warm and then shakes pretty heavily.

How does it run just cruising at 25?
It runs pretty well. I do hear it miss every once in a while.

How does it run at higher speeds?
Again, it runs pretty well with the occasional miss.

How does it run under heavy acceleration?
Actually, it seems to do pretty well. I don't know that I'm getting all the power out of it. However, I may be -- it's just too new of an engine for me to know.

How does it run when climbing a hill?
Again, pretty well.

Does it run hot or over heat?
No, it does not seem to be hot.

One more for you... it does often auto-diesel when I try to turn it off. I have to let out the clutch with the brake on to get it to turn off. I've got premium gas in it and it still doesn't help.

I'll try the leak test a little later. Thanks guys!

 

I love stacked question's. In all fairness, repairing problems can be like watching a magician pulling hankies from his mouth. It seems to never end. Dicer2000 your in good hands. You'll be squared away in no time.

 

Sounds like idle circuit (also control's low speed) of the carb. is dirty. What does everyone else say ?

 

It would make enough since given what we have so far. Another idea would be the check the fuel filters. If he bought this as a running vehicle is possible that some shit has found its way in and could act similar.

A known vacuum leak isn't helping but I think we are getting closer.

Question, if the car is attempting to idle parked does it clear out and run better when you throttle it?

 

Is this the same motor that you had the head work done to?

 

Here is a video of the start and a few minutes of idle.

 

My bad, I missed that one. Good thing it's in the same area/part though.

 

Thanks for the video, dang that's a slick looking car from what I can see!

Could your idle be set to low? It does kinda seem fuel related given the answers you've given. Lack of fuel at idle could be a dirty carb, poorly set carb or partially blocked filter.

The dieseling could be a vacuum leak, if it's not getting hot, starts fine and runs fine over all I lean away from it being timing.

 

For the moment this doesn't seem to be an issue. Runs good under load, and good on hills.

 

To be honest, I'm taking over from a guy who did an amazing job. Another car had become his passion, so I am lucky enough to get to go forward from his work.

 

Not that it would affect your idle but any chance you have a 153 (or at least a 153 head)? Attached is the picture of the manifold on my 153 and it looks a lot like yours. One problem I noticed when I went from the stock 1 barrel cast iron manifold to the Clifford manifold I no longer had hot exhaust gas directed to the bottom of the manifold to help atomize the gasoline and it didn't run as well. I must admit I have never seen a 181 manifold, didn't even know that they made them.

 

Wow, that looks just like it. From what I understand the 181 is an newer conception of the 153. It's almost the same engine except for just a little bigger bore. But obviously, I'm no expert.

One thing i dont like is I can't have my manifold heater like in the model a engine!

 

Do you have a 181, or 153? That intake won't fit the 8 port 181 head. EDIT Charlie beat me to it. Is it still a boat cam or is it a fresh automotive cam? Is valve train all adjusted properly? Like the others said, fix the known vacuum leaks, then progress to other possibilities.

 

181 is bigger bore and stroke 4.0x 3.6, vs 3.875x3.25. 181 is 8 port head, 153 has siamesed intake ports.

 

The 153 was introduced in the Chevy II in 1962. It continued as an optional engine in the Chevy II through 1970. I didn't follow the industrial engines but in the early seventies you could get a 153 or 181 in your Mercruiser Marine application. I assume the industrial version tracked this introduction date. The 153 head will bolt onto a 181 block and this may be what you have. The picture shows the two heads.

Charlie Stephens