Machine work

[69stang_250]

Hey there guys,

For my build I am having to rethink and adjust things based off of some news I got from the body shop.

Here is the new specs and would appreciate any advise or opinions.

250 (30 over)
255 pistons ( 7cc dish milled in )
CI Head polished with 58 cc chambers ( this puts my CR around 10:1 +- .2 and DCR 8 +- .4 )
stock rods with ARP bolts
CS 274 cam 110 LS ( I am thinking about the 280 108 LS but not sure how that will work on the street)
Stock rocker assembly rebuilt.
Stock timing chain set
Holley 4bbl carb ( debating the 600 vac sec or 670 street avenger. not sure which would be the better for the 250)

Honestly from what I have seen, I really don't see this engine making peak power over 5500, but I really do not know, and its going to driven on the street more often than not.

For this build and those specs, What machine work do you guys say is mandatory? And what would you guys say is optional or I could do my self?

Like Line boring, rod polishing, crank polishing, dynamic balancing, ect.

Thanks guys.

 

[drag-200stang]

Only do crank line bore or hone if a straight crank will not turn fairy easy . Wish I could define that for you better.

 

[69stang_250]

I understand what you are saying.
Before taking the crank and pistons out, the entire rotating assembly would turn with almost no effort at all.
With the pistons removed the crank would turn with very little finger pressure.
I will be measuring the crank and mains today and going to see if there is any major measurement differences on them.

I am asking this because of what the machinist quoted me on his work to prep the engine for building.
And honestly $1000 seems pretty high to me. I do understand time is money and machining is a very time consuming job, but still sounds pretty high to me.

 

[rbohm]

boring the cylinders, rebuilding the rods(straightening, machining both ends to make them round again), and machining the crank as needed. on top of that, the block deck, the head surface both need to be squared up, plus any valve and guide machine work needed. depending on the labor rates in your area $1,000 is about right these days. gone are the days of boring cylinders at $4 per, and gone are the $25 per hour labor rates as well. the shop might also be balancing the rotating assembly as well, again depending on labor rates in your area.

 

[BCOWANWHEELS]

balancing is a total waste of money unless your going to spin engine 5k or more, straighten rods ????????????

 

[69stang_250]

I have heard that from many people, however, I will be balancing the engine. These engines do have harmonics more than most other engines and I don't plan on taking the bottom end of this engine apart any time soon.
Also, after balancing many aircraft rotor systems and seeing how much not doing that properly can affect drive train wear and longevity, balancing is never a waste of money or time.

The things I know I will need done are:
bore/hone
Mag
rod bolts installed
balance the rotating assembly

Is there anything else that you guys think should be done?

 

[62Ranchero200]

Unless your crankshaft is in excellent condition with very little journal wear, the journals might need to be turned slightly undersize.

Have you considered using ARP main studs? Considering the cost of the aluminum head, they're a bit of extra security on the bottom end.

I run the 274/274/108 cam in my 250 with the aluminum head, but my HP peak is still just over 5,000 RPM, so no need to spin the engine any faster than that.

With a DS2/MSD setup the 274/274/108 cam idles and runs well on the street.

I had my rotating assembly statically and dynamically balanced as well.

Thanks
Bob

 

[CNC-Dude]

Along with changing the rod bolts, you'll need to recondition the rods as well. If you replace the stock main bolts with main studs, you will also need to likely align hone the block. This is often overlooked because it isn't really understood by most people that don't work in that industry that changing these fasteners changes the way the rods and block are torqued when you use them.

 

[chad]

A lill late to the thread -

"...anything else…"
but I'd say:

back cut valves, 3 angle valve job

if not stressed yet.

 

[drag-200stang]

Along with changing the rod bolts, you'll need to recondition the rods as well. If you replace the stock main bolts with main studs, you will also need to likely align hone the block. This is often overlooked because it isn't really understood by most people that don't work in that industry that changing these fasteners changes the way the rods and block are torqued when you use them.

In a perfect world, I agree 100% but my experience has been "oh that bozo with the 6 - any kind of crap we give him will be just fine... and he'll pay good money for it". Now days, I will not give them the opportunity. Only if its truly broken and needs fixing, I'll only do it if I can't. And I usually regret that decision but there's only so much you can do yourself. Your results may be better than mine.

 

[bubba22349]

Hey there guys,

For my build I am having to rethink and adjust things based off of some news I got from the body shop.

Here is the new specs and would appreciate any advise or opinions.

250 (30 over)
255 pistons ( 7cc dish milled in )
CI Head polished with 58 cc chambers ( this puts my CR around 10:1 +- .2 and DCR 8 +- .4 )
stock rods with ARP bolts
CS 274 cam 110 LS ( I am thinking about the 280 108 LS but not sure how that will work on the street)
Stock rocker assembly rebuilt.
Stock timing chain set
Holley 4bbl carb ( debating the 600 vac sec or 670 street avenger. not sure which would be the better for the 250)

Honestly from what I have seen, I really don't see this engine making peak power over 5500, but I really do not know, and its going to driven on the street more often than not.

For this build and those specs, What machine work do you guys say is mandatory? And what would you guys say is optional or I could do my self?

Like Line boring, rod polishing, crank polishing, dynamic balancing, ect.

Thanks guys.

Depending on your skills and access to some equipment you might be able to do some of that prep work. Things such as De-burring and general clean up of the block, the Rod Polishing, Crank De-burring of the casting flash etc., Micro Polishing the crank journals, if they still Mic in spec (you need a way to spin it like a Lathe), weight match the rods and pistons (an accurate scale is needed). X2 I also agree if the crank spins free (with no effort) then a line bore or hone of the mains isn’t needed on a budget build. Good luck

 

[BCOWANWHEELS]

guys this is all a engine machinist,s job. if you want to jack leg it then you,ll get a jack leg job....

 

[69stang_250]

Thanks for all of the advise y'all.

Some of the work I may be doing myself, like the engine cleaning and deburing, micro polishing the crank if needed, and pressing the piston pins. Bore/hone, rod work, balancing, and magnifluxing will be done by the machinest.

I'm not scared of doing jobs that are looked at as specialty jobs done by specialists. Hot rodders did it back in the day and there is no reasone they can't do it today. And you can go to a machinest and still get a "jack leg" job done. I am in no means trying to cut corners, but I am trying to make sure I am not missing anything I need to get done and not getting told I need to do something that is more of a waste of time and money.

 

[chad]

"...optional or I could do my self? Like Line boring, rod polishing, crank polishing, dynamic balancing…" & static balance
I'd agree - all optional.
* 'clean up' mill to head/block if not true anymore (exh too?) all depends on specific engine (wear),
* and final mill head of total.075 due to thicker gaskets today,
* again 3 angle valve job & back cut (at least) intake valves (& exh. if not keepin in hi revs alot),
* all the port'n polish U want to the intake (pocket port), both sides of exh, combust. chambers, valve faces,
* hardened washers under the head studs/bolts,
* watch the (I think) #11 head bolt. They can run long into the water passageway (actually hit the impeller on the H2O pump) so may B grind it down a
lill but definatly coat it w/RTV to keep the coolant frm leaking thru,
* performance cam.

"...Stock timing chain set…"
not sure what U mean but the '69/70 supplies more low rev tq - laters had smog adjustments.

That's $1,800 around here (w/all new cam, pistons, valves/springs, retainers, truing the crank, "averaging' the c.c, & on and on can't list it all) . Did not zero deck the block, "cc" the c. chambers or harden the valve seats.
From there U can actually do these 3 or 4 things (what is 'optional' above), get the '77 & later head, the sky's the limit - Mike's head, the Oz. Some build an engine that revs 7,000 + rpm, puts out over 400HP and so on.

 

[69stang_250]

Well the head work I know is going to be $1000. That is assembling the head, cc the chambers, three angle valve job, back cut valves and polishing the ports and bowls.

The short block machine work I am getting done is:
Bore/hone
Clean
Mag
Rod bolt install
Piston install
Rod re sizing
Balance

When adding all that up from some of the prices I have seen around on line, I just thought $1000 was a little high and before I told the guy what my plans for the engine was he started throwing out parts and things that he would be doing..... I had to tell him to slow down lol he has a very reputable shop around here, but I'm not one to be pushed around and go with what someone says is required without having an explanation why. Ya know what I mean?

 

[drag-200stang]

I hate to bring this up because there is no good way to get it done. Block bore hone or at least hone with a torque plate would be nice. You would be surprised how much the bores distort, they all do.