'69 340 Questions

-
I just bought 440 Low miles stored inside since it was pulled. The only thing that was good were the valve covers and the crank. Never buy a motor with the heads on. I got it cheap enough. The crank was forged and std. No loss
 
GR5 said:
Hello,

I just purchased a ‘69 340 that I plan to swap into my ’69 318 automatic Barracuda. I was told it was a running engine before it was yanked out of the vehicle. The original owner sold the carb and intake separately. I was also told it has a 508 camshaft that needs to be broken in and it’s a standard bore. I’m not sure why the camshaft was replaced in the first place especially if he had planned to sell it. That’s all I know about it and any information I don’t know I’ll have to discover myself as I cannot contact the original owner.

I’d like to get people’s opinions on what the best course of action would be to get this engine running. Should I pull the heads to see exactly what I have? Should I put an intake and carb on it and run it? I’m hoping to not do a full rebuild since the engine was running.

Right now my plans are to use a stock 340 intake that I already have, 340 exhaust manifolds and I’d welcome a carb recommendation. I do have a Edelbrock 600 cfm (1406) if that would work, but I’m not opposed to getting a different one if need be. I’m also not opposed to a camshaft swap if need be.

My objective is to have a good running and reliable street engine. I’m not looking for a high horsepower race motor.

I am new to engine work but it is something I’ve always wanted to do and what better way to learn?

I understand there is probably more information I need to provide so please ask away.

Thanks to all,

Mike
Click to expand...
If you have an intake and exhaust manifold slap them on though a carb on then motor and try to get it to fire up. As is. Not every seller is bad I don’t think it will kill you or hurt anthing to bolt on some parts and try to fire it up. I don’t like all the tear it down responses added work that may not be needed. I’ve bought quite a few motors that dident have a carb or what not and I through some pile of **** carb I had in gas and the motor fired up again with the 508 cam problems lol.
 
I wouldn't take the chance. A couple of gaskets and be at ease with your purchase. It could run perfect but you might destroy something you could have corrected. Why throw your money away or always wonder how long will it last . Just my opinion from looking back at many motor purchases. You never know whats inside until you look.

I recently bought a low mile 318 that I heard run. It had a miss but I thought nothing a tune up wouldn't fix.

69383valiant and I were changing the valve covers. He saw pieces of the valve seals. We went to change them the exhaust valve where the pieces were from. would not hold air. The valve was stuck open.

I tapped it a couple of times and it closed up. After getting the spring off I left the air off and found it was carbon on the stem. Marvel mystery and worked it up and down.

If we wouldn't have taken the valve cover off . I would have never known and probably bent a valve or ruined the engine.
 
Last edited:
Hello All,

Thanks for all the replies so far. I finally had a chance to spend some time in the garage and got one of the heads off. The piston isn't a standard bore, it is .030 over as you can see and I assume a stock style piston would have a flat top. There is some slight scoring on the cylinder walls also shown in the pictures below.

Thanks,

Mike
IMG_0558.jpg
IMG_0557.jpg
 
They look to be a .030 cast piston replacement s.The cylinder wall doesn't look good . Thank god you tore it down. looks like the top ring end gap was tight and the ends touched when the got heat in them.

Take the pan off and check a bearings What is the casting number 340-what? That will determine if you can go .040 it should sonic test ok if its a low number. 340-1 is the best 340-8 would be the worse.

Move the crank front to back and check the thrust bearing clearance. If the motor was foot braked with an automatic and a low stall. Or stop and go with stick it will show wear..

Having to big of a cam with to little of a stall wears the thrust bearing pretty fast. A motor that idles free in gear with a lumpy cam is better than one that chugs.

Mine idles free a 1600. 6yrs of hard street and track driving and the bearings and cylinder walls were perfect. My son sonic cleaned the parts and reassembled with new total seal rings and king bearings. Good for another 8 years at rpms up to 8500 constantly.

Its the builder not the motors. If they are done right these little small blocks haul *** and stay together . Like an electric motor if they are balanced within 1/2 gram. One thing we did find was the comp push-rods were wore bad. We went with Smith Bros. A little pricey but you get what you pay for.

I have seen 360 crate motors worse than yours after a year. Do you think they put the best machinists on them. I don't think so. Fix what yo have

DSCN2807.JPG


DSCN2809.JPG


DSCN2811.JPG


DSCN2812.JPG


DSCN2813.JPG


DSCN2814.JPG


DSCN2815.JPG


DSCN0187.JPG


DSCN0087.JPG


DSCN0193.JPG
 
Glad you tore it down. Sad but not surprised the guy lied to you.
 
That one pix of the bore is not all that great. Looks, glazed, worn, and plenty of scratches on the side of the bore (where scratches/scores are typically less common than on the thrust faces). Yeah, those pistons look like the Silvolite or Sealed Power/Federal Mogul cast replacement ones.

Hope the block can be bored enough; I would not be surprised it it needed to go beyond .040" over to clean up, but a good machinist needs to look at it. With it already at 4.070" bore, consider having the walls sonic tested to see if there is enough meat left to safely bore out if if needs to go more than .040".
 
^^^ Certainly could be.... if, like you say, and near .100" below deck, then late 340 factory pistons. If right around 0 deck, then the ones ID'd earlier.
 
Thanks, I'll check the casting number tonight when I get home and I will eventually get the pan off and will report what I find.

I apologize if this question shows my ignorance, but does it matter that the scoring on the cylinder walls is so minor that it's difficult to feel with a finger nail?

Thanks,

Mike
 
the scoring is not good. how bad is it is up to u. I do not think the rings did not have enough gap. u could remove a piston or 2 and remove some rings and throw them in a couple cylinders and measure endgap. if not bad ball hone the cylinders, clean and assemble. not everyone has a mega budget
 
GR5 said:
Thanks, I'll check the casting number tonight when I get home and I will eventually get the pan off and will report what I find.

I apologize if this question shows my ignorance, but does it matter that the scoring on the cylinder walls is so minor that it's difficult to feel with a finger nail?
Click to expand...
IMHO there has been a lot of crud in there. The cylinder's wall's shininess/glazing is my bigger issue.... I have to highly question how well the rings are sealing anymore. I would expect a lot of blowby when you step in the gas with bores looking like that. And then that leads to questions on overall ring condition and wear on the ring lands. If the ring lands are sloppy, then the rings will never seal well.

Flip the engine over and take off the oil pan. Take the oil pump off and measure inside clearances and look how badly the tips of the pump rotors are chipped/gounged/scored and that will give some idea of how dirty the engine may have been. Then pull some rod and main caps and look at the bearings; that is going to tell more about how well/poorly this was built and how it was maintained, and what you have going forward..

The final bit is to pull a piston or 2, like from the cylinder shown after the rod cap is off, and look at the piston skirts. I suspect you will see a lot of scoring, and if there are any dark patches on the aluminum skirts, then the pistons got too hot. You can also examine the ring side clearance (which tells land and/or ring wear).
 
b 4 you take any pistons out check the deck clearance plus or minus at all four corners and report they should all be close to the same
measure the thickness of the outside head bolt casting- about an inch- do each end of each head they should all be close to the same
drain the oil b 4 flipping engine over :) ask me how I know
 
Oldmanmopar said:
Take the pan off and check a bearings What is the casting number 340-what? That will determine if you can go .040 it should sonic test ok if its a low number. 340-1 is the best 340-8 would be the worse
Click to expand...

I checked the casting number and it is 340-6. Could you please elaborate on what you mean by the higher the number the worse it is? I guess I don't know what the dash number means.

nm9stheham said:
Flip the engine over and take off the oil pan. Take the oil pump off and measure inside clearances and look how badly the tips of the pump rotors are chipped/gounged/scored and that will give some idea of how dirty the engine may have been. Then pull some rod and main caps and look at the bearings; that is going to tell more about how well/poorly this was built and how it was maintained, and what you have going forward..

The final bit is to pull a piston or 2, like from the cylinder shown after the rod cap is off, and look at the piston skirts. I suspect you will see a lot of scoring, and if there are any dark patches on the aluminum skirts, then the pistons got too hot. You can also examine the ring side clearance (which tells land and/or ring wear)
Click to expand...

Thanks, I will get these checked and will let you know what I find.

Wyrmrider said:
b 4 you take any pistons out check the deck clearance plus or minus at all four corners and report they should all be close to the same
measure the thickness of the outside head bolt casting- about an inch- do each end of each head they should all be close to the same
Click to expand...

Will do, thanks. I'll report back on what I find. Is a dial caliper sufficient or would you recommend using a dial indicator and magnetic base?

Thanks,

Mike
 
Use a dial indicator and mag base for the deck to piston measurements if you want adequate consistency to see if the deck heights are even. The trick to accurate measurements there is to have each piston exactly at the top of its stroke, and that is best to do with the indicator. And be sure to position the pistons consistently; they rock a bit in their bores. Best to measure right above the pin.

One problem with measuring this and getting a solid answer is that the rod lengths can vary, especially if any reman rods have been put in there; you just don't know about that at this point. And if the crank as been turned poorly, then that is a another source of variation in deck heights. The only completely accurate way to know is to move the same piston+rod from hole to hole but that does not get rid of crank variations. If I wanted accurate measurements for a flat deck, I'd measure after all the new parts have been assembled and checked for consistency.
 
340-6 is up there . It was a late cast . 340-1 is the first one out of the ladle and the first mold to be checked by QC. The core shift on 340-1 motors is near perfect. That does not mean a 340-6 is bad it could also be perfect. I have not seen many that were but it should be sonic checked unless it is a mild street motor build. I will never build a 340-6 for me unless it is a bone stock motor. Because I am hard on a race motor.

I once had a 340-6 from a late model that took a whole cylinder out. The head bolts were just hanging there. They will usually flex the block off the turn using the factory mounts on the side of the block. These blocks with that high of a number should be using a front and mid plate and even then they are not recommended for a sprint chassis because of the distortion of the walls during the flex off the turn.

Don't just clean that block up. Take the block to a shop and have it checked and bored for pistons that will be installed. You need the pistons going in before its bored so the shop can fit the bores to the pistons. You don't buy pistons for a bore . you bore the cylinder for the piston. Have them clean up the crank and fit the bearings. Buy new rods its cheaper than resizing yours . If the crank is wore its cheaper buying a rotating assembly.

That block needs more than just a ball hone. If a cylinder is not concentric, Meaning a close thickness all around. It will egg shape when hot and cause premature wear .

Plan the build and you will never regret it. It is more costly to build it twice than to build it right once.



Street car no Bottle no Boost. full interior full exhaust music on the return road 3650 lbs. mid 10's. Not that fast but it stays together and never skips a beat.

 
Absolutely correct nm
I do it at pull down to get in the ballpark but if it's a blueprint project then do it again the way U suggest- blueprint projects can get cut twice
and the rods are done to wherever I want them to be
I can measure the deck from the mill tooling so can get it square that way

Interesting comments on the sprint motors Old guy- never done one road race, circle track, drags, boats, trucks, motorhomes, but never a sprint motor
 
nm9stheham said:
One problem with measuring this and getting a solid answer is that the rod lengths can vary, especially if any reman rods have been put in there; you just don't know about that at this point. And if the crank as been turned poorly, then that is a another source of variation in deck heights. The only completely accurate way to know is to move the same piston+rod from hole to hole but that does not get rid of crank variations. If I wanted accurate measurements for a flat deck, I'd measure after all the new parts have been assembled and checked for consistency.
Click to expand...

This makes complete sense. There is a lot of stack-up that will introduce a wide tolerance in the end. I think I'll take the measurement anyway as it is good practice and a chance to learn something new. I will be curious what the dimensions are though.

Oldmanmopar said:
Plan the build and you will never regret it. It is more costly to build it twice than to build it right once.
Click to expand...

I agree, I'm taking it slow but in the end I have no issues taking it to a machine shop to get it checked/cleaned/machined. I do want to be able to build as much of the engine myself in the garage with my nephew. You mentioned having the shop fit the crank bearings, aside from that and the machining what other tasks should I definitely have the machine shop perform?

Thanks,

Mike
 
GR5 said:
This makes complete sense. There is a lot of stack-up that will introduce a wide tolerance in the end. I think I'll take the measurement anyway as it is good practice and a chance to learn something new. I will be curious what the dimensions are though.



I agree, I'm taking it slow but in the end I have no issues taking it to a machine shop to get it checked/cleaned/machined. I do want to be able to build as much of the engine myself in the garage with my nephew. You mentioned having the shop fit the crank bearings, aside from that and the machining what other tasks should I definitely have the machine shop perform?

Thanks,

Mike
Click to expand...
Cook and clean the block Clean Clean and Clean some more.

Cam bearings. Oil pump drive bushing. Core plugs and all plugs they remove for cleaning.

Do not let them shot pean the block . Most shops don't do that anymore and I would tell them not to if they do.

We clean them in a cook tank before the machine work. Then we spray it down with straight Super Clean and rince. repeat this as many times as you see fit when you get it home.

Remember this. A shop that doesn't bag there work for pick up stay away from. When you go to a shop ask to see some finished work. If the jobs are not bagged. Walk away and go elseware . They are not someone you want doing any machine work for you. Dirty machinists and or shop is the worst nightmare for a new motor .
 
speaking of reman rods
as you say they can be all over the place- I can fix that
but a lot are ground on an angle at the parting line so that the big end will "pull in" and they can make them rounc
think about it
if you cut the cap flat you will NOT reduce the side to side of the big end- only the top to bottom
so you can end up seeing some daylight at the sides
NO BIG DEAL bearings are not round anyway
put the cap on a flat plate and see if there is any daylight at the inside- if so cut them flat or pitch the rod
angled parting lines put a big strain on the bolts
and you wonder why new rods may be a better deal than having me correct, rebuild/ bore hone/ rebush to factory length or whatever you need and put in new bolts, then balance
 
GR5 said:
You mentioned having the shop fit the crank bearings, aside from that and the machining what other tasks should I definitely have the machine shop perform?
Click to expand...
I think you mean cam bearings, not crank bearings.

Machine shop list for block only:
- Assuming a rebore for new pistons (which I am presuming will be needed): With going over .030" overbore in that 340 block, a sonic check of wall thickness is first IMHO. Consult with the shop on this matter.
- Inspect in general
- Cook block, and put in rust tank too if they have one and it is needed. You can look in the water jacket and pretty easily tell if the coolant was not changed and it is all crudded/rusted up.
- Pressure check for any cracks in water jacket; you just don't know the history on this one.
- Bore and hone. You will need to have the pistons to give to the shop before they do this. This means that you need to make decisions on what pistons to use pretty early in the process. (And that means you need to target the compression ratio you want/need for the intended use of the car/engine, along with deciding if you are sticking with the stock heads or doing something else.)
- Install cam bearings
- Intermediate shaft bushing is optional; you can do that yourself if you like but some of them need a special tool to finish off.

Options on block that go beyond a basic rebuild IMHO:
- Any decking to change compression ratio or to 'even up' the cylinders
- Check of the crank bore for alignment or mains and saddles and any needed corrections. (This becomes mandatory if the crank shows any serious damage.)

For the crank, you can start with an inspection yourself. Carefully measure the journal diameters with accurate micrometers in 2 places minimum around each journal. Look and feel with you fingernail for scoring around the journals. Keep in mind that the thrust surfaces around #3 main may be worn. I only know how to check that clearance with a new thrust bearing; maybe someone knows how to measure that and to what spec. If the crank is worn out of spec or has bad scoring, then the shop turns it down for undersized bearings (rods and/or mains).

Also inspect the crank and rod bearings for any major issues. Pix are welcomed.

Inspect the damper for cracks in the rubber.

Rods and heads are another discussion.
 
Do not deck the block unless to square it. Keep the 956 deck height or you will be cutting every intake to fit for the rest of its life.

Also to do a set of heads . clean and surface heads, Reface Valves, valve guides, harden seats, Springs, retainers, and keepers. you will get at least $1000 plus in them and you still have old Iron heads. It is more cost effective to just buy new aluminum heads.

If you are using a Hydraulic cam with new edelbrock rpm heads . Swap out the springs that are recomended for the cam. Most of the springs that come with them have a high seat pressure and the lifters will sink when it sits.

I usually recommend a solid lift or roller for the springs that come with the heads. adjustable rockers should be on your list. Even if they are older 273 style. There is nothing better than to being able to adjust every valve on its own. Motor balance is important . Intake charge as well as mechanical.
 
You must log in or register to reply here.
-

Back
Top