maroon91rs

I found a 350 for sale in my area that the guy is letting go for only $125. Its a 2 bolt block, and the casting number indicates the following...

Casting # CI Yrs Mains Notes
14093638...350...87-95...2 or 4...Roller or flat tappet cam
one-piece rear seal

So I was wondering if anyone knows how much it usually costs to get the machine work done to convert a 2 bolt block to a 4 bolt, straight or splayed, but preferably splayed. Im going to take a look at the motor sometime this week to see if everything looks ok, but if its going to cost an arm and a leg to do the conversion I'll just pass on it and wait to find a 4 bolt block if it would be cheaper. Thanks to anyone that can help!

ede

figure around 500, easier and cheaper to use the 2 bolt or get a 4 bolt unless you want splayed caps.

RB83L69

The parts are $200-300, for the caps; and the machine work to install them is usually something like $150-300.

There is no comparison between aftermarket billet steel splayed main caps, and factory cast-iron straight-bolt ones. The aftermarket ones are alotgether superior. You might as well try to compare a factory cam to an aftermarket cam by looking only at the price of what you can get a used factory one for and comparing that to a new aftermarket one, to determine if it's "worth it" to buy the new one. Makes just about as much sense.

"Cheaper" is not always "better". As with most things, in this matter you get what you pay for.

If the aftermarket route is too expensive, then you're better off to just run the 2-bolt setup; there's very little to be gained by using the factory 4-bolt stuff.

You will pay out the wazzoo for a factory roller 4-bolt block, because there are very few of them. Non-roller 4-bolt blocks are extremely common, that being the base for a TBI truck motor.

urbanhunter44

iTrader: (3)

no real need to use 4-bolt mains, unless you're going to be pushing really high HP numbers.

I'd just go look for a 2-bolt roller.

maroon91rs

I would like to get around 500bhp using nitrous, which is why I would prefer a 4 bolt, and I definetely want a roller. If this block is a roller like the notes say it should be, do you think it would be wise to push it to 500 on juice? I saw a conversion kit online last night that has 4 bolt splayed caps for 200 bucks, which is why I asked about the machine costs. If a 2 bolt could hold up to what I want to do, I'll just go that route. I'll call up the machine shops around my area and see what they have to say for pricing, so I guess all I want from you guys is input on using a 150-200 shot on a 2 bolt block. Thanks.

five7kid

iTrader: (14)

If that block was originally installed in a truck, it may not have been fully machined for the roller lifter provisions.

Your money would be better spent in good rods & rod bolts, rather than 4-bolt mains. You could even get a steel crank and spend less money between it and the rods/bolts than the splayed 4-bolt cap conversion would run you.

People spray 2-bolts to that level all the time.

I'd say get a ZZ4 shortblock, but the hypereutectic pistons might not be too happy with you spraying them. But, keep it rich and even they shouldn't squawk.

maroon91rs

Thanks for the advice five. Good to know that I can spray that high with a 2 bolt as long as the rest of the bottom end is tied up pretty good and the tune is perfect. I figured it would be safe but I just wanted to make sure

About the roller provisions. If its not machined for rollers, I can do that conversion for pretty cheap correct? I thought Ive read about doing that conversion to a non roller block, only needing the spider that locates the lifters and tapping the block so the spider can be bolted down. Am I correct in thinking that? I'll do some searching on that subject and see whats said about it as well.

I'd get a short block, but money is tight and Im trying to do this on a budget, while still using optimum parts for what I wanna do. I know finding a block and building it myself can be cheaper in the long run. Plus I wanna build the motor myself just so I can say I have. I've helped build a motor before, but I havent yet done my own, and man do I got the itch!

Thanks again for the help!

five7kid

iTrader: (14)

Take a look at the picture attached to the first post in this thread https://www.thirdgen.org/techbb2/sho...hreadid=265257 .

The spider mount bosses have to be machined for a flat as well as being tapped, and the lifter bore tops need to be machined to accept the anti-rotation pieces. Plus the cam sprocket mating face needs to be machined and tapped for the cam retainer.

I missed my opportunity to get my brother's non-roller truck shortblock core so I could see all these things for myself, but from what I understand, the casting provisions are there but not all are machined/tapped. Whether it would be cheaper to have a shop machine those things or get retrofit roller parts is a trade-off you'd have to investigate yourself. Typically, retro stuff is pretty pricey.

jeep_guy

im gonna chime in because i have the same block and have some questions allong the same lines
the block i got is the same casting but is a factory 4 bolt but had a flat tappet cam being that it wat a truck motor. but it also appears to have all the provisions for a factory roller setup, now the question i have is did all of these blocks have factory roller capabilities and if so what exactly do i need to do that

bnoon

Most often you do get what you pay for, but there are cheaper alternatives if you know what you're looking for. I paid $45 plus shipping for a set of new billit steel splayed caps off of Ebay. Another $40 got me the ARP fasteners. I drilled and tapped the new holes myself, and I'm spending $70 for an align bore right now. That's $155 for a four bolt main set up that's stronger than most all factory four bolt main blocks. If I wanted the machine shop to drill/tap the holes, it would have been another $60... Cheap insurance for spray in my book...

I'm also doing a roller cam conversion on my non-roller block. Almost nothing to it once you get a set of low mileage 3.1/2.4 roller lifters... This conversion is costing me less than 100 bucks in parts with me doing my own labor. Of course, this is on a 305 block I have, but we won't go into the "waste of time" issues right now...

five7kid

iTrader: (14)

If the provisions are machined and tapped, it has the capability. My brother told me his old block was not machined or tapped. Accounts vary, but it seems the trend is for most truck blocks that have a flat tappet cam do not have the machining done. It wouldn't be out of character for the factory to typically not machine them if it isn't going to be used, but to come up short on the truck line and pull some machined blocks over from the passenger car line to meet their production numbers - and still put flat tappet cams in the truck blocks, even though the roller provisions have been machined.

I believe I've heard the 350 HO crate motor block has been machined for factory roller tappets & cam, even though it comes with a flat tappet cam.

maroon91rs

What machining other than tapping the holes has to be done? I read something about milling the tops of the lifter bores for a lifter stay or something of that nature I believe. Do the tops of the bosses have to be milled down?

bnoon

You're asking about the lifter bore mods to go to roller in a non-roller block, correct? If that's the case, pretty much you just need to clearance the portion of the block right next to each lifter in order for the little retainers to fit over the lifters. You can see what needs done once you have parts in hand.

You will also need to drill and tap a couple of holes in the valley for the spider to bolt down and hold the lifter retainers in place. Then you can either drill/tap the front of the block for the cam thrust plate, or run a cam button with shims (like retrofit roller kits do).

jeep_guy

when i got my block i didnt really know what i was getting into but i quess i got lucky. now about the cam retainer plate or a cam button, i need some expalining on that. what i understand i can use a cam specificly for factory rollers and use a stock retainer plate or use a retro roller cam and use a cam button but how exactly does that work.

Stekman

Due to the design of a roller cam, there is a thing called "cam walk." The cam will literally thrust forward. The cam retainer plate or the thrust button (cam button) prevent this.

The retainer plate dos this by literally creating a hole that isn't big enough for the cam to fit through. (On a factory roller cam, there is that stepped lip, that catches the retainer plate. That also is the need for the "factory roller block" timing set.)

On a retro fit setup however, there is no machined step. There is no tapped holes for the retainer plate. So another method is needed. The thrust button is just that. A little chunk of metal, either solid or with a needle bearing design, that simply installs in the center of the cam sprocket and gets held on by a triangular plate. This way, the cams tendencies to move forward will just end up pushing that thrust botton into the timing cover, preventing forward walk.