Hello, here's a quick backstory of where I'm at with my 85 Delta 88. I'm trying to get the fine tuning done so I can use her as a daily driver. I think I'm almost there in the home stretch but my mechanic buddy that I grew up with is no longer in the area so I'm on my own figuring things out. So I apologize in advance if I'm asking rookie questions but I'm in the need of someone that actually knows what they are doing, lol.

Here's a video I took today

2015 I got the car with a blown head gasket and seized piston
2016 I bought a 307 SBO short block from a closed up machine shop that the customer had never picked up. It came out of an 80s cutlass apparently. It was bored .060 over. Also came with 7A heads.
2017 - 2020 Collected parts assembled engine and installed

I bought a mild cam from jegs, edlebrock 600 with electric choke (adapter plate and spacer), electric fuel pump, HEI distributor, removed smog pump and equipment, removed compressor and condenser, currently have the heater core bypassed, relocated alternator to passenger side (still need to get a 47.5" belt, 48" is too loose, 47" too tight), cast reproduction headers from a company in PA that makes them with out the bypass pipe.

As of right now it runs, idles but overheats (I think) after idling. I'm also getting a carb backfire when giving it quick throttle.


After about 10 minutes of idling it'll creep up to here, run rough and die. I just changed the t-stat to a 160 today but I'm still having this issue

I'm not sure if where I mounted the probe for the temp gauge is a problem and getting a higher reading?

This is as hot as it got after shutting down. Not sure if I should be worried about anything being damaged at this temp?

Here is my fan setup, I'm thinking of going electric fans. Not sure if this will help

The alternator belt looks to be riding low in the pulley. I'm going to buy a new one and see if that helps along with the shorter belt.

temporary $8 coolant reservoir from auto zone working well
video of overflow while gauge is reading 250


Any thoughts of where to start to fix my carb backfire and overheating issue?

My thoughts are to get a pressure regular and gauge on my fuel line between the pump and the carb. My buddy said he wired it to the ignition so when I turn the key it comes on, I think it stays on while running. I'm not sure if this is an issue but I'd like to dial it into the 6.5 that the carb manual is calling for. After that I'm not sure. Might be that the gas is old too so I'm going to fill up a fresh jug and put it in. Let's hope it's that simple, lol.

As for the overheating I'm thinking to remove the mechanical fan and install electric fans. I like that they run after you turn the engine off. I really don't know if this will solve my issue. I'd like to realistically drive this every day but I need to straighten these issues out first.I should also mention that the radiator, hoses, and water pump are new along with the thermostat.

Any advice would be greatly appreciated.

 

My thoughts:

Flex fans suck. They don’t move enough air for a street driven car. And you don’t have a fan shroud.
Get a factory thermostatic clutch fan and a shroud. The GM engineers knew what it they were doing.

Backfire on throttle blip sounds like a lean condition to me. Maybe a vacuum leak or accelerator pump issue.

Coolant temp will climb after the engine is turned off due to no coolant flow and fan not running. Don’t worry about it.

 

I thought the black cover was the shroud?



I went to check my spare engine from a 83 Delta 88 and it's got a 4 blade fan with no clutch it appears.

Will it work with the 4 blade fan and buying a clutch https://www.rockauto.com/en/moreinfo...215087&pt=6812 ?
When I look up cooling fan for my year car a lot of different results pop up. I was wondering if something like https://www.summitracing.com/parts/o...ake/oldsmobile or https://www.summitracing.com/parts/o...ake/oldsmobile may work better than the 4 blade?


I will have to check for vacuum leaks. The carb does sound like it's sucking hard but I'm not sure if that's just the electric choke

 

Sorry I didn’t see the shroud in the picture.

Running warm at idle could be not enough air flow (fan issue) or retarded timing. With a GM HEI the initial should be around 20 degrees.

Electric choke would not cause any difference in sound vs a hot air choke.

 

Okay so I'm thinking https://shop.advanceautoparts.com/p/...323/10029299-P and https://www.rockauto.com/en/moreinfo...215087&pt=6812

Is it okay to go severe duty with the fan clutch or should I get another style? Also do I just bolt the fan to the clutch then the clutch to the water pump / pulley? Sorry if this seems like a silly question, I just can't seem to find any diagram of how it all goes together.

 

Back fire through carb on fast throttle is called Lean Pop, caused by a vacuum leak or more often than not old gas. Put some new highest octane gas you can easily get and a bottle of octane boost. AS for the over heating, I would start by flipping the fan around the right way so the bent part of the blades is on the back side. And for sure get a shorter belt on Alternator.

 

You do realize this fan is on backwards, right? In any case, remove that POS flex fan and throw it as far as you can. Get a factory clutch fan.

 

Good catch Joe, yeah that fan is backwards, no doubt your issue. Try flipping it, if it still gets too warm, that 4 blade moves a lot of air, they out perform the factory 307 5 blade clutch fan.

 

Huh? The factory clutch fan moves substantially more air than the four blade fixed fan. Fan CFM is directly related to blade area and fan RPM.

 

Talking the 5 blade version, not the 6 or 7 blade fan, Joe. I know a guy who actually got his 403 to run cooler with one. It was a 85 Buick, originally with a 307. The car ran 13's in the 1/4. He had replaced the clutch, still ran too warm his liking, I think like 215. The 4 blade fixed it, never above 195 after. Circle track guys prefer that fan, probably because it can't fail and cools surprisingly well. It cooled my 350 great, even with a scaled up 2 core Copper Brass rad, never got above 195 without a shroud. It is a big power killer being a direct drive fan without a doubt. A 307 is easy to cool, I have only ever one overheat due to a water pump that had a front bearing explode. It sure is better than that flex fan.

 

Anecdotal "proof" is not proof. People who have never hit a deer swear that this "proves" their deer whistles work. Circle track is not idling in traffic with the A/C running. Obviously a race car wants the highest reliability possible, but race car equipment rarely translates into "best for street use". People run Powerglides in their street cars because that's what the drag racers use. That's about the last trans you would want on the street. In any case, I've owned five 1980s 307 cars, all with A/C and stock cooling systems. Never overheated even in hot, humid mid-Atlantic summers. I would never use a stock four blade fan. Common sense should tell you that if a fixed four blade fan cooled acceptably, GM wouldn't have incurred the cost of using a multi-blade clutch fan on these cars.

 

Joe, try that 5 blade on a 403, it doesn't cut it, it didn't on mine either. Maybe Frank got a bad clutch, I replaced mine as well, almost no difference. Pretty sure GM put the 5 blade on the 307 because the small bore is easy to cool and it saved money over the 6 blade. God bless their bean counters. That 4 blade will cool that 307, no problem but will kill power, not a lot to spare on a 307. Heck even the flex fan will probably cool that 307 just fine, not hard to cool. Agree to disagree, anything much above a 307, the 5 blade doesn't cut it.

 

Thanks for all the input fellas, yes definitely my dumb dumb mistake of having the fan on backwards... haha. I did put it back on correctly, still crept up to 230 at idle. I'll try to put my big 4 blade fan on today. I'd still like to get the stock clutch and fan on.

Any preference for 5 blade vs 7 blade? I was messing around with my 94 2500 with a 350 TBI in it yesterday and noticed it has a 5 blade fan with clutch. Would this work? Finding a car with a small block olds at a junkyard is about unthinkable in my area, but would any GM fan / clutch combo work and what should I look for?

I got some 93 octane gas, added a thing of octane booster along with some lucas fuel system deep cleaner. I'm still getting a lean pop with quick throttle blip and also if I give the throttle too much. I'm not sure if I tuned the carb right, the manual said to turn the screws all the way in and then back them off a turn and a half until it idles lean as possible. I tried to richen it up but was still getting the carb backfire and instead of stumbling and returning to idle it seems to die instead. With it running lean it'll stay running but just has the carb backfire if you hit the throttle too quick.

Also, I was looking for a replacement water pump and crank pulley. I cannot find any marking on my pulley. It's unlike any type of water pump pulley I've seen for an olds and I'm wondering if it's the wrong one and may be why I'm having trouble with the belts. It's a 3 groove pulley and the outer most groove (radiator side) is larger diameter then the other 2 groves that are the same in size. Every replacement 3 groove pulley I have found has the same size groves or the outer most grove is smaller. I'm not even using the third groove so I'm wondering if I can buy a 2 groove that will work or if I should keep the 3 groove setup in hopes that everything will line up perfect. I figure I'm going to have to redo the belts again but the alternator belt just riding way too low in the pulley groove and I'm wondering if that's because it's worn? The pulley on mine looks like the outer most grove has the diameter of a KN stamped pulley but the inner two groves look to be KK style.

Everything is kind of a mess with this because I had the car, a spare rocket 350 from a 70s cutlass, a ton of extra parts that came with it, and the freshly machined and assembled 307 short block bored .060 over at my buddies shop. The original engine with the seized piston and head gasket was taken out and accidentally scraped before i got any accessories off. I ended up buying a spare 307 from a 1980s delta 88 for the brackets that came stock as it was cheaper to buy the whole engine with everything then a few brackets. It's been a great learning experience, I look forward to driving this car for years to come. I just gotta get these last kinks worked out, almost there!!

 

More blades will move more air. Are you sure the thermostat is opening? The last time I had a car that the temp shot up like that, the t-stat was stuck closed. New doesn't mean it's good.

 

Your truck fan is a reverse rotation and a different fan hub pattern, so it won't work. A 6 or 7 blade clutch fan was Olds heavy duty fan option. That 70's Olds 350 is a better motor choice than the current 7A 307, if it is a good runner for your heavy Delta 88. Try the 4 blade but even that flex fan should have ran cooler than 230 degrees. Make sure you have good flow through your top rad hose and thermostat is opening as mentioned.

 

Yes, when I start, temp climbs to about 190 on my gauge, t stat opens, drops back to 160. If I'm cruising it'll stay cool, after idle it seems to stay at 190 as long as I don't idle too long. This is with a 160 t-stat. The previous was a 195 and it would creep up to about 210, open, drop to about 190 and still stay around same temp driving around after idle. Even after it idled to 230, I drove it around and it dropped back down to 190. It's partly the reason why I'm wondering if the aftermarket temp probe is reading a bit higher since I put it on top of the intake. Not really sure though.

 

I've seen the 6 and 7 blade repros. I'll grab one of those and the clutch.

I got the 72 350 rocket for a deal. It was sitting in a guy's garage from the 80s for a project. Eventually I'd like to build it up and drop it in. As of right now it's completely disassembled. Good block and heads though.

The flex fan appears to be a much smaller diameter so maybe that's the problem with it. I'll double check t-stat and hose as well.

 

Get a temp gun, I had an aftermarket gauge read 10 degrees high. You don't have enough air flow at low speeds. That means the fan isn't pulling enough air. A shroud is a good idea, had one stock to help direct air. There are also factory flaps that direct air through the rad, not around it. Try the 4 blade and go from there.

 

Thanks I have a temp gun, where's a good place to point it to get an accurate reading? I do have the stock shroud on. The AC condenser coil is still on there, I think I'll remove that as I have no plans of AC atm. I don't think that'll fix the problem alone but may help. The 4 blade fan seems much bigger in diameter so hopefully that'll make the shroud more useful as the flex fan is small

 

That four blade fan shown above is bent and should not be used. Do not try to straighten it as it will be out of balance. I recommend using a quality HD fan clutch and seven blade fan. There're are el cheapo clutches that leave much to be desired and should be avoided.
The accuracy of the temp gauge has been questioned in prior posts. Although proper calibration is important the boil over shown in the video leaves no doubt to me the engine is overheating.
The camera moves too quickly for me to study this in the video but is the water pump turning fast enough? You have a mix and match pulley set up. I wonder if this is contributing to the idle speed overheat. Is the water pump impeller intact/not damaged? I know there are several different pump shaft lengths and impeller sizes. Is the installed pump the correct one for this application/pulley set up?
Another and larger concern of mine is that this engine however new it may be has been overheated so many times that there may be internal damage. ie: blown head gasket(s), a cracked cylinder block or cylinder head(s), scuffed pistons, etc. No fan/clutch, shroud or thermostat will help if any of this conditions exist. If this job was in my bay I would want to perform a compression test, a leak down test, and a cooling system pressure test (looking for internal coolant leakage) before going any further.
Best of luck, please keep us posted.

 

Post a better picture of the 4 blade fan.

 

Thanks yes the fan is very bent and I decided to find the proper fan/clutch combo before attempting to run it anymore. It's only overheated 3-4 times which I know is not ideal but the coolant looks clean, oil looks clean, exhaust has no smoke or vapor. I'm just gonna hope for the best and keep trying. I really don't know if it's the right water pump or impeller. I do know that it was bought new and put on by my mechanic buddy. It measures 6 inches from the base of the pump to pulley so I'm assuming I have a 6" pump? Also I wouldn't put it past my "buddy" to have cheaped out on the radiator. Maybe it's too small? I really don't know how to tell what size it is tbh.

Here are some pics I just took. I found an "LT" marking on my water pump pulley. I also took a better picture of my top shroud cover while it's off from the back side to see if I'm missing any pieces. I removed the condenser coil for better airflow (hopefully)

I'm still fuzzy on how to get the proper pulley / belt setup going on her.


setup from the top with the top fan shroud removed

top half of fan shroud

stock 4 blade has about double the "depth" as the flex fan



fan is very fan sadly




"LT" Mark on pulley



water pump

no more condenser coil

 

Your 4 blade is supposed to be bent, moves more air due to the bends. Here is my factory 70 fan.

 

The blades are pitched to move air. My concern is the length of the blades end to end are bent as the OP shows.

 

If you are talking about the curved ends, that's how they were made.

 

No not the curved ends, not the twist that makes the pitch. Bent as the OP shows in-his pictures.

 

It looks right to me. It has bends are over the blades with the ends curled up on each blade at the ends.

 

I ended up finding the stock 5 blade fan and clutch on ebay for a decent price. The fan looked like it was mounted backwards how it came but I figured it would try it and if it didn't cool, I would swap it around. It ended up being orientated correctly as my cooling issue is now fixed! I get a consistent 160 while driving and it won't go over 190 even after idling for 10-15 mins. Thanks for all the advice. I ended up backing the left screw on the carb about 3 full turns and it's seemed to fix my carb backfire issue. The video I took of me driving it was before I backed out the adjustment screw. I had a backfire from take off, I think it was just running a bit too lean.

The fan shroud was rubbing at the top so I made some spacers and got longer screws. Even with the top of the shroud off she was staying much cooler.

I was hoping to take her through inspection tomorrow but my horn isn't working right. It was weak before and worked kind of intermittently so maybe it's a ground issue? Worse case I can replace it quickly. I'm looking forward to putting some miles on her now.

Here's some pics and videos, now to get everything else fine tuned. My window motors seem weak. I'm not sure if I should just replace the motors but the window belt dressing gaskets are all bad. Does anyone know a good source to get these?

Thanks for all the help.

 

Now you see how useless the flex fan is? The 307 isn't hard to cool, glad to see it is fixed.

 

Useless indeed! Just another thing I had to buy cause of my mechanic "buddy". When we pulled the old motor he scraped it and I was pissed because I wanted to get parts off it. He said "I'm only putting new stuff on there, all that old stuff is junk". Well the OEM fan was just another thing I had to buy. Bought a whole spare motor because of all the brackets etc I needed!.

I guess those engineers at GM knew what they were doing, even in the 80s!