73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: eastalan315 on October 24, 2023, 05:54:57 PM
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I have 1987 v10 that I’m in process of restoring with my son. Appears that at some point there has been a different engine installed so I’m wondering if anyone can help me identify what it is so can get like new gaskets and belts for it.
Thanks in advance.
Alan(https://uploads.tapatalk-cdn.com/20231024/0831f2a71631705efaad9998101aee96.jpg)
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A search for GM Engine Casting Number 3970010 on the interwebs indicates that is was used from 1969 to 1979 on 327 and 350 SBC with either 2 or 4-bolt mains. Are the stamped letters and numbers still on the front passenger's side pad?
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Here is some pics of other markers on the block. Although don’t see any on passenger side. Thanks Alan
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(https://uploads.tapatalk-cdn.com/20231025/ac71299291648eace3f61235c9e74fa3.jpeg)
(https://uploads.tapatalk-cdn.com/20231025/8d721479a5ed5a3aadd1c6137358b3f2.jpg)
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Need help with identifying the engine type in this truck. My son and I are in process of doing a restore and obviously someone along the line has dropped a different engine in this truck. Need help knowing like what belts and gaskets to order for replacement. Thanks Alan(https://uploads.tapatalk-cdn.com/20231025/6e2c09b44251f80cf4ab968eff87c748.jpg)
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(https://uploads.tapatalk-cdn.com/20231025/a1eec89a4ee2cf2fd4fad2e96814d145.jpg)
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A search for GM Engine Casting Number 3970010 on the interwebs indicates that is was used from 1969 to 1979 on 327 and 350 SBC with either 2 or 4-bolt mains. Are the stamped letters and numbers still on the front passenger's side pad?
Look on the cylinder deck pad at the right front of the engine (passenger side) above the water pump.
Edit: the engine code comprises the large alphanumeric digits stamped into the milled pad imaged below.
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What BD said. Look to the front, passenger's side. These are stamped in, so sometimes they are milled away if the block was surfaced. It is very likely a 350 and either 2 or 4-bolt mains.
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Man (per bd) that's a lotta orange... ;)
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Get the casting numbers off of your heads too. Take pictures of the oil pan. Does it have the dual or single dipstick bump out? Belts depends on what was in the truck for pulleys. Just match up your existing belts.
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Hey everyone, (I am the son of the man who wrote this post) the numbers on the front passenger side of the block have been decked off sometime in its life. I have the block casting number, and the numbers on top of the head under the valve covers. But the numbers I have will not tell me everything about the engine, like whether it’s a 327 or 350. So where else can I identify that?
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I think all you have left is the head casting numbers to get you close.
Also, per VZ, the oil bumps may give a clue.
Short of that, You could tear it down and measure the bore and stroke. PIA though.
Did it run with the belts you have on it? They have part numbers.
It may be that you have to do some detective work that the engine bore and stroke will not reveal.
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Here are few pics of the block and heads. Anyone able to identify engine size.
Also to answer question did it run before removal. Answer is yes it ran very strong. (https://uploads.tapatalk-cdn.com/20231204/bd88dc12d439404d218949283d03d554.jpg)
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Someones been busy... 8)
The main bearing caps may have been used in different size motors, so may not be as helpful.
Look like a clean and well maintained motor.
The head casting numbers will give you an indication of the combustion chamber size, that may lead you to what the size of the motor is.
While the motor ran 'strong' what is your search for the size for?
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3932442 is the casting number on the crank = 267,305,350..cast...medium journal...3.48" stroke
3970010 is the casting number on the block = ....350...69-80...2 or 4
that rules out 327, so based on the block and the crank this would be a 350 produced between 1969-1980 with 2 bolt mains.
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First of all, thank you guys for helping me identify the engine. I very much appreciate it.
Secondly, I am going to attach a picture of the main cap bearing. It has a small groove in it that will just barely catch ur fingernail when ran across it. I was replacing the rear main seal and noticed the wear lines. What is y’all’s opinion on what action should be taken based on this? I am going to remove the other caps and inspect the bearing and see what they look like.
I was just about to slap some paint on this thing and put it back on the frame because everything seemed roadworthy so far.
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(https://uploads.tapatalk-cdn.com/20231211/a21fa7626dc788bd912f532f86a88379.jpg)
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At this point I would at least use some plastic gauge to verify the actual wear.
With that data, you can determine if it's worth it to go further.
FWIW, if it ran strong, didn't smoke or rattle or clack, I would run it till things change.
If the wear is heavy, I would probably change out the bearings. I know someone is going to flame me for not suggesting polishing the crank. ::)
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Okay noted,
Is it possible to replace crank main bearings without removing the crank and removing all of the pistons/connecting rods? If so how?
I am thinking I am going to replace just the crankshaft bearings because the connecting rod bearings are still solid no play in them. So it would be ideal if I can replace the crank bearings without having to disturb the rods and stuff.
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Yes it's possible.
Pull all of the caps off, you'll notice one end of the bearing has a flange that is keyed into the block and caps.
Push the opposite end of the bearing down into the journal, careful not to scratch the crank. (stiff plastic spoon)
Once the key is exposed you can slide it over the crank journal and pluck out.
It might help to apply a little lift to the crank, careful where you apply pressure.
Slip new bearings in opposite way.
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Okay sweet, I watched some YouTube as well, and saw techniques very similar to what you just mentioned, so I’m gonna give it a shot.
Would you suggest I need to check the bearing clearances with plastigauge to ensure I have the correct amount? Or should I just check the back of the bearing for what size it has stamped on it and buy replacement of the same size and roll with it?
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Plastigauge will only show how much the bearing has worn, which would account for most of the clearance.
If you're going to change out the bearings, it's just an academic exercise.
The size/oversize will be stamped on the back.
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Okay, I checked the size and I believe it is .040 thousandth undersized.
I am going to attach a picture of the back of the bearing.
Would you agree it is .040 thou. Undersized?
(https://uploads.tapatalk-cdn.com/20231214/b29c9e14d476277df228e6bb7dd6b296.jpg)
Thanks Johnny P.!!!! And others.
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Sure looks like it!
Just as an academic exercise, which is 'undersized', the crankshaft or the bearings? ;)
When they grind the crankshaft, they remove material, making the main journals 'smaller'...
So they have to 'grow' the thickness of the bearings to make up for the difference.
.040 is referring to the size of the crankshaft main journals being 40 thousandths undersized.
Easy to get the two mixed up... ;D
Having said that, if it were mine, being this deep in it, I would do the rod bearings as well.
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Initially I was saying it incorrectly, but when I went to buy the new main bearings it dawned on me it. Haha.
I sure have learned a lot because of this engine.
Thank you for the correction on that!
I just got the new bearings installed and the motor turns over smooth as butter, so it’s Re-assembly time. And then a fresh coat of Chevy orange on her.
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Nice!
Look forward to your progress. ;)
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I’ll make sure to post some updates in here.
Most likely will have more questions too…. Haha
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Hey guys, I have a quick question…
What spark plug should I be running for my motor that we talked about above, 69-80 350 SBC..
The plugs that came out of it are ACDELCO R45T, but I am having a hard time finding those for sale.
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R43CTS
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Okay, is that one any different than the R45T? I just don’t know how to make sure I’ve got the right one.
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R - Resistor
4 - 14 mm Thread
5 - Heat Range (range 1-5, 1 being colder, 5 being hotter)
T - Taper Seat
S - Extended Tip
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Thank you
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The R43CTS spark plug runs slightly cooler than the R45T. The "C" in the part number refers to a copper core, which conducts heat away from the electrodes more efficiently than a standard core plug effectively providing a broader working heat range. The cooler plug in conjunction with the copper core reduces the propensity for engine ping. The "S" refers to an extended tip, which projects the electrodes slightly further into the combustion chamber. As long as there is sufficient clearance between the piston and the spark plug tip, which is the case with the vast majority of engine configurations barring those that use exotic aftermarket pop-up piston crowns, the extended tip unshrouds the electrodes for deeper penetration into the cylinder and improved exposure to the swirling air-fuel mixture. The swirling air-fuel mixture tends to cool the unshrouded extended tip electrodes more effectively than standard tip electrodes, while deeper penetration into the cylinder places the electrodes in a better position to ignite the mixture for more complete combustion.
The only observable physical differences between the R45T and R43CTS are the extended tip of the R43CTS and subtle differences in the masses and shapes of the center electrode ceramic insulators.
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Thank you BD,
I also have another question regarding fuel delivery,
My truck has what seems to be a fuel pump in the fuel tank cap (there is electrical connections on the cap) but it also has a mechanical fuel pump on the engine. My questions is why does it have both and which one do you guys recommend I stick with. The mechanical or electrical one? Or do I have to have both?
Thank you in Advance..
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When you say the "cap" has electrical connections, are you referring to the round flat plate with hose nipples that attaches directly to the top of the fuel tank? The original engine used Throttle Body [Fuel] Injection (TBI). TBI relies on an in-tank electric fuel pump that delivers 11-12 PSI regulated pressure. The carbureted engine that resides in the vehicle now uses an engine-mounted mechanical fuel pump that delivers 5-9 PSI, depending on the model of the pump. As long as there isn't a fuel delivery problem that is being masked by an electric pump, the engine only needs the mechanical engine-mounted pump. When the original TBI engine was swapped with a carbureted engine, are you sure that the electric fuel pump wasn't defeated and removed from the tank at the same time?
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Well I cant tell you if the electric pump was operational, but it was definitely hooked up electrically.
Maybe they left the electric pump in there and just hooked up the fuel lines to it because it was easier than finding a new way to hook up the lines to the tank?
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If the in-tank pump works, you will be able to hear it run for at least a second by standing next to the tank when an assistant cycles the ignition key ON.
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So if the electric pump does work would you suggest I use that? Or go with the mechanical?
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The TBI fuel pump produces way too much pressure for a carburetor. Although you could regulate the pressure down to 7 PSI, doing so would heat the fuel unnecessarily and possibly damage the pump, depending on how you go about it. Use the mechanical engine-mounted pump to feed a carburetor.
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Okay will do.
Will it be necessary for me to change out the fuel pickups? Or just hook into the existing nipples on the cap of the tank?
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If I were performing the job, I would use the correct fuel pickup unit for the application then reconfigure the hoses and wiring accordingly.
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Thanks bd!!
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Hey do you guys have any suggestions of the best brand to buy a full set of fuel lines from?
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I get metal and braided lines from Inlinetube.com or classictube.com
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Hey guys, question for y’all.
So we installed the engine on the frame today to give it a test run up.
The starter will just barely turn the engine over, I tried 2 different batteries and a jump pack hooked up to it. With the same results.
We removed the spark plugs and cranked it over to make sure there wasn’t anything interfering in the cylinder. After we took the plugs out, the motor turned over better but still was not fast by any means.
What is y’all’s opinion? Bad starter? Something inside the engine interfering?
Also, I switched out the main current carrying wire that was run to the starter with a good jumper cable and it didn’t help.
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Starters get tired, slow, and funky.
I bought a new battery, thought it was bad because my starter acted the same, slow funky.
New starter, (along with new battery) WOW! Fast turn over and great performance!
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Starters get tired, slow, and funky.
I bought a new battery, thought it was bad because my starter acted the same, slow funky.
New starter, (along with new battery) WOW! Fast turn over and great performance!
Well I hope that my starter is the problem..
My next step will be trying a new starter and maybe a new power wire that runs from the battery to the starter.
What gauge wire do you recommend for the starter?
Also, one of my friends (a fellow squarebody guy) recommended that I get the “mini high-torque” starter to replace the starter that I have now. What is y’all’s opinion on that? Worth it? If you have a brand that has treated you well, plz share that too.
The advice is MUCH appreciated.
Thank you
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I have always used the old Delco-Remy starters that came stock on these trucks, but have in recent years gone through a couple. I seems that this is another case of, "They just don't make 'em like they used to!" I also have headers on all of my rigs and accessing that starter is not fun. It is also pretty darn heavy. Jump to a couple of years ago when my last "stock" starter failed and left me stranded about 70 miles from home. I then bought one of the RobbMc starters and I would never buy a different starter ever again! This starter is only 8.5 pounds and spins the engine over much faster than a stock starter ever could. It also will continue to spin the engine over fast, even if your battery is fairly low. The stock starter is nearly 20 pounds and massive in size. This starter is relatively tiny and provides a lot of space to headers, even if you don't clock the solenoid to the bottom. I didn't. You will pay for that starter. They are about $300 vs. the $81 or so for a new ACDelco stock style starter, but it is made in the USA, they solidly back their product and will rebuild anything they sell, and in my opinion, well worth it to save from the hassle of replacing your stock starter frequently.
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I've been using 6449 (Lester industry number) which is what late 90's Chevy trucks used. the only thing is that you'll need a couple of Dorman starter bolts (p/n#678-107). Smaller, more powerful, and readily available.
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Thanks fellas,
Yesterday evening I switched out the starter wire for some brand new fresh 2ga wire and the starter turned over the motor as it should, so this problem is resolved for now.
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:D