340 X block question

[Les Gibson]

Hello all. I have a question to ask if anyone here has had this experience. The 422 stroker small block in my Arrow is based on a 340 X block. 4.10 bore with 4.00 stroke. I'm currently having it freshened up at a reputable engine shop here in Maine. Last week the shop owner asked me to come over so he could show me something about my block. My immediate thought was what could this possibly be as the engine was running strong at the end of this past season. He showed me what he called 'cap walk' with the 3 middle four bolt caps. He told me that the outer portion of the caps even when torqued down are not sitting flush on the block surface. He told me that with the caps torqued down he could probably put a two thousandths feeler gauge between the cap and the block. He also showed me some discoloration on that portion of the caps ( around the outer bolt hole) and the corresponding area on the block. He called it 'cap walk'. He told me that as a result of this the crank main line bearings would be slightly oval instead of round. He said he's seen this in other X blocks but they were much worse than mine. The good news is he told me he could make this between 95 to 99% right and for what I do the engine would be fine. He told me the main bearings did their job and no issues with the K1 crank or K1 rods.
Has anyone here who has run a X block encountered this issue and, if so, what was the correction? Please don't tell me to ditch the X block and go with something else as that's not going to happen, at least not this time. Thank you.

 

[MOPARMAGA]

Hello all. I have a question to ask if anyone here has had this experience. The 422 stroker small block in my Arrow is based on a 340 X block. 4.10 bore with 4.00 stroke. I'm currently having it freshened up at a reputable engine shop here in Maine. Last week the shop owner asked me to come over so he could show me something about my block. My immediate thought was what could this possibly be as the engine was running strong at the end of this past season. He showed me what he called 'cap walk' with the 3 middle four bolt caps. He told me that the outer portion of the caps even when torqued down are not sitting flush on the block surface. He told me that with the caps torqued down he could probably put a two thousandths feeler gauge between the cap and the block. He also showed me some discoloration on that portion of the caps ( around the outer bolt hole) and the corresponding area on the block. He called it 'cap walk'. He told me that as a result of this the crank main line bearings would be slightly oval instead of round. He said he's seen this in other X blocks but they were much worse than mine. The good news is he told me he could make this between 95 to 99% right and for what I do the engine would be fine. He told me the main bearings did their job and no issues with the K1 crank or K1 rods.
Has anyone here who has run a X block encountered this issue and, if so, what was the correction? Please don't tell me to ditch the X block and go with something else as that's not going to happen, at least not this time. Thank you.

All blocks pretty much do have cap walk.
What I did to correct it I haven't seen the results yet. But I drilled in between the cap and register and installed roll pins at an angle into the block in theory it holds the caps in place.
Mine is a big block, the small blocks are much easier to do that to .

 

[Les Gibson]

All blocks pretty much do have cap walk.
What I did to correct it I haven't seen the results yet. But I drilled in between the cap and register and installed roll pins at an angle into the block in theory it holds the caps in place.
Mine is a big block, the small blocks are much easier to do that to .

That may very well be what my engine guy plans on doing.

 

[MOPARMAGA]

That may very well be what my engine guy plans on doing.

Could be, I know people do it and have success.

 

[Desoto291hemi]

I wish you had some pics to show
I would be curious to see the main bearings too

If it is cap walk. The bearings should show signs as well
Whatever you do
Don’t swap out that block
It’s not hurt. It will last a long time to come and still be making power

Tommy

 

[Les Gibson]

I wish you had some pics to show
I would be curious to see the main bearings too

If it is cap walk. The bearings should show signs as well
Whatever you do
Don’t swap out that block
It’s not hurt. It will last a long time to come and still be making power

Tommy

Nope not swapping out the block. My engine guy says there's no reason to and I agree with him. I didn't think to take any pictures when he was showing this to me.

 

[mbaird]

Y

Nope not swapping out the block. My engine guy says there's no reason to and I agree with him. I didn't think to take any pictures when he was showing this to me.

Your lucky to have an attentive engine builder close by .

 

[SSG_Karg]

A little off topic but, what piston do you run in that engine? I also run a 4.10”x4.00” stroker (factory block).

 

[Rocket]

I know a bracket racer in upper state NY that runs at Lebanon Valley and he roll pinned his x-block as well.

 

[ch1ll]

Considering your block is probably 50 + years old it's to be expected. Sounds like the bottom of the block needs to be resurfaced to minimum clean up and the bottom of the caps as well. Then you will need to align hone the main bearing bores.

Just go to brand racing on youtube and look at how far out the head mating surfaces are when he decks the block. He takes a piss cut( like .002) to reveal how un flat it is. Blocks move over time with heat cycling and they weren't faced that accurately at the factory to begin with.

 

[RustyRatRod]

I don't get why he cannot fix the issue 100%. The caps need to be refaced on the block side. The block needs to be refaced where the caps bolt on. Finally, the block needs to be align honed or bored, but with a VERY light cut to the block side, to prevent needing a shorter timing chain. That will 100% address the issue of an egg shapped crank bore. Then pin the block, run a girdle or "whatever" you decide on so that it doesn't happen again. If he cannot do that, then it's time to find a new shop.

 

[Oldmanmopar]

Buy new billet caps and have them fitted and line bored. Is you block 4 bolt mains, Note the 2 different style main caps. Make sure the shop doing the work has a new line bore machine in the 4th and 5th picture . Ask them to see it. If not don't let them do it. You won't find another X block very easy.

We have seen some shops do their work on bed mills one main at a time like in the back ground in Steve's shop in the last picture . Not consistent. Just a heads up for your knowledge.

In the past we had 2 of our X blocks ruined a Shady Dell. That is why Steve has his own machine shop now with employees he trusts.

 

[Oldmanmopar]

He does 4 bolts and side bolts.

 

[Bobzilla]

In the past we had 2 of our X blocks ruined a Shady Dell. That is why Steve has his own machine shop now with employees he trusts.

Does your son make his own billet steel main caps? If not, does he have a current source for small block billet steel main caps.

Note: my question is aimed only at X and R blocks capable of four bolt mains.

 

[Sterling]

I have had a main cap issue with a 360 block, I attributed it to my dad running the whole season on the MSD rev limiter. Mike at B3 had some new caps fitted and lined honed. The X block I have is only 2 bolt mains, thought of having it converted if I build it.