Condition Of My Motor

[st66ng]

Hi everyone,

I just joined this site and think it is great there are so many people devoted to keeping these inline sixes running.

I have a 1966 Mustang with a 200ci that needs a little TLC.

I had a plug fouling issue on 2 of the cylinders and found out that both those cylinders had broken valve seals that must have been leaking oil into the cylinder.

As of now I have the head removed and I am trying to figure out how far I need to go with motor. The car is driven in Southern Ontario, Canada so it is stored for the winter and driven occasionally the rest of the year. It doesn't need to be a performance motor, though it would be nice. It just is not in the budget at this point.

I did a compression test on the motor and here are the results:

#1 152 psi
#2 160 psi
#3 165 psi
#4 175 psi
#5 160 psi
#6 165 psi

I have the cylinders numbers from the front of the car to the back.

I was able to get some measurements of the bore. According to the information I found the original bore was 3.680"

I measured all cylinder bores approximately 1 1/2" down and measured them twice 90 degrees to each other and all measurements were between 3.681"-3.683" so that seems pretty good.
I measured the cylinder with the biggest ridge just below the ridge or about a 1/2" down and it measured 3.686"

Are these numbers okay?

Everything in the motor appears to be stock, I was told the motor was rebuilt back around 1990 but I don't know the details of the rebuild.

I would like to know what you think I should do to the motor while I have it all apart, I have all winter to work on it so down time is not an issue.

I am looking for a reliable motor at this point that will hopefully not need any work for a long time if I do it right.

Would recommend a total engine rebuild or would that be going to far?
Could I just do the head or should the bottom end be done as well?

Thanks in advance,

Jay

 

[CoupeBoy]

If Iwere you I'd fix the head, *maybe* upgrade the cam, but I'd leave the rest of that block alone! Normally I'm lucky if I get 130-140 per cylinder. Externally I'd upgrade the ignition to a Duraspark II or DUI.

that block condition sounds great

-ron

 

[falcon fanatic]

I second coupe boy's analysis, except that I would definitely do the cam since you have the head off, and, since the head is in the shop, do a little head milling with the aim of boosting the compression a tad to complement the cam. The *maybe* for me would be spending a couple hundred extra on some porting work in the bowls (or do it yourself, it's easy if you have the tools)

 

[aahsac]

If you aren't going to be going for maximum performance the I wouldn't go through the expense of having it professionally ported. You can ask your machinist to back cut the intake valves. That should give you some better flow at low lift.
You really should cc the head though. You said it was rebuilt before, you didn't mention what head gasket was on it when you took it apart. You need to know if the head was milled before so you'll know how much you need to mill it. If you old head gasket is a steelie then you know that a pretty good cut is required just to maintain compression.

 

[fordconvert]

I would CC things. Even if you do it yourself it will give you an idea what you are going to end up compression wise. You never know what piston combo you have in there or what has been done over the years. I did it with a syringe from the dollar store and some ATF. I got within 2 cc's of what the machine shop got when they did it with their fancy tools. Glad I did because I have some non standard pistons in my otherwise good bottom end. With 'regular' later heads I would have got 6:1 compression. I ended up having the original (66) modified head worked on to maintain 8.2:1. I would have been guessing a long time what was wrong if I just threw on another head.

With my project I ended up not touching the bottom end. I bought 3 other used motors and used the best looking oil pump and cam with new lifters. Head got properly rebuilt by a good shop. Its been running great for almost seasons now, around 4000 miles.

 

[rbohm]

8) i third ron's opinion. leave the block alone, fix the valve seals, maybe upgrade the cam if you like.

 

[CoupeBoy]

I do have to agree with the others, you should get the head combustion chambers checked out and measured. Then find the compressed thickness of your headgasket that you are going to use for re-assembly, or post it's brand/part number somebody on here can tell you the compressed thickness.

A couple other measurements then truck over the the Compression Calculator on the Schjeldahl's website, who also wrote the Falcon 6 Performance Handbook (which I recommend). Then you can check to see how much to shave off the head to achieve that perfect compression ratio and what you should be able to expect for engine output.

-ron

 

[Lazy JW]

.....

..... doesn't need to be a performance motor, though it would be nice. It just is not in the budget at this point....

Howdy and WELCOME to the forum!

As noted above, higher performance isn't in the budget for now but reliability is still important. With that in mind:

A. Those compression numbers are already pretty good so it would appear that the compression ratio wasn't adversely affected during the reported "rebuild". It certainly won't hurt to CC the chambers but with those compression results it's just gonna tell you that all is well.

B. If you think an upgraded cam is in your future, go ahead and do it now. It will cost $200+ for a cam and lifters, plus a timing set and gaskets. These things always cost more than you think by the time it's all done. Plan the budget carefully before starting this project.
C. I would NOT remove any pistons but I would definitely check out the main and rod bearings. It isn't difficult or very expensive to roll in a set of bearings if the clearances are a bit loose.

D. If you have the time, inclination, and access to a die grinder a little bit of mild port work will pay nice dividends and doesn't cost much at all. Do this BEFORE getting any valve job done, then have the intakes back cut 30º. While you are doing the porting take a few minutes to clean the obvious barnacles out of the exhaust manifold.

Have fun,
Joe

 

[st66ng]

Thanks for all the replies,

My biggest concern was the ridge at the top of the motor, and if I left the old rings in there how much longer they would last. I would hate to do the head and then have to do the block shortly after, but I guess its been working fine for this long so far.

I am going to think this through before I get started so I will continue to read up and this forum and consider your recommendations.

I do have a die grinder and have used them for many years as a Tool and Die Maker so I might consider doing some minor head work before the valve job.

That compression calculator posted by coupeboy is pretty cool, I might take some measurements and put them in there and see where I am.

Thanks for the advice

 

[Lazy JW]

....

I do have a die grinder and have used them for many years as a Tool and Die Maker ....

Reckon maybe you should be the one giving lessons then ,eh? 8)
Joe

 

[st66ng]

....

I do have a die grinder and have used them for many years as a Tool and Die Maker ....

Reckon maybe you should be the one giving lessons then ,eh? 8)
Joe

I wouldn't go that far, I have not done any porting on motors and I am sure there is a specific art to that. I will have to do some research before I start hacking my head away. Some areas of the casting look kinda thin to be removing much material.

 

[Lazy JW]

Check out this thread:

http://fordsix.com/forum/viewtopic.php?t=2962

And this:

http://fordsix.com/forum/viewtopic.php?t=2960

 

[aahsac]

If the ridge that you are talking about is at the top of the cylinder bore I wouldn't fool with it unless you are ready to take the pistons out the top. The ridge is normal.

 

[st66ng]

Yes the ridge I am referring to is at the top of the cylinder bore, I am a little concerned about the cylinder ring wear since it is something I can not check without taking the pistons out. But I guess my compression numbers do show them as being good.

I may just leave the bottom alone for now like everyone suggested and focus on the head and ignition. Wost case scenario, I have to do the bottom end later on and won't have to do the head. The head does come off fairly easily anyway, I would just be out the cost of some coolant and gaskets.

Lazy JW, thanks for the link it will be helpful when I do some mild port work.

 

[PaulS]

Before deciding not to go into the bottom end run an oil pressure test with a mechanical gauge. If it is low then new bearings are in order.