Minimum bore amount? Max valve size?

[350kmileford]

I have a dual bolt pattern 200 block. It is currently .040 over, with low miles. Is it alright to bore it .010 more to .050"? I'd prefer not to go all the way to .060".'

What are the largest diameter valves I can use on a '66 head? Can it accept enough machining to hold a 1.84 intake and 1.56 exhaust (the biggest that classic inlines sells)? If the head will accept the larger valves, is that route reasonable considering
that year head had the smaller volume intake? I plan on going with a larger cam, direct mount 2v carb, headers, etc.

 

[MPGmustang]

Howdy,
From what I have recently learned from Mike, and my research here on the forum, is that the cast iron heads can only go up to 1.75 intake and 1.5 exhaust valves.
I can see a potential increase in air Velocity, as the log is smaller, (Velocity is more important I believe to an extent... don't know much about it tho) but I think you would make more power with the larger log, IMO.

I think if your going direct mount, you would want to find a larger log.

don't know much about the bore...

Richard

 

[bubba22349]

I usally like to stay .040 as max for a street car (they are thin wall) some blocks will go .060 ok only way to know is to have a sonic check. You said its a low miles at .040 is it worn in the bores? If not why bore it you could just hone it a little and install a new set of pistions.

 

[350kmileford]

I don't believe it was worn too bad. The block has been buried in the garage for ages now, I'd need to check it out again. I just figured that if I'm gonna do a rebuild might as well do it right. But, if it is acceptable to just re-hone it I might do it.
I might not have access to a larger log head... Should I not waste my time with the smaller one then? I NEED to rebuild the engine soon, and I want more power. As usual, funds are limited, but I will fork over the money to have an old head flow better if it will be worth it.

 

[Lazy JW]

..... I NEED to rebuild the engine soon, and I want more power. As usual, funds are limited.......

Mild pocket porting doesn't cost much and will definitely help, also a proper three-angle valve job; don't forget the 30º backcut on the valves and pay careful attention to the compression. A mild cam will work nicely with this sort of rebuild.

Never bore a block that doesn't need it; far too often we waste money and iron boring engines "just because".
Joe

 

[350kmileford]

Ok I will reconsider the engine bore. I had asked about it here before but never really got an answer.

As far as the carb mount goes, will there be any sort of clearance issues? Any reason I shouldn't do it on the smaller head?

 

[bubba22349]

On the head if you have a nice small log head you could use it for sure. The mod's that Lazy JW suggested I will second if you need to replace valves than it won't be that much difference in cost to go with the larger valves, at this point with a valve job and surface and the pocket porting etc. So now should you look for the late big log head or not? If you could find one for a good price you could gain a little more power for the extra cost of the core head. Rebuilding labor and parts are going to be about the same for either head on average if you need to add hard seats in the early head than that may cost as much as the late core head. Decisions decisions

 

[350kmileford]

If these pictures will help:
http://i47.tinypic.com/24fagqg.jpg
http://i46.tinypic.com/novuyo.jpg
http://i46.tinypic.com/2hxagp1.jpg
http://i45.tinypic.com/izuvck.jpg
http://i50.tinypic.com/nzi13s.jpg
The ridge at the top of the cylinder doesn't really stick out, just feels a little rough. Feels like it could be easily scuffed out.
My biggest concern is if I want to run new rings, do I need to rehone? How critical is the honing angle and amount that I hone? (if I do it myself)

 

[bubba22349]

Looks real good to me if you don't have a ridge that catches your finger nail its great. Bores still show the original cross hatch from when it was honed. If you have a ball type glaze breaker and a 3/8 to 1/2 drill some solvent clean them up and wash the rest of the block with Tide or solvent dry with air gun and assemble it. Are the pistons still with it?

 

[350kmileford]

Yea they are. They do have a dish in them though, I need to figure out what the dish volume is.
Again, new rings or not? I don't know if the last rebuild was an economy build or if quality parts (rings) were used.

 

[bubba22349]

Is this a complete engine? Well on the rings if they are still good condition they can be used over again bearings also if they measure within spec and show no signs of damage. However if you don't know what they are or what to look for, you will need to check to see if are cast or moly. How much use did they have? You would need to look close at the face. Do you have some pictures? I have been using a moly ring instead of cast for many many years they are long lasting. The use of moly rings has been fairly standard even rebuilder jobber engines. A cast ring will work pretty well if the cylinders show wear or have taper in bores yours look far better than that . Do you have all the bearing and a fresh gasket set yet? Also with a re-ring kit price being so inexpensive you sometimes pay more buying the individual parts separately even if you don't buy the rings.

 

[350kmileford]

The rings should still be on all the cylinders. I chucked all the bearings a while back, aside from the cam bearings which are still installed.

All I knew about the engine before I disassembled it a few years backs is that it was a 'low miles' engine but it did smoke. I did not get the head that came with the engine. I figured the smoke was probably from the head but I wanted to tear it down for inspection to be safe.

 

[bubba22349]

All I knew about the engine before I disassembled it a few years backs is that it was a 'low miles' engine but it did smoke. I did not get the head that came with the engine. I figured the smoke was probably from the head but I wanted to tear it down for inspection to be safe

That creates a problem since you don't have the head to check so you at most have a 50/ 50 chance if the rings and piston go back in the same holes that it would work. Ok that said I have seen many good overhauled or rebuilt short blocks were someone bolted a worn out head on top of it and you have the failure you described! If you want to try it yourself then you are only going to be out your time and some gaskets as those bores do look very good in the picture make sure to stager the ring gaps the right way though! Do you have a way to measure bores and pistons? If I were doing it for a paying customer then I would need to get a fresh moly ring set or a re-ring kit to raise the odds.

 

[Lazy JW]

Given the situation you have described I would put fresh rings in. They have been run in an engine which smoked and it is difficult to evaluate rings even under good conditions. Check carefully for excessive side clearance between the rings and lands, if that looks ok then a fresh set of rings should fix it up nicely.
Joe

 

[350kmileford]

I just realized I don't absolutely need to use the spare block I have. I might just rebuild a head, and then install it and a new cam on the existing engine (in car) Assuming the block passes visual inspection, that is.

Is there anything stopping me from swapping cams while the engine is in the car? Would I need to pull all bodywork off the front of the car? I just want to do it as quickly as possible since the car is my daily driver. I will risk not milling the block.

 

[bubba22349]

Lots of cams have been put in with block installed in the car you used to be able to tell the racers they would have a hole cut in grill enough to side cam in. At a min. you need to pull it down to the short block to fix the head, radiator, grill the entire front drive pulleys, damper, pan, front cover etc. Depending on your skill level and tools and equipment by the time you do all that it may be faster to just pull engine. Personally I hate working on them in the car beyond pulling the head.

 

[Lazy JW]

...... I just want to do it as quickly as possible since the car is my daily driver......

This the key phrase. Do you have an alternate plan for backup transportation if you run into trouble after the head is pulled?

 

[Anlushac11]

You can install larger valves, Classic Inlines sells up to a 1.84" intake and 1.56" exhaust.

Due to the poor flowing ports in the log head installing larger valves entails increaed costs for minimal gain and it reduces low end throttle response.

Most people have been running 1.75" intake with backcut and 1.50" exhaust. This seems to give the best balance of improved flow with good throttle response.

There is some debate as to whether a exhaust port divider does any good. Most people say its a pain to install for minimal gain. The purpose is to divide and smooth out exhaust flow in the center two exhaust ports.

IMHO ANYTHING that helps exhaust flow on the log head is a must have.

 

[JackFish]

...... I just want to do it as quickly as possible since the car is my daily driver......

This the key phrase. Do you have an alternate plan for backup transportation if you run into trouble after the head is pulled?

+1. DON'T get into a driveway cam swap if you really need the car and it's running OK.
I did that and ended up having to buy another car. Shit happens.

 

[Anlushac11]

If I recall correctly one of Mr. Murphy's laws was that "Anything that can go wrong will go wrong, usually when you are least prepared for it. "