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Hello everyone! I just bought a 1964 Oldsmobile Dynamic 88 4 door with the high compression 394 Rocket motor. It has 98K miles. The guy who sold it to me could not get it running for awhile. He sold it to me for cheap. $500. I found the points were junk and replaced it and it fired right up. Over the course of this week iv been trying to get it to idle and run better. Oil pressure is 40 psi when cold. When coming to a stop the car dies. Under hard acceleration the car stalls and just about dies The biggest thing that concerns me is there is quite bit of white smoke from the PCV valve and dip stick tube. Does anyone have suggestions?
Things that have been reminded or replaced:
-Carburetor was completely rebuilt with new Walker gaskets
-Changed oil
-New coil
-Has an electric Edelbrock fuel pump with a regulator (came with it)
Things that I still could do to improve it:
-I bought a timing light to do timing
-Compression test
-New spark plugs
Did you check the dwell before setting the timing? Do a compression check and or a leak down test. The smoke is probably blowby due to bad rings and valve guide seals.
Dwell if im right is the gap between the points. I did set it with the thickness of a match book. White smoke seems to increase with temp. I will do a compression test. But i don't think the acceleration issue is related to the blowby. It also almost stalls when changing gears.
Dwell if im right is the gap between the points. I did set it with the thickness of a match book. White smoke seems to increase with temp. I will do a compression test. But i don't think the acceleration issue is related to the blowby. It also almost stalls when changing gears.
How thick was the matchbook ? A matchbook is enough to get it started/running, but far from good enough to run properly. Dwell is set with a dwell meter. Then set the timing.
How thick was the matchbook ? A matchbook is enough to get it started/running, but far from good enough to run properly. Dwell is set with a dwell meter. Then set the timing.
^^^this^^^ It will never run right until its tuned properly.
White smoke is one of three things:
1) Steam from a head gasket leak
2)Transmission fluid though a SlimJim has no connection to intake to suck it into combustion chamber
3) Brake fluid from a master cylinder leaking into the power booster
Blowby smoke is bluish and comes from worn oil rings or valve guides, or bad valve stem seals. A clogged PCV system can also cause it.
Up front, 394 are notorious for worn valve guides and valve seals esp if they've sat any length of time. How much oil is this engine using? Losing coolant?
Tune it properly to get 30 degrees of dwell, then set timing at 2.5 degrees BEFORE top dead center to start. Doubt that engine would tolerate the recommended 5 deg on currently available premium fuels.
Stalling between shifts is not unusual on a SlimJim if it has sat a while. Usually worse on first shift as there's a big ratio spread there. SJ performance is also tied to engine performance and some critical throttle linkage adjustments.
Can't emphasize this enough. To live with this car you need the 1964 factory shop manual set or at the very least a good professional trades edition general service manual covering 1964 cars. Chilton, Motor's, Glenn's are good ones.
Last edited by rocketraider; November 6th, 2020 at 08:39 AM.
Dang $500. What a steal- looks pretty good!! Keep playing with it- it will probably get better with use and tweaking. Welcome to the site. Keep us posted!!
White smoke is one of three things:
1) Steam from a head gasket leak.
A point of clarification here. Water itself will not produce white smoke; it is the antifreeze that makes the smoke. I learned this after my first engine rebuild that was losing coolant. Folks would ask if there was white smoke out the exhaust, there was not, so they said it's not a head gasket leak. I was a poor kid and did not use antifreeze after the rebuild, just water, as I didn't want to waste money if there were any leaks. Winter was approaching, and as soon as I put antifreeze in, white smoke out the exhaust. Head gasket was leaking around that dang stud head bolt that I didn't have a deep enough socket to tighten with the torque wrench, so I just "feels good enough" tightened it with a box end wrench.
Last edited by Fun71; November 6th, 2020 at 11:24 AM.
THANK YOU EVERYONE FOR THE FEED BACK AND WELCOME!!!
I found a problem. So I did a compression test and here is the following:
#1:150
#2:145
#3:150
#4:150
#5:0 !!!!
#6:150
#7:135
#8:150
How in the hell could I get 0? I reset it twice with no avail. Oil pressure is 40 psi so I think its a stuck valve or blown valve seal. What do you guys think?
Last edited by 64Guy; November 6th, 2020 at 12:48 PM.
Pull the valve covers and distributor coil wire and watch the valvetrain as engine is cranking over. 394 have rocker shafts so look close for wear where the rocker arms ride on it, and also a broken or worn rocker arm. If a valve isn't working you'll see it. If looks like one is stuck, either strike the valve stem with a plastic mallet or a brass drift and that might free it. Dump some penetrating oil around the valve shaft first.
I'm leaning away from a head gasket since it's only one cylinder, but anything's possible.
Have you checked manifold vacuum to see what it's doing at idle?
idle vacuum was excellent. In spec. Yeah ill take that cover off and see what's happing tomorrow. I did a wet compression test on that cylinder today and still zero.
1964 Oldsmobile Dynamic 88 4 door with the high compression 394 Rocket motor. It has 98K miles.
When coming to a stop the car dies. Under hard acceleration the car stalls and just about dies
I had those issues occasionally with my 69, plenty of carburetor adjustment resolved it... As rocketraider mentions modern gas quality is a major problem for our cars especially when tuned to factory spec. Premium high test fuel (93 octane) is a must plus an octane booster.
Originally Posted by 64Guy
The biggest thing that concerns me is there is quite bit of white smoke from the PCV valve and dip stick tube. Does anyone have suggestions?
Originally Posted by oldcutlass
The smoke is probably blowby due to bad rings and valve guide seals.
Agreed, I had smoke coming out of the same locations with a 66 442, had a problem with one cylinder...
Originally Posted by 64Guy
So I did a compression test and here is the following:
#1:150
#2:145
#3:150
#4:150
#5:0 !!!!
#6:150
#7:135
#8:150
Looks like the engine is a bit tired, I also have a 10.25:1 Olds V8 but its a 350. Compression was tested at around 110,000 miles and was showing 180-190 PSI.
Zero compression is usually a stuck or burned valve. It could be a hole in a piston but that is less common. Put compressed air into the cylinder and see where it leaks, intake, exhaust or crankcase.
Do you feel notable pressure out of any crankcase vents? That would indicate a ring/piston problem.
If it has sat for a long time, soak the rings, drive the car and retest before condemning the rings. The rings on the pistons that are a little low on compression may be sticking just like a valve as another member noted.
Alright so I have some furthering developments. When taking off the valve over I found 4 hard plastic piece which look to be a valve stem seal. I'm not 100 % sure but here is a picture if someone could tell me. The valve train for the cylinder is functioning as normal. Here is my question: Could a bad valve steam seal create a blowby issue or did the valve bend and kill the seal? I unfortunately don't have a bore scope to see the piston condition.
The bad valve seal isn't allowing blowby, they are for oil control not sealing compression. A valve seal cracked/broken is normal due to age. If a valve was bent that much you would see it but on the bottom of the guide inside the head, not topside by the spring or rocker arm.
Alright I ran air into the cylinder. I taped the rockers with a rubber malate to make sure there was no pressure on the springs. The air came out of the PCV hole on the passenger rocker cover. Meaning if I think I know it is a bad ring or a hole in the piston. I'm going to buy a bore scope this week to get a better look inside. In the mean time I think because of its tiredness and age I should just rebuild it. Does anyone have advice to what should be "must replace items" with this particular motor? Also If anyone knows of a engine gasket kit for the 394 please let me know.
It sure sounds like a hole in #5 piston, probably from someone feeding it low octane gas. I can speak from experience high compression 394 do not like 93 octane, much less 87. They were designed for 100+.
Agreed. Tear it down and see what you're dealing with. It won't be a cheap engine to rebuild but parts are out there.
Since odds are you'll replace at least one piston, find a set of lower compression pistons. 9:1 will tolerate this horse **** currently called gasoline and will still take that 88 down the road right sharply.
Also find the elusive LH dual exhaust manifold and go true duals. Even with the 2 barrel it might surprise you. Switching to a 4 barrel involves the transmission throttle linkage so I would personally stay away from that switch.
Keep us posted man. For 5 Ben's you aren't out that much if you decide it's more trouble than it's worth, but a Wedgwood Mist 64 is a nice piece to own.
Curious where you're located. Somebody might be close by or know of a good machinist.
Alight thanks. I bough a bore scope and had a look. From what I saw there was no holes or damage to the piston. It must be rings then. what's odd is I thought even when the rings were bad you would still have compression? Could i just buy OEM type rings instead of boring it out to fit different ones?
Okay so since my last post I have removed the engine from the Oldsmobile and now I'm going to starting to tear it down to see what is going on. Today I pulled the driverside cylinder head off where piston #5 is and found there was no holes in the Piston nor any issues on the cylinder walls or cylinder head. I found a graveyard of valve stem seals on the passenger side valve train area. So my next question is how could I have no compression when everything looks to be fine and having no obvious sighns of damage? One thing I noticed when taking the cylinder head off is two out of the 4 bottom bolts on the cylinder head were slightly loosened. Not loose like you could finger tight pull them out but they were looser than other ones. My plan with the engine is to get all new valve stem seals, new gaskets all the way around and new piston rings. Any recommendations on where to find rings?
You may as well disassemble the rest of the engine and clean the parts .
The next step is to take it to a machine shop and let them tell you what should be done .
It's remotely possible that you may get by with a set of rings and honing the cylinders .
But that will be determined by the wear in the cylinders .
Your machinist will make a determination as to what size to bore it '
I don't want to stick a lot of money into this motor because how the frame looks under the car. Some parts are soft. I just want to get the minimum complete. Like new gaskets, seals and rings. I do not want to have to buy new bearings if i don't have to. Does gm not sell just OEM rings anymore? The cylinders have little to no scoring. I have a hoaning kit here I just need to find rings.
*****RINGS SIZE MAY NOT FIT ORIGINAL PISTONS. MAKE SURE TO DOUBLE CHECK YOUR MEASUREMENTS. INCLUDING: BORE SIZE, WIDTH AND DEPTH OF THE RING GROOVES*****
Put the head on its side, exhaust facing up, pour diesel fuel or parts cleaner in the exhaust port to see if it leaks through the valve. Repeat same on intake side. Or, you can pour liquid into the combustion chamber and do both at the same time.
Could air coming out the PCV be from leaking intake valve?? Depends on if it was from intake manifold side or crankcase side of the valve? I agree cylinder/etc looks fine unless there is broken or super worn out rings. Following you along. Yeah I agree if the rest of car is "soft" you will have to consider if you want to completely rebuild engine- won't be cheap, And how is the slimjim,? they can be troublesome.....
My dad's 68 307 ElCamino did much the same thing. Developed a bad miss at about 45k miles. At 49k the dealer determined #5 had no compression. My dad said he needed the trucklet to drive to work that night and the service manager said if he drove it home, to work and back, and back to the dealer next day it would be out of warranty. They gave him a ratty old brown Plymouth as a loaner and he made me wash the tobacco juice spit off it before he took it to work.
They replaced the cracked head but in a year or so another problem cropped up. All that time running with no compression, once compression was back to normal it started blowing oil past #5 rings and it became an oil hog, fouling #5 plug every week.
One of my first projects in auto tech school was yanking the 78k mile 307 and putting a 30k mile junkyard 73 350 in it. It ran for years on that engine, finally succumbing to rust.
My dad's 68 307 ElCamino did much the same thing. Developed a bad miss at about 45k miles. At 49k the dealer determined #5 had no compression. My dad said he needed the trucklet to drive to work that night and the service manager said if he drove it home, to work and back, and back to the dealer next day it would be out of warranty. They gave him a ratty old brown Plymouth as a loaner and he made me wash the tobacco juice spit off it before he took it to work.
They replaced the cracked head but in a year or so another problem cropped up. All that time running with no compression, once compression was back to normal it started blowing oil past #5 rings and it became an oil hog, fouling #5 plug every week.
One of my first projects in auto tech school was yanking the 78k mile 307 and putting a 30k mile junkyard 73 350 in it. It ran for years on that engine, finally succumbing to rust.
Don't expect to see a big crack because chances are if cracked, it's at valve seat area and need valve opened to find crack
So I got the pan off of the half disassembled 394 and after taking off the oil sump pieces of piston came out and some ring. Again the walls of the cylinder are not damaged. No gauges or scraps. Broken piston skirts are #5 and 3. Could this be finally the reason for no compression on cylinder #5? Also is it common for the bottom of the skirts to break? Here are some pictures and a video link. Let me know. Thanks!
Looks like you've found it, but if the compression rings were still set there should have been SOME compression. Did you find any pieces that looked like part of a ring land in the pan? For pistons to break off skirts like that someone had really abused that engine in the past.
Decision time. Fix it, or cut your losses and part it out. If it has a good rear bumper with no rot thru, that can recoup what you paid for the car plus your time and labor tearing it down.
Leak check the valves as posted in #28. If they aren't leaking then yes the compression problem is only ring/piston related. If the car is "soft" look for a couple of used pistons, put in rings, possibly bearings, timing chain, gaskets and drive it if you'd like. In short, only fix what is wrong vs a complete rebuild.
If all of the valves are ok, clean the heads and replace the valve seals.
If your just looking for a decent driving car look for a good used piston. Clean up what you have, throw a set of cheap rings in it replace the bearings and timing chain, reassemble and enjoy. Make sure the short block is decent, that way if you have problems later your not removing the engine to fix it.
Im not familiar with those cars, is frame rot a common problem? Did somebody give it the “sculptors” bondo bodywork treatment and a cheap paint job? Looks like a pretty nice car.
Iv reviewed your guys suggestions and i think i just want to do it for the long run. Iv had many co works say these motors are some what of a rarity. High compression 1st generation Rocket engines are few and thin. Ill keep it for a long time and just sell it if it doesn't work out. My plan is to have the block taken to a shop to get bored and honed. Then decked and cleaned. I got 2 of the pistons out last night and the cylinder walls look relatively nice. No major damage or scoring. The connecting rod bearings that I took out so far look pretty hashed. The scoring is pretty big on one side, I can grab it with my finger nail. So my plan is Gasket kit, Pistons, Connecting rod bearing, Main bearings and Valve stem seals. The only thing i don't have a good understanding of is how clearances work with new bearings. Does the crank have to be turned for new OEM bearings?
Also just as a oops by me when the engine was upside down i thought the to brown pistons were numbers #5 & #3 but I was wrong. its actually #4 & #6. So its not my compression issue iv been having with #5.
Find a shop that has done Olds 394's, it's better not to be their first rodeo.
OEM bearings? I think what your asking is about standard/original size. If the crank is in good shape it would not have to be cut/ground smaller, probably just polished. If the crank needs to be resurfaced/ground smaller then oversize bearing inserts would be needed to account for material that was ground off. This is normally done in increments of 0.010" as you'll see bearing inserts at standard size, .010, .020 or .030"
Be careful what pistons are used, one of the attractions of those motors is the "Ultra High Compression", get the wrong pistons and that becomes just a decal. This is why it pays to be selective about the rebuilder.
Good luck!!!
Last edited by Sugar Bear; December 10th, 2020 at 10:28 PM.
November 5th, 2020, 06:20 PM
Plans
