69442C

Can anyone tell me what the correct cylinder cranking pressure would be for a 69 442 with a 400 motor? The engine is freshly rebuilt with stock compression pistons, bored .030 over, standard FelPro gaskets and otherwise stock with the exception of a Mondello 20-22H cam and Comp Cams roller tipped rockers. The block was decked slightly during the rebuild to level the surface to the crank but only a few thousandths were removed. I did a compresion check on the motor and I think the pressures may be a little high. I am getting a low of 185 and a high of just over 190. This engine also has low vacuum, down around 13 inches and I cannot find any source of a vacuum leak. Not sure if this cam is causing me these issues or not.

ah64pilot

I don't know what the compression should be for a 400 engine...I doubt you are going to get an answer on that. There are so many variables even two engines built identically can be different.

As far as your vacuum is concerned, I have run JM20-22 before and never had a problem with vacuum. It's not such a long duration that you should have vacuum issues. I would check your manifold ports again, check your carb ports that they are all plugged up.

What kind of carburetor are you running?

rustyroger

I beleive the 442 engine had a 10.5-1 compression ratio, so pressures around 180-190 sound about right. a variation of 10psi between all 8 cylinders sound like a good job by whoever built it.
Roger.

69442C

Thanks for the info. I was looking to see if there was a factory cranking pressure spec for when the engine was new. My engine guy said these specs existed but he needed to find some of his older books.

I'm glad to hear that you have used this JM20-22 cam and didn't have vacuum issues. From what I have read about cams, this cam should be fine as Mondello told me. Yet I have this low vacuum issue which really has me puzzled. I have been over everything on the engine multiple times and even replaced the intake gasket/pan just to see if that would do it. But I keep coming back to the same result. Everything that consumes vacuum has been disconneted and the ports sealed and plugged. Same result. So all there is with vacuum is the carb, intake and runners in the heads. Carb is the original QJet and it was restored by Sparky. Even sent it back to him and he says it's perfect and it's set to factory specs.

This car came to be as a failed restoration/basket case and the engine was not running. In fact, the engine had water in it at some point as 2 cylinders were siezed from rust. As a result, the only thing I can think of is there may be an internal crack in the intake manifold or one along the bottom. Engine builder says it was magnufluxed but I can't come up with any other place where vacuum would leak. I have a 70 455 intake that will work for test purposes so now that I know you have not experienced low vacuum with this cam, I'll give this a try.

The only way I could get the engine to idle was to step up the jets to what would be a 78 jet (70 is stock). But the plugs are black from too much fuel. To me, this says vacuum leak and the extra fuel is trying to mask that problem but causing others. Carb is semi responsive when trying to adjust the mixture screws. The compression test was to verify the valves were sealing and it seems all is OK there, as I would expect with an expensive rebuild.

oldcutlass

There was another thread with relation to this and he chased his tail for awhile. I wonder what finally solved his issue! Basically it started as the off idle circuit engaged at idle.

I believe as stated earlier anything less than 10#'s variance in compression test is excellent. Did you do it both dry and wet??

69442C

I saw some of that other thread but never read all of the lastest postings as my problem is just low vacuum of about 13 inches. In drive, the vacuum assist on the brakes starts to go away as the lower RPM with the car in gear creates lower vacuum. The booster is fine as I have the same low vacuum with everything that uses vacuum completely disconnected from the motor. My compression test was done dry and the difference between all cylinders is probably 7 psi.

I wouldn't call myself an engine builder but I have been quite a few motors over the years (we're the same age as I saw you say you were 53 in another post) and I have restored quite a few cars. This issue is just so odd and I have done all of the normal stuff one could suggest. Even Sparky and my engine guy gave up with suggestions as I had already covered them. Something keeps telling me there is a problem with the intake manifold.

I was hoping someone could tell me about the JM20-22H cam and AHPilot did just that and was able to say he had no issues with this cam and low vacuum. So now that I can rule that out, I keep coming back to this intake manifold. I also tried another QJet and had the same result. There's a lot of money in this motor and the guy that built it (I chose to not do this one) is excellent and very detailed. And it looks like the compression test confirms that. I worried the cylinder pressure may be too high, again questioning the cam, but I guess not. I'm grasping at straws as I have done everything that I and others can think of. Looks like an intake swap will happen this weekend and if nothing else, to rule it out. The car is a high end restoraion and is not complete so I am not able to drive it other than in the driveway. No front sheetmetal or interior.

442scotty

I always thought the cam you are using was a low vaccum cam and not recommended for use with power brakes...read that somewhere...you can also try a different carb..I use an edelbrock (weber?) on mine...easy to adjust the fuel mixture. Never been crazy about rochesters..just my own bad luck getting them to run right...

Rickman48

I'm just gonna throw some things out there;
My DD bone stock '69 442 pulled 23 inches of vacuum after valve seals, spring shims, and new rockers/stands. [original Q-jet]
Actually reduced the jets on a BB 396, to 68, even with a 284 duration .505 lift Crower cam. [780 holley]
Increasing the jetsize shoulda had no effect - idle circiut is seperate!
I agree, sounds like a cracked manifold/sealing problem. I generally smear a light coat of permatex around the edges of the intake ports, before the gasket, to both hold the gasket and eliminate possible leakage.

matt69olds

Before tearing into the engine, do some basic diagnostics. Where is the initial timing set? Does the timing advance with engine speed? Are the advance weights free to move? Spray carb cleaner around the intake and carb mounting surface, any change in idle speed? Are you sure the timing chain was installed correctly?

69442C

I've read that anything over 239 duration will cause power brake booster problems. This cam is 226/230 and was already mentioned that others have used it with good vacuum readings.

Yes, I ran a bead of RTV around all of the ports on both sides of the gasket. This is why I keep coming back to the intake manifold being cracked internally as I have no other place to seek a leak. Since water was in 2 cylinders at some point, I suspect the intake had standing water in it to. If it froze... crack into the heat passage??? That would never show up with a magnaflux as it's internal. Grasping at straws. Would love to see those vacuum readings and hopefully I will once I exorcize the demons out of this thing.

All of the basic stuff was done. Initial timing was set at 8 BTDC and has been pushed all the way to 14 BTDC to see if things would change. Still low vacuum. The distributor was rebuilt and set up on a Sun machine with results and specs provided. Advance does work per the specs. I've gone through 2 cans of starting fluid over the past month trying to find a leak on the motor. Nothing. Chain was installed correctly and cam was degreed when installed.

MDchanic

Two thoughts:
1. If it's a crack inside the manifold, it would have to be big enough for you to find by sealing one end of the exhaust passage and blowing air into the other end. It would have to be there, as anything into a water passage would make something wet or bubbly, and anything into the valley that was big enough would be visible.

2. Any chance the cam was mis-stamped and is actually bigger than you think? Obviously checkable with a dial indicator and some patience.

- Eric

oldcutlass

Here is the link to the thread, last time he posted he was changing to an edelbrock carb. Maybe you could pm him??

https://classicoldsmobile.com/forums...sue-q-jet.html

69442C

I appreciate the thoughts and ideas so far. So far it's looking like the intake comes off tomorrow.

69442C

Opps, screwed that response up. Hopefully you can see my comments.

69442C

LOL! See what I did. Maybe I'm low on vacuum.

ah64pilot

I think he said he had the cam degreed...he would have found out then if it was mis-stamped.

If your intake manifold was cracked internally between the runners and the heat riser passage you would never find it, and it would probably cause a low vacuum scenario. In my first response I ask if you double checked the ports because I've done that once before. I paid a shop $85 (hour labor) to put a rubber cap on a vacuum port that I missed. Stupid me.

69442C

The only ports I have left are the ones on the carb. Everything on the intake was removed and plugged. The carb ports were all capped and I even plugged the port going to the choke pull-off just to make sure that thing wasn't leaking, which it wasn't and shouldn't as it was new. I put thread sealant on the carb bolts and also on the small bolt that holds the dashpot bracket to the manifold since it threads into the intake passage. There's nothing left to seal up or plug. I even tried plugging the PCV inlet to the carb just for the heck of it and that did nothing. This is what puzzles me. In my mind, the only other place for vacuum to leak is inside this intake manifold or one of the intake ports in the heads. The heads were magnafluxed so I would think if a crack was in a port or runner it would have showed up.

Rickman48

How about the primary throttle shafts on that carb??
Know I had that problem on a 305 w/CCC carbs - replaced 3 times in 230k miles, but the older carbs had better metal!
Seems stiff return springs wear them out.

69442C

Those were replaced by Sparky when he rebuilt/restored the carb. And the problem exists when I use another carb too.

This is the kind of stuff that makes drinking look like a good idea!!

ah64pilot

Do what you said you were going to do, change out the intake manifold and see if it gets better. It could be that the one you're using was cracked somehow.

69442C

Thanks for the input on the cam. I wasn't sure if that would be causing it and you, having used one, eliminated that concern.

ah64pilot

Yeah, no way that cam would cause that. I have run that cam in EVERY 455 I've built, except this last one. I've never had vacuum issues with it, in any of the 3 engines I've put it in. Brakes worked great, vacuum secondaries worked fine...no problems at all. Assuming you haven't missed something obvious, I would try swapping intake manifolds to try to isolate the problem.

69442C

I'll try to swap that intake this weekend. Hopefully it's not in the 3 digits for temperatures, like we are close to today.

gregvm

You disconnected everything vacuum? Including PVC and vac. advance? Vac advance would retard the ignition timing at idle. Sooty plugs could be OIL, not gas. Sucking oil from UNDER the intake into the runners, where the starting fluid test wouldn't show up. If you've milled the heads/block, that can cause mismatch on intake to head angle.(did you have any trouble starting the intake bolts?) To have that low of vac, you have a pronounced leak. If you remove the intake, and if the intake runners on the heads are oily....there's your problem.

Greg

69442C

Yes, everything that could use vacuum was disconnected. The vacuum advance is ported so there is no vacuum to the advance unit at idle. When I re-sealed the intake several weeks ago, the bolt holes lined up perfectly and there was no issue installing them.

I removed the intake today and have the incorrect 1970 intake installed which will do just fine for test purposes. Although this means I will need to do another intake swap. The intake that was removed did have some residue on the runners as did the heads and it was a black soot like was on the plugs and is also showing a little on the tail pipe tips. So this seems to tell me I had combustion gases in the intake runners. The only way that could occur in my mind is if it was sucking air from the exhaust cross over passage. I had the car jetting really rich which was showing in the combustion process but that was the only way it would idle. Odd. I don't think raw fuel would leave any black soot and I did not have any back firing with this motor. So I'm cautiously optimistic that I may have found some proof that there may have been an internal issue with this intake. I looked it over but didn't spend a lot of time on it and I didn't see any cracks but if there is one it may be in a place where I can't see it. I have everything bolted back together but I didn't run it as I ran out of time as we took my daughter out to dinner for her birthday. I picked up a set of 70 jets yesterday for the carb and I will put them in tomorrow morning to get back to the original set up and then will start it up to see what I have. Keeping fingers crossed.

CQR

A couple more thoughts on this. You don't say how it runs at cruise or what your vacuum is there. So these are things that pop into my head.

1. restricted exhaust. (not likely but it will cause a low vacuum at idle and especially at cruise RPM.)

2. Valves holding open when running.(had this issue on a ford 302. the block was decked and ended up having to install shorter pushrods.) (motorworks replacement engine.) had extremely high HC and CO at idle, also ran fairly ragged at idle and surged at cruise. Compression showed good, but as soon as it ran the lifters pumped up a little and held the valves open.

69442C

Good thoughts and I also had explored your second thought. The engine builder set the lifter pre-load with a dial indicator and says he went on the lower end of the range. But just to see, I marked the adjustment nut and backed everything off 1/4 turn. All that did was give me a valve tap. So I put things back where they were.

The car is a restoration project and is not roadworthy at this time. I wanted to make sure it ran OK before I installed the front sheetmetal. Good thing as I wouldn't want to be hanging over nicely painted fenders trying to fix this problem. There is no heat riser on the drivers side manifold and the exhaust flows well out the tail pipes.

Thanks anyway,
Brian

69442C

Well, the manifold did not solve the problem. Double checked the installation with starting fluid to make sure the turkey tray seal wasn't leaking and it is fine. At this point, I want to try another carb and one that I know is working correctly. The other one I tried was an old one that came in a pile of parts and I just threw an accelerator pump in it, cleaned it a little and threw it on there. In speaking to a friend today, he has a friend with a 68 442 who just had his carb redone and he told me that car runs great. He said he was certain the guy would allow me to use his carb to see if it would make the car run correctly. That guy is on vacation but will be home at the end of the week. Hopefully I can get it one day next weekend and see what happens.

When I look into the my carb with it idling (poorly), I can see quite a bit of fuel coming out of the nozzles or venturies. I really don't think it should do this. My fuel pressure is 5 PSI (probably a little low) and I pressed down on the power valve with a small rod with the car running (as suggested by Sparky in the past) and it is down. So it seems to be putting a lot of fuel into the engine. But what is strange is when I cover a good portion of the primary side of the carb with my hand or partially close the choke, the engine smooths out and vacuum goes up. I guess it could be something really goofy with this carb and trying the one from the other guy's car will let me know.

In the meantime, I guess I'll work on the interior.

mmcilroy

I've been struggling with the exact same problem for the second summer. If you find the problem or have any updates I would love to hear them. Cliff Ruggless had me open some passages and it gave me a slight improvement but still only 14" (max) of vacuum at a 900 RPM idle in neutral, 5" in gear at 700 RPM. just need a "little" more and I think things would be good.

69442C

What cam are you using? Is your engine basically stock or what is differnt from stock?
Brian

mmcilroy

Here's what I have in there.

Block - 1972 - 350 Bored .030
Heads - 7a Heads, measured in at 64cc
Sealed Power L2321F Pistons (.076 x 2.44 dish, 5.8cc's?)
http://www.flatlanderracing.com/trwolds.html
Cam - Compcams XE268H with matching lifters, roller rockers, springs and push rods
http://www.compperformancegroupstore...DSCAMHydFlatXE

My compression readings were almost exactly the same as yours. I have double, and triple checked everything. Rebuilt, replaced carb(s) and intake manifolds at least 3 times. I was thinking it was my cam but others have said I should have higher vacuum and comp cams tech support says I should be at a min. of 16".

69442C

Oh boy. This is all too similar with the exception that I'm working with a 400 motor. This isn't good news.

69442C

Today I was able to meet up with a guy who has a 68 442 with a 400 motor. His car is stock with 44K miles on it. He just had his carb rebuilt and we ran it and it ran very well. I recorded 17" of vacuum at roughly 700 RPM. I installed the carb I have, that was restored/rebuilt by Sparky and it made the car run poorly. In fact, it ran the same crappy way it did on my engine and it caused the same 13" of vacuum and a rough idle. No amount of adjusting would make it work any better. The exhaust smelled bad and it would also cause our eyes to burn. If I partially closed the choke or partially covered the primary section with my hand, the engine would smooth out, vacuum would increase and the exhaust smell/eyes burning would go away.

So the good news is I am now confident the problem resides within the carb. It's already been back to Sparky once and he tells me everything is perfect, which is obviously not the case. So tomorrow I will take the carb to the shop that rebuilt the car for this guy with the 68 442 as he says many local people use this shop and all have been very pleased with the results. Hopefully, I'll be able to say the same. I'd give Sparky another crack at it, but I would lose about 3 weeks in doing so and I'm not willing to risk losing another 3 weeks. The local shop can turn it around in a couple of days.

501Paratrooper

Glad to hear it's the carb and not something major, I've been watching this post as my 400 is being rebuilt now.
Good luck on your resto.

69442C

Thanks. I was quite pleased but at the same time disappointed to find that the carb was the problem. I've lost a lot of weeks on this issue and I spent a lot of money getting this carb restored so I wouldn't be going through this. I'll be interested to see what this other carb shop says.

If I can get the engine running correctly, I can move ahead and hopefully get this car done in another month or two. I was able to drive it out of the garage a couple of weeks ago and this was after 5 years of work (photos attached). It's an original special order Nugget Gold color and I don't recall ever seeing another '69 Cutlass or 442 in this color. I doubt many were ever ordered this way which makes it very unique. Add the fact that it's a conv 442 with factory air and I have to believe this combination wasn't produced in much quantity.

501Paratrooper

Looks good, I've never seen that color either.

oldcutlass

Your carb is not dropping back into the idle circuit!

69442C

You're probably correct as this would explain the lean condition on idle and the lack of adjustability. Hopefully this local shop can get me squared away. I suspect an incorrect gasket or something is blocked.