overly high compresion psi

[DjGriff]

Hello , i am new to this forum so hey to all out there. I am helping(working for)a friend to restore his 1962 Lincoln and i am having trouble figuring out why the 430 has 230+ psi when doing a comp check.
Let me first state that the car was purchased with a fresh rebuilt motor so i am dealing with a unknown as far as what was really done. The very first thing i do with any engine is check cranking comp and this motor came up all even,but very high in the 230 psi+- 5psi.
The owner told me he was having major trouble restarting the engine after it reached operating temp and that it would rattle under any kind of load. After trying to get it to run by pulling the dist timing way back (like to 4 after TDC) it ran a little better but was eating gas and still rattled a bit. What my brain told me was who ever put it together must have missed the valve timing by a tooth or the timing gears were not indexed properly at the factory. Well to my amazement the cam was lined up fine as far as the timing marks were concerned.
The next thing i did was get my degree wheel and 1in dial indicator out and check what was there.

The only reference i had was an intake opening of 22 BTDC in an old Mitchell Motors manual. i checked most of the cam manufactures and none listed the MEL specs but most of the stock/oe timing of similar size engines of the time spected out from:

Intake Valve Opening @ 18-24 BTDC
Intake Valve Closing @ 55-65 ABDC IC @.006

Exhaust Valve Opening @ 55-65 BBDC
Exhaust Valve Closing @ 18-24 ATDC

It seems a reasonable total around 250 degrees or so. What i came up with was very close but a little shorter with

Intake Valve Opening @ 16 BTDC
Intake Valve Closing @ 55 ABDC .........@.006

i also checked at .050 and came up with

Intake Valve Opening @ 13 BTDC
Intake Valve Closing @ 28 ABDC

wich is very close to the specs given on this site.

On the exhuast i got

Exhaust Valve Opening @ 32 BBDC
Exhaust Valve Closing @ 13 ATDC

and that seemed close enough for the valve timing to be acceptable what gives ?

Why is this thing got so much cranking psi (stock is kinda high at 180psi)?
Even if it has .030 or .040+ bores and pistons that still should keep the static comp below 10.5 (stock 10.0). Also the builder left out the oil galley plug in front of the distributer. So what else could he have done wrong?

One last thing is i believe the exhaust valve timing listed in this forum is at .006 and not .050.

Like the intake listed above 258 is a bit long @.050 but just about right for total duration@.006). My figures on this cam show it to be a little worn at 248 in and 250 ex @.006 and 192 in and 202 ex @.050 and lobe lift total of .240 (down .010 from spec) the cam is correct with a ^(triangle casting before the last cam brg)
Any ideas why there is 50+psi over stock(180) ?

I am going to buy a new cam for it but if stock is only giving me 10 more deg duration i might have to have a cam ground a little longer yet to bleed off some low speed psi so this thing can be driven by the owner. Thanks for reading this and any info at all would be very appreciated DjGriff

[Chris Craft crazy]

FWIW, I have a 1958 lincoln maintenance manual that lists the compression as 200 psi +/- 20...

Timing is listed with an automatic as 3 degrees minimum, and 6 degrees maximum Dwell is 26 1/2 to 28 1/2

The manual states that above average compression pressures is an indication of deposits in the cylinder. (not that that may apply here)

[DjGriff]

Thanks CCC, for that info the 200+-20 makes me feel a little better,if that was stock the info i have only goes back to 1964 and just lists 180 psi .the problem still is causing the owner of this classic Lincoln to not want to drive it .Any one else out there with cranking compression specs for a 62 430 ?Any one with a camshaft with more duration or overlap(smaller LSA) Thanks again Chris Craft crazy for the feed back and to everyone that read my post DjGriff

[Theo]

Airman, welcome to MEL Air Base. On a complex case and a large post like your OP (Opening Post) I felt that I had to edit and format the lay out in order to get things sorted and for better reading.
Your cranking pressure appears to be not over average. I assume that there is a different problem. Sometimes it's a number of problems.

Fuel quality? Is the owner to shy to spend on the best highest octane gas available?

Did you check the Distributer's timing advance curve? It might be to steep. What's the total advance?

Tune up O.K. w. max. vacuum and the carb set accordingly?

Is the cam dialed in correctly? Almost all modern cams compare to old stck. cams 4° advanced. So using a straight up position on the sprockets will yield a 4° advance on the cam. You'll have to retard it 4° to achieve a stck. standart zero advance install.

We don't know what cam has been stuffed into your engine. It's good to see that you're knowledgeable and that you have your tools so you can check the exact cam motion. Check out this 1958 Lincoln Premier chart on a stck. cam. Click it for a larger view.

[Theo]

.........and I am having trouble figuring out why the 430 has 230+ psi when doing a comp check

As CCC and I have stated, 200-220 psi is within the expected stck. pressure.
It looks like you guys can be lucky having the original pistons w. the correct dome and the correct compression ratio. Halleluja !

The owner told me he was having major trouble restarting the engine after it reached operating temp and that it would rattle under any kind of load.

Yeah, that's a common problem w. most all our vintage beauties. Rel. high compression, lousy gas, incorrectly mounted starters and design flaws like exhaust manifold being too close to the starter, mess up the starting process.
Incorrect distributor and vacuum settings add in many cases. A high torque starter or a gear reduction high torque starter is mandatory to allmost all american vehicles of this high compression period. I use a high torque starter by Accel for instance. There are other good products available.

After trying to get it to run by pulling the dist timing way back (like to 4 after TDC) it ran a little better but was eating gas and still rattled a bit.

Also check for any lean condition either vac. leaks or carb setting. Carter style Edelbrock supports swapping needles, springs and jets for fine tuning. But that's probably not necessary if you get your Tune up right w. your stck. components.

What my brain told me was who ever put it together must have missed the valve timing by a tooth or the timing gears were not indexed properly at the factory. Well to my amazement the cam was lined up fine as far as the timing marks were concerned.

Incorrectly indexed cams do not shift too far from what you basically want to get. As I mentioned previously, try to retard the cam 4°. I'm pretty sure it will help a lot if not eliminate your problem

Even if it has .030 or .040+ bores and pistons that still should keep the static comp below 10.5 (stock 10.0).

Oversize pistons never raise the compression ratio because the manufacturers design them destroked to compensate.

One last thing is i believe the exhaust valve timing listed in this forum is at .006 and not .050.

I forgot where the listed information came from. So unless we don't have bone hard data to prove them wrong I'm not touching it at this time.

.... I might have to have a cam ground a little longer yet to bleed off ....

The bleed off makes a lot of sense. But again, check for other things first.

Thanks for reading this and any info at all would be very appreciated DjGriff

You're welcome. We're looking forward to watch your project as closely as you keep us updated. MEL cams are hard to get. Let us know what cam stock or custom made you're going to purchase once things make it absolutely necessary.

[Treinarts]

A thought: 462 cam timing gears are different than 430 cam gears. They bolt up the same but the timing is different.
I don't recall the exact difference, but an advanced or retarded cam can effect static compression.
Oregon cams can give you what ever you want for about 130 dollars plus shipping. I had them grind a 428scj hyd cam pattern for me on my 430 core. TJR

[DjGriff]

Thanks to everyone, for your input and thoughts,i already had spoke to the owner of this cool old car about running higher octane gas even if it means mixing expensive race gas with the best pump gas we have in SoCal(91) and i installed an offset bushing to retard the cam 4degrees (8 crank). I found a shop in SE Los Angeles that had a stock 430 cam on the shelf that i went to buy but after comparing it with the one i have i left it down there.it had the same casting marks and # and would have been pointless.They did supply me with the oil plug (in front of dist) and had some correct pushrods that i grabbed. while the dist was out i installed some heavier springs and i will wait on limiting the total mechanical adv. until after i put it back together it had a new Pertronix ignitor conversion already and i might limit the vac adv or lock it out if need be. The carb is a new 2bbl Motorcraft that is probably not correct, but the spark plugs and vacuum readings(after finding and fixing a few major leaks back when he first brought me the car) all look good. As far as the hot start problem,i installed some heavy cables(0 gauge) from the Bat to a new HD starter relay and on to the starter and a 1gauge for the neg. we put a 1000 cold cranking amp battery in and i took one of my Harley exhaust heat shields and put it on the exhaust after moving the pipe as far away(by loosening at the manifold and taking a large pry bar )from the starter as possible. although less than an inch the air gap from the shield is now about the same as it was without it and the jury is still out on that one. Thanks to all for the info and one last note the shop with the cam is Perfekt Engine on San Pedro street SE Los Angeles.and Modern Engine in Glendale Ca lists gasket sets single gaskets and some timing and valvetrain parts for the Mel

[Theo]

Thank you for your shopping tips. It's much appreciated. I copied them to the MEL Parts Shopping Guide section.

Whay did you exchange the stck. valve springs? They're usually O.K. as long as you don't go wild w. an other cam.

[DjGriff]

Hello again, I put the heavier springs in the distributor not the valve train, sorry i was using abbreviations (dist for distributor) to slow the mechanical advance a bit. i will let you know how it all turns out. Thanks very much

[Theo]

You're welcome. Thank you for sharing your experience on this particular client car. We're looking forward to see how thing develop.