matt_lamb_160

Well I got started on the webber carb today, full rebuild and some work in the venturi's and stuff to get it flowing better. I take the end of the screws off that protrude on the other side of the throttle plates.
 


 
Then I clean up the overhang that is in the small part of the venturi and clean up the throats, blend all the sections together and open up the gaskets a tiny bit so there is no gasket overhanging in the throats. I also sand the boosters a little and polish them up as well as the venturi's.
 



 
Then put the carb together, The carb flow tested at 274cfm, a 13cfm gain. Dosen't sound like much but it is around 5% which is quite good for not changing the dimensions of the carb.
Then I started testing with the aircleaner assembly. modified housing with aircleaner inside went up to 260cfm. then I thought about raising the housing with a spacer to gain some space above the carb, this got flow up to 263cfm.
 


 
Then I started to think about how the air was entering the carb, one thing that I have learnt with flow testing is that air doesn't like to enter something with a sharp edge, that's why you put playdo at the entry to make a radius entry, so why not see if the same would work for the top of a carb??? well it does make a difference. I tested the carb first by itself and with a radiused top flow went from 274cfm to 285cfm!!! that is a huge gain so I'm now thinking about how to make a top for the carb that makes a radius.
So testing with the aircleaner now with the spacer and the radius on the carb the whole lot pulled 274cfm. To put this into perspective I started with 235cfm with the original carb and housing and now I have 274cfm, a 39cfm gain and staying within the rules of the class. WINNING!!!
 

http://m.ebay.com.au/itm/111287100575?nav=SEARCH
 
http://m.ebay.com.au/itm/161068665080?nav=SEARCH
 
Hope that worked.

Yep. I have used that cam (208 deg one). Perfect FWY cam with 2.77 gears. I have used it with 3.27 gears as well and it works well. Goes to 4000rpm easily enough. You will have way more grunt below 2,200rpm with the EFI mani over the 4brl setup. 4brl is slightly better above 3000rpm. I have used both with this cam. You can go higher than 10:1 if you modify your ignition advance curve.
 
The 225 Impco is a perfect match for the cam and either a B2 or a model L Impco will work.

Now that Sly's manifold is done I will be starting this head on Monday, I'm looking forward to doing this one. I will start with a spare head port to get a shape and size I like then transfer it to Chris's head. I'm not going to change the chamber shape on this head as it has been layed back a little and removing more material will start dropping comp, I will do the spare port chamber the same as Chris's so to compare apples with apples. 

200 - 250 how are they going to tell when you have the sump on.  rules were meant to be broken. LOL.

I am sure it will be great, can't wait to see the results.

Thanks Tony, no external oil drain at this time but the next one will. I am going to build an engine for myself so I have full control of how things are done and all of these extras will be done. Then I just have to find a car to and driver to use it and test it for me LOL.
Chris 238cfm of head flow is possible and requires a great port shape to achieve, in this speedway catagorey I personally think that unless the rest of the flow figures increase in the lift range then with the manifold as big a restriction that it is the topend flow is wasted. David Vizard has a book called "how to port and flow test cylinder heads" and is a good read.

Starting with a cut std. port would be interesting. I'd like to see the valve guide area on a std one.

Absolutely. You have added heaps to the discussion Clevo.
 
Maybe Wazzy needs a custom set too, haha.

Absolutely. You have added heaps to the discussion Clevo.
 
Maybe Wazzy needs a custom set too, haha.

Hey it's a forum bro and we will not all agree unless it's a question on how much of a cock XrGlen is...So keep your ideas coming,no one is forcing there views we are all discussing.Just shows how people do things differently to get the same results is all.This thread has opened alot of eyes about what works and what people use which was the hope/intention of the thread too...but it is still open to V8 turbo stuff so lets hope them boys join in too cos my ute is a boring POS to talk about for too long.
 
Wazzy's run a solid cam,don't actually know cam spec's but you would think 600 lift 275 duration atleast,I think it still runs Paceys and a 2.5"race exhaust?,head by Barbagello (yes the guy who doe's Pro Stock engines/cars) 13.5 mechanical injected 6"rod ACL slugs,crank trigger MSD 4600 stall 4.11 geared XE.Correct me if I got anything wrong Glenn.
 
Wazzy supplied my guide plates and tray (till I went custom sump which meant new tray) and a fuck load of knowledge.Very smart articulate man but still a QLDer so I can't rep him too much. 

I wonder how dear the Del West skinny stem valves would be? Fuck all that shit off and put some super light weight skinny stem items in there and run a much lighter spring and yet still rev the thing till 7500 with less stress on it....Hmmmmmmm TBH I don't like my chances this year but a big bore de-stroked big RPM xflow has always interested me.
 
230-232 cubes fat bores light weight EF crank,grouted block,roller cammed straight runner head and custom pipes and extractors for a 7500 plus xflow.That sounds like some real fuck off fun.  

See that feeling through the seat of the pants seems to contradict the theory that the 6-3-1's are better in the top end.  If the 6-2-1's are still making torque at the high rpm then that means that the HP ceiling is also raised.  Anyone that's spent anytime on a dyno knows that HP takes over when torque drops off.  Hmmmm me thinks two sets of pipes back to back on dyno and track only way to settle this. Time and Money once again. 
 
See how the secondaries stop short on the 4.0l set.  I reckon that has more to do with ease of fitment up to the Cat convertor than actual exhaust design.  I'd like to see a bit more length in that secondary before they meet the collector - especially as they have all just done a tight 90 to get to the collector.
 
One area where pacemaker are well ahead of the others is the pipe over cone design.  when I up my secondary pipe sizing I take the secondaries to the exhaust shop to have the ends expanded so that you get that same pipe over cone thing happening. 

You're mad!

Ok, wagoon that's fair.
 
Clevo, if you are looking for pulse tunning you use a baffle collector between the primarys and secondaries which in effect creates a big step anyway as a result of the collector volume. Without the step up you do not have two seperate volumes to tune (also why I do not like the 50-50 split) and you could use a 6 into one setup instead. The step up is a part of how tri y setups work. The 6-3-1 setup could be better (I have not put too much thought into it), but the 6-2-1 is a long standing arrangement.
 
Sly, if you do go 6-3-1 just watch your firing order and make sure the exhaust pulses entering each collector are evenly spaced.

Re-ran some numbers and you are close to wanting 1 3/4" primarys.
 
Two options both are 6-2-1 configuration, the other configuration doesn't change much (not sure what the support for the 6-3-1 is based on really). For both options the tail pipe can split into a twin system after the collector. As Ando said push the mufflers back as far as possible. Both are for peak HP at 6,500 rpm. If you think it is higher you can shorten the primary and secondary lengths a bit.
 
With your big cam it is boarder line whether you should use baffle or merge type collectors (I would go for merge purely based on what I have read) for between your primaries and secondaries. If you use merge type aim for a 10deg tapper.
 
Don't stress about the lengths too much for the primaries and secondaries but they should be a pretty good target.
 
Option 1 Peak Torque Under 4,500rpm:
 
Primary Pipes: 1 5/8", 25" long
Secondary Pipes: 2 1/4", 12" long
Collector: Type Venturi merge, Min Diameter 2 3/4", Nozzle length (tapper from secondaries) 5" (or ~10deg taper), Diffuser (Min Diameter to Tail Pipe) length 2.7" (or ~8deg taper)
Tail Pipe/Collector Outlet Dia: 3.5" (could get away with 3 1/4" but going bigger with the correct collector costs nothing, if you choose to not use 3.5" it changes your collector diffuser length only)
 
Option 2: Peak Torque at or over 4,500rpm:
 
Primary Pipes: 1 3/4", 25" long
Secondary Pipes: 2 3/8", 12.5" long
Collector: Type Venturi merge, Min Diameter 2 7/8", Nozzle length (tapper from secondaries) 5.3" (or ~10deg taper), Diffuser (Min Diameter to Tail Pipe) length 2.25" (or ~8deg taper)
Tail Pipe/Collector Outlet Dia: 3.5"
 
This is my own approach based mainly on my understanding of acoustic tuning, what I have read and dyno. comparisons of others (I have not tested it myself as it cost $$$). I have PipeMax, but I do not use it. Interestingly Clevo’s primary diameter (most important in my opinion) and total extractor length are about the same as mine (it is the combined length that you tune for). PipeMax seems to use a 50-50 split whereas I split my primary and secondary lengths to target two octaves, I doubt you would notice the difference but I think the 50-50 split is odd.

Need cam timing if you want length estimates (for what they are worth, diameters are more important).

move closer people down here in country vic need a shop that 1 dont rape people and 2 can do the porting jobs not (arr it not a stock engine we dont want to touch it

ive used most of the shops out here now and still have not found one that give a ship im not a know all but i do know what it is i want


good luck chin up and i know how you feel ive had people knock back my old engines and payed more for a engine that makes less numbers and just dont work. i fitted up a car with a engine a while ago but offered my old one (said i have this engine it want 14.0 in my own car all fresh not run since rebearing and i want $2500 tuned complete and making 220rwhp thru a auto with dyno sheets) he did not want it instead got a shitter that had all this work and lasted him 100km before needing a rebuild
 
one thing you learn when you pay for work is to find somone to do good work. ive seen so many people do shit work charge the earth and it all needs redoing 10 seconds later. i did a cortina like this a few years ago he got stung everywhere he went in the end i did the whole car cause i felt sorry for him

I get your frustrations mate. Nothing worse than no it alls that really no nothing and not being able to get work done. Possibly the two things I hate the most.
 
Plus, people need to pay. What is $50 really?
 
I hope things pick up (they will, it is just a matter of time). People are always afraid to try new people. Perhaps you could get some of your final work flow tested independently? Might give people more confidence?
 
Before and after engine dyno results? Build an 11sec Cortina with you business name on the side, haha. I am not sure, all the quick ways to build a reputation seem to cost $$$.

how sweet does that sound!! and lift those front wheels and gone.  Having seen this car in the flesh and heard it sit at idle it truly is an amazing beast, driven and owned by a top bloke to boot.
Yeah cammed up LS1's run as quick but this is old school technology going seriously fast.  Perhaps we all just smash a certain magazine with emails demanding a write up???

Exhaust to inlet ratios should never go below 60%, high ratios (above 80%) are not a concern so long as you are not giving up inlet flow to improve the exhaust. There is a heap of stuff in technical papers/books that came mostly out of MIT back in the day (Charles Taylor mostly) and have since been supported by people like Vizard and Bell.
 
I would not be worried about low lift ratios of 85% (not that this will be an issue in your case) and would be trying to make sure I had at least 70% most of the time. I would consider the ideal 75% as an average value over the whole lift cycle which can be altered by the cam and/or the head.
 
In your application you need to analyse the ratio with the inlet manifold on and you will need to make the assumption that, on the exhaust side, the head is the most restrictive item. Then make sure you don't get less than 70%. Chances are the stock exhaust valve size will be ok.
 
Also the point you make about the higher lift lobe and fat part of the cam is exactly what I was trying to say and is why I recommended up to 0.55" lift.

I like that you have to work with a restriction, means you need to do it right. Your head achieves the manifold flow at less than 0.35" lift. In lift versus flow terms you don't really need more than 0.45"-0.5" lift. But then how do you get the duration you need and a fast ramp rate if you have such low lift? I would be aiming for 0.5"-0.55" lift with as flat a nose as possible (but this would require a helpful cam grinder). Running more lift will give the same flow but will require the engine to do more work (as Ando said). I would also be running wide-ish lobe separation (110 or so deg.) to help with the restrictive intake. The head's ports are better than they need to be, but because the cross-section has been maintained there will be no negative effects. The low lift mods are all that was really required, but this head is a great all rounder and will work with much better intakes as mentioned above.
 
We need square cam lobes and some magic way of keeping the lifters on them, haha.

Only on paper and the calculator does the manifold drag it down.  The great low lift figures will trick the manifold into flowing more is my tip. 
 
That cam is a okay for speedway 2 barrel applications.  I would have gone for a wider lobe sep to soften the torque delivery and I don't like the exhaust duration being longer than the inlet, should be the other way around to give more time for the air to flow through the manifold restriction.  The inlet also opens later than a 392c but each to their own.
 
Has the owner run this cam before?  If so did he like the way the power came on etc. 
Keep up the good work. 

Great work mate. Does the port work include opening the throats, I assume it does otherwise the low lift improvements are surprising.
 
I had convinced myself that when using a cam with 0.45" lift port work other than in the bowl area would be pointless as the heads would not be port limited at that point (they would be valve limited).
 
An even more progressive test which showed the influence of valve guide shaping alone would be interesting.

Do you think guide shaping has much of an influence under 0.5"-0.55" lift? Do you recon you'd get 200cfm without it? This is interesting for high k engines with modest lift cams and turbo builds.
 
Good work again. You have shown real evidence that you are searching for what makes the biggest difference and not just opening every up and saying "it must work, the car does 12s". Restricted classes of racing are best for separating who knows and who doesn't. Keep showing your efforts and I think it will pay off.