2V 250 Bottom ends

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Anonymous

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Hello All.
Well the top end is sorted with a 2V and 3x weber setup but I want to build a strong bottom end that will handle 6-6500rpm doing circuit , sprint and hill climb work in a 4dr XM with a single rail.
At the moment all is stock, lots of torque (diesel!!) but am not confident over 5,500 rpm. Do I keep the standard stuff and do some balancing etc or can I fit later model crank, rod, piston combos in?
Roller rockers?
Any ideas would be great.

Thanks
 
Do the x flow 200 rods go in a pre crossflow motor? Which pistons?
 
Yes, they'll drop right in. You use the ACL piston P/N 6MKRY 9412 or the competition set 6MKRY 9413.
 
Ok so I get a set of 200 rods from a xflow, ACL comp pistons, ARP rod bolts, so what do I do with the crank?
Who makes the best balancers, timing chain kits?

This old girl has been running the webers/2V/250 for 20 years so I thought its time to give her a birthday.

Thanks.
 
id just crack test it mabey take 10 off it to give it nice clearences again and then rev to where ever it stops making power the cranks will handle 7500 with out failing.
drift
 
Ok now where do I get the rods from? Anyone got any lying around?
Who make the best harmonic balancers?

Thanks again.
 
I dont know if you have done this before, but if not, this is basically the process I use when rebuilding the bottom end.
You'll need to take the block to a reputable machine shop and have them check the bore. They will be able to hone it out and tell you what size (oversize) piston you'll need. Give them your 200ci rods as well so they can remove the old pistons and check them for straightness and damage. You could get them to fit new rod bolts and resize the bigends too if you want to do the job correctly. Give them the crank so they can see if it needs regrinding (I think this is where Drift was talking about removing 10 thou) and what undersize bearings you need.
Once you know what size bore your at you can order the new pistons and bearings and have the machine shop fit the pistons to the rods. They can also fit the crank and rods to the block and take the measurements to "zero deck" the block. At this stage give them the balancer and flywheel/flexplate as well so they can balance the whole rotating assembly.
Then its just a matter of taking it all home and assembling the lot with the aid of a few strips of Plastiguage and some feeler guages to check they done their jobs correctly.
 
yeah 10 off the crank to get the clearance's nice and tight again as after 30 years or so they do wear.
if going to use arp rod bolts you must resize the rods as they are done up to a much higher tension deforming the caps more.
same with the main caps.
timing chain i beleave is same as xflow one and same with harmonic balancers.
it all comes down to how long your string is and how much money you got.
ust something for the street to make nice power for anther 20 years.
basicly just freshen up what you have.
want a drag engine then
crack test the block and have cylinder wall thickness checked
have locktight injected into the block while in a vacume state.
bore out to 40 thou no more as you start flexing the cylinder walls and overheating.
if using larger valves mabey even suclop out above the pistons to reduce the showding the walls give.
line bore the main tunnel and cam tunnel
resize the rods and check length weight balance as well take at least 24 rods
use custome forged pistons.
this will give you a bottom end able to handle 8000rpm up shifting and 7500 down shifting
cost approx 10g.
head buy a alloy 2v thats coming out have it ported out for your carbys and cam it will save you money over the cast one as it wont be able to get ported out as far.
drift
 
drift cortina":cykjnj41 said:
yeah 10 off the crank to get the clearance's nice and tight again as after 30 years or so they do wear.
if going to use arp rod bolts you must resize the rods as they are done up to a much higher tension deforming the caps more.
same with the main caps.
timing chain i beleave is same as xflow one and same with harmonic balancers.
it all comes down to how long your string is and how much money you got.
ust something for the street to make nice power for anther 20 years.
basicly just freshen up what you have.
want a drag engine then
crack test the block and have cylinder wall thickness checked
have locktight injected into the block while in a vacume state.
bore out to 40 thou no more as you start flexing the cylinder walls and overheating.
if using larger valves mabey even suclop out above the pistons to reduce the showding the walls give.
line bore the main tunnel and cam tunnel
resize the rods and check length weight balance as well take at least 24 rods
use custome forged pistons.
this will give you a bottom end able to handle 8000rpm up shifting and 7500 down shifting
cost approx 10g.
head buy a alloy 2v thats coming out have it ported out for your carbys and cam it will save you money over the cast one as it wont be able to get ported out as far.
drift
Click to expand...

Or drop in a Chev for half the money and twice the HP! :twisted:
Drift what does Locktiting the block involve?, is it resin filling the block to the water jackets as per drag cars or something different?
 
The motor will be used in a circuit / targa / hillclimb car so big revs arent a major concern but torque, reliability, and a sweet sound when revving out in 3rd gear coming on to Phillip Is main straight are very important!
I will start hunting out some rods and have already spoken to CHI about that alloy head, actually sounds like a bargain when compared to rebuilding the 2V to suit ULP, and going up a valve size.
 
nope something different and what you do to a chev 101 block to handle 800hp with out cracking like the motown blocks will.
as i said the block is placed into a vacume as in space then locktight is run through the oil gallaries and water gallaries filling all the little cracks in the casting and maching.
vacume released lock tight is then compressed into block becomeing soild rest the locktight in the galries etc just runs out.
ok sound good go ok
soild cam big mutha 300deg
200 rods acl raceseries pistons
crank balanced and lightend off bit doing it
alloy 2v head if insit going with cast or ue to rules lots of port work.
twin system exh finshing under drivers seat with 2 short hot dog mufflers.
should be able to reach 300hp at around 5500-6000rpm with the sidedraft's and a big cam.
drift
 
Excuse my ignorance but what do they do when they res-ize rods? I read before that the arp bolts are don eto a higher torque setting so they have to be re sized. Hows that work?

"alloy 2v head if insit going with cast or ue to rules lots of port work. "

What does that mean, is that tech talk or typing with an accent?

Thanks
 
If you're disqualified from a cast alloy (new) head - or even a 2V head, then port it to the max.
 
When conrods are assembled at the factory the bolts are torqued up and then the big end bore is honed perfectly round. If you replace the bolts (or even just through use over the years) the big end bore can become slightly distorted. When they resize the rods they will remove the caps and grind the mating surfaces flat, install the new rod bolts (these are normally a press fit) and torque them up. Then they rehone the centre back to the original size (the big end got smaller due to removing metal from the mating surfaces)
Doing this ensures the bearings are seated square to the crank and the pressure of the rod is distributed evenly across the bearing, not doing this can lead to the bearings wearing out quickly and you endup with a big end knock. If you intend to rev the engine regularly it would be worth replacing the bolts because if one of them fails you will probably need a whole new engine.
 
Thanks for that about the rods, I kind of thought that would be the case.
I am not concerned about class eligibility just having fun so if the cyl head puts me in a higher class it will only mean my finish number will be bigger!
Its all about fun really, finishing higher costs more.
 
sorry moniter is just about stuffed and can get very blurry.
if rules are open id go the alloy head thats coming out see the small block section or classic inlines site for more info.
or if you have to use the cast head send it away and have it ported out as far as possible mainly on exhaust side as a standerd 2v head max out at around 220 hp no matter what ya do they simply cant flow enough.
rods as what nod069 said.
this also has to be done if you run arp studs/bolts for main caps as well.
 
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