Since my son can get his learners next year, he's been nagging me about stroking the spare 253 sitting in the garage. So my first question is, how far can a 253 be safely overbored? What crank, rods and pistons are used? I'm thinking of a 3.5" stroke crank, but may consider a bigger unit. As we need to keep a relatively stock appearance, I'm thinking of pre pollution red 308 heads ( stock or ported? ). And lastly, as it will probably be run on straight LPG ( the boy doesn't have a job yet! ), I will need a sensible cam selection.
Generally I'm after sensible suggestions, but feel free to throw in a couple of silly ones, provided they're funny.
253 stroker options
Started by
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, Nov 18 2008 02:10 PM
24 replies to this topic
#2
mr5000
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Posted 18 November 2008 - 03:59 PM
just a question but how come your building him a 253 for his learners soon as he gets his ps he wont be allowed a v8
#3
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Posted 18 November 2008 - 04:08 PM
Here are my specs
Bottom End
Holden 253 Block
Offset Grind Crank
Balanced and Blue Printed
305 Chev Pistons
SJ Chev Conrods
Compression 9.5:1
Bore 3.766 Stroke 3.180
You can probably go a bigger bore than i have, Something like 60 thou i have heard is still safe on 253's. Not sure what capacity that would make it?
But Ryan is right, P platers cant drive V8's on their P's... Unless this is for a track car?
Bottom End
Holden 253 Block
Offset Grind Crank
Balanced and Blue Printed
305 Chev Pistons
SJ Chev Conrods
Compression 9.5:1
Bore 3.766 Stroke 3.180
You can probably go a bigger bore than i have, Something like 60 thou i have heard is still safe on 253's. Not sure what capacity that would make it?
But Ryan is right, P platers cant drive V8's on their P's... Unless this is for a track car?
#4
_202LX_
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Posted 18 November 2008 - 04:16 PM
best way to get a higher capasity 253 is to sell it and buy a 308!
#5
_CHOPPER_
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Posted 18 November 2008 - 08:06 PM
Here are my specs
Bore 3.766 Stroke 3.180
You can probably go a bigger bore than i have, Something like 60 thou i have heard is still safe on 253's.
A stock 253 is 3.625" bore, want to double check your numbers?
Didn't know about the new P plate laws, not my problem though.
#6
_@milco@_
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Posted 18 November 2008 - 09:33 PM
i reckon you would be better off building a high comp (10ish to 1 comp) 253, rather than stroking it put the money you were gonna spend on the crank ect... in to some nicely ported heads, manifold and quality pistons/rods, build it up to the 300hp 253 article posted here and it will go very very well i have drive a car built to the article and it was a very very fun and quick car to drive
#7
yel327
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Posted 19 November 2008 - 05:29 AM
Chopper, there was an article about this either on this forum or at Fastlane some time back. I think they ended up around 290-300 cubes using a 3.48" stroke crank, but it was a massive overbore. I do remember reading it and thinking "geez that's a lot of money to spend to get to 5 litres", although such an engine would be a very different animal to a 308.
#8
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Posted 19 November 2008 - 06:51 AM
A stock 253 is 3.625" bore, want to double check your numbers?
Stock 253 bore is 3.625"
Stock 305 SBC bore is 3.736"
030 over 305 bore is 3.766"
To get the right deck height with a 253 mini stroker you need to use the 305 piston which neccesitates the 0.110" to 0.140" overbore. Like I have said before, the 253 has really thick cylinder walls and can easily accomodate this sort of overbore.
FWIW a standard 305 SBC has a stroke of 3.48" so using a 355 crank in a 253 with the 305 pistons will net 305 cibic inches, a 030" overbore will lift it to 308 CI. The 305 pistons will need to have the tops trimmed down to remain level with the deck with this much stroke.
Hope this helps.
#9
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Posted 19 November 2008 - 11:54 AM
Thanks for that Struggler, is that using 5.7" long rods and what pin height does the 305 piston have?
#10
Struggler
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Posted 19 November 2008 - 09:16 PM
Thanks for that Struggler, is that using 5.7" long rods and what pin height does the 305 piston have?
You will need to cut the pistons down regardless of rod length, obviously more with the longer rod.
As the 305 has the same stroke as a 350 I assume the pin height is similar, ie. 1.560"
#11
_Toranamuk_
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Posted 19 November 2008 - 11:00 PM
If you can get your hands on an old copy of "The essential HOLDEN V8 Engine manual" by Larry O'Toole (published in 1999) there is a section in there on page 139/140 on a stroker 253 I built back then for the guy that developed a new crank for 253's.
It was 3.543 stroke, used a 5.850 conrod with 2.00 BE & a Buick 3.720" piston, took it to 308 cubes.
Made good HP with a stock cam, heads, manifold & carby & made excellent torque & t was only 9.2:1 comp.
I still have the motor in pieces as the prototype crank was soft (120 rockwell), the replacement crank is longer stroke, 3.6".
Personally, for the expense of building it, I'd go with stock stroke, bigger bore, good comp, smartly ported small inlet valve heads with a 1.6" exhaust valve, ported stock dual plane manifold & a Rochester carby.
Cam doesn't have to be too big, look for a dual pattern, something around 224/228 050" will perform well, give a bit of a note at idle & still achieve reasonable fuel efficiency.
Ive had similar combo's in Torana's with Supra 5sp gear boxes & 3.7:1 gears run mid 13's cosistantly & pop out the occasional low 13 (13.2 was best) yet be very happy mild street cruisers.
There's lots of options.
I'll ring you soon about the 308.
Craig
It was 3.543 stroke, used a 5.850 conrod with 2.00 BE & a Buick 3.720" piston, took it to 308 cubes.
Made good HP with a stock cam, heads, manifold & carby & made excellent torque & t was only 9.2:1 comp.
I still have the motor in pieces as the prototype crank was soft (120 rockwell), the replacement crank is longer stroke, 3.6".
Personally, for the expense of building it, I'd go with stock stroke, bigger bore, good comp, smartly ported small inlet valve heads with a 1.6" exhaust valve, ported stock dual plane manifold & a Rochester carby.
Cam doesn't have to be too big, look for a dual pattern, something around 224/228 050" will perform well, give a bit of a note at idle & still achieve reasonable fuel efficiency.
Ive had similar combo's in Torana's with Supra 5sp gear boxes & 3.7:1 gears run mid 13's cosistantly & pop out the occasional low 13 (13.2 was best) yet be very happy mild street cruisers.
There's lots of options.
I'll ring you soon about the 308.
Craig
Edited by Toranamuk, 19 November 2008 - 11:02 PM.
#12
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Posted 19 November 2008 - 11:27 PM
I'll ring you soon about the 308.
The 308 was picked up and paid for yesterday.
Can the 253 be bored out to 3.800", or is that pushing it too far?
#13
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Posted 20 November 2008 - 12:27 AM
^ From memory there is only 3.75 till you hit water, was along time ago and I dumped the idea and just went for a 308, struggler would know better.
#14
_trac-torqueraceengines_
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Posted 20 November 2008 - 12:59 AM
HEY THERE, I WOULD SUGGEST 30 THOU 305 CHEV FLAT TOPS, GO WITH THE PRE-POLLUTION HEADS, GIVE THEM A NICE PORT JOB TO MAKE THEM FLOW, IF YOUR GOING WITH GAS YOU WANT TO KEEP THE THING AS SHORT STROKE AS POSSIBLE. GAS BURNS VERY QUICKLY, IN FACT BY THE TIME THE PISTON HAS TRAVELLED 30% OF THE DISTANCE DOWN THE BORE, ITS ALREADY BURNT AND GONE, SO THE LESS DISTANCE THE PISTON HAS TO TRAVEL, THE BETTER, SO TO COMPENSATE FOR THIS, THE BIGGER THE PISTON FACE, THE BETTER. YOU NEED TO GET AS MUCH GAS IN THERE AS POSSIBLE SO YOU MAKE MAX POWER. GAS BURNS QUICK BUT IT HAS THE SAME BTU RATING AS MATHANOL. PETROL: 8000BTU; LPG AND METHANOL : 11,000BTU. REMEMBER THIS... LPG AND NATURALLY ASPIRATED LONG STROKE ENGINES DO NOT MAKE POWER!! KEEP IT SHORT, THEN YOU WILL GET RESULTS. MAKE SURE YOU GIVE THE BEARINGS A LITTLE MORE CLEARANCE AS GAS BURNS HOTTER, AND DO NOT DECK THE BLOCK SO THE PISTON IS AT 0.0 CLEARANCE, YOU WILL HAVE NOTHING BUT DRAMAS. IF YOU WANT MORE INFO ON HOW TO MAKE THIS THING HAUL, SEND ME A MESSAGE AND I CAN THROW YOU SOME MORE IDEAS. I HAVE A FEW CAM SUGGESTIONS FOR YOU FOR GAS, DEPENDING ON HOW HARD YOU WANT THIS THING TO PULL. JUST REMEMBER, IF YOU DON'T GET THE BORE/STROKE COMBO RIGHT, IT WONT GO AND YOU WILL GET LOST TRYING TO FIGURE OUT WHY. I THINK LPG IS GREAT, BUT YOU NEED TO UNDERSTAND HOW IT WORKS BEFORE YOU BUILD A MOTOR TO RUN ON IT EFFICIENTLY. REGARDS, JERRY (THATS MY NICKNAME, JEREMY IS ME.) TRAC-TORQUE RACE ENGINES. I ALSO HAVE A FEW 253 STROKER CRANKS AND RODS TO AUIT ON THE SHELF WITH ALL THE REST OF MY HOLDEN ONLY RANGE OF GOODIES. ENJOY, HOPE THIS HELPS YOU OUT. AS WITHCOMP RATIO, WITH GAS YOU CAN PUSH THAT UP AROUND THE 11.5:1 - 13:1, IF YOU WANT TO RUN FORKLIFT LPG, YOU CAN GO AS FAR AS 14.5:1, AND YES WE HAVE TESTED THIS OUT AND HELL IT MAKES THEM GO HARD!!!
Edited by trac-torqueraceengines, 20 November 2008 - 01:12 AM.
#16
Mort
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Posted 25 November 2008 - 12:02 AM
^^ and what about breaking it into paragraphs for the older generation.
Mort
Mort
#17
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Posted 25 November 2008 - 08:10 AM
im so tempted to post up my special graph once more... for the older generation.. 
Whats the difference between forklift LPG and normal LPG? I have an abundance of FL LPG around here....
Whats the difference between forklift LPG and normal LPG? I have an abundance of FL LPG around here....
#18
Peter UC
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Posted 25 November 2008 - 11:50 AM
Florklift LPG is straight Propane as opposed to a Propane/Butane mix. You can get straight Propane in certain places like Supergas. One thing though unless your engine is tuned to run on straight Propane don't use it. Not that it will do any damage but the economy will drop as Propane has a lower calorific value than Butane.
#19
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Posted 25 November 2008 - 12:05 PM
Will your car smell like a forklift as well?
#20
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Posted 25 November 2008 - 02:42 PM
Can the 253 be bored out to 3.800", or is that pushing it too far?
As there has been no definite answer posted, does this mean it's a 'maybe'?
#21
TerrA LX
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Posted 25 November 2008 - 03:00 PM
I was under the impression, all those years ago, when these things were at their height of popularity, that 111tho over was a standard 305 Buick, not chev piston.
If you used an oversize there was not enough meat left as there is only 128tho from standard to water.
Was under the impression chev pistons are too fat.
Could be wrong as this was some time ago and Im sure there are OP who could have done the job differently.
Sorry I could not be of more help.
If you used an oversize there was not enough meat left as there is only 128tho from standard to water.
Was under the impression chev pistons are too fat.
Could be wrong as this was some time ago and Im sure there are OP who could have done the job differently.
Sorry I could not be of more help.
#22
MRLXSS
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Posted 25 November 2008 - 03:01 PM
Is that 175 Thou? If so, then no... Water jackets get in the way... (unless re-sleeving fixes that?)
I think 80thou? is the biggest you can go before you hit water, but that depends on how good your block is..
I think 80thou? is the biggest you can go before you hit water, but that depends on how good your block is..
#23
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Posted 25 November 2008 - 08:24 PM
I was under the impression, all those years ago, when these things were at their height of popularity, that 111tho over was a standard 305 Buick, not chev piston.
If you used an oversize there was not enough meat left as there is only 128tho from standard to water.
Was under the impression chev pistons are too fat.
Could be wrong as this was some time ago and Im sure there are OP who could have done the job differently.
Sorry I could not be of more help.
A Chev 305 and a Buick 305 have exactly the same bore and stroke.
Knock a welsh plug out of a 253 and measure the bore wall, its about a quarter of an inch thick.
Will it go 3.800 ? I don't know but I can't see why not.
MRLXSS You say 080 is the biggest overbore poss. yet your engine is .140 over...WTF ??
#24
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Posted 25 November 2008 - 08:35 PM
MRLXSS You say 080 is the biggest overbore poss. yet your engine is .140 over...WTF ??
LOL! Dont i look like a fool! I just repeat what others tell me! LOL (Bit like a pet bird... allo cocky)
Edited by MRLXSS, 25 November 2008 - 08:40 PM.
#25
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Posted 25 November 2008 - 11:16 PM
Struggler is prolly in the best position to answer these questions, take my comments with a grain of salt as that was what I was told when I chased this route up a long time ago. I dumped the idea and went with a 308 instead...
Never late in a 308.
Never late in a 308.
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