budget 401 build

guffey24

This is my first post on this site, My name is Josh and I am from North Carolina I came to this site because word has it that you guys have all the info on the AMC motors a little info on my Jeep CJ-7, not a daily driver, and not a show Jeep, I am not looking for chrome, I want the basics, I want to reuse as many parts as possible cam will be replaced, and any parts that are not usable yesterday when it was raining I took a couple of hours and carefully tore down my 401, to the bare block, I have everything labeled in boxes for reassembly I have helped tearing down a few chevy's with dad some years ago, but this will be my first AMC, and I want it to be good the first time patience and time, I have plenty I snapped a few pics, and found some things in dissassembly I am guessing the fuel pump needs replaced any suggestions, comments are welcome, along with some low budget upgrade ideas

guffey24

I am guessing the fuel pump needs replaced

The heads seem to be in good shape, havent really messed with them much

The block is in good shape, cylinder walls look very good, I will no more about them, after it is cleaned up

Several of the pistons have some chips out of them, this one being the worst, dont know where the pieces ended up

Timing cover has some spots, I am guessing, that was caused by the fuel pump falling apart

guffey24

As amember of some other forums, I have had people tell me this can someone explain what this means and maybe show some pics I would clean and enlarge the oil drain back holes in the lifter valley, possibliy add extra ones. I would drill a smaller hole in the cam bushings to increase oil pressure on the rods & mains. Cross Drill the crank for improved oiling. I would most likely replace my timing cover with a new one if there was wear in the oil pump area-a switch to Davis Martins aluminum street gears for the oil pump. Modify the heads for Adjustable rockers with guides. Run L2380 F pistons from a '71 401 for the increased compression Of course have it balanced and some mild porting and bowl blending on the heads.

82Waggy

First things first, Of course have the everything cleaned and then magnuflux the block and heads to check for cracks. Have the bores measured to determine what overbore will be necessary and then choose pistons. Have the crank measured to determine if and how much it must be ground - it will need it. Since cost is a factor, you will probably want to stick with press pin stock style pistons - be careful about compression ratio as you do not want to exceed about 9.2:1 on pump gas for a daily driver. If the budget will allow, consider going with the KB354 piston with bushed rods and floating pins with zero deck clearance - with the available head gaskets this will establish an .045" quench distance. Keep in mind however that the KB354 piston option will bump compression ratio to near 9.7:1 with stock 58cc chambered heads - you would therefore want to open the heads up to about 65cc to keep compression ratio down closer to 9:1 - this adds conciderably to cost. The decks of the block and the heads will likely need to be milled flat, if not taken down some to help establish quench height and compression ratio. Have the rods reconditioned/resized with new ARP rod bolts. Get with a good machinist - ask around in your area for recommendations. Hopefully they will have a torque plate to use when they finish hone your cylinders. Search through this forum for a complete list of what could be done in a post entitled "My 401 Machining and Parts List" - posted about a week ago. This will give you an idea of what you may be up against - but it was intended to replace everything except the core components (crank, rods, and block) and uses an MPEFI setup. Modify the list to suit your build. Forget about oiling mods for now. Unless you are going to build something radical the best thing you can do is to upgrade your pump and make sure everything is very clean. If the inside of the pump housing is scored you will need to replace the timing cover and get new pump gears - find them here in the E-Store. Aluminum pump gears are not necessary - and probably not desireable for any particular reason. After the pump, the next mod in line is to increase capacity with a deep sump pan - few need to go any further than that. Will you be using the stock intake manifold? Determine what your performance goals are for this engine and get back to us.

82Waggy

Here are a few "gotchas" to keep in mind. If you replace head bolts with new, like ARP's, it is imperative that you have the bores honed with a torqueplate and the new bolts to simulate installed cylinder distortion that will result. ARP bolts do not strecth as much and will distort the cylinders more than stock bolts will. Same deal on main cap bolts or studs. Changing from stock will distort the caps differently and would require align honing with the new fasteners for proper bearing fit. Nothing wrong with retaining the stock head and main cap bolts for a mild build.

1980_Cj7

Hmmm, we replaced the rod bolts with ARP's in the first rebuild. Maybe that explains the bearing wear pattern.

Having trouble finding anyone with a torque plate, and all the shops keep saying it isn't necessary. And we just got new ARP head bolts for this rebuild!

I know what intake Josh is using (wink, wink). Hey Josh, how'd it clean up?

Goose

I will leave the more detailed suggestions to those with the technical knowledge, But If this is your first AMC.. a couple things we have all found out the hard way.. You should replace the timing cover almost certainly.. The oil pump cavity is probably hosed (and looking at the number of parts/pieces that were floating in the oil (pistons and fuel pump shrapnel) and of course the oil pump and bottom plate this isnt as expensive as you might think and Matt here at bulltear has the best quality of these parts. two If you replace either the Distributor gear or cam gear replace as a matched set..(I have built Small block Chevy's for years, and this floored me! I have never even considered such a thing. I used to pop distributors in and out every weekend (one for race one for street different curves etc.) Those two items are the ones that stand out as different from most other engines I have had apart. Good luck and Welcome!!

82Waggy

1980_Cj7 wrote
Hmmm, we replaced the rod bolts with ARP's in the first rebuild. Maybe that explains the bearing wear pattern.

Having trouble finding anyone with a torque plate, and all the shops keep saying it isn't necessary. And we just got new ARP head bolts for this rebuild!

I know what intake Josh is using (wink, wink). Hey Josh, how'd it clean up?

Did you have the journal end of the rods resized with the new ARP bolts in place? If not, I can guarantee that they distort differently and will wear the bearings unevenly. Mine were resized with the new bolts torqued to 50ftlbs (stock is only 38ftlbs).

Honing cylinders without a torque plate will result in distortion of the cylinders when you torque the heads down - made even worse by the use of lower stretch ARP head bolts over stock. With tight piston to cylinder wall clearance you do not want to eliminate this step.

I can lease you a torque plate - deposit equal to cost (I want it back) - refunded upon return less $55.00. You pay shipping both ways. PM me if interested. It is brand new - used on my two motors only (they don't wear out). Maybe you and Josh can both use it (55 per motor).

guffey24

1980_Cj7 wrote
Hmmm, we replaced the rod bolts with ARP's in the first rebuild. Maybe that explains the bearing wear pattern.

Having trouble finding anyone with a torque plate, and all the shops keep saying it isn't necessary. And we just got new ARP head bolts for this rebuild!

I know what intake Josh is using (wink, wink). Hey Josh, how'd it clean up?

George, how's it going, manifold cleaned up very well, thanks again

I am going to take my time with this build and post pics and questions as I go

jeepsr4ever

These guys are on the right track. The basics should be done with specail care for the engine due to its age and heating/cooling cycles. Hot tanks will also distort castings because nothing is torqued so its a good idea to start with a strong and true foundation (block work, heads). Decking, line honing and boring with or without a plate (with preffered). For the basics a good strong oil pump, a upgraded oil filter adaptor smaller hole cam bearings and I would leave the mods at that. I would seek a roller timing chain and a lower end camshaft. Get a basic head job done and run at least a edelbrock performer intake and a decent carb. Fuel pumps are cheap. This would be a ideal build for what your asking but if you want it on the cheap.... Check the bore thuroughly and check pistons for broken skirts and cracks. You could re-ring and do a budget build but you may not get the best longevity out of it.

1980_Cj7

82Waggy wrote
Did you have the journal end of the rods resized with the new ARP bolts in place? If not, I can guarantee that they distort differently and will wear the bearings unevenly. Mine were resized with the new bolts torqued to 50ftlbs (stock is only 38ftlbs).

Honing cylinders without a torque plate will result in distortion of the cylinders when you torque the heads down - made even worse by the use of lower stretch ARP head bolts over stock. With tight piston to cylinder wall clearance you do not want to eliminate this step.

I can lease you a torque plate - deposit equal to cost (I want it back) - refunded upon return less $55.00. You pay shipping both ways. PM me if interested. It is brand new - used on my two motors only (they don't wear out). Maybe you and Josh can both use it (55 per motor).

Don't know what the first shop did with the rods. I did have them spot face the caps for the bigger nuts on the ARP studs. Fuzz taught me that one. I'm gonna mention this to the new shop tonite though. I think they are a lot more thorough as when I mentioned to them to match the rod lengths when honing for the pin bushings, they said yes, that is all part of reconditioning the rods.

Don't know if the block was already honed or not. Last I talked to them they said all they needed to do is wash it out yet, so it might be too late. Something else to worry about now, especially with the new hypereutectic KB354's which call for real close clearances.

82Waggy

1980_Cj7 wrote
Don't know what the first shop did with the rods. I did have them spot face the caps for the bigger nuts on the ARP studs. Fuzz taught me that one. I'm gonna mention this to the new shop tonite though. I think they are a lot more thorough as when I mentioned to them to match the rod lengths when honing for the pin bushings, they said yes, that is all part of reconditioning the rods.

Don't know if the block was already honed or not. Last I talked to them they said all they needed to do is wash it out yet, so it might be too late. Something else to worry about now, especially with the new hypereutectic KB354's which call for real close clearances.

Well, many do not use a torque plate but I sure wouldn't use the ARP head bolts in that case.

guffey24

I took the block to the local machine shop, they have cleaned it, magnafluxed it and bored it .30 over I am going to get the block back and have a good look at the work they did local NAPA machine shop did it for $173 this machine shop is trusted pretty well in the area, same group of guys working there for over 30 years I know I am not done with the block yet but funds limiting me to baby steps you guys have offered alot of good info, what would be your next step, I am thinking in a couple of weeks, I could buy the master rebuild kit, and have looked at the maddog-racing kit advertised on ebay, seems to be a good deal on everything, and all parts are US made any other kits I should look into?