Cam selection & carb jetting

Question and answer direct with GC. Competition engines and 'live' projects only. Good photos to illustrate your post are expected.
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Betargovia
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Cam selection & carb jetting

Post by Betargovia » Thu Jun 22, 2017 7:53 pm

Guy,
I am looking for advise on my 2.0l Engine detailed below.

Recent History;
Engine block rebuild about 2 Years ago with new pistons, rods, bearings on crank & pistons, oil pan mod. All good simply failed to continue working on the Head, timing & jetting! Blew Cylinder gasket after 2 hours on German highway 3rd cylinder towards the exhaust. Engine had good torque at low revs and loads of Power see Picture attached ( taken by my passenger).

Engine spec so far followed pretty much your Stage II outline;
Compression ratio 10:1 with 5mm domed cast 0.2mm oversized pistons
Carbs; 40 Solex ADDHE’s dia increased to 45 though, overhauled with new gaskets etc. bearing good. NEED REJETTING
Cam’s; NEW NEEDED, 288° cams were found with thin shim fouling, have Standard & VX cams but that’s it
Springs; have uprated double springs from hot cams & standard, VX
No valve caps till now needed
Cyl. Head VX # 5936188 fully ported, guides shortened, WILL GET RESURFACING only
Valves from VX Valves with larger 43.5mm Inlet / 36 exhaust with sodium in EX valves, TO BE BLUEPRINTED
Lubrication, standard oil pump measured is acc. to Spec, good pressure see picture above with hot oil
Oil pan modified the oil pan with Betaboyz last baffled sump kit
Oil cooler 7 rows
Crankshaft standard, no mods made but cleaned and blown out etc.. at block rebuild with new Pistons ( approx..1500km ago)
Con Rod forged Delta rods
Main bearings all uprated Mahle with regrind of the bearing alignment in the block
Head gasket was Spesso Racing NEED NEW WOULD USUALLY BE AGAIN SPESSO RACE..
Headbolts reinforced Delta bolts
Clutch “ Sportclutch” uprated..
Ignition Standard, 2nd Series no ignition box only distributor with Bosch Coil
Ignition plugs
Electrical Fuel pump
Last series Uno Turbo cooler with short circuit on Engine only, thermostat sits in Cyl Head.
Exhaust 4-2-1 with uprated silencer

Am looking at finishing it for Street use with some 170HP, no racing or rallye envisioned. Engine shall be stable and not a nervous bumblebee specifically when using in town.

Hope to get your good advise in particular to the Carbs & Cams and other details to get there.

Thanks in advance,
André
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Guy Croft
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Re: Cam selection & carb jetting

Post by Guy Croft » Sun Jun 25, 2017 7:17 pm

oh dear dear

your spec is complete nightmare, I had to stop reading it!

Nothing from GC and an engine disaster.

Why did you not consult me first? Because I am 'expensive'..? Well now you have to spend twice!!

What do I advice? Start again and work with GCRE this time and throw everything else in the bin.

Well-done Betaboyz for copying an old GC sump design without even an email to thank me, even that is years out of date..!

G
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Betargovia
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Re: Cam selection & carb jetting

Post by Betargovia » Mon Jun 26, 2017 6:20 pm

Guy,

Thanks for your reply, hough I am somewhat not sure if thats it?

Thats your advice - throw all in the bin and start working with GCRE-

Been through all the procedures to register, listed in great detail all my Engines Spec and asked kindly for advice. Honestly great respect for your work but I am greatly disapointed with your answer.

Did consult you like 3 years back, never talked about camshafts & carb jetting as I firstly re-built my engine block which is good enough for it's intended purpose now.

Now I am consulting you for the timing and mixing.

Andre
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Guy Croft
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Re: Cam selection & carb jetting

Post by Guy Croft » Mon Jun 26, 2017 10:00 pm

nah, I'm not so bad really, respected member!

Might be an idea to start again with some GC parts, though!!

GC
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Betargovia
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Re: Cam selection & carb jetting

Post by Betargovia » Wed Jun 28, 2017 6:35 am

Okay, what about this, imagine the cylinder head is built up with some GCRE 3A cams with triple springs.

What jetting needs to be done on the ADDHE 40 (45's) and on the Cylinder Head next to resurfacing the head and blueprinting the valves of course.
What would be the approx output and engine characteristic?

Regards
Andre
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Re: Cam selection & carb jetting

Post by Guy Croft » Wed Jun 28, 2017 3:46 pm

Can you give me the full spec on the cams Andre?

G
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Betargovia
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Re: Cam selection & carb jetting

Post by Betargovia » Wed Jun 28, 2017 5:44 pm

Wanted to use your Stage II 3A cams

Regards
Andre
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Re: Cam selection & carb jetting

Post by Guy Croft » Wed Jun 28, 2017 7:12 pm

well, with the general spec you've got (43.5/36 valves, 10/1 CR) GC 3A cams should (SHOULD) yield over 174 bhp on 45 DCOE with 38 or 40mm chokes.

The 'bored-out' Solex thing I would junk tbh and buy some new Webcon 45 DCOE and Webcon linkage, marry to Facet interrupter Fast-Road (cylindrical) pump in boot, Filter-King regulator underhood with inline gauge kit and set to 3.5 psi ignition on engine off...

How much bhp you get will depend to an extent on the ex header and silencers, nothing aval on the aftermarket will be any good except to say that the Primaflow header isn't a bad choice if money is tight.. feel free to consult with me on that later.

You'll need a 13 row oil cooler with thermostatic control.

Engine temp will need to be controlled to 75 deg C. This can be hard to do. You'll need a sealed cold-air intake with remote filter otherwise the engine will detonate over and over.

You'll need NGK B9EGV plugs - I am an agent for NGK racing if it helps. Timing and jetting we can talk later.

Let me see some photos of the engine and engine bay - high def but not too big (100kb max) so I can get a handle on this.

G
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Piotrek125p
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Re: Cam selection & carb jetting

Post by Piotrek125p » Wed Jun 28, 2017 7:20 pm

GC, are 3A/2B cam combo will be a better choice for road engine ? When we talked about my spec. you suggested to use a 3A/2B cams, not 3A/3A.

Betargovia, your engine spec is quite simillar than mine, check this threads:

viewtopic.php?f=13&t=3377

viewtopic.php?f=13&t=3368
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Re: Cam selection & carb jetting

Post by Guy Croft » Wed Jun 28, 2017 7:28 pm

Fair comment Piotr


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Piotrek125p
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Re: Cam selection & carb jetting

Post by Piotrek125p » Wed Jun 28, 2017 7:34 pm

Further, mine spec and Betargovia spec. is quite simillar with Steve Hinson engine spec. for his Monte Carlo.

Betargovia, check a 2013 GC book, in case stories you can find a Steve Hinson engine thread, in my opinion this is an ultimate fast road 2L engine, something like I want to make for my 125p.

GC, please tell me what is your opinion about 3A/3A combo in road engine. It is will be enough trackable for stock 131/132 and Beta gearbox ?

In my opinion 3A/2B will give more middle range torque so driving it on a road should be quite pleasant.
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Betargovia
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Re: Cam selection & carb jetting

Post by Betargovia » Sun Jul 02, 2017 12:51 pm

Thanks GC & Piotr,

apreciate the tips Piotr, about your won & the Hinson engine. Agree, I need a recent of GC's book.

The 3A/2B combo sounds interesting as I don't want a nervous car in particular when being around in town. Understand where you are coming from with Webcon Carbs, have always been doing fine with the Solex and just overhauled em.

Please find a few pictures attached, 48-47 from restauration , 45-46 most recent condition before head came off. Will take a few better pics mid-July, business & holiday trips coming up.

GC, how can I get a recent copy of your Book? You still have my CC details etc. can you ship to my parents in Germany?

Thanks for now,
André
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GC #154

Guy Croft
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Re: Cam selection & carb jetting

Post by Guy Croft » Mon Jul 03, 2017 10:48 am

Hi Andre

book is always available, I have printed digitally.

Order form is at

www.guy-croft.com/viewtopic.php?f=1&t=3156

Does your airbox induct cold air from the front? I can only see an air duct that goes over the cambox...

GC
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