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Norm,
The engine under discussion here is a low compression engine. (8.75 : 1 )
120 to 130 PSI would be a normal cranking compression pressure.
The thread you referenced, discusses a Starfire high compression engine. ( 10.5 : 1 )
Yes, I agree that the pressures vary too much to call it " good ".
Last edited by Charlie Jones; April 11th, 2024 at 11:06 AM.
Too bad you didn't do the compression test when you started.
Then you wouldn't have to pull the engine twice.
Oh well, at least it will be easier ( and cleaner ) to remove this time.
Shoot a shot of oil in the low cylinders and see if they come up.
If they do the problem is rings.
Remove all the plugs before performing the compression test. No benefit fighting the compression of seven other cylinders when you're only interest is to measure compression in one cylinder (at a time) - the battery & ignition system will thank you.
Something to consider here is that the engine has sat unused for however long, and the lifters, even the best of them, have a tendency to leak down, (collapse), and sometimes it can take a while before they pump up again even with oil pressure. The issue is usually due to sludge or carbon build-up inside the lifters that is difficult to "cure" short of removing them and disassembling and cleaning, or just replace them with new. I've been going through your thread since I've also got a 64 ragtop with the 394 and slimjim transmission. I need to do this same thing with mine, since I've never heard it run and I have no idea who did the so called "overhaul" and what was actually done. I got this one, and a spare, from my dad who got it from the original owner after he lost interest in it. I'd like to know what you find out when you pull it out again. Something that I've ran into with old Cadillac engines that have sat for a long time is the wrist pin drying out and what oil does get splashed up there isn't enough to get between the pin and piston. I've had 2 engines just begin to knock like hell when I fired them up after sitting for years. One was a '72 472, the other was a '77 425 that my father in law had and quit driving due to his age.i know you didn't want to pull the distributor out, but it might have been a good idea. You can drive the oil pump with a drill to prime the engine and pump up the lifters and prelube the bearings prior to starting it.You also mentioned that you don't know what the oil pressure is. When you turn on key but don't start it, did the oil light come on? It should. If not, you wouldn't know if you lost pressure or not.Just for test purposes, I'd use a mechanical gauge on it. The idiot light doesn't tell you anything until it's too late anyway.Good luck with your engine, I wish you the best. Rick
Last edited by Cadman-iac; April 18th, 2024 at 06:03 PM.
Something to consider here is that the engine has sat unused for however long, and the lifters, even the best of them, have a tendency to leak down, (collapse), and sometimes it can take a while before they pump up again even with oil pressure. The issue is usually due to sludge or carbon build-up inside the lifters that is difficult to "cure" short of removing them and disassembling and cleaning, or just replace them with new. I've been going through your thread since I've also got a 64 ragtop with the 394 and slimjim transmission. I need to do this same thing with mine, since I've never heard it run and I have no idea who did the so called "overhaul" and what was actually done. I got this one, and a spare, from my dad who got it from the original owner after he lost interest in it. I'd like to know what you find out when you pull it out again. Something that I've ran into with old Cadillac engines that have sat for a long time is the wrist pin drying out and what oil does get splashed up there isn't enough to get between the pin and piston. I've had 2 engines just begin to knock like hell when I fired them up after sitting for years. One was a '72 472, the other was a '77 425 that my father in law had and quit driving due to his age.i know you didn't want to pull the distributor out, but it might have been a good idea. You can drive the oil pump with a drill to prime the engine and pump up the lifters and prelube the bearings prior to starting it.You also mentioned that you don't know what the oil pressure is. When you turn on key but don't start it, did the oil light come on? It should. If not, you wouldn't know if you lost pressure or not.Just for test purposes, I'd use a mechanical gauge on it. The idiot light doesn't tell you anything until it's too late anyway.Good luck with your engine, I wish you the best. Rick
Rick, I have the engine out and disassembled. Visual inspection, I see oil in the rockers, and the valley. I didn't notice if the oil light came on when I turned the key- pretty dumb of me, because of course it should. I thought about a pressure gauge and new sending unit, even if only for test purposes. Heads look really good, and I'm told they were done. Local shop can do the block next week- cam bearings, hone/bore the cylinders, new freeze plugs. He says he can provide the numbers I need to order the bearings, or he'll provide them so I know they're right. We're still in the talking phase, but he's highly respected as an engine builder locally, and booked out 6 months with builds. He's going to do my block between builds just because I guess he wants to help a guy who wants to do the build himself? Most of these guys really want to help from my experience- and quick cash is always a good thing in business.
Dave,
Are you putting in a new cam and lifters?
When you disassembled the engine, did you put the lifters in order somewhere so they could go back on the same cam lobe?
If you didn't, you will need to buy a new cam and lifters.
The reason is that a cam lobe and a lifter face "wear in" together.
Switching lifters around on a cam can result in galling and rapid wear.
Wiping out a cam, and filling the rest of the engine with "shrapnel".
Dave,
Are you putting in a new cam and lifters?
When you disassembled the engine, did you put the lifters in order somewhere so they could go back on the same cam lobe?
If you didn't, you will need to buy a new cam and lifters.
The reason is that a cam lobe and a lifter face "wear in" together.
Switching lifters around on a cam can result in galling and rapid wear.
Wiping out a cam, and filling the rest of the engine with "shrapnel".
Hey Charlie- yeah, I tagged every lifter and push rod, and every piston and connecting rod. I was very meticulous about it, each piece was done one at a time, tagged... everything. I laid out the head bolts in sequence in a box and put it aside, by the torque sequence in the book. That said, the camshaft shows wear and the lifters too, so they should be replaced. Lifter foot is concave, and the cam shows wear across the entire top of the lobe. Pistons are scored along the skirts, and the machine shop strongly suggests boring the cylinders out like .030 over and using new pistons and pins.
My next big question is whether I should go with a mild performance camshaft (I think I will) and the higher compression pistons- I think I'll let the dude at the machine shop guide me on that one, but I'd like to use the Super 88/Starfire 10.5:1 pistons. You can see the wear pattern extends all across the top of the cam lobe, and down the sides. The lifter feet are concave
Piston skirts are scored, and the machine shop wants to bore the block .030 over and use new pistons. I might go with the higher compression pistons.
Yeah, that Cam's good life is over.
Of the three types of pistons shown in an earlier illustration, only the 10.25 to one compression pistons are available now.
They are available from Egge, Fusick, and Kanter.
To my knowledge, the 8.75 and 10.5 pistons aren't made any more.
Fusick sells Starfire camshafts and Camcraft cams will grind any cam you desire.
Yeah, that Cam's good life is over.
Of the three types of pistons shown in an earlier illustration, only the 10.25 to one compression pistons are available now.
They are available from Egge, Fusick, and Kanter.
To my knowledge, the 8.75 and 10.5 pistons aren't made any more.
Fusick sells Starfire camshafts and Camcraft cams will grind any cam you desire.
My guy in Ware comes highly recommended- the machine shop. He builds motors, he's booked out until October, or so he says. He's going to do the block for me, and since he's doing the bore, he's ordering the bearings, and I would think the pistons and rings. I'll have to ask him about the camshaft- but he's doing the block so that includes the camshaft bearings. I'm lucky to have him. Otherwise, I'd be waiting months for a good machine shop to do this work for me. I spent all day on everything else- I've got nothing to do now until Edgar Machine in Ware Massachusetts (shameless promo) does the magic. If he had a website I'd share the link...
My guy in Ware comes highly recommended- the machine shop. He builds motors, he's booked out until October, or so he says. He's going to do the block for me, and since he's doing the bore, he's ordering the bearings, and I would think the pistons and rings. I'll have to ask him about the camshaft- but he's doing the block so that includes the camshaft bearings. I'm lucky to have him. Otherwise, I'd be waiting months for a good machine shop to do this work for me. I spent all day on everything else- I've got nothing to do now until Edgar Machine in Ware Massachusetts (shameless promo) does the magic. If he had a website I'd share the link...
How does the engine run ?
I replied in another of your threads about cams. Kinda confusing when you have several threads started and same questions are asked. https://www.camcraftcams.com/
I replied in another of your threads about cams. Kinda confusing when you have several threads started and same questions are asked. https://www.camcraftcams.com/
The engine doesn't run- not now anyway. It's torn down. And sorry about the different posts, but some things feel like a "general question" to me. Going forward, I'll stick to this thread. I have a shop that is taking on the machine work for me. He agreed to do the block between his bigger builds, so he's going to clean it, magna-flux it, replace the freeze plugs and cam bearings, bore the cylinders and hone them and set me up with correct pistons for the new bore. He's going to check the crank for wear and for round, and polish it, provide the main and rod bearings. I'll buy a new camshaft and lifters, a new oil pump too. I've got to complete the build. I expect to have everything back in the barn by the end of next week- I guess I'll see how it looks then.
I don't like feeling like I have to trust him to do it right, but if I want a builder to build me a complete engine I won't have the car on the road in 2024. No one reliable near me can do the job before October. It's madness that a person can't get an engine built in less than 6 months time- it makes me think there's lots of money to be made if you can build engines. Not too many people are doing it anymore, I guess. So it is what it is- dude says he'll do the machine work on the block, the rest is up to me. I'm okay with that.
I'll tell you how it runs when I'm done. It's just money and time, right? camshaft with the block behind #1 piston, there's 7 more pretty much like this one laying on an old towel
Iv ran into that exact same discussion on my project build. I had the thought of using Starfire/98 10.5:1 pistons in my 394. Unless you have access to 93 Octane gas with an octane booster or racing gas, I would advise against it. The motor would have to be detuned in order to run okay with lower octane gas. Charlie and a few other stated to me it just isn't worth it also because race gas is far and thin across America. I ended up going with 10.25:1 pistons using 93 Octane and no booster. Plenty of power and 91 is achievable if i just adjusting timing.
Also all those piston brands are great! I was originally going to go with EGGE but due to budget restrictions, I went with Rebuilders Choice Pistons out of Boonton, New Jersey. Great Pistons and knocks off a little on price.
Iv ran into that exact same discussion on my project build. I had the thought of using Starfire/98 10.5:1 pistons in my 394. Unless you have access to 93 Octane gas with an octane booster or racing gas, I would advise against it. The motor would have to be detuned in order to run okay with lower octane gas. Charlie and a few other stated to me it just isn't worth it also because race gas is far and thin across America. I ended up going with 10.25:1 pistons using 93 Octane and no booster. Plenty of power and 91 is achievable if i just adjusting timing.
Also all those piston brands are great! I was originally going to go with EGGE but due to budget restrictions, I went with Rebuilders Choice Pistons out of Boonton, New Jersey. Great Pistons and knocks off a little on price.
Kanter lists PST2179 and PST2180. I'm thinking the 2179 is the piston I want, it says it's for the 394 2 bbl engine. It does not specifically list the compression ratio. Do you know which ones you used? Also, I'm guessing these have full floating wrist pins, which don't need to be pressed. The tech guide says if the pins are properly fitted, they should slide in place with a little hand pressure, and fall out under their own weight.
Unfortunately I bought my pistons in 2020 and eBay cant re-pull the listing. I got them with shipping for about $520. I have a picture from the listing but the picture is pretty small. They had a black RC label and they were 0.30 over. They were cut to match OE 10.25:1 pistons. you could always call RC & ask what's available. Here are the only 2 picture I have of the pistons
The block is in the machine shop since Friday, "Eddie" (as I'm calling him) said he'd probably get it done this week. Edgar Machine in Ware is doing the work- so I call the guy Eddie. He never actually introduced himself, or handed me business card, so I'm just going to call him Eddie. His office is full of heads- if they were shrunken, he'd be a world class witch doctor. But they're rebuilt heads waiting for customers to come pick them up. His shop has engine blocks everywhere in various stages of completion. Eddie said he'd clean mine, and magnaflux it, check the bore and the deck and tell me what he thinks. I need camshaft bearings, and he said he'd plan to do those and the freeze plugs. Other than that, it's likely that the block needs the cylinders honed, and not much else.
I'm looking over the pistons to see if I really need to replace them. Rods look good, Eddie is going to polish the crankshaft, and again, if it needs more, he'll let me know. If I want to drop some money (just because) I can ask Eddie to bore it out .030 over and buy new pistons. It's not a bad idea. That would mean I have a block that been cleaned and magnafluxed, decks certified flat- or milled- center bore certified, cylinders bored .030 over, new camshaft and cam bearings, new lifters, new main and rod bearings, new rings and pistons, new oil pump... that's a pretty complete engine build for something I do mostly in my barn. It's good money spent- to bore it .030 over and get new higher compression pistons, but that's up to Eddie. I wish I really knew his name...
April 11th, 2024, 10:49 AM
