302 main bearings

Trying to salvage a ford 302 which had a failing cam and lifter. It was full of mud, looked like grid blast stuff.
Cleaned everything and now seeing if it makes sense to rebuild it.
When I installed the crankshaft and fit the caps, with this engine I am not able to turn the crank with lot of force.
When I measure the diameter crankshaft diameter it is 2,2375" which is undersize 0,010. The bearings used are also undersize 0,01 which makes sense. When measuring the inner diameter of the bearing, it shows ovality. The max dia is 2,248" and min 2,233". This means a large clearance of 0,0045 to 0,0105" while 0,0027" is advised.
These measurements are done on the used bearings...
My feeling is that the holes in the blocked are not aligned since when the caps are removed, the crank rotates freely without out of roundness of the crankshaft journals.
If this is the case, since machining costs are such high in Europe, it makes no sense trying to re use the block.
What is your opinion ?
 

Randy V

Moderator-Admin
Staff member
Admin
Lifetime Supporter
possibly the main caps installed out of order or crank bent?
 
Trying to salvage a ford 302 which had a failing cam and lifter. It was full of mud, looked like grid blast stuff
.Quite normal for an ex USA motor, the average American car does not seem to get its oil changed beyond the first/second owner, likely the 'grit' is material from the failed lobe and lifter.
Cleaned everything and now seeing if it makes sense to rebuild it.
When I installed the crankshaft and fit the caps, with this engine I am not able to turn the crank with lot of force.
Is this with a rubber or 'dogs turd' rear main seal, If the rear main seal was dogs turd type there is a pin in the rear main cap that must be removed before fitting the 2 piece rubber type- if you have a later 5.0 block with 1 piece seal disregard this comment.
When I measure the diameter crankshaft diameter it is 2,2375" which is undersize 0,010. The bearings used are also undersize 0,01 which makes sense. When measuring the inner diameter of the bearing, it shows ovality. The max dia is 2,248" and min 2,233". This means a large clearance of 0,0045 to 0,0105" while 0,0027" is advised.
These measurements are done on the used bearings...
Why are you measuring the old bearings, that will only tell you how worn they were, use new bearings, be aware that bearing shells/inserts have ovality built into them, the clearance should be slightly greater at the parting line where top & bottom shells meet.
My feeling is that the holes in the blocked are not aligned since when the caps are removed, the crank rotates freely without out of roundness of the crankshaft journals.
Caps fit with Arrow forward and are numbered front to rear.
If this is the case, since machining costs are such high in Europe, it makes no sense trying to re use the block.
In the last 50 years I have rebuilt hundreds of Ford Small Blocks, I think I have had to align hone or bore the main bearing tunnels on two occasions, you would have to be very unlucky to strike the odd one out.
Try this, don't fit any seal, just fit the top 5 brg shells in the block and set the crank in place, as you mentioned it should now turn freely, OK now fit one cap at a time, tap it into the register location with a soft copper or lead hammer and fit the bolts and torque gradually to spec, still turn freely?, Good, then repeat the process until all are fitted, If you strike the one that stops it turning you know which to look for.

What is your opinion ?

COLOUR="Blue"]Only takes a stray bit of gasket or sealer behind a shell, a locating tab out of place or a rear main seal out of place to lock it up.[/COLOUR]
 

Attachments

  • Rear Main Sealx.jpg
    Rear Main Sealx.jpg
    133.2 KB · Views: 307
The caps are indeed numbered and in the correct position.
In the past, i built 4 to 5 stroker blocks and they all turned freely with the caps torqued to spec. I know measuring the used bearings is not ideal but despite the bigger clearance, 4 out of 5 caps prevent the crank to turn freely. Tonight I will measure all the other diameters. Let see if that gives more insight. This engine ran only 20 miles after the last rebuild according to the previous builder and seller. The original advert and pictures are on this forum, showing a nice and shining engine. I have a micrometer and guage to measure the diameters. I have heard the engine running on my visit.
I remember the huge wobbling of both waterpump and crankshaft. Also the rear pivot bearing to support the gearbox shaft shows ovality.
The harmonic damper was bad for sure since i noticed the outer ring was not in line anymore with the inner portion.

Perhaps better to buy first the new bearings and restart the measurements.
The rear seal is split rubber seal which is greased and is not the route cause. Number 5 cap is the only cap which let the crank turn freely.
 
Going by what you are saying I think the block may have the wrong caps with it. Its not unheard of for caps to get mixed up in engine shops, I would put the caps on the block , torque them down with no bearings or crank in and measure the housing diameters.

Bob
 

Mike Pass

Supporter
Hi Andy,
You seem to have a few problems there.
As you say the crank pulley was visibly wobbling I think a check of the crank is in order as it's no use checking the block with a bad crank. Set the crank between centres on a lathe etc. and slowly rotate it with a dial gauge on the mains, crank nose etc. to check the runout.
If your car is not yet registered and you plan to do this via the UK IVA procedure then the age of the block is important. If the block is pre 1975 then the engine is deemed to be that age and only needs to have no visible smoke. Check the casting numbers on the ledge above the starter motor. If the block is in fact pre 1975 then it is probably worth saving if it has no cracks.
Give it a thorough cleaning anyway before you crack test it or do any more checks. I don't know if you have a good machine shop near you who you can trust to do the work properly or what you think is expensive for machining work. I have just had a block done correctly and it cost £800. Expensive maybe but probably a lot cheaper than the alternative which is a bad engine. At least there is a known straight clean sound base to build from.
The work done was the same as described in this video with the addition of notching for a stroker crank and screw in oilway plugs.

https://www.youtube.com/watch?v=xQFlaDhWsck

Cheers
Mike
 
Some magic and good news today.
I started all over today, remove the crank again, measured all the 5 main journals and they are surprisingly all 2.2375" (0.010 undersized).
Next, measured again the inner diameter of the caps with the old bearings still on.
Now I found other readings which didn't show ovality. And surprisingly they all measure 2.240" given a diameter difference of 0.0045". (Horizontally they are indeed wider).
Dividing by 2, which I forgot yesterday, it gives a clearance of 0.00225" which is within specs (0.0027"). :thumbsup:
Measuring if the crankshaft is bent or not...
Fixed cap #1 #3 #5 and measured the journals with a dial guage to see movement while turning the crank.
journal #2 -> 0.0015"
journal #4 -> 0.0005"
Removed cap #3 and measured
journal #3 -> 0.0007"
the front of the crank where the damper fits on -> 0.0005".
According to a book which I often use (SBF engines from HPbooks), the allowable measurement is 0.004". Which means again good news :shocked:
So was this crank to get stuck again...strange enough...it turns now smoothly. Still scratching my head why it now suddenly is okay and yesterday night (perhaps too late) didn't wanted to move.
Next steps : measure the end play in the length of the crankshaft and start checking the rods...
After all a good day and perhaps there is still some music in this block. :pepper:Thanks so far for the good support guys !
 
Still not in the safe zone...
checked the cylinder bores today.
Don't have a 4" micrometer so I started with a caliper which is less accurate (10 times less as a micrometer) and a inner dial guage.
Using this I method the bores measures

Cyl 1: max 4.0385" and min 4.0370"
Cyl 2: max 4.0380" and min 4.0370"
Cyl 3: max 4.0380" and min 4.0370"
Cyl 4: max 4.0380" and min 4.0370"
Cyl 5: max 4.0395" and min 4.0385"
Cyl 6: max 4.0395" and min 4.0390"
Cyl 7: max 4.0400" and min 4.0395"
Cyl 8: max 4.0410" and min 4.0400"



Could be a measurement error.
The deviation is +/-0.10 mm = +/-0.004"
so still in smallest condition is showing 4.035.

Used another digital caliper and measured the top diameter of the bores.
It measure 4.040".
The block shows really 0.040 overbore...

The pistons are Silvolite 1177 which have a 0.030 overbore but I found a manually stamped on top of the psiton the number "40"....could it be the catalogue is wrong ?.
The sideskirts of the piston measure 4.035


nd the left side of the engine looks to have bit bigger bores compared to the right side...
 
Last edited:
1177 is the basic Silvolite part number for ford 302 pistons eg 1177 - 020 is 4.020 bore, 1177 - 040 is 4.040" bore etc. Most manufacturers have a ' measure point ' at a set height on the piston skirt, you might find in this instance that you have 4.035" up close to the oil ring groove and something like 4.039" at the slipper tab for the 4.040" bore. Really for checking stuff today all you need is a set of 'Snap' spring loaded bore gauges and a good set of digital calipers to make it easier for older eyes.
 

Mike Pass

Supporter
I think you need an accurate method of measuring the bores and piston diameters so you can work out what you have and the amount of wear.
You may be able to bore and hone the bores to +40thou but the +30 pistons will need to be changed out for some +40 thou ones. The piston bore clearance will depend on the type of piston. E.g. JE forged pistons recommend min 2 - 2.5 thou on a 4"bore.
You are not beaten yet.
Cheers
Mike
 
Hi Mike,
The pistons seams to be also 40 oversize as jac says, this type of pistons 1177 have all bore sizes. On top of the piston, barely visible and hidden under the carbon deposit, found a stamped number "40" which makes sense. Mystery solved. Boring, honing and decking would be te best but to my feeling it was done recently, only debris in the engine, sandblast sand? And bad silicone used causing leaking from all sides made the engine failing, a lifter oil channel was probably blocked and caused the camshaft to be eaten on 1 lobe.
The plan is for now is to replace all bearings, gaskets, new camshaft and lifter, valve seals, valve springs and oilrings, new damper, oilpump and pickup. Honing, put everything together and should be good to go.
Now looking which cam spec will suits me most.
Since it is mainly a cruiser, i will select a cam with more torque at low rpm and less horsepower in the high rpm. Perhaps occasional track day and coming fast out the corner is also a bonus.
Compression ratio is only 8,5 with this setup using rpm heads. Actually more could be retrieved from the heads if using higher compression ratio like 10 or 11 but only possible with other pistons.
For now I am happy with the setup.
First try to get it running again and we see from there what needs to be improved.
 
If you do a trial assy of the short block you will probably find that the pistons only come up to about 0.030" below the deck surface, you can retrieve some of your lost compression ratio by swapping to 289 rods ( 5.155" vs 5.090 of 302 ) and skimming whatever is reqd to set them flush with top of block @ TDC. Having done that you MUST check valve to piston clearance thru two engine rotations to ensure clearance. I would also strongly advise checking all lifters for rotation over those two cycles along with either grooved lifter bores or face oiler lifters.
 

Mike Pass

Supporter
Glad the pistons are +40 thou. You should be able to get away with a cylinder hone to bed the rings in. Make sure all is clean especially the oil galleys. Pull out all the oil way plugs and get a brush in there to scour out all the swarf from the scuffed cam. If you have a suitable tap you can thread the ends and put in screw plugs which are a lot more reliable.
Looks like you can get a reasonable working engine out at the end. Good news - you could do with some after some of the problems you have had.
Beware the oil you use to bed the new cam in. Dose it up with plenty of zinc additive. I now use Lucas racing Oil once it is bedded in to keep the cam lobes healthy.
Cheers
Mike
 
Still not in the safe zone...
checked the cylinder bores today.
Don't have a 4" micrometer so I started with a caliper which is less accurate (10 times less as a micrometer) and a inner dial guage.
Using this I method the bores measures

Cyl 1: max 4.0385" and min 4.0370"
Cyl 2: max 4.0380" and min 4.0370"
Cyl 3: max 4.0380" and min 4.0370"
Cyl 4: max 4.0380" and min 4.0370"
Cyl 5: max 4.0395" and min 4.0385"
Cyl 6: max 4.0395" and min 4.0390"
Cyl 7: max 4.0400" and min 4.0395"
Cyl 8: max 4.0410" and min 4.0400"



Could be a measurement error.
The deviation is +/-0.10 mm = +/-0.004"
so still in smallest condition is showing 4.035.

Used another digital caliper and measured the top diameter of the bores.
It measure 4.040".
The block shows really 0.040 overbore...

The pistons are Silvolite 1177 which have a 0.030 overbore but I found a manually stamped on top of the psiton the number "40"....could it be the catalogue is wrong ?.
The sideskirts of the piston measure 4.035


nd the left side of the engine looks to have bit bigger bores compared to the right side...

The discrepancy in the bores is down to the machinist . When you set up the cutter on the boring bar and start boring each bore will rub a bit off the cutter. If the guy doing the job cares about what he is doing he will reset the cutter after two or three bores and bring all the bores to size with the hone when he is finished . In reality some of these shops dont care and will run the boring machine down all of them without correction, a quick hone and thats it hence the variation. A lot of piston scuffing you see on stripped down engines is where they have been run on a tight bore :thumbsdown: In some cases they start at the front of the block and work their way back so the rear bores are the ones that end up tight which is the exact opposite of what you need with a V8, good machine shops will give the two back cylinders which generally run a bit hotter half a thou more clearance .Most of them just hope the customer does not own a bore mic. I bought my own Van Norman boring machine and a Delapena Hone because I was sick to death of arguing with machine shops over shoddy work.

Bob

Edit: dont buy any measuring equipment , it will drive you insane:flameon:
 
Last edited:
Thanks guys, I still learn new things. Great info.

Good tip about the rod, this helps indeed. But will become to costly for me.
Since I am trying to minimize the costs for this rebuild (saving money for coming years to build a new 347 stroker).

Good story about the boring. Didn't knew this and makes sense. In this case, the machine shop didn't do a really great job since left and right are clearly different.

Mike, thanks for the link to the compression calculations. I am already well equipped with some excel sheets which also calculate the dynamic compression ratio and I have software which is called "dyno" which calculates HP/torque/airflow/etc... all the engine spec are loaded in the software (from airflow of the heads to camshaft advance settings) and it does its thing. Which I use to select the best specs for the cam (to my drivestyle whishes) since there is a nice iteration module with it so it iterates and changes whatever I want and stores the best options. Nice tool.

Today I removed the camshaft bearings. see picture. easy job with the right tool.

Checked the sideskirts of the pistons. They show clearly vertical marks. see picture.

Checked the piston walls. The honing pattern is mostly gone and lots of vertical marks..not deep but visible. Hope the honing will remove them.

Visually inspected also the bores for the lifters.
Most of them have wear spots and one had marks. This one was the one where the lifter was eating the lobe. Now I have to find out if the bores are still within spec. My book let me down on this so I will also check internet sources to see what is allowed. Your input is offcourse more as welcome.
I used one lifter and compared the bores and some are nice tight and some show some slight wobble. Needs to be checked since when this is over specs, it is still game over.
attached also a picture of the piston mark telling it belongs to gt40 :laugh:
 

Attachments

  • IMG_1954.JPG
    IMG_1954.JPG
    138.2 KB · Views: 317
  • IMG_1955.JPG
    IMG_1955.JPG
    151.1 KB · Views: 291
  • IMG_1956.JPG
    IMG_1956.JPG
    113.7 KB · Views: 309
  • IMG_1957.jpg
    IMG_1957.jpg
    120.8 KB · Views: 254
  • piston 40.jpg
    piston 40.jpg
    127.6 KB · Views: 289

Mike Pass

Supporter
Hi Andy,
It looks like a lot of the metal powder from the scuffed cam has gone through the engine. The bores should be salvageable. Is any steel powder embedded in the pistons? Try the finger nail test to see how bad the bores feel. If the lifter bores are too worn they can be sleeved. This is often done on race engines with bronze sleeves which are grooved to get good oiling and the correct clearance.
The boring and honing job seems to have been very poor as they should be spot on exact. The grinding metal paste will have done a good job of wiping out the honing pattern! You should be able to get a useful motor sorted until you do the stroker.
What year is the block?
Cheers
Mike
 
Back
Top