Compression readings and assessment

[timkingsbury]

Yes I can do a most of this myself. Pulling the fluid drive though does require a fair amount of donor parts.......plus the drive shaft will end up needing work I can't do myself. Need a different bell housing, a clutch, and probably a different transmission plus a different floor board. And then there is a pretty fair amount of work to do without access to a hoist. I think if I am going to go this route a T5 swap makes more sense.......I can't see doing all this and then not have full synchromesh.

 

Jeff

Well you can certainly get full syncro in lots of mopar transmissions.  In my opinion a t5 makes zero sense in a pickup application.   If you switching to a modern rear end as you seem to be, then you will have the parking brake looked after if you wish to go to a modern transmission without the hand brake on the back.  Explore using a mopar a833 4 speed. Way less $ than your budgeting, better transmission and way less challenges.  Drop me a pm if you like.

 

TIm

[55 Fargo]

So what's happening here?

This thread started with the "topic" of engine compression and internal condition of the said engine.

So what are the finding? Any compression tests done yet, I would have thought this was done a while back, but perhaps not?

So when do you plan to do a thorough compression and leak down tests?

Then the topic went to a T5 conversion, where did you come up with the number of $4000?

So as you and others can see, you can get some more power by adding the mentioned modifications, and to ditch the fluid drive unit. The A833 conversion has been mentioned, but you seem to prefer the T5 conversion, any idea why?

Look forward to your "tests" and plan Jeff, whichever way you decide to proceed...

[Jeff Balazs]

Well Fred this thread started off with me in an assessment mode. I was hoping to get some actual compression numbers from members who have rebuilt their engines and maybe done some mods. That way I might be able to determine if my engine was putting out close to what it is supposed to.

But then it went the way a lot of threads do.

 

Jeff

[NiftyFifty]

I don't think I believe that the more you pull out of these old flatties that the reliability doesn't drop. Since I had my head shaved, I've been through about 3 head gaskets and I think the raised compression is what my issue is, as the block was checked when it was in for machining and head decked at the same time. I've checked again and head is still flat at a pancake. The more and more you ask of that engine, the more strain on rings etc not meant for that type of power. Now most of us not having our trucks as daily drivers can warrant the risk...not sure if your willing to do that Jeff?

I say build your 230, or as mentioned above...start from scratch with a 251/65 with the correct bell housing, build it with a few upgrades, and then put a T5 behind it...that's likely the only way to keep the nostalgia, and be sure your getting from A-B when you need too. A complete conversion is great, but the fab and custom work needed are pretty great, and nobody could convince me to do all that kind of work without working in front IFS and disc brakes, which adds another $25-3000, as now your out powering the steering, suspension and brakes. I regret a lot not doing it on mine, but at this point it would be like throwing the same amount of $ out and starting again...I've already done that on this last build.

If your compressions are 110+, your engine isn't really all that weak, so may be something to that fluid drive power loss, I can't say, never been in one before.

Edited February 14, 2016 by 4mula-dlx

[55 Fargo]

I don't think I believe that the more you pull out of these old flatties that the reliability doesn't drop. Since I had my head shaved, I've been through about 3 head gaskets and I think the raised compression is what my issue is, as the block was checked when it was in for machining and head decked at the same time. I've checked again and head is still flat at a pancake. The more and more you ask of that engine, the more strain on rings etc not meant for that type of power. Now most of us not having our trucks as daily drivers can warrant the risk...not sure if your willing to do that Jeff?

I say build your 230, or as mentioned above...start from scratch with a 251/65 with the correct bell housing, build it with a few upgrades, and then put a T5 behind it...that's likely the only way to keep the nostalgia, and be sure your getting from A-B when you need too. A complete conversion is great, but the fab and custom work needed are pretty great, and nobody could convince me to do all that kind of work without working in front IFS and disc brakes, which adds another $25-3000. I regret a lot not doing it on mine, but at this point it would be like throwing the same amount of $ out and starting again...I've already don't that on this last build.

If your compressions are 110+, your engine isn't really all that weak, so may be something to that fluid drive power loss, I can't say, never been in one before.

3 head gaskets, how much was this head "planed". There are others who shave the head down  a lot, and do not go through head gaskets.

What's your current compression ,over 130-140 psi?

Some of Tim Kingsburys and George Asches engines don't eat head gaskets, and they are hi-perf compared to your engine.

Wonder what is going on in your case...

What is going on in your case?

[NiftyFifty]

Shaved close to .125 or 1/8", SND around 125-30 when it was new. Things are all over now with my rings sticking last year, but I'll test again after a few good runs this spring. I'm not the only guy going through gaskets, there are a pile of threads with the same issues in past on here, and it's all in relation to the build. Maybe I solved my issue with spray copper gasket on mine this time vs dry before, that's to be seen yet too. Talk to any engine builder, the more you pull out and add on, the more your chances of breakage go up, and that includes other drive line parts that are affected. The discussion is based on a daily driver, and I know I wouldn't be comfortable using mine for that, and it was a mild build...add a new intake and extra carb and start shaving the head more and building the heat higher and now you have to start doubting each trip.

[Don Coatney]

In my opinion the fluid drive loss of power is minimal. Suggest you do a forum search for the driving experience forum member James Douglas has posted with his huge heavy weight Desoto on the streets of San Francisco. I have had the pleasure of touring the streets of San Francisco and also highway travel in this car. Made me a believer of fluid drive. Only on the steepest of hills is first gear required. If fluid drive was an easy swap into my Plymouth I would do it.

 

Also doing a T-5 swap in my Plymouth was not all that difficult and I am happy with the results. The T-5 I used is from a Chevy S-10 and has a somewhat low gearing from a standstill but in my opinion would be well suited for a Pilothouse truck. I have never talked to anyone who has actually done the Mopar A833 swap so I do not know how well suited that swap would be for a Pilothouse or a car.

 

[Jeff Balazs]

OK....so now I know.

Compression test today   93#   82#   85#   76#   85#   86#

Hot with throttle wide open, Plugs clean and tan, does not burn oil or smoke, Vacuum @ a hair over 20"

It has about 1500 miles on it since I started driving it........older rebuild 40 over/10 under.

 

Jeff

[55 Fargo]

Those numbers are on the low side, did you do a "wet test" on any of them?

[Jeff Balazs]

Those numbers are on the low side, did you do a "wet test" on any of them?

No. Got to drive it to work tomorrow and I didn't want it smoking.

 

Jeff

I wonder if I could just re ring it? When we checked all the bores they were clean nand well within spec for a 40 over bore. No sign of taper either.

[55 Fargo]

No. Got to drive it to work tomorrow and I didn't want it smoking.

 

Jeff

I wonder if I could just re ring it? When we checked all the bores they were clean nand well within spec for a 40 over bore. No sign of taper either.

Why not in truck ring and valve job, good for another XXXXX miles, probably get some more pep, shave the head a bit the same time...

[timkingsbury]

Shaved close to .125 or 1/8", SND around 125-30 when it was new. Things are all over now with my rings sticking last year, but I'll test again after a few good runs this spring. I'm not the only guy going through gaskets, there are a pile of threads with the same issues in past on here, and it's all in relation to the build. Maybe I solved my issue with spray copper gasket on mine this time vs dry before, that's to be seen yet too. Talk to any engine builder, the more you pull out and add on, the more your chances of breakage go up, and that includes other drive line parts that are affected. The discussion is based on a daily driver, and I know I wouldn't be comfortable using mine for that, and it was a mild build...add a new intake and extra carb and start shaving the head more and building the heat higher and now you have to start doubting each trip.

Well at the risk of sending the thread in the wrong direction here,   125 thou depending on what engine and what generation of head you have on it, could indeed be

the cause of blowing head gaskets.   I am trying to follow.. what is "SND around 125-30"   ?   

[Don Coatney]

Just an FYI on compression testing.

 

 

My fresh engine readings without a shaved head. 255 CI Desoto engine.

 

 

Milling chart.

 

[timkingsbury]

OK....so now I know.

Compression test today   93#   82#   85#   76#   85#   86#

Hot with throttle wide open, Plugs clean and tan, does not burn oil or smoke, Vacuum @ a hair over 20"

It has about 1500 miles on it since I started driving it........older rebuild 40 over/10 under.

 

Jeff

Rock stock, none shaved head would be 120 pounds when it was fresh.  So with 6th at 86 pounds its getting tired.    Time for rings, and/or a rebuild if you

want it closer to its original condition.

[Dave72dt]

My thoughts were similar plus a cylinder with even an lower number. The bigger question is whether or not a freshened engine with it's related expenses will give you what you want or leave you "almost, but not really happy yet", and out a bunch of money and time.

[Young Ed]

No. Got to drive it to work tomorrow and I didn't want it smoking.

 

Jeff

I wonder if I could just re ring it? When we checked all the bores they were clean nand well within spec for a 40 over bore. No sign of taper either.

 

That shouldn't have changed in 1500 miles. Were the rings loose when you checked the bore or didn't you pull the pistons? Did you go over the valves when you were building it?

Edited February 15, 2016 by Young Ed

[Jeff Balazs]

No Ed I left it all alone other than checking the cold clearance on the valves.

 

Jeff

[Merle Coggins]

Tight valves that won't quite seat could also cause compression readings to be low. It may not hurt to readjust the valves hot to eliminate that.

 

Merle

[NiftyFifty]

When you get the time, do a wet compression, that will give you your answers on rings or valves, but throwing rings at it would likely be a temporary fix at best. Was there good or any cross hatching left when you checked the cyls? If not, new rings would need the block honed first and possibly ridge reamed, neither of which I would do with the crank in unless you can 110% guarantee its spotless before it goes back together. I got just a tiny bit of gasket dust in a 305 once, and it took the bottom bearings out...thought I had it clean

[Jeff Balazs]

Thanks Guy's;

Lot's to think about here. I am just guessing but it is probably down 10 to 20% on the power it should be making if all was fresh. That is a lot for one of these trucks. I am kinda surprised it has been running as well as it has. Go figure.......with numbers like these I would have thought that It would have shown more on the vacuum gauge. It idles rock steady at a shade over 20"  Might explain the gassy smell at the exhaust though which I have always thought was a mite bit strong. Surely this has had an effect on the acceleration.

 

My original plan was to drive it this way for a while and when time and money permitted do a rebuild. That is sounding like it may just need to get pushed forward. If I go ahead and rebuild this along with doing some mods I feel more like it will make enough power now....compared to when I thought it was running closer to spec's.

 

Jeff

[NiftyFifty]

Best option, find a different engine, and build it while,your still cruising yours...at 40 over already, it wouldn't be my first choice for a rebuild, which could put you to 60 over.

[Jeff Balazs]

Best option, find a different engine, and build it while,your still cruising yours...at 40 over already, it wouldn't be my first choice for a rebuild, which could put you to 60 over.

Yes that would be ideal. They are not exactly thick on the ground here but I may be able to find something. I have not seen anything other than 23" 218s....the longer blocks didn't seem to be popular here? I suppose a late 230 would be OK though. Right now the engine that is in it is a 54 T342 230.

 

Jeff

[NiftyFifty]

Well even another 230 built up isn't bad, but I would also look at the T5 change at the same time...make it a one shot drop in. I know there are still 251/65 floating around up here, but shipping would be crazy, even with your big $ advantage.

[Jeff Balazs]

The advantage of staying with the same size 23" block is that I wouldn't need any of the bolt - on stuff like manifolds, distributor, water pump etc......just a good core. If I go forward with headers etc......it would all fit. Besides I have never even seen the larger engines locally.......just 23" examples. And I am not going to buy a donor vehicle....... that is a slippery slope we hear about all the time here.

 

Jeff

[Jared Duramax]

If I were you i would be pulling the engine out and going through it. If the engine is still in specs i would just re ring, hone, re bearing and shave the head about .050" to gain a bit of power but not so much to the point of possibly dropping reliability. I would have the valves ground and get a neway seat cutting kit and do the valve job your self. I rebuild lots of flathead equipment engines that just have low power from years of use and it never takes much to get all the power back. I wouldnt do an engine swap because then you are into swapping transmissions and then it takes the originality out of the truck.