How many psi for compression test 318)
- Thread starter Rosetti
- Start date
Yes, Poly 318. Those are good engines. You can do a compression test but like someone may have mentioned, if the engine hasn't ran for a while the test results may be low and inconsistent. Get it running on all 8 cylinders and drive it for a thousand miles or so. Then your test results will be more correct.
Here's what I think the plan is going to be:
1 - I'm going to try to get the engine up and running by replacing the gas, and changing the oil out.
2 - Then, I'm going to continue with the restoration over the winter time (body work, electrical, interior, etc.).
3 - Front disc brake conversion
4 - I should be up and running by spring/summer, Then I can do a proper compression test once I've driven it around for a while. If anything is up with the engine around that time, I'll deal with it then
Best case scenario: the engine is good, and I don't have to do anything
Worst case scenario: the engine is shot, then I'll just have to be REALLY careful when taking the engine out to rebuild/replace (by removing the hood, & safeguarding the engine bay).
I don't want to overthink it, however, I'm open to suggestions as to how you guys would proceed from here.
I ask again if you've checked the condition of the various frame structures under the car, the condition of the brake lines and the brake mechanisms in each wheel, the condition of the various suspension joints and bushings. I don't believe you've said much about your familiarity or history with this car.
Regarding the poly 318, my '67 Canadian Monaco originally came with that engine, my dad was never impressed with it, we changed it out for a small-block 318 during restoration in '87, my dad said it was a big improvement. If you work on the poly you'll have to pay attention as to what parts you order, because there are some (probably many) parts that will not interchange with an LA block. There is a polysphere website where you can learn absolutely everything there is to know about that engine and the differences with the LA engine.
One big question I have is how well an original 318 poly engine will stand up to today's unleaded gas packed with ethanol. Specifically the valve seats.
Perhaps someone here has the experience of running today's gasoline on an orginal polysphere, but if not then you might have to go to the A or B body forums to ask about that. The valve seats can be "hardened" as part of an overhaul, if there still are shops that can perform it.
Also note when ordering parts online (or by phone or at a parts counter) that a lot of parts systems will automatically think you have an LA block if you are talking about a 1967 car, even in Canada. You should instead probably say that you have a 1966 Fury with 318 when looking for engine parts.
Regarding a front disk brake conversion, in my opinion you will gain absolutely nothing from it except a lighter wallet.
Regarding the poly 318, my '67 Canadian Monaco originally came with that engine, my dad was never impressed with it, we changed it out for a small-block 318 during restoration in '87, my dad said it was a big improvement. If you work on the poly you'll have to pay attention as to what parts you order, because there are some (probably many) parts that will not interchange with an LA block. There is a polysphere website where you can learn absolutely everything there is to know about that engine and the differences with the LA engine.
One big question I have is how well an original 318 poly engine will stand up to today's unleaded gas packed with ethanol. Specifically the valve seats.
Perhaps someone here has the experience of running today's gasoline on an orginal polysphere, but if not then you might have to go to the A or B body forums to ask about that. The valve seats can be "hardened" as part of an overhaul, if there still are shops that can perform it.
Also note when ordering parts online (or by phone or at a parts counter) that a lot of parts systems will automatically think you have an LA block if you are talking about a 1967 car, even in Canada. You should instead probably say that you have a 1966 Fury with 318 when looking for engine parts.
Regarding a front disk brake conversion, in my opinion you will gain absolutely nothing from it except a lighter wallet.
Last edited:
I didn't really get a chance to lift the car on the hoist as of yet. I will be doing that once the other project is out of the shop. I feel that brake lines and gas lines are not the end of the world, that was in the original plan anyway. But do you really think that the disc brakes would be a waste of time? Should I leave that until later on to see if it's even a good idea?
Curious as to why you would be opposed
You don't need to put the car on a hoist to have a look at the frame. Just get on your back with a flashlight. Where has this car been for the past 10, 20, 30 years? In a climate and humidity -controlled glass box, or in someone's shed, or in a barn or field?
Regarding the disk brakes, I said you'd gain nothing from them. You can of course put them in, so you can say the car has disk brakes, but you won't notice a difference (unless you're going to be racing the car at a track maybe). The disk brakes might even feel spongy compared to the drums.
Between 1985 and 1995, when I was in university and driving the 401 between London and Windsor, and even driving on a couple trips all the way down to Key west (trip 1) and New Oreans (trip 2), my cars were C-body Dodges with 4-wheel drum brakes. And they performed flawlessly.
Regarding the disk brakes, I said you'd gain nothing from them. You can of course put them in, so you can say the car has disk brakes, but you won't notice a difference (unless you're going to be racing the car at a track maybe). The disk brakes might even feel spongy compared to the drums.
Between 1985 and 1995, when I was in university and driving the 401 between London and Windsor, and even driving on a couple trips all the way down to Key west (trip 1) and New Oreans (trip 2), my cars were C-body Dodges with 4-wheel drum brakes. And they performed flawlessly.
Last edited:
Sounds like a plan. If all is well, you may have saved me some time, as well as like $1300.
It's been outside for the past year, and with an owner that was actually driving it before that. Other than that, no more info on the vehicle.
But it's going on the hoist in about a week or 2 anyway, so I'll keep you updated.
Thank you again for the tip on the brakes.
Jakter
Active Member
I would go with disc brakes.
Millions of cars on the road have proven them effective.
Millions of cars on the road have proven them effective.
Blusmbl
Member
I have Wilwoods front and rear on mine but I don't think I'd suggest them for a street only, daily driver type car. There aren't many good disc brake options for C bodies. Leed has a kit that from what I hear works ok, but trying to use OEM parts right now is a bit of a pain - it's hard to get reman calipers for either the early or '73 style discs the last time I checked.
So should I just stick to drums?
My 2001 RWD Dodge Ram 1500 has rear drum brakes. Millions of cars in the 50's and 60's drove billions of miles with drum brakes. Back then, there were cars that didn't have power brakes (vacuum assisted brakes) and the only way you could have that was with drum brakes. You need vacuum assist with disk brakes.
Disk brakes are easier, I'll say far easier to work on, to change the pads vs drum brakes. I'm not sure they could have put ABS on drum brakes (my Ram has ABS but only for the front disk brakes).
From a modern manufacturing and maintenance perspective, the evolution from 4-wheel drum to 4-wheel disk brakes on passenger cars is completely understandable. And yes, I believe that people put way more miles on cars today and drive them harder (and for the past 20, 30 years) vs what they did 40 - 60 years ago. If you really intend to drive this car hard and fast, every day, for the next 10 years, then you probably would see some benefit from installing front disk brakes, maybe even all-wheel brakes. But here in Ontario, the car will rust away long before your investment in disk brakes would give you any payback.
What a lot of people here aren't saying is that the biggest factor in whether disk brakes makes sense for you is - the size of the engine. The 318 isin't going to throw that car around to the extent that disk brakes will make a difference.
Disk brakes are easier, I'll say far easier to work on, to change the pads vs drum brakes. I'm not sure they could have put ABS on drum brakes (my Ram has ABS but only for the front disk brakes).
From a modern manufacturing and maintenance perspective, the evolution from 4-wheel drum to 4-wheel disk brakes on passenger cars is completely understandable. And yes, I believe that people put way more miles on cars today and drive them harder (and for the past 20, 30 years) vs what they did 40 - 60 years ago. If you really intend to drive this car hard and fast, every day, for the next 10 years, then you probably would see some benefit from installing front disk brakes, maybe even all-wheel brakes. But here in Ontario, the car will rust away long before your investment in disk brakes would give you any payback.
What a lot of people here aren't saying is that the biggest factor in whether disk brakes makes sense for you is - the size of the engine. The 318 isin't going to throw that car around to the extent that disk brakes will make a difference.
This is the general feeling that I've been getting from people in this forum. This is in no way a race car, so in my mind, it was "disc brakes = safety". It's nice to have a different perspective on things, and this is actually good news for me, because spending $1,300 to $1,500 on the conversion kit when it's not really needed, would be money well spent on other aspects of the build.
I'll stick with the drums in the beginning, and if I feel that discs would be better, only then would I make the switch.
Thank you so much for your insight.
Blusmbl
Member
It depends on your driving style and how much you’re going to use it in traffic, honestly.
I've had lots of vehicles with 4 wheel drums, and for normal light cruising they were fine, same for single instance panic stops. Drums don't dissipate heat as well as discs do though, so repeated hard stops they will fade.
My '68 300 would be fine when it was cold, but after an hour drive in stop and go rush hour traffic the brakes would have noticable fade and not work well. I've only ever had that happen with discs during extreme trailer tow scenarios, never in regular traffic like I've experienced with drums.
I've had lots of vehicles with 4 wheel drums, and for normal light cruising they were fine, same for single instance panic stops. Drums don't dissipate heat as well as discs do though, so repeated hard stops they will fade.
My '68 300 would be fine when it was cold, but after an hour drive in stop and go rush hour traffic the brakes would have noticable fade and not work well. I've only ever had that happen with discs during extreme trailer tow scenarios, never in regular traffic like I've experienced with drums.
Hey John.
I did the compression test, and it is as follows:
1: 50. .2: 75
3: 110. .4: 100
5: 75. .6: 110
7: 110. .8: 50
Please note, I still haven't driven it at all. It was parked for at LEAST one year on a field, then at the back of our shop, and then I just pushed it in, threw in a fresh battery, and did the test.
I don't know if driving it around for a while will change the results at all, but I'm at a point where I have to decide to continue the restoration, or stop everything and deal with the engine.
I'd appreciate whatever info you can give me.
Thanks in advance
Blusmbl
Member
If it hasn't been run in a long time it likely had rust on multiple cylinders, this is totally normal for vehicles in storage. I'd run it and get it warm first before doing the compression check. If the numbers are still as bad as what you just showed it could use rings at a minimum, but I'd run the engine for a bit before writing it off.
i would drive it a bit and check again. #1 and #8 are really low, but some miles to knock the rust off could be the answer.
That's kind of the plan. I just wanted to check with you first. I appreciate the feedback, and I'll let you know how it goes.
Thank you again for the quick response, and the great info.
65sporty
Old Man with a Hat
If you still have the plugs out, I would put some oil or penetrating oil down in the cylinders. Especially 1,2,5 & 8
Similar threads
