Rebuild 356 normal engine

[fred bronson]

I have a 1962 normal with about 220000 miles on the engine. I have had the car since 1964 and I am the second owner. The crank brook in 1979 and was replaced with a used crank. I had the valves done at the same time. I have performed all of the other work on the engine. I considering rebuilding the engine. I did a compression test and No. One is 110 No. Two is 109 N. Three is 105 and N. Is 103. With these numbers is a rebuild called for?
The engine runs fine but think more hp might be nice.

[Ron LaDow]

Fred,
You can get an easy, noticeable power increase by bolting on a 1720cc P/C set and if you keep the N carbs and cam, you will not affect the longevity.
But please, pay attention to the combustion chambers. An increase in the bore increases the 'swept area' side of the C/R calc and the inevitable cut at the head sealing surface decreases the 'chamber', both serving to increase the C/R.
You won't have problems if you make sure the conical surface of the head is cut to match the bore:

If you do NOT have the conical section cut, you can end up with a secondary, peripheral 'chamber' (red) which has a very high instant C/R, along with increasing the main chamber C/R.

Here, the chamber conical section is cut to match the bore size (point "Y"), removing the peripheral chamber. Reducing Z to .04" (or less if you are willing to make sure it never gets to .02") will help your power and fuel economy.
Oh, and regardless of who you buy from, get a full-flow in the engine lube system. You will love being able to see your dipstick through the oil after 1,000 miles.

[fred bronson]

Ron
Thank you for the information.
Do you think that the crank is OK and should the heads and valves be redone. The valves begin to float around 4800 rpm. Just what is this full-flow in the engine lub system?

[Ron LaDow]

Ron
Thank you for the information.
Do you think that the crank is OK and should the heads and valves be redone. The valves begin to float around 4800 rpm. Just what is this full-flow in the engine lub system?

Fred,
Pretty sure the valves aren't floating at that RPM; you're running out of intake air funneled through the N carburettors. But the heads should certainly be checked for the condition of the sealing surface, the valves and springs need inspection. And if you fit the 1720 kit, the heads need that machining.
But the 4800RPM sign-off is a good reason your crank should be just fine; RPM kills cranks and yours has seen little of that. Have it magnafluxed to make sure there's no cracks.
However, since you have that many miles on it with the crummy stock oil filter, it may be used up from wear. The stock bypass oil filter gets 7% of the output from the oil pump. The other 93% of unfiltered, DIRTY, oil goes to your engines bearing's. My company and others sell systems to filter 100% of the oil as most all cars built after 1955 have had.
Here's a link to an article I wrote for the Registry: http://www.precisionmatters.biz/pdf/ful ... ration.pdf

[John Brooks]

Fred. Did you do a leak down, when you checked the compression?

[Neil Bardsley]

Sounds like you are happy with how your car runs but would like a bit more power? How much money are you happy to spend? It sounds like you going to do the work yourself? If so ask your what you want from your engine and how often you will use it.

Another way to get more power is to do a rolling road. You may get quite a few more years use.

[fred bronson]

John
No I did not do a leak down test. I only have a compression tester and I don't know if that can be used.

Ron sent some information and it is very interesting but I have some questions.

[David Jones]

Fred, buy a leak down tester but be aware you need over 100 psi air pressure to operate. Do not buy one that operates at low pressure such as at 30 psi. These do not work properly. There a many out there for a reasonable price such as this one.
https://www.amazon.com/Performance-Tool ... own+tester
Ask away with all your questions, remember there no dumb questions only dumb answers.
I would suggest after so many miles a complete rebuild will be in order. No matter what oil filtration system you have, some wear will have taken place and I would imagine your piston rings and valves/guides will show the most wear. Even though Ron suggests magnafluxing your crank I have personally always thought that it is a waste of time on a part that is so old still in service as a crack could develop right after the rebuild just like having a heart attack right after a physical. if you buy a new or used part it is worth the trouble to crack test if no history of the part is known.

[Ron LaDow]

Even though Ron suggests magnafluxing your crank I have personally always thought that it is a waste of time on a part that is so old still in service as a crack could develop right after the rebuild just like having a heart attack right after a physical. if you buy a new or used part it is worth the trouble to crack test if no history of the part is known.

David, I'm in agreement most always, but here, where the part has been limited to <5KRPM, it's as good a candidate as you're going to find.
But beyond that, it may well be irrelevant with that amount of miles in an un-filtered engine; check the dims before spending a penny on it.

[Jacques Lefriant]

Hi Ron
now i am of the opinion that a new crank is an option that should be considered. you would think that cranks statistically have a normal distribution failure curve. i don't think there is much in the way of records of time till failure. you could make the case that engines operating without a full flow filter are more likely to fail due to improper marginal repairs. question are you better off getting a new crank or investing in a fullflow filter after the harm/fatigue had been done?
j

[Jay Darlington]

i'm an armature engine rebuilder like you and doing a 58 1600n as we speak. here's some ideas, you can have the pistons cut to match your heads fairly simple, contact Walt at Competition Engineering. your heads with that many miles will probably need guides and possibly valves. I also replaced my springs, that turned into a nightmare. i'm not sure what type of spring you have but mine were not available but replacement spring are, but are different so I also needed new retainers. also with the heads apart I was advised by several to replace the brass intake seats. i'm not sure yours will have them they supposedly stopped somewhere in that area. one thing I noticed is that one thing leads to another.
Jay D.

[David Jones]

Jay, bronze seats are not an issue with unleaded gas, that was an issue with unhardened steel seats because they needed the lead to cushion the impact of the valve closing and preventing weld metal transfer between steel valve and steel seat and consequent valve seat recession. Aluminium heads have hardened seats as a rule so running unleaded gas is not an issue and also most all 356's do not get enough mileage put on them for valve recession to ever be a problem even if they did not have hardened seats.
Just fix the guides and replace worn valves and recut the seats.

[Jay Darlington]

there at the machine shop now probably done already I hope. the problem as I here it, is that they have a tendency to want to fall out.
Jay D.

[Jacques Lefriant]

+1 on falling out.
j

[Eric Wills]

This.