340 build

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1930

1930

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Ok so Craigslist strikes again, as some of you may know ( and just to keep short ) I recently acquired a 340.

I took wise advise and didnt even try to get it going as it sat, instead I took it out this A.M and tore it down to see whats what.

I have never seen a camshaft in such bad shape, at least one lobe is almost nonexistent.

Whatever, its still a 340, the cylinders look ok/decent ( Im gonna have them honed, its already .060 over ) and I do believe that it was just recently rebuilt as the seller stated. I dont know what happened with cam other than maybe a bad startup.

I have alot of questions. Can someone tell me what this engine may have originally come out of by the numbers on the block? Im curious

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020.jpg


021.jpg
 
Id like to calculate compression as it sits now so that if need be I can have any machine work done to get to my ideal compression ratio but Ive never checked deck height on an engine where the piston sat above the deck surface already?????

When I set the used fel-pro head gasket on there it is just barely below the top of the head gasket.

How so I measure this?

I see reading past posts that a 340 of this vintage would typically have its pistons sitting above the deck surface, so again how do I do the math.

The engine came to me with Edelbrock Performer aluminum heads which I am planning to use as well.

It has also been bored .060 over and has speed-pro pistons in it which I still have the box for

I could be wrong but it looks like there was light contact at one point between the intake valves and the tops of the pistons. Very light mushing in some spots of the pistons.
 
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Using a dial indicator is best, but however you do it, get a piston at TDC and measure its height above deck as precisely as you can.

BTW, those are TRW forged pistons. Nice. They would normally have the same compression height as the stock cast early 340 pistons, which is .018" above the deck. But measuring it is a good idea to see where, in case the block has been decked. Pulling them would be good, to look for cracks, broken rings, etc. I personally would put in fresh set of rings with the hone. Being forged pistons, the piston to cylinder clearance will probably (and should) be up around .003" to .004", typically.

Are the heads perfectly flat outside of the main combustion chamber? Or is there a very shallow circular machined area around the main combustion chambers that is about the size of the head gasket hole? (I just can't see for sure in the pix.) That fact is important to know for CR; there are 63 and 65 cc chamber Edelbrock Performer heads.) The ones with the shallow machined areas around the main chambers are intended for 340 pistons like yours.

For targeting static and dynamic CR, what is the intended use? That will drive the cam and will in turn drive the CR targets.

I have never seen a cam lobe like that.... wowzer!
 
Thanks, Ill get better pictures and more information tomm when back at the shop. Ill get better pictures of the cam as well. I dont think the picture above does the camshaft justice on just how bad it is eaten up
 
If you measure all the pistons, you will see just how "UN" square the deck is from the factory.
 
you will be surprised just how far off the deck is.
mine was low on the front left and low at rear on the right. Nice and flat.....Just now quare.
If you measure all the piston, you will get the idea. It's not the pistons fault. its the deck of the block.
 
I had a 340 with a cam like that, it had far too much spring pressure and Comp cams roller tips that were too tight
 
I'd be real careful to make sure the block has all the correct oil gallery plugs in place. And make sure the con rod oil spit holes on the rods near the bad lobes, are facing the cam like they're supposed to.
 
rustycowll69 said:
somebody really likes to use a lot of silicone sealant.
Click to expand...
You have no idea. I couldnt remove the intake for nothin. I tried everything I could think of, I ended up removing the heads first and then still had to pry at the area between intake and block with a scraper.

The engine is covered in silicone everywhere.

I bet they had no leaks
 
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BTW, with that cam lobe(s) so badly wiped, I'd think you found some metal in the pan. If not, then it is somwhere, and needs to come out. It goes into the oil pump, the filter is AFTER the pump. So look at the pump lobes and see if they are chewed and scored.

I personally would be pulling it apart now to clean all the oil passages under pressure; hot soapy water from the car wash at least followed by a scalding hot rinse. or a trip to the machine shop to get it cold tanked at a minimum.

I'd be looking hard at all the bearings too.

And your pix of the block SN is all lens flared and unreadable; can you just list the SN here?

BTW, others have reported that the Edelbrock heads' installed valve stem seals ain't none to good so you might look for some better viton seals; 70aarcuda may have a PN.

Is there a point to the balance thread link?
 
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nm9stheham said:
BTW, with that cam lobe(s) so badly wiped, I'd think you found some metal in the pan. If not, then it is somwhere, and needs to come out. It goes into the oil pump, the filter is AFTER the pump. So look at the pump lobes and see if they are chewed and scored.

I personally would be pulling it apart now to clean all the oil passages under pressure; hot soapy water from the car wash at least followed by a scalding hot rinse. or a trip to the machine shop to get it cold tanked at a minimum.

I'd be looking hard at all the bearings too.

And your pix of the block SN is all lens flared and unreadable; can you just list the SN here?

BTW, others have reported that the Edelbrock heads' installed valve stem seals ain't none to good so you might look for some better viton seals; 70aarcuda may have a PN.

Is there a point to the balance thread link?
Click to expand...
I did find sediment in the bottom of the pan, Im sure it all throughout the engine, I plan to have it cleaned out by the machine shop. Ill try to remember to check the pump deal but wouldnt it be prudent to just replace the pump while Im all there anyway?

FW340*31070567 Thats what Im seeing just below the drovers side cyl head The * sign I cant read that number but may be a B. ( light stamping )

Thanks for the tips on the seals. Ill try to remember that.

The balance thread was just for my reference cause Im still looking for the correct flywheel
 
Yes on a new pump, IMHO. They don't cost a lot.

There is some occasional bru-haha over standard versus high volume pumps; they are only 20% different on the flow capacity for the SBM ones. The HV will have better pressure at idle and lower RPM's but they are really not all that much different.

Per some info on FABO, the Mellings all have the higher pressure relief springs, at around 72 psi. I personally would go for that for regular street engine use.
 
Heres what I got so far and a bunch of pictures showing how I got to these numbers. Ive got to now decide if the project is worth pushing forward with. I really do not want to get into buying more pistons ect and anyway its already maxed out as far as I know ( .060 )

First thing I did was wire wheel the deck and the tops of the pistons really well, I installed part of my piston stop tool and turned the crank until the piston hit the top of the bar, removed bat and set up my dial indicator to measure the remaining travel, anything that I thought odd I re-measured at least one more time, within reason the piston height measurement is correct.

I then pulled the piston as far down in the bore as I could by spinning the crank and took X measurements. These measurements are fairly close. Im limited by equipment but the tools are junk either.

Hopefully everyone can open and view the PDF file. Not sure how else to clearly post the results.

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Picture 393.jpg


View attachment 1715036649
 

Attachments

  • Scan0002.pdf
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so why don't you want to go on with this build. Everything looks normal for a standard block.
I don't understand what the dial down in the hole was all about thow????
 
Cudafever said:
so why don't you want to go on with this build. Everything looks normal for a standard block.
I don't understand what the dial down in the hole was all about thow????
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Ive got no problem with assuring you that you know more about this sort of thing than I do, Im a bodyman with limited mechanical experience.

Did you look at my measurements. Im under the impression that the bores are worn out? I dont know whats acceptable.

Is .003 acceptable? I didnt think it was.

The dial down in the bore picture was a mistake, Ill see if i can remove that picture.
 
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Looking at your file.....uh oh FORD ALERT! LOL.... The piston numbering is from Ford. Mopar is odd 1,3,5,7 on the driver's side and even 2,4,6,8 on the passenger side. Anyhoo...

It looks like you have some deck slope front to back on both sides (with the back higher) but you can live with that. The big variable I'll bet is that there is about .005" variation (as a guess) in rod lengths; they are probably shortest in the holes you marked 2-4. Nothing is a disaster there, just not 'blueprinted'. The average above-deck compression height number is pretty close to the standard early 340 number of .018" above deck. The piston-to-deck variation you have will give you about 1/4 point variation max in static compression ratio between highest and lowest pistons as shown, all else being equal.

The bore measurements looks pretty encouraging to me. Question: what is the meaning of the diameter 2 numbers? Top and bottom diameters? If so, that is not much taper at all. If anything, your bore diameters are too small for forged pistons.

It takes a lot of care to get accurate measurements with a telescope gauge: I do it all the time, but I take a lot of readings and have a feel for setting them. They are easy to set a bit small so your bore diameter readings may be on the small side... which would be good. (Not being critical, I just don't know how good you are at using telescope gauges....) A bore gauge at the machine shop would be nice to use and would give you accurate numbers in a trice.

And as said before, .003" to .004" is normal for forged piston clearances. They change a lot more over operating temp than cast or cast hypers.

IMHO, time to pull the pistons and check the skirts and bores, and measure the the pistons and bores more accurately. The measurement point may be on the thrust faces about 1" above the bottom of the skirts, but I have not had any TRW's in a long while so don't recall that for sure; perhaps someone here knows better, or your shop does. (It could also be measured at the pin height on the thrust faces.) It would also be time to check the rings grooves for side clearance; with 1k miles they oughta still be fine.

Did you ever look at the bottom of the heads and see if they had those shallow circular areas milled around each combustion chamber (or not)?
 
nm9stheham said:
Looking at your file.....uh oh FORD ALERT! LOL.... The piston numbering is from Ford. Mopar is odd 1,3,5,7 on the driver's side and even 2,4,6,8 on the passenger side. Anyhoo...

It looks like you have some deck slope front to back on both sides (with the back higher) but you can live with that. The big variable I'll bet is that there is about .005" variation (as a guess) in rod lengths; they are probably shortest in the holes you marked 2-4. Nothing is a disaster there, just not 'blueprinted'. The average above-deck compression height number is pretty close to the standard early 340 number of .018" above deck. The piston-to-deck variation you have will give you about 1/4 point variation max in static compression ratio between highest and lowest pistons as shown, all else being equal.

The bore measurements looks pretty encouraging to me. Question: what is the meaning of the diameter 2 numbers? Top and bottom diameters? If so, that is not much taper at all. If anything, your bore diameters are too small for forged pistons.

It takes a lot of care to get accurate measurements with a telescope gauge: I do it all the time, but I take a lot of readings and have a feel for setting them. They are easy to set a bit small so your bore diameter readings may be on the small side... which would be good. (Not being critical, I just don't know how good you are at using telescope gauges....) A bore gauge at the machine shop would be nice to use and would give you accurate numbers in a trice.

And as said before, .003" to .004" is normal for forged piston clearances. They change a lot more over operating temp than cast or cast hypers.

IMHO, time to pull the pistons and check the skirts and bores, and measure the the pistons and bores more accurately. The measurement point may be on the thrust faces about 1" above the bottom of the skirts, but I have not had any TRW's in a long while so don't recall that for sure; perhaps someone here knows better, or your shop does. (It could also be measured at the pin height on the thrust faces.) It would also be time to check the rings grooves for side clearance; with 1k miles they oughta still be fine.

Did you ever look at the bottom of the heads and see if they had those shallow circular areas milled around each combustion chamber (or not)?
Click to expand...
Im not exactly positive what you mean by shallow circular area but if I had to guess id have to say they are not there. The head is flat until it drops down into the combustion chamber.

As far as what you said before I.E ........003" to .004" is normal for forged piston clearances..........its not that I didnt take the time to read it but more like I am forgetful or did not quite understand.

So if .003-4 is normal than why are some of my readings .001?

Where would unacceptable piston measurements start for this particular engine or for any cast iron block for that matter?

Anyway what I done next was wire brush on my drill the head surface/combustion chambers and valves in preparation for cc ing. Its absolutely amazing that the manufacturer can get each combustion chamber the exact same ( and I mean exact ) Ive measured quite a few heads now thanks to the teachings of people on this board and I can say Ive never seen a pair of heads identical in every way.

Not sure where they should be but 63cc was the magic number for these.

Quote: Question: what is the meaning of the diameter 2 numbers?

I measured the bore in the same place as far as I could go down with the piston in, these two meaurements reflect vertical and horizontal measurements. I hope that makes sense, in other words I measured one way and then just rotated the tool so that it might make an imaginary cross if that makes more sense.

Quote: IMHO, time to pull the pistons and check the skirts and bores, and measure the the pistons and bores more accurately. The measurement point may be on the thrust faces about 1" above the bottom of the skirts, but I have not had any TRW's in a long while so don't recall that for sure; perhaps someone here knows better, or your shop does. (It could also be measured at the pin height on the thrust faces.) It would also be time to check the rings grooves for side clearance; with 1k miles they oughta still be fine..............

Here is where your kinda losing me, I understand pull the pistons, I can easily measure crank but it sounds like you are telling me to measure the pistons themselves???Ive never done this, did not know it was necessary? As far as i knew I would pull the pistons and measure the cylinder at a few different places, top,bottom and in between looking for taper and egg shape.

I am interested in hearing more about checking ring grooves, I have never done this.

I am clear I am gonna have to replace all bearings and I will also replace the rings but I would still like to understand how to take the measurements.

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Ill have to stop here for the day, will try and do bottom end tomm. Is it possible at this point to come up with a very close compression ratio this engine would have had?

I believe camshaft stats play into all of that but assuming I had a stock cam would it be possible?

Im not gonna run a stock cam but measuring what was left of some of the cam lobes from the cam removed Id say it was a bone stock cam.

Although I find anything P.O told me believable at this point he did tell me that he had a puple cam in it which somehow got bent and he replaced it with the one that I pulled out.
 
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