I am building my bottom end. Q's

mywhite89

Registered User
Ok I have a $1100 tax return coming. The whole check plus extra is going toward getting my bottom end built.

Some parts I was looking into so far:
-forged pistons
-forged rods
-rod bearings (That goes beyond my little tax return already:) )
-main bearings
-main studs
-stud girdle
-camshaft

-Then having the block decked, bored, and magnafluxed

I need some guidance on a good combination of pistons and rods, and a camshaft.
I thought about just buying the parts from coy miller but maybe I can get them cheaper from elsewhere and still have just as good of a setup

I am going to get the block bored .20 over and I remember reading a thread of xr-7 dave's about how he has his stock cranks custom turned for a little extra clearance on high performance sc's. I guess you can work out those specs out with a machine shop.
 
A few posts down there is a good thread about rebuilding the lower end. Long story short, you have the option of using stock rods and XR7 Dave is working on a deal for stock-replacement forged pistons (no need to rebalance engine). If you want to upgrade rods you can go with 351W rods. For bearings i used clevite 77's, others prefere sealed power. Its up to you. Apparently you really dont need to upgrade main (or rod) bolts unless you're going all out racing engine, but if you do upgrade you might have some clearance issues using the ARP set (do a search about it, some cutting is involved), particularly if you run a stud girdle (or at least with a windage tray). Cam...not too familiar with this, but there are TONS of threads about choosing a cam. Small search will yield all the info you need. Good luck!
 
If you are rebuilding your bottom end you should seriously consider buying new Rod bolts. Out of all of the rotating assembly, they take the most abuse and arent that expensive even for the ARP set.

When you have the engine machined, its not really what you want the clearances to be at .. its what the engine needs to have done. If you have alot of wear or taper inside of the cylinder walls, you might be able to get away with .020 over, but could end up needing .030. Your deck surface might not need to be decked if it doesnt need it. You can run a straight edge across it and a feeler gauge to check for any clearances across the deck surface.

Your machine shop will be able to tell you what work needs to be done after taking a few measurements on various parts of the engine. Bottom line is, get your machine work done first, then you can buy parts.

- Dan
 
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I want the bottom end to be as strong and well built as it can be. I plan to buy the MPIII blower and FMIC, but first things first. The 351w rods use the same size dimesion bearings as our motors do? Thats pretty nice, I could probably get those from summit racing I guess then.

My cylinder walls don't look bad, still have the crosshatches in them for the most part, I just want them all to be good to go for sure. Maybe I can just get by with stock dimension pistons in that case.

The stock pistons on these cars arn't forged. They are 1 level under that, I can't pronounce the name,....polypneumetic or something like that.:confused: some weird name, that someone is about to laugh at me for buchering.

How about a part number for those forged 351w rods?
 
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Ddubb said:
If you are rebuilding your bottom end you should seriously consider buying new Rod bolts. Out of all of the rotating assembly, they take the most abuse and arent that expensive even for the ARP set.

When you have the engine machined, its not really what you want the clearances to be at .. its what the engine needs to have done. If you have alot of wear or taper inside of the cylinder walls, you might be able to get away with .020 over, but could end up needing .030.

Definitely getting main studs. Main girdle, maybe over kill?????

So what your saying is I should take the block in before deciding to go with .20 over pistons? From the looks, I could probably get away with putting the stock ones back in if I wanted to but thats just by my eyes
 
Learn from my mistakes. My supercpoupe has been down for over two years for what should have been a 2 mnth rebuild. Do you homework and source your parts and info , definately get part numbers where aplicable, but dont order any engine parts prior to going to the machine shop. Let them tell you what they think you need and go from there. I lost a buttload of time having to send parts back and waiting for new parts only to have those parts installed and have to send something else back. WHat a major pain in the ~~~. Try to figure out how you are going to use your car and build it accordingly. Dont buy yourself the biggest cam out there if you plan on driving primarily on the street. I have to agree that you should only really need a stud girtle if you are building an all out race motor or plan on some really high rpms. I think the cam is the only thing you could probably order without any of the internal specs. again do you haomework and choose wisely.

Rick
 
Rick Mink said:
Learn from my mistakes. My supercpoupe has been down for over two years for what should have been a 2 mnth rebuild. Do you homework and source your parts and info , definately get part numbers where aplicable, but dont order any engine parts prior to going to the machine shop. Let them tell you what they think you need and go from there. I lost a buttload of time having to send parts back and waiting for new parts only to have those parts installed and have to send something else back. WHat a major pain in the ~~~. Try to figure out how you are going to use your car and build it accordingly. Dont buy yourself the biggest cam out there if you plan on driving primarily on the street. I have to agree that you should only really need a stud girtle if you are building an all out race motor or plan on some really high rpms. I think the cam is the only thing you could probably order without any of the internal specs. again do you haomework and choose wisely.

Rick

Thanks for the info. I am planning on having it as a weekend summer car, with occassional strip use. I want it to be fast when I ask for it to and not have to worry about things breaking because I decided to turn it loose on the highway.

New parts I have collected so far:
-Full engine fel-pro gasket kit
-BHJ balancer
-new slave cylider
-ARP head studs
-spec stage II clutch
-spec lightweight flywheel
-aluminum driveshaft from that GP on tccoa (still waiting on)

A million more parts and a good tune and I will be ready to play
 
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351 rods are longer thus won't fit with stock pistons.

If you want the strongest bottom end:
H-beam rods with ARP bolts
Weisco forged pistons
ARP Main Studs
Polished crank
King or Felpro main bearings
King Rod Bearings
Main cap girdle
Windage tray

At least that's what I've talked myself into for the most part.
 
I FINALLY got my engine back from the machine shop a couple days ago. I dropped it off in November, and March is almost over now. Thats about 4 months Ive been waiting just for the machine work. Its for my 1994 SC.

I had spun a rod bearing, so my crankshaft needed some welding, plus a grind and polish .010 over, speced out for Clevite rod and main bearings included - about $270.

The engine block needed to be bored .020 over, they sand blasted and resurfaced the heads, did a 3 angle valve grind. Reconditioned the Rods and installed the bolts ( which were salvageable for some odd reason .. sometimes you spin a rod bearing and ruin the rod also, mine happened to shrink from the heat and the machine shop was able to re-use them ) .. installed new rod bushings, cam bearings. A bunch of parts that were washed. Everything else was within specs - $800 later.

I am going for a basically stock build, and since the factory rods are being re-used Its not as important to be re-balanced - although it is always a good idea to have your rotating assembly balanced, especially if you plan on making alot of horsepower .. normally about $250. If you use new Rods and pistons you should defiantely get it balanced.

I have a bunch of rebuild parts, which are always good to replace if you have a high mileage motor. Sealed power Pistons .020 over, Rod, Main, Cam bearings, Rod bushings, Piston Rings, Timing chain and gears, new Tensioner, Oil pump, Felpro upper and lower gasket set, ARP Rod bolts, and Head studs, Freeze plug kit, Flexplate Bolts .. Im sure there are a few other parts but thats most of them for the internal engine overhaul. Plus Assembly Lube, Camshaft lube, Sealers, Engine block paint, Oil additive to help the break in. About $700 later more.

I have almost $2000 invested in this project already on a basically stock build. Not trying to make a ton of power, I just want it to last. Plus I had to buy new Motor mounts, Oil pan .. still looking for an Oil dipstick tube .. lots of little parts for the outside of the engine as well.

You want to really plan on your build to what you're going to be using the engine for, and what actaully needs to be replaced. Aside from all of the parts that you would normally replace, there are alot more that should be replaced for peace of mind. The Main stud girdle may be a little overkill .. but its up to you. If you use the ARP Main studs, there is a possibility you may need to have the mains Line Honed if the caps dont line up using the studs.

Theres a saying I keep in mind when rebuilding engines .. something Old, something New, something Blew.

- Dan
 
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Ddubb said:
I FINALLY got my engine back from the machine shop a couple days ago. I dropped it off in November, and March is almost over now. Thats about 4 months Ive been waiting just for the machine work. Its for my 1994 SC.

I had spun a rod bearing, so my crankshaft needed some welding, plus a grind and polish .010 over, speced out for Clevite rod and main bearings included - about $270.

The engine block needed to be bored .020 over, they sand blasted and resurfaced the heads, did a 3 angle valve grind. Reconditioned the Rods and installed the bolts ( which were salvageable for some odd reason .. sometimes you spin a rod bearing and ruin the rod also, mine happened to shrink from the heat and the machine shop was able to re-use them ) .. installed new rod bushings, cam bearings. A bunch of parts that were washed. Everything else was within specs - $800 later.

I am going for a basically stock build, and since the factory rods are being re-used Its not as important to be re-balanced - although it is always a good idea to have your rotating assembly balanced, especially if you plan on making alot of horsepower .. normally about $250. If you use new Rods and pistons you should defiantely get it balanced.

I have a bunch of rebuild parts, which are always good to replace if you have a high mileage motor. Sealed power Pistons .020 over, Rod, Main, Cam bearings, Rod bushings, Piston Rings, Timing chain and gears, new Tensioner, Oil pump, Felpro upper and lower gasket set, ARP Rod bolts, and Head studs, Freeze plug kit, Flexplate Bolts .. Im sure there are a few other parts but thats most of them for the internal engine overhaul. Plus Assembly Lube, Camshaft lube, Sealers, Engine block paint, Oil additive to help the break in. About $700 later more.

I have almost $2000 invested in this project already on a basically stock build. Not trying to make a ton of power, I just want it to last. Plus I had to buy new Motor mounts, Oil pan .. still looking for an Oil dipstick tube .. lots of little parts for the outside of the engine as well.

You want to really plan on your build to what you're going to be using the engine for, and what actaully needs to be replaced. Aside from all of the parts that you would normally replace, there are alot more that should be replaced for peace of mind. The Main stud girdle may be a little overkill .. but its up to you. If you use the ARP Main studs, there is a possibility you may need to have the mains Line Honed if the caps dont line up using the studs.

Theres a saying I keep in mind when rebuilding engines .. something Old, something New, something Blew.

- Dan

In terms of lower end work, sounds exactly like what i did to mine. I just had the shop balance my rods and piston assemblies since I used stock rods with new OEM Sealed power .20 over pistons. Otherwise (with the exception of me adding a 94-95 windage tray) thats exactly what I did.

Mywhite89, PS...if you're boring the engine its good to keep in mind that 30 over is pretty much the max you can go on the block. I decided to go 20 just in case in the future I need to bore it out again, i have that 10 to play with.
 
Ddubb said:
I had spun a rod bearing, so my crankshaft needed some welding, plus a grind and polish .010 over, speced out for Clevite rod and main bearings included - about $270.

...
- Dan

Did they regrind the fillets in the main journals? Did they re-treat the crank after the welding and grinding?

Note the benefit of the Felpro and King main bearings are the oil channels machined into the bearing that goes 3/4 of the way around the bearing. A real advantage to these bearings.

As far as the main girdle. Overkill, perhaps. Make it bulletproof, certainly. For now, I'm having to skip it. Of course bulletproof at 300rwhp and bulletproof for 600rwhp are two completely different goals.
 
Mike8675309 said:
Did they regrind the fillets in the main journals? Did they re-treat the crank after the welding and grinding?

Of course. I took it to Ed's Crankshafts in San Leandro, Ca. They specialize in Crankshafts only and theyre the best in the Bay area.

- Dan
 
Sell the spec clutch and buy a centerforce.

Also the stock pistons are hypereutectic.

Hypereutectic Pistons...
Accident Waiting to Happen?

23 Mar 99 -- TA Performance has noticed an increase in customer reported engine failures, due directly to the use of Hypereutectic Pistons. These newer pistons are very hard, thus brittle. These pistons have proven to be un-forgiving with spark detonation. The latest report received was analyzed and the results were as follows... at least one cylinder experienced spark detonation, resulting in one piston failing, then fragments of the exploded piston were introduced into the intake manifold and distributed to other cylinders resulting in an addition of 4 more pistons "exploding". This is not a recall on be half of TA Performance, because TA neither recommends nor sells these pistons, other parts warehouses push these pistons because of their flashy name, TA only recommends two types of pistons: cast for stock and mid performance street applications, and forged for high performance street and race applications. Over the last few months we have averaged approximately 3 calls per month regarding failed Hypereutectic pistons.

Hypereutectic pistons are cast pistons made from aluminum with over 16% silicon content for strength and durability. The term 'hypereutectic' comes from eutectic.

Special melting processes are necessary to ‘supersaturate’ the aluminum with additional silicon content. Special molds, casting and cooling techniques are required to obtain finely and uniformly dispersed silicon particles throughout the material.

These newer pistons are very hard, thus brittle. They have proven to be un-forgiving with engine knocking. For this reason they are great in naturally-aspirated engines, but should be used with caution for 'nitrous', super- or turbochargers. Generally speaking, forged pistons are a better choice for high boost.

Hypereutectic pistons are used in many original equipment engines. They are favored because of reduced scuffing, improved power, fuel economy and emissions. The reduced thermal expansion rate allows the piston to be run with reduced clearance.

Hypereutectic pistons suck. Ford finally realized this and built the SVT Cobra DOHC 4.6L w/ a fully forged bottom end to support the boost from the m112 supercharger. Stock block cobras are spitting out 800 hp with turbo or better superchargers.
 
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Thus I use this rule.

Under 400rwhp and no nitros, stock pistons and rods will do just fine.
Over 400rwhp or planning to use nitros, forged pistons and stronger rods necessary.

I asked about the crank just because most folks are not going to understand that you can not simpl grind down the crank journals and call it good. A good machine shop should know that, but some just don't bother to discuss it with guys.
 
Scott Long said:
Sell the spec clutch and buy a centerforce.
Why? I've heard good things about this clutch.

Thanks for all the information, there are soo many tricks and little things to remember. This will be my first built bottom end, and I want it to be the best I can make it at pretty much any cost needed.

Guess my next step will be to take the block in, get it all checked over.
-That will set me up for buying pistons and rods
-Then I can take all the necessary parts in for balancing the rotating assembly and figure out then if I need undersized bearings.

What does the machine shop actually do to balance the rotating assembly?
Will I need to bring them rod and main bearings at that time ?
 
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