what cam were you running switchedon?
I am unsure of my compression, but it is pretty high, it ONLY runs on BP Ultimate, or avgas if I had some
how do i get the best out of a 253?
Started by
_oikurtman_
, Jun 08 2006 12:08 PM
57 replies to this topic
#26
makka
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Posted 15 June 2006 - 12:40 AM
#27
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Posted 15 June 2006 - 02:39 AM
wow, good figures u pulled there Switchedon!
Did u ever run it down the qtr?
Did u ever run it down the qtr?
#28
_Oldn64_
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Posted 15 June 2006 - 06:05 PM
People forget all too easily thatthe commodore cup racers run 253's. These are capable motors and worthwhile as a cheap option BUT. will cost the same as a 308 to build and also are more determined on head choice. So as per above, if someone knows what they are doing for teh 253 you will have a animal on tap. I have a number of 253 that I have built that do similar figures, and they are really nice to drive. One guy actually asked me whether the 253 was really a 308. I had to show him the cast markings. NEVER think the 253 is teh pourer cousin.
Cheers
Cheers
#29
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Posted 16 June 2006 - 03:03 PM
can I have some specs please Tim, especially on the heads and cam.
#30
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Posted 16 June 2006 - 05:33 PM
thats crap...anyone who tells you that you are wasting your time with a 253 obviously hasnt tried hard enough to pull the monster out that lies beneath the typical boat anchor reputation they have. mine produced 264 rwhp, stock 4 barrel hq manifold and quaddy, the secrets lie in the comp and heads, mine ran 12.5:1 comp(avgas only or meth) and minor port work you just need someone who knows what they are doing, we recently put a cain tunnel ram on with twin 600 holleys and it made 318.2 rwhp at 7600rpm, unfortunately though i killed it apparently the ring lands wont stay where they are meant to when you turn it to 8500 for a minute.also line honing will gain power for you too...
if you spend that same time money and effort on a 308 and only run it avgas or meth, then you would end up having more than 400hp.
#31
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Posted 16 June 2006 - 06:55 PM
my old 253 i had in my SS ran the standard 4 barrel manifold from a 308, a Rochestor and Brock aircleaner from a VH and electronic dizzy with 0.040" oversize flatop ACL duralites, X rods and a cam to match the slightly larger valves. I only ever had standard exhaust manifolds with 2" pipes with the crossover and ran an M21 rather than the M20 with 3.08 rear end. It went very well when you punched it, and even a little better after i got rid of the massive clutch fan for 2 thermos, yet it was very good on fuel driving on a trip. It also gave plenty of 308's and VN V6's , and on one occasion an XW 302 a good flogging.
#32
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Posted 16 June 2006 - 11:41 PM
i ran a cam dynamics cam in this 253, it was a hydraulic with anti pump ups, 496 lift, 294/294 int and exh, rev range 3200-6800. but advanced the cam timing to improve top end power to compensate for the twin tunnel ram manifold, it was a fantastic combo that i would definately use again, it proved itself time and time again, the cam really is too big in a 253 for street use though, min 3000 stall which makes it a pig in traffic, was good with the manual though.
#33
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Posted 17 June 2006 - 02:52 AM
Ok been two years since I looked at this stuff so here I go...can I have some specs please Tim, especially on the heads and cam.
Cam I used was a Crow Cam grind #170 (it is a Commodore cup grind) and you where able to get it then. Not sure how availible it is now but I am sure it will be able to be Created. Cannot recall properly what the profile was but it didnot like idling for long. Great pull from 2000-7300. Ran a Carby (same as Matts with hanger H) so richer again, with standard 308 secodnary needles. The heads where smoothed on teh exhuast side (match ported) and the inlet side increased to create a 2mm Lip. (ie step into the head, so teh head port was 4mm in diameter than teh inlet. The small radius was smoothed and the large radius rounded so that it pointed to the inner corner of teh valve. The valve sizing was up graded slightly on the exhuast and the inlet kept the same. The head bowls were CCed to 52cc each and the pistons were acl race series. The crank was machines (offset grind) by only .5mm which was actually the race rules of teh period. This droppe dthe comp back to about 9.2:1.
Primary pipes where 1 3/4 4,2,1's and the secondaries 2 1/4" Cross over pip occured under the gearbox crossmember and exited in a single 2 3/4" system. Ran only one muffler and one hot dog. The muffler is connected about the rear seat (approx 40cm from diff assembly.
The cam was 2 degrees retarded and the rockers 1.7 on inlet and 1.6 on exhuast. thsi combo is not for the faint hearted. You will need to drive the engine but great torque and power was made. Best suited for a manual as vacuum at idle is a little poor. I always ran a double stack air filter so that the air velocity through the filter was not too great. filter hieght was 5" tall by 14" diameter. Always ran a race tray/cold air intake.
The other trick is using the original rocker covers. The chrome ones either leak oil everywhere through the breathers or the covers do not sit right on the head and therefore leak at the gasket surface.
The rockers where yella terras and the pushrods where selected engine by engine. (ie deck hieght etc etc) I always used a 5 thou tin head gasket (like the original holden ones) And got a mate to make them. unfortunately he past away a year and a half ago and I have not found anyone who can do them anymore.. :(
Well that is all teh grey matter can vaguely remember I how this helps.
Cheers
#34
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Posted 18 June 2006 - 12:18 PM
cheers Tim, so you had a commodore cup engine?
the intake port was 2mm bigger all the way round?
what primary rods did you use? I have a set of AN (308) secondarys, But I havent got round to trying them yet. Mine runs well with CX's in
the intake port was 2mm bigger all the way round?
what primary rods did you use? I have a set of AN (308) secondarys, But I havent got round to trying them yet. Mine runs well with CX's in
#35
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Posted 19 June 2006 - 12:59 AM
I have a friend how use to race Cup. I have had two cup motors (or equivalents) that I have built. The above heads are nto permitted in the racing rules as teh CC's of teh ehad are too small. From memory that is the only thing that is not permitted. Cannot remember what the primaries or teh secondary hangs are 100% off teh top of my head but I do have a spare cup kit out in teh shed somewhere from our last tunign session. I am sure if I looked through teh garage I could find them for you.cheers Tim, so you had a commodore cup engine?
the intake port was 2mm bigger all the way round?
what primary rods did you use? I have a set of AN (308) secondarys, But I havent got round to trying them yet. Mine runs well with CX's in
Cheers
#36
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Posted 19 June 2006 - 12:05 PM
Specs on a Crow 170 Master are as follows:
Dur @ 0.050": 219/219
Lobe lift: 0.286/0.284
Adv Dur: 280/280
LCA: 111
Int Lift with 1.7:1 Rocker: 0.483
Exh Lift with 1.6:1 Rocker: 0.457
And its a hydraulic cam.
Commodore Cup racers used a control head manufactured by Yella Terra. It was referred to as the 'Hi-Torque' from the days when Yella Terra still did cast iron cyl heads. They were painted black for ID purposes out of YT.
Dur @ 0.050": 219/219
Lobe lift: 0.286/0.284
Adv Dur: 280/280
LCA: 111
Int Lift with 1.7:1 Rocker: 0.483
Exh Lift with 1.6:1 Rocker: 0.457
And its a hydraulic cam.
Commodore Cup racers used a control head manufactured by Yella Terra. It was referred to as the 'Hi-Torque' from the days when Yella Terra still did cast iron cyl heads. They were painted black for ID purposes out of YT.
#37
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Posted 19 June 2006 - 03:10 PM
I was pretty sure that the cc cars ran a solid cam?
Tim, it would be good if you could see what 253 stuff you have lying around, I might be interested in some if you want to get rid of it.
Tim, it would be good if you could see what 253 stuff you have lying around, I might be interested in some if you want to get rid of it.
#38
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Posted 20 June 2006 - 12:10 AM
mate the cheapest way to get better fuel economy and power is shaving the top off the heads and block if its a full rebuild mine is getting froabout 8.5 :1 to 10:1
cheers chevy
cheers chevy
#39
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Posted 21 June 2006 - 10:56 AM
How about injected VN heads on a 253 for economy and power??
Roller rockers would be good idea, dont roller rockers reduce friction? therefore reduce fuel consumption?
Electronic dizzy
Healthy gear box, if too much slip or holds back in gear change (auto) will use more fuel.
my2c
Roller rockers would be good idea, dont roller rockers reduce friction? therefore reduce fuel consumption?
Electronic dizzy
Healthy gear box, if too much slip or holds back in gear change (auto) will use more fuel.
my2c
#40
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Posted 22 June 2006 - 02:41 AM
How expensive is it to get VN heads and a manifold to suit a carby??? Would it be cheaper to just get some Std Read heads worked up a bit?
Im looking at getting some L34 Heads for my Stroker...
Im looking at getting some L34 Heads for my Stroker...
#41
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Posted 22 June 2006 - 10:29 AM
keep your eyes peeled on ebay and sooner or later you should find VN heads etc
#42
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#43
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Posted 22 June 2006 - 06:21 PM
it was mentioned in a n earlier post, that the block would need releiving to allow valves to open, and something about the fluffy being too small to get the best out of the big ports and valves...How about injected VN heads on a 253 for economy and power??
Roller rockers would be good idea, dont roller rockers reduce friction? therefore reduce fuel consumption?
Electronic dizzy
Healthy gear box, if too much slip or holds back in gear change (auto) will use more fuel.
my2c
#44
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Posted 22 June 2006 - 06:34 PM
I haven't read the whole thread, but to answer the original question, from my experience and from what I've seen and heard: A 253 is NOT cheaper to run than a 202 full stop!. It will however be a nicer engine to run in a Torry. If you want it to be cheap to run, then run it on either straight gas or duel fuel.Hey guys,
I've been convinced to change my 202 to a 253. I've been told that it will actually be cheaper on fuel, but is there anything I could do to make it even cheaper to run? its my daily driver...
I've got a set of genie extractors which I'm putting on it, as well as a twin 2.something inch exhaust, but it has a broken crossover just after the extractors. Should I repair the crossover or cut it out?
Any ideas on carbies or cams?
Cheers,
Kurt.
If not, and you decision is purely based on fuel economy, then stick to the 202 until you can get yourself a gas setup.
#45
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Posted 23 June 2006 - 01:17 PM
hmm...
well the old man gave me a blue 253 and trimatic the other day so i'm at no loss to fit it and try it...
I'll let you know how it goes, but no doubt i'll be back on here half way through when something goes wrong!
Cheers.
well the old man gave me a blue 253 and trimatic the other day so i'm at no loss to fit it and try it...
I'll let you know how it goes, but no doubt i'll be back on here half way through when something goes wrong!
Cheers.
#46
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Posted 24 June 2006 - 01:10 AM
christ vn heads are expensive marveswell go small block if your gonna go that far mate
#47
_1QUICK LJ_
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Posted 24 June 2006 - 09:23 PM
vn heads are waaaaay too big for 253, and as for economy a properly set up mild 253 shits on a 202 but it must be setup properly, and im not talking about 253s with say a lumpy 286 crane cam ect. but if you put the equivelent cam to a 286 crane in a 202 it wont get good economy either. my 13sec 253 could muster 26mpg on highway and 23mpg city.
#48
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Posted 25 June 2006 - 10:57 AM
Back in the mid 90's SM did a build up of a 253 (not a high dollar effort from memory) and that produced 347hp so there is life in these engines.
#49
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Posted 25 June 2006 - 02:17 PM
have you got any details of that build Howard?
#50
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Posted 25 June 2006 - 02:26 PM
It was covered in the 1996 May/June and July/August issues of SM. I can dig the out and scan the article if any one is interested.
Basic specs were 253+.060 = 261cu, 10.5:1 comp, 238 degree cam (@.050), 1.85"/1.5" intake/exhaust, basic head porting, 600 Holley (though they thought a 500 may have gone better), idles at 950rpm, runs out strongly to 7000rpm.
Basic specs were 253+.060 = 261cu, 10.5:1 comp, 238 degree cam (@.050), 1.85"/1.5" intake/exhaust, basic head porting, 600 Holley (though they thought a 500 may have gone better), idles at 950rpm, runs out strongly to 7000rpm.
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