401 short block rebuild opinions......

OK, just got off the phone with the machinest. He builds race motors in his spare time. But he is not an AMC guy. So I have a little concern. Here is the info:



Bore and hone block

Clean block

Magniflux block

Install cam bearings

Install brass or ss freeze plugs

Microfinsih crank

Change pistons on rods

Check rods

Paint block

Parts:

Pistons .060 over Silverlight (Keith Black?) stock compression, rings, main and rod bearings, cam bearings, timing chain and gears, oil pump kit, gaskets, cam, lifters, springs, retainers (cam will be the Comp Cam EX262 kit)

Not including any head work needed other than installing parts.

Total price, $1580.00

Assembly additional $400.



My only worry is the block being bored .060 over. He said if I use good quality cooling parts, it would be fine.



Thoughts? Price?

Thanks.........

(I also posted on IFSJA if anyone is interested)

 

If it was a chevy, I would say that is probably a bit high for parts and a bore job but maybe not for AMC-and 60 over would certainly make me nervous. A little core shift and the walls may be very thin. Heating due to thin cylinder walls will also cause ring seating/sealing problems and probably a short life for the rebuild. I would be looking for another block that would clean up at 030.

 

aallison, my brother in law in an AMC guy there and has been building motors since the early 80s. If you want to talk to an AMC guy and get his opinion I can try to put you in touch with him. He's a pretty easy going fellow and I've seen some of the stuff he's built. Top notch stuff. Lives in Lake Asbury near Van Zant park. lemme know

 

I've not heard of good things coming from taking a 401 more than 0.030-over. I've been wrong in the past, but it seems like a gamble with a lot of your hard-earned money.

If it were me, I'd rather put all that money into a 0.060-over 360 that could take a beating like a ragged mutt, but I'm kinda kooky.

 

I think AMC doesn't recommend going over .030, I think many machine shops have the technology now to measure the thickness and advise safe overbore for individual blocks.
Why does it need to go 60 over, in the case of the 360 I am currently building I had 1 cyl with bad rust pitting, it wouldn't clear up at 40 over so we sleeved 1 cyl and I ended up with a 30 over block. Probably wouldn't be cost effective to sleeve more than a couple of cylinders.

 

I seem to remember something along the same lines as the rest of these guys with going more than .030 over on the 401, just a question..do you really want a 401..for that kind of money a guy could do a chevy conversion and have something that parts are more available for and won't break the bank to buy parts for?

 

and weighs less....

 

Chevy motor in a CJ?? I'd rather stay AMC if I can. But I'm starting to think other motors might be possible and me not have some sort of attack........

Of the people that think .060 is too much, do you know of anyone personally that has done this or, like me, have read it on the internet while couch wheeling and assume it's correct?

 

I worked in a machine shop in the 70's. The machinist would bore 30 no problem, 40 was OK but 60 was only done at owners request. That was normally done for increased displacement.

 

Are you really sure it needs .060 overbore to clean it up? Thats some really deep pits and or wear.

 

Actually he said it was .007 out of tollerance and to clean it up he doubles that so really it needs to go .014 bigger. But the next size pistons he can find (not too much looking I'm sure) are .060. So that is where the number comes from.

I want to meet with him and actually see and talk about it insteadd of an over the phone discussion. It was suggested to hone it and let it go at .007. It would not be the best thing but it would be better than taking the risk of an .060 bore.

I really want to use this block if I can. Finding a 401 in Fla. is almost impossible. I'm looking over the Southeast but so far, nothing I'm interested in or it's way more than I want to spend.

 

That's crap. I might find another machinist. In all of about 5 minutes I found some in various sizes.

.040 over

Kanter auto

.030 over on amazon

Here's a machinist in J-ville that does very good work. If you go and talk to him he'll help you out or point you in the right direction. He builds very high end race engines of all sorts and his shop is a museum of sorts.

Gary Johns Automotive Machine
2392 W Beaver St,
Jacksonville, FL 32209
(904) 388-8808

Dover cylinder head in Orange park can work wonders with heads. I've done numerous sets of Chevrolet heads there and he also did my current buick heads.

hope this helps

 

So he is saying it could go 20 or 30 over with no pronlem, I think I would see if you can find some 30 pistons and see if he is OK with that, Did the machinst say he thought 60 was OK ?
I don't think looking for another block would help, most used blocks are going to have some wear. I would be surprised if you found a used block that would go back standard bore. Your problem is not the block but parts supply.

 

It is already 30 over. It needs to go to 60 to clean up the bores. Going to 040 over is not ehough.

But I think I have a plan.......

 

That makes sense, already 30 over.

I havn't seen any 401's locally for a while, last year there were at least 3 on Craigslist at 1 time so they do show up.

 

It's being sonic checked Tuesday or Wednesday............

If the sonic check comes back bad, I have a plan to make a 391 stroker 360......

 

i have a 401 block that is also already bored 30 over. it was showing about 6 to 7 thousandths wear. machine shop 1 was quick to say sure lets bore it out 60 over. i said no way. machine shop 2 said no way also. the cylinders still have all the cross hatching in it. not sure why it would have that well defined of cross hatching and have that much wear to it. to make a long story short i put a 360 in the jeep and stuck the 401 in the shop. I think one of these days i am either going to just hone it out to 40 over and slap some pistons in it or just leave it loose with the 30 over slugs and find me a gremlin to put it in. it ran great when i pulled it out of the wagoneer when i bought it. after i test drove it at the dudes house i never even started it for fear of doing something stupid again ( dont ask) and blowing it up before i ever pulled it out of the wagoneer.