When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I have pulled my 355 engine yesterday to do some fixes over wintertime. Today, i took the heads off and found that cyl. #8 has something like rust pitting on the wall. There is a visible (and very slightly feelable) mark, which i assume its from this kind of rust pitting. Speedpro flat top .030 pistons. All other bores look very great with visable hone markings all around.
What would you guys do in this case?
Re-ring?
Re-hone?
next oversize + new pistons 🤔
my plan was to dig a bit deeper, since i still have oil consumption problems with this engine.
I guess, my #7a's need a bit work like getting intake and deck side resurfaced (because of rust pitting near waterpockets). When i disassembled the passenger side head, i saw that my intake valves are completely covered with black, burnt oil. On some, oil was pooling on the valves. So i noticed, that my valve stems have (for my opinion) a lot play in the valve guides. I guess that the guides are worn out and need a replacement. Maybe there are some sugestions in good valve guide sets? Maybe bronze?
It looks like rust pitting because it is. How long did that motor sit? Overbore is the only way to fix that.
Thanks for the anwer, joe!
I drove it the whole summer.
The engine was rebuilt by previous owner. He did the overbore to 4.087. After the rebuilt, he told me that the engine was sitting for a longer time. About 3 years or something.
i was expecting this answer. Seems like i have to do a full rebuilt on this motor. I have a second engine block lying around. Maybe its a better idea to bore this one on 4.087 too instead of going to the second oversize?
Last edited by 71OldscutlassS; November 20th, 2021 at 01:01 PM.
I have a second engine block lying around. Maybe its a better idea to bore this one on 4.087 too instead of going to the second oversize?
That would be the way to go if everything in the present engine is in good shape. The pitting might not clean up at .060 oversize.
If the rest of the cylinders all look ok I would almost bet that the rust pits were there when the other guy rebuilt the engine. If it was from sitting around it should be in all of the cylinder, not just one.
Yeah that sucks, rebuild time. As said those pistons can be swapped over to a virgin block. Make sure those Speedpro forged pistons have .0045" piston to wall clearance. They are more modern pistons that require half the clearance and are lighter with much better ring packs. The 12cc dish DSS is available in 4.125" bore and the 10cc Mahle 4.155", which most 350 blocks will go to with acceptable wall thickness. So don't just chuck that block. Consider getting the guides machined on top for positive seals. Yeah quality bronze guides should be used, cast iron guides need .0028" minimum clearance on the center exhaust valves. The #6 heads I bought had .003" clearance on the new cast iron guides and positive seals, no oil usage issues.
That would be the way to go if everything in the present engine is in good shape. The pitting might not clean up at .060 oversize.
If the rest of the cylinders all look ok I would almost bet that the rust pits were there when the other guy rebuilt the engine. If it was from sitting around it should be in all of the cylinder, not just one.
The pits would be in 1 or 2 cylinders that have valves open when sitting.
Yeah that sucks, rebuild time. As said those pistons can be swapped over to a virgin block. Make sure those Speedpro forged pistons have .0045" piston to wall clearance. They are more modern pistons that require half the clearance and are lighter with much better ring packs. The 12cc dish DSS is available in 4.125" bore and the 10cc Mahle 4.155", which most 350 blocks will go to with acceptable wall thickness. So don't just chuck that block. Consider getting the guides machined on top for positive seals. Yeah quality bronze guides should be used, cast iron guides need .0028" minimum clearance on the center exhaust valves. The #6 heads I bought had .003" clearance on the new cast iron guides and positive seals, no oil usage issues.
Yeah, i heard that the speed pros require more clearance in the bores comparing to Mahle or DSS pistons. Thanks for all this informations!
I will not junk the current block, but since my current speed pro rotating assembly is already here and balanced, im really coming closer to use my spare block and bore it to 4.087.
my 355 has never got some surfacing on the deck or/and the heads, so i would like to get this done too, just for better sealing of head gaskets.
so if im using stock stroke (3.385?), speed pro flat tops, thick fel-pro head gaskets and have the block deck and heads just resurfaced, i think (hope) it wouldnt affect compression ratio or intake manifold fitment very much?
Is there an advice for a good set of bronze valve guides for positive seals? I once have seen bronze guides from brodix for 17,99$ each. Seems expensive to me.
The intake valves are looking terrible on both heads.
I also noticed (while pulling the locks out with a magnetic rod) that my exhaust valves are stainless and my intake valves not. Even, my locks have only one groove, so the edge on the valve, where theyre getting pressed to from the valve spring was a bit burred, so i had to use a fine file and smoothen these burrs to get the valves out of the guides. Maybe it would be better to get valves and retainer locks with more grooves.
I think, the guides are totally shot. I tried to make the wear visable on the pictures:
Before you dissembled the top half, did you do a leak test?. I bet the rust pits don’t affect the engine as much as you think. If you haven’t done a leak test, then, you really should do one. I’ve seen many pitted bores with under 3% leakage.
Before you dissembled the top half, did you do a leak test?. I bet the rust pits don’t affect the engine as much as you think. If you haven’t done a leak test, then, you really should do one. I’ve seen many pitted bores with under 3% leakage.
No, i havent done a leakdown test before disassembling, since my plan was just to do some head work.
I was thinking that too, the pits are not deep, but i think it will damage the rings in this spot in a longer or shorter time. I have new Sealed power 0.030 rings lying around and i am really thinking about to take my second block (got it for 100€), check it for cracks etc., get it bored and drop the whole rotating assembly with the new rings in there.
and finally drop my hopefully sucessfull rebuilt #7a or maybe the new edelbrock sbo heads on it and call it a day. Im just not sure yet what to do 😃
Or, maybe just sleeving that one cylinder. I have to talk to a machine shop.
Get a quote on both blocks and the heads. The burr on the valves is normal. I had to do the same to pull an exhaust on my #6 head. Not a lot of miles on them. There will be some carbon on the valves. Until the guides are measured, it is only conjecture.
Ok, good to hear that the valve burrs are normal. Would you replace the valves too with this kind of wear in the guides? Maybe going to 2.000 intake valve size?
these are my water ports on the intake surface of the heads. What should i tell the shop to do? Just surfacing down till the surfaces are clean? Or are there some measurements to keep in mind? Im thinking about because intake fitment. Sorry for the questions, but im a beginner in engine building
I have to call the shop to get some information about prices. Here in Austria/Germany, machine work can be an expensive service. :/
so, the head works needed would be:
- resurfacing head to block surface
- resurfacing head to intake surface
- get bronze valve guides (for positive seals) and have the machine shop intall them.
- installing new valves (2.000 intake?)
are there some sets of bronze valve guides recommended?
sometimes, i would love to have a mopar or chebby, where you can just buy a set of sb aluminium heads for a good price and bolt them on.
Last edited by 71OldscutlassS; November 21st, 2021 at 05:54 AM.
The aftermarket intake gaskets are much thicker, a reasonable cut off both should be fine. Yes, new good quality valves. Do a 1.625" exhaust valve (W31 sizes) as well with the bowls opened with a cutter. Yeah, machine isn't cheap here either. My bill was over 3 grand. Good luck.
The aftermarket intake gaskets are much thicker, a reasonable cut off both should be fine. Yes, new good quality valves. Do a 1.625" exhaust valve (W31 sizes) as well with the bowls opened with a cutter. Yeah, machine isn't cheap here either. My bill was over 3 grand. Good luck.
Yeah, i know the blue fel pros are thicker 👍
thanks for your informations!
which set of intake and exhaust valves would you recommend? Brand? Stainless? Which lenght do i need? Are there any other things i need to know before ordering?
Talk to one of the Mark's on here for valve brand. You will want W31 replacement valves for size and length. Yes, the Felpro heads gaskets are .042" compressed. I actually meant the composite intake gaskets. I could not fit the untouched RPM intake and Mr Gasket Ultraseal intake gaskets with milled #6 heads.
Last edited by olds 307 and 403; November 21st, 2021 at 10:31 AM.
Talk to one of the Mark's on here for valve brand. You will want W31 replacement valves for size and length. Yes, the Felpro heads gaskets are .042" compressed. I actually meant the composite intake gaskets. I could not fit the untouched RPM intake and Mr Gasket Ultraseal intake gaskets with milled #6 heads.
Ok, thanks a lot!
Oh, my fault, i red it too fast 😁. As head gaskets, i will use the thicker .042 fel pros. They have been used in the engine without any surfacing too. Maybe that has also been the reason why i always had some problems with intake fitting. It always seemed like the performer manifold is too loose between the heads. I only got it sealed with the thick Mr.gasket 405's.
No, i havent done a leakdown test before disassembling, since my plan was just to do some head work.
I was thinking that too, the pits are not deep, but i think it will damage the rings in this spot in a longer or shorter time. I have new Sealed power 0.030 rings lying around and i am really thinking about to take my second block (got it for 100€), check it for cracks etc., get it bored and drop the whole rotating assembly with the new rings in there.
and finally drop my hopefully sucessfull rebuilt #7a or maybe the new edelbrock sbo heads on it and call it a day. Im just not sure yet what to do 😃
Or, maybe just sleeving that one cylinder. I have to talk to a machine shop.
Unless you do this right you’ll be doing it again. It seems you’re all over the place here. Come up
with a plan and stick to it.
The right thing to do would be to sleeve the bad hole and go to the next oversize piston, ie 4.100 etc.
Then surface the heads or replace them.
Finally you mention the new Edelbrocks, but right now you don’t have a sound base to bolt them to. Don’t waste your money on those. They won’t fix your problems.
Last edited by cutlassefi; November 21st, 2021 at 01:46 PM.
Unless you do this right you’ll be doing it again. It seems you’re all over the place here. Come up
with a plan and stick to it.
The right thing to do would be to sleeve the bad hole and go to the next oversize piston, ie 4.100 etc.
Then surface the heads or replace them.
Finally you mention the new Edelbrocks, but right now you don’t have a sound base to bolt them to. Don’t waste your money on those. They won’t fix your problems.
Yeah, i would like to do it right once. My fault was to buy a "rebuilt" engine and maybe trusted too much that everything would work like it should, and now that im diggin deeper to troubleshoot the problems, i opened a can of worms.
just for understanding, why would you sleeve the bad cylinder AND going to the next oversize?
I heard of some guys here that they had no problem to use "used" pistons, so if i go to 0.030 over on my second block, get the decks resurfaced and put my existing rotating assembly (if the pistons are in good shape) in there should do the job, since i was happy with the speed pros and the goal nr.1 now is a healthy shortblock before thinking about the heads.
Reason for the next overbore size is because when you drive in a sleeve, you’ll knock the adjacent cylinders out of round.
Yes you can reuse your existing rotating assembly if it’s in good shape.
Reason for the next overbore size is because when you drive in a sleeve, you’ll knock the adjacent cylinders out of round.
Yes you can reuse your existing rotating assembly if it’s in good shape.
Aah, now i got it! Makes sense, something new learned!
Today, i measured the Valves that i pulled out of the heads, and found that the exhaust valves are already 1.625. Is this really the stock size on 7a's?
can i just purchase aftermarket exhaust valves from Melling for example, with the same specs and install them (after new guides have been installed for sure)? Or do i have to do some lapping?
Im curious, since the 7a's have induction hardened valve seats.
Another question would be, if im going to prepare the heads for 1.995 intake valves, is it necessary to install hardened valve seats? because if the valve seats get machined for the larger valves, i guess the induction hardened material would be gone?
[QUOTE=71OldscutlassS;1385716
can i just purchase aftermarket exhaust valves from Melling for example, with the same specs and install them (after new guides have been installed for sure)? Or do i have to do some lapping?
[/QUOTE]
It is very very rare to not have to remachine the seats when installing new valve guides. The guides almost never go in the same exact angle as the originals. Sometimes if you use bronze liners they will be pretty close but still almost never will you get away with only lapping.
Originally Posted by 71OldscutlassS
Another question would be, if im going to prepare the heads for 1.995 intake valves, is it necessary to install hardened valve seats? because if the valve seats get machined for the larger valves, i guess the induction hardened material would be gone?
Intake seats are almost never an issue as far as needing hard seats. I would not concern myself with it at all.
If you are going to use a less expensive stock type valve I have had the best luck with the Eloy brand from SBI
It is very very rare to not have to remachine the seats when installing new valve guides. The guides almost never go in the same exact angle as the originals. Sometimes if you use bronze liners they will be pretty close but still almost never will you get away with only lapping.
Intake seats are almost never an issue as far as needing hard seats. I would not concern myself with it at all.
If you are going to use a less expensive stock type valve I have had the best luck with the Eloy brand from SBI
Thanks for your help and the informations!
I guess, ill try my luck with Melling valves (V0974 and V1457) since im in europe and theyre easy to purchase through rockauto.
Today, i pulled the Piston from the rust pitted cylinder:
the scoring on that piston looks very bad on this picture. The "funny" thing is that it only scored under the rings.
i tried tried to smoothen the scoring out with scotch brite, but since im not an engine building expert, i dont know if its a good idea to re-use this piston in a fresh bored engine block in case of reusing the whole rotating assembly for sure with new rings.
That piston should be thrown away and replaced. Most machine shops fail to pin fit pistons and use sufficient piston to wall clearances. Hence, future engine issues. Your block looks heavily pitted and I would use a different block or get that one sleeved. Your budget will dictate your engine build path.
That piston should be thrown away and replaced. Most machine shops fail to pin fit pistons and use sufficient piston to wall clearances. Hence, future engine issues. Your block looks heavily pitted and I would use a different block or get that one sleeved. Your budget will dictate your engine build path.
ok, so im gonna pull all pistons to check if the others are in good shape. If yes, hopefully these are sold as each somewhere. The block i have lying around has a different casting in the lifter valley than my current block (the 2 holes, where 455's have taps to bolt in the oil baffle):
Current:
The other block:
the cast numbers on the timing case are the same (395558 2). This is the ident code of the other block, so i guess its a 1969 block:
This is the ident code of the rust pitted block:
i think(hope), it should be no problem to use the 1969 block.
That piston is an example of either following the .001" clearance on the box or the .002" in the instructions for piston to wall clearance. Consider the Mahle or DSS pistons in the other block. They both will provide better quench due to taller height, they require about half the Speedpro's .025" for 0 deck. Compression will end up only a bit lower, despite the 10 and 12cc dish.
That piston is an example of either following the .001" clearance on the box or the .002" in the instructions for piston to wall clearance. Consider the Mahle or DSS pistons in the other block. They both will provide better quench due to taller height, they require about half the Speedpro's .025" for 0 deck. Compression will end up only a bit lower, despite the 10 and 12cc dish.
yeah, i know about this issue with the wrong clearance instructions. I heard that the speed pros need 0.0045 wall clearance. but nr. 8 is the only cylinder with scoring on the wall. And im pretty sure that it scored from the rust pitting. Tomorrow, im going to pull the other pistons, then i will see how theyre looking.
i think the speed pros are "good enough" for my goal. but in case of reducing blow-by, pistons like Mahle or DSS who need the half of the speed pros clearance would be the better way to go.
You should have no problem buying a single speed pro piston. That's what I would do. If your going for all out power and maybe racing, then, I would consider a better piston and ring pack. You'll be surprised how much power you'll get out of those speed pros. You have to work within your budget and check all of your clearance several times. Curious, how was the rod bearing from that cylinder.
Last edited by joesw31; November 28th, 2021 at 12:52 PM.
You should have no problem buying a single speed pro piston. That's what I would do. If your going for all out power and maybe racing, then, I would consider a better piston and ring pack. You'll be surprised how much power you'll get out of those speed pros. You have to work within your budget and check all of your clearance several times. Curious, how was the rod bearing from that cylinder.
I think thats the way ill go. I was happy with the performance of the engine, it made good power and pulled nicely up to 5.500 rpm. Summit only sells them as a kit, but maybe i can contact them to ask if its possible to purchase one single piston.
Today, i pulled the other pistons and all of them are in good shape. No scoring. Just the black coating which they have is nearly completely off. Is this normal?
Btw, can this single pitted/scored cylinder nr.8 be the reason of the oil pulling pcv issues i had on this engine? I mean, can one single cylinder make that much blow-by?
I found that my rod bearings are 0.020's (mahle), so i assume that the crank was machined. Surfaces of the crank where the rods are attached are looking very good.
I pulled the lifters (Lunati micro trol) and camshaft (Lunati 272/276) too. I installed that camshaft last winter, before i swapped this engine in the car. 3 lifters have been a bit hard to pull, because of a very slightly burr on the bottom where they ride on the cam. Is this normal? The lobes of the camshaft are not flat and are looking like they have normal wear.
any thoughts about re-using the cam and lifters in the new block? I numbered the lifters, so they would go on the same lobe like they have been.
I know, best would be replacing both, but i like the cam and it is not available on summit or from lunati at the moment and shipping to europe is very expensive, so i try to avoid ordering every part i can.
Thanks for any thoughts, i really apprechiate all of your help!
Last edited by 71OldscutlassS; November 29th, 2021 at 10:51 AM.
Summit only sells them as a kit, but maybe i can contact them to ask if its possible to purchase one single piston.
Federal Mogul has discontinued a lot of their individual pistons. I think you put a W in front of the part number for a single. Is it an L2320 ? I can check to see if my warehouse has any singles sitting around.
Federal Mogul has discontinued a lot of their individual pistons. I think you put a W in front of the part number for a single. Is it an L2320 ? I can check to see if my warehouse has any singles sitting around.
Good to hear, a single piston will cut down on cost. Yeah, that cylinder is probably your oil burning issue along with worn valve guides.
Yeah for sure, the worn valve guides are not helping with this issue
when i pulled the exhaust valves, i saw that oil was dripping down through the guides. Intake valves have been completely covered with oil, and also with some pooling on the valves in the intake runners, but pcv was pulling oil too, since even the carb gasket was soaked with oil and i had oil in the intake manifold right under the carb.
any thoughts about re-using the cam and lifters in the new block? I numbered the lifters, so they would go on the same lobe like they have been.
I know, best would be replacing both, but i like the cam and it is not available on summit or from lunati at the moment and shipping to europe is very expensive, so i try to avoid ordering every part i can.
Reusing a camshaft in a different block is not an issue, but new lifters should be used. Reusing lifters in a different block may be an issue.
Reusing a camshaft in a different block is not an issue, but new lifters should be used. Reusing lifters in a different block may be an issue.
Ok, good to know!
Just for curiousity, why may are used lifters in a different block a problem? And why is it not a problem to use new lifters on a used cam? I always thought that lifters and cam should stay together after they have been broken in together.
I guess new lifters on a used camshaft need the same break in procedure as with a new cam?
November 20th, 2021, 11:17 AM
