Yes, like so many others, got several irons in the fire right now. Long story short, been fighting with overheating and low vacuum on this rebuilt Olds 350 almost since day one. Traded this engine for a motorcycle, early last year. Yes I've looked at ALL the obvious stuff. I'm a master auto tech for a living, but this one has me really scratching my head. Facts! Rebuilt 1973 Olds 350 Cutlass engine TH350 Trans Properly broken in by me Good oil pressure Good compression and leak-down results. (no bubbles in radiator) OEM style radiator tested by reputable local shop (15" electric fan running all the time) (Cannot use stock mechanical fan, because of close fit.) New "Hi-Performance" water pump goes to 200 degrees and beyond, within about 15 minutes of running. Barely achieves 15inhg of manifold vacuum. Engine cranks right up and actually drives decent. So... The question is, can retarded cam timing be causing the low vacuum and overheating?? Dammit Man, already not happy removing intake to inspect a motor that was supposed to be ready to go. (I'm done talking with the guy I got it from. He didn't do the work and is almost clueless. Machine shop is out of business too!!) He claims the cam timing was checked by the builder. Bought this car to fix and flip and so far, it's been nothing but a headache. Honestly would have been better off going late model LS route, even though it's not old school. Help!! JT
How much vacuum does it have,crank some timing in and see what happens.The 390 cad I just helped guy with was doing the same thing,the dist wasn't hooked to manifold vacuum as recommended was yours?
Let's see more pics of that electric fan set-up. 8 times out of 10 an electric fan is the problem, not a solution....especially with old, lower fin count radiators. Many electric fans are just not enough, either not enough wattage in the fan motor for enough flow, or not enough radiator coverage. If it is installed as a pusher fan, that doubles it's ineffectiveness. You can degree the cam off a pushrod tip, no need to tear the engine down for a check like that.
using a vacuum gauge, I cranked almost 18 degrees of initial timing into this to try and increase vacuum and decrease engine temp. Didn't help. Also idle vacuum varies from 10-12, (taken at intake runner) which is also affecting the performance of the Quadrajet carb. Seller told me it was a mild "RV" style camshaft.
Good thing he put a “mild RV cam” in. Better start with some lift and duration measurements. And check TDC with a stop and make sure the timing ring hasn’t shifted on the balancer if that can happen on an olds. I’m inclined to blame the overheating on the fan/radiator combo, and the low vacuum on camshaft, not necessarily related. The other easy thing I might check is the exhaust manifold temps with an infrared thermometer during warm up. Those shouldn’t get very high at idle unless it was really retarded.
An RV cam is probably hydraulic and you won't get accurate readings with a lifter that has oil in it. Those are are .842" diameter, so get a solid lifter, chev. or Pontiac or olds, measure at the lifter with dial indicator, 360 degree timing tape on balancer, and a cam card with exact opening and closing specs. Otherwise a guessing game. You need the exact specs or pull cover. I am not a fan of unilite distributor to many module timing problems, if the cam timing is way off, compression test should give you a clue. Yes cam out of time affects vacuum and temp. Your vacuum should be 18" +. Try more advance 30 degrees, if engine still cranks fast enough and you pick up vacuum your on to something, maybe an HEI swap if doubts about actual timing out of the Mallory unit.
From the front pad the block is a '68-'70 350. What number is on the cylinder heads? On the driver side look below the leading head bolt in front of the spark plug, it may be partially blocked by the Alternator bracket. #5 through 7a heads are the best, these are heads from 68-72 with 64cc chambers From '73-76 #8 heads were installed, they have 79cc chambers. I prefer GMB pumps, they are(or were) good castings 130-1260. And the Hi-Performance model was AL, 130-1260P. Flow Kooler sells the same pump for thrice the price They grind off 'GMB' and put their sticker over it. Looks like you are using the original mechanical sensor. Verify that the sensor is NOT touching the floor of the coolant passage, it should be in the coolant flow and not touching the floor. If it does it will be reading closer to engine OIL temps not coolant temp. Intake looks like a factory 'A4' aluminum intake, which should be fine. There should be cross hatches and A4 prominent in the valley between the front coolant crossover and intake runners. You must use the proper turkey tray 'valley pan' gasket for the intake manifold. There are three, if not four, different 'normal port' valley pans. If your intake is an A4 intake you will need the valley pan for an '80-84 307. Using the appropriate sealant for the intake and water ports? Typically, RTV doesn't work that well(i.e. long) and if the surface has a hint of oil the rtv will not seal. It is a PITA as the turkey tray needs both sides sealed. Just a dab to 'wet' the tray around the ports. Gasgacinch works for intake ports if the manifold and heads are flat. I don't recall anyone using copper spray gasket for the valley pan. It just makes a right shit of the the installation and won't seal proper. Will also need to recheck the intake manifold bolts after ~500miles. They tend to back out. Original bolts/thick steel washers work pretty good as the washers are thick and soft enough that the bolts bite into them and deform. Need to flatten of flip the washer to make them effectively usable. If the manifold is an Edelbrock Performer(EGR), the port surface on these were never good and requires a machine shop to clean up. Valley pan won't seal regardless of how much goop is put on. Verify EGR block off plate is sealing. Foil type gasket is the best, some of the thinner paper gaskets don't seal. Can create an exhaust leak, intake leak, or both. One of the things I love, and hate, about the SBO is they run so damn smooth. Even when they are running like absolute ass they still run smoother than some other brands that are perfectly tuned. You know it. Retarded timing will more heat into the engine/exhaust rather than making power. Timing should be in by 3Krpm. 34-38° depending on CR and what the engine likes. Base timing on the low compression '70s engines was 20° @ 1100rpm. If you do have #8 heads, go with this as your initial. This isn't a Chevy, 6° at idle is not the Olds way. Unless its a 10.5:1 CR from a 'W' car. Screw what anyone else claims. Everybody lies. Verify. Get that timing gun on the balancer and verify where your base timing is. There were a few different SBO dampers. Verify your damper ring is correct and has not spun. At worst pull #1 plug and do ye olde finding TDC with a spark plug stop make your marks and find TDC. Rocket engines timing sprockets should have the dots on the timing chain set in both the 12 O'Clock position for #1TDC. If they are dot to dot then it will be on #6TDC. An Olds will run with really screwed up timing. Ford Windsors won't and Chevys will make a lot of noise. Olds, it will run... I know from experience Verify plug wires are in the correct order, and Olds rotor goes counter-clockwise(unlike Chevy).
Mad Mike, been a professional mechanic for over 40 years, used to own my own garage, back in the 80's. We worked on a ton of Oldsmobile engines, and being a Diesel shop, even did countless gas conversions. Anyhow, thought I knew these engines, until now. Always willing to learn something new...especially from someone with your experience. How about if I buy you a plane ticket, to sunny Florida, to come help me figure this out. LOL
UGH!! Looks like I'm pulling the front cover off this engine in the near future. Absolutely committed to fixing this and not just pawning it off on some other sucker...like he did. This engine was actually supposed to go in HIS 1951 Oldsmobile, but he decided to go Mustang II and LS route, so he listed engine for sale/trade. We traded a half-restored Honda Dream motorcycle, just needed final assembly. Think he got the better end of the bargain. "Rocket engines timing sprockets should have the dots on the timing chain set in both the 12 O'Clock position for #1TDC. If they are dot to dot then it will be on #6TDC. An Olds will run with really screwed up timing. Ford Windsors won't and Chevys will make a lot of noise. Olds, it will run... I know from experience "
I've fallen to the fault of being familiar with something/subject and not looking at a given problem from a normal diagnostic angle. Being too familiar has it's pit falls as 'it is NEVER this/it couldn't be this/no one would do that'. Hard to be unbiased when dealing with familiar territory, but when someone has had their paws on it, start fresh. Get back to basics. Lets not be too hasty just yet It's probably something super simple that just needs to be verified. I've done many a 'D'oH!' in the garage when I realized a simple error, usually from glazing over a common non-issue that is an issue. In my 1A.M. ramblings I didn't finish my thought. With the intake already off, you have access to the valvetrain already. Find #1 TDC. Find it using a piston stop, forward, then backward, make your marks on the damper, divide it in half and see if the damper mark is correct. With TDC found, now find #1TDC on the compression/power stroke via cam timing. Watch the lobes, and verify the lifter is on the base circle for both IN/EX for compression/power stroke. Mark the base of the distributor where #1 tower is, and pop off the cap. Where is the rotor pointing? Is it within a couple degrees you should be OK. Rotate engine to line up damper TDC mark with base timing mark. If the tab is an older tab that only goes to 12° mark, find the 10° mark, measure that distance from 0°, double it and make a mark on the damper that will allow you to use the 0° mark as your 20° base timing mark. Look at the rotor, rotate distributor housing to line up #1 tower. Rotor should be pointing to #1 tower. Base/initial timing is now set. Can verify this when the engine is running using an adjustable timing gun. If it's facing the wrong way, then you know whatever goober setup the engine did dot to dot on the timing chain and then stabbed in the distributor 180° out and gnarfled the garthack. A simple re-clocking should get you back. If the distributor rotor is pointing in the correct direction, inspect its condition. How are the flyweights? What kind of springs are used? Are there springs? How are the bushings for the flyweights? Check that the rotor easily moves(advance mechanism) by hand and returns to 0° advance. Verify any an all fasteners are properly tightened. Story time. Dozen years ago I was helping an older neighbor with their OT '76(?)Buick Park Avenue(403 Olds). Hard to crank and start but when started would not idle down. Made for a peppy Park Ave. Believed what she told me that her mechanic of 20years gave it a full tuneup after replacing battery and starter(!). Stuck the timing light on and was chasing timing, a bit erratic. Probably spent a good hour on it before simply popping the distributor cap. Someone had removed the advance weights, hooked the advance springs up to allow some movement on the timing plate, but the rotor was mostly locked in full advance. Distributor, mechanically, was trashed. New/rebuilt HEI and it ran silky smooth. It was a lesson in 'Trust but verify.' Never found out the true story, mechanic had retired, a son or grandson was also involved before it showed up at my door.
Hey Fellas, it's been a long time since I posted anything about this issue, because took me this long to figure out. So as of a few weeks ago, got the Olds engine all back together and running great...almost. As some of you and ME suspected...the cam timing WAS retarded by 4 degrees (only option I had, using the crank sprocket with 3 positions) Since we last spoke, I did a deep dive into this engine, going as far as, removing the cylinder heads to inspect for coolant passageway blockage and removed the camshaft. Found a number on the back of cam and matched it against a similar "RV" cam listed on Summit's website. Using those specs, I determined the cam timing to be at least, 4 degrees retarded. After waiting FOREVER for parts from a certain OLDS Hi-Perf shop in California, installed the cylinder heads, advanced the cam 4 degrees and performed a compression, whilst leaving front cover off, for access. Sure enough, all cylinder compression jumped from 140psi avg, to almost 170psi avg!! There was the clue I was looking for!! Long story short, finished assembling the engine adding Mondello's heat riser intake block off plates to intake. Also swapped a known good Edelbrock carb. Had to crank up ignition timing to around 32 degrees with manifold vacuum plugged in. Bottom line, engine purrs like a kitten, has 20 inches of vacuum at idle, starts with the touch of a key AND never goes above 200 degrees. (wound up reinstalling original radiator and 16" electric fan). Still want to retrofit the aluminum radiator I spent $300 on and a fan shroud. Pretty sure that will bring the temp down a bit. Been driving this ole girl all over town and it feels so good. Finally!! 3 1/2 years in the making. Unfortunately, she has to go up for sale. Can't afford to keep it. Working on a few last-minute details then will post on the Hamb marketplace. Thanks again, to all whom commented on this thread. JT
Honestly on the "hi-perf" water pumps..... nearly every vintage rod and muscle car I've worked on with overheating issues had one on it. One 49 Chevy I worked on I pulled the supposed hi perf pump off and replaced with a regular replacement and temps dropped. I put hi perf water pumps in the same category as flex fans..... gimmicks lol
Greg, only have a 2 garage and it’s full of 2 dream cars. My 1969 Nova SS 350 4 speed, that I bought at 16…fully restored. And a 1939 Ford Std Coupe Hot Rod, gifted to me by my late friend and mentor, whom actually helped me get the Nova as my car. Plus, daily driver is a 33 year old Volvo 740 wagon that needs periodic attention.
Thanks for letting us know what fixed the problem. So often the OP never posts the fix and leaves us all hanging. Plus it may help someone else with a similar problem. Good job.
It would be interesting if the occasion arises to have the stock OEM and HP water pumps on the bench at the same time. Over the years magazine descriptions of stock pumps, OEM pumps for AC equipped cars, HP pumps etc have sometimes listed conflicting mechanical details. Larger Ø impeller, impellers with more, fewer or alternately cut down vanes. Impellers with backing plates/shrouds. Pulleys/sheaves sized to speed up or slow down pump speed. Probably housings with differences in "cut water" length and locations too. I would not be surprised at all if there are big differences between OEM and aftermarket replacement-in-kind pumps.
Good to see that you got it figured out and running right. I've run more rigs with 350R Olds engines than I can count including the 51 Merc I had for 32 years and put around 100K on with 72 350R . They will still run with a sloppy timing chain until all the plastic teeth on the original gear fall in the pan. Not well though. I've got one out of a 76 Seville stashed for a future project that will never happen in my lifetime.
I've always run stock water pumps, but recently, used a FlowKooler cast iron pump on my SBC and have been astounded at how cool it runs. They will be a part of my builds moving forward for sure.
D'oH! Glad to see you got it sorted. One of the sucky things in our hobby when working with unknown parts, an unknown cam is the biggest 'gotcha'. SBC pumps are are capable of this if the impeller vanes are straight due to the straight ports and divorced(from block) housing. 'Newer' engines use clocked/angled feed ports for improved flow from impeller rotation, angled vanes to improve low speed flow, and the backing plate is usually part of an integrated wp housing/timing cover.
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