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  #46 (permalink)  
Old 10-27-2012, 04:16 PM
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Quote:
Originally Posted by F-BIRD'88 View Post
Get him to bring you back a pair of 750 holley blower carbs.

Re 600 carbs and sec metering plates: the plate once correctly tuning for your motor on the dyno will work just as well as a sec metering block.
no need to turn the carbs sidways. just get two metering plates and
modify for screw in holley jets (simple drill and tap threads) and dial them both, in on the dyno.
real simple.

The 750 blower specific carbs will get you very very close to max performance, out of the box. Any required tuning/jetting will be minor ...The EFi is going to be a big water of time and money.

Water meth injection is much more effective when injected above the blower.
When below the blower you would have to account for the rise in manifold pressure under boost and compensate in the injection pressure
same with the EFI. Boot referenced fuel pressure.

When the fuel and or water/meth is injected below the blower, the blower is not cooled by the fuel.
The air is not cooled (charge air intercooled) near as effectively. Two big reasons why:

The 750 blower carbs will do a whole lot better job on this motor , than EFI.
They will make more power too. Thats 3 big big reasons, for a fraction of the price.

if you're going to stick with the 600's and want to optiminze them they will work best if you cut the choke horn off, mod the body for boost referenced power valves and mod for swappable screw in air bleeds and optimize the primary metering blocks.
(idle feed restriction, (power valve channel restriction size)

I would not bother. just get the right 750 blower carbs. Those you can mount sideways.
great , ok will tap the front secoundary metering plate to accept the jets . i do have a base plate below the carbs ( above the blower ) that have 2x allen key screws in the back ( facing the driver ) should be able to inject in there with water meth ?

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  #47 (permalink)  
Old 10-27-2012, 04:35 PM
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Quote:
Originally Posted by F-BIRD'88 View Post
I would not mod the blower carb adapter base plate. I'd leave that as is...I would use two 4bbl carb spacer style water injection plates (looks like a 4 bbl nitrous injection plate, or typical common 4bbl carb spacer)
Snow Performance is just one of many good Water injection system companies.
no i dont need to adapt the plate i have, it already has 2x allen keys screws in the back of it . unless they are meant for something else ?
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  #48 (permalink)  
Old 10-28-2012, 01:54 PM
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hi guys .

had a great day today . finally got it to idle for a while at 950 - 1000 rpm. eventually it burnt off the old oil and mosture from the engine where it had been sitting . i have put 2x videos below for you to see .

i do have 1x problem still. my neddle valves get stuck every now and then . i have set them, to just show the fuel level at the sight plugs . but sometimes while its running and i turn it off the electric fuel pump carrys on pumping fuel and out into the carb and out of the breather tube. hopefully its just a sticky needle valve, will replace them next weekend and see if that fixes it .

i am getting there now. i also jacked up the back and ran the trans and got around 6 litres of dex 2 atf oil in the c6 auto box. does that sound about right ?
cheers again







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Old 10-30-2012, 05:45 PM
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hi all . i also have a trans rad cooler but a small one so intersted in how may litres or quatrs it should roughly take ? cheers
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Old 11-04-2012, 02:18 PM
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hi all . i have taken a video this weekend of my engine running with the vacum gauge rigged up to below the carbs but above the blower. there is a take off to the rear of the blower that i was able to screw a fitting into to get a take off for the vacum guage. so i have got the engine settled around 850-900 rpm and the vacum reading @ idle is 16-17 . so whats your thoughts on my power valve requirements ? cheers for all your help guys. i am well made up to have it starting and running smooth now. your posts really helped and have got me up and running. t bird . i went with your figures and they are fine at present and the engine is idleing a hell of alot better.

the video is here . cheers all

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Old 11-04-2012, 03:37 PM
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Quote:
Originally Posted by F-BIRD'88 View Post
If you had low 5psi boost you could do this different....But you don't.

you need to cut those ugly carb choke horns off too.

cheers . will speak with the dyno guys as they have pv blanks and the higher jets. i am running around 11 psi which is better than what i thought at 14 psi . i do have a blower snout which is the retro looking one. is there any reason for cutting off the carb horns for any better set up ? or just coz you think they are uglily ? they will be covered by the blower snout anyway so wont be seen , i just dont put it on when running so i can see the boosters etc to make sure the needle valves have shut off
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Old 11-04-2012, 03:54 PM
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this are the timing figures i have at the moment . they need fine tuning but are getting it ideling at 850-900 rpm which im happy with . especially with the lupmy cam i have .

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  #53 (permalink)  
Old 11-05-2012, 03:15 PM
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no not at this stage. i like the vac sec on a blower , as the blower can decided when they come on and i get better mpg around town etc. once dialled in they will be fine ,

regarding the cam , i specifically got this crane "supercharger cam " from them as it was a good moderate to fair ride cam for my set up. i didnt want a mad unrelistic cam. dont agree i am choking it. yes i agree there are bigger duration higher lift blah blah cams out there. but i want a reliable daily driver not some unrelistic strip car.

i have contacts in the film industry and concierge so i do want to use it commercially . something that would be more uncomfortable with a big arse cam.

again a matter of opinoin and not fact as are alot of mods on cars.

did you have any thoughts on my question earlier on my c6 oil capacity with a front mounted oil cooler ?

cheers shaun
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  #54 (permalink)  
Old 11-05-2012, 03:19 PM
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thanks cobalt for sending the diagram on the transtion slots . that fixed that problem , top man
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Old 11-05-2012, 03:20 PM
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Quote:
Originally Posted by cobalt327 View Post
0.032"-0.035" max on the plug gap.

The way the PV is supposed to work is it will stay shut until the engine load causes the vacuum to drop to below the PV rating, at which point the PV opens and enrichens the air/fuel mixture to help overcome the load the engine is under.

So, check to see what the vacuum reading below the carb and above the blower is. If this reading is less than the number on the power valve, the power valve will be open and the engine will be overfueled. The engine doesn't need to be under a load for there to be fuel coming in from the power valve. If the vacuum at idle is lower than the power valve rating, there will be excess fuel, for example. This might be part of the reason you have a rough, 'lumpy' idle.

But since the carbs aren't boost referenced, the PVs should be shut- even when you want them open. That is, unless one or both PVs are ruptured from a backfire or old age. Newer Holley carbs have backfire blowout protection for the PV- if it's functioning properly. If not or if the carbs don't have blowout protection for the PV, then they could be damaged allowing fuel in when it isn't needed. If the wrong PV gasket is used, or two gaskets are accidentally used, there can be a fuel leak. Just things to look for when you take them down for cleaning.

If the initial ignition advance is too low, that will also account for a poor quality idle, and can cause the primary butterflies to be open too far. If the butterflies are open too far the engine will be pulling fuel in from the transition slot of the carb instead of running mainly on the idle circuit. If the timing is advanced at idle and the carb curb idle screw is backed out to close the primary butterflies, the idle mixture screws should become functional.

Sometimes the secondary butterflies need to be cracked open farther than "normal" to add bypass air to get the idle back to normal. Sometimes you even see where the primary throttle blades have been drilled w/small holes in them to add bypass air, although this is seldom really needed if the other methods (secondary bypass air and increasing the timing at idle) are used.

Something else to look for when you first pull the carbs is to see what the transition slot looks like. It should be between a "square" and a slot about 0.040" long. If this is too long, that's when the engine will be trying to idle on the transition circuit instead if the idle circuit. Photo below shows what I'm referring to.



If the carbs aren't boost referenced, I wouldn't want to run it on the dyno. The dyno loads the engine heavily, and w/o the PV adding fuel it can go lean. You have to be sure that the PV's were working when the blower is making boost and the vacuum drops.

This is a concern to me because of the small carbs. If you had a pair of 750 cfm carbs you might not need boost referencing at low boost levels- but this would need to be verified before loading the engine.

A 65 PV might open later than you need. It wouldn't surprise me for you to end up w/an 85, as an example.
cheers for the advise !!
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Old 11-05-2012, 07:05 PM
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You are quite welcome, Shaun. I'm still following this thread and will add when appropriate. I'm sure you'll get this sorted out and before you're done you'll be driving a BEAST!

Mark
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Old 11-05-2012, 08:25 PM
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Been following this thread and learning a lot
Hope you get it all worked out 671 and I have to agree with that cam not sounding to lumpy, hell mine fires like once every few seconds
I also have to agree with the sideways carbs, they fit and look quite well if done right, here's mine





Unfortunately you really cant hear the motor in that

Best Of Luck and hoping to hear you got it all figured out shortly
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  #58 (permalink)  
Old 11-10-2012, 03:04 PM
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hi all .

been working on the car again today . so i pumped twice from cold. choke off secound turn of the engine and off it went. kept it for 1500 rpm for a moment and then it happily idled at 900 rpm.

looking forward to the dyno in a coulpe of weeks .

i will jump to another subject concerning my brakes. and will come back to you all when i get some updates after the dyno and i hope to get a video and some figures for you !!

last question until i come back to you.

currently i have millers running in oil. and i have now had the engine running and idleing for a bit. whats your opinions on keeping this oil in for when i go to the dyno ? i am in the mindset of running in the engine quickly and not over 1500 odd imiles as most stupid manufactures advise. bed the rings in quick under load before its too late. i have seen the evidence to make my mind up. so with that said would you recoomend this oil as it will alow this or a semi synthetic as the running oil i have is mineral !!

cheers all - and amazing advise.
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Old 11-11-2012, 11:17 AM
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hi all . had the engine running for a while today . sorted out my brakes but my alternator still isnt charging.

however the car didnt want to start when hot . and i got a back fire through the exhausts ( not the blower - that never happens now ) as i have a wasted spark system im thinking my mixture is too rich ??

am sure this will be sorted when im off to the dyno and they plug in their lambda sensors.

any ideas ? i didnt pump the throttle. went to catch a couple of times but nout . all good from cold . just when its hot

expect the pv will neede to be changed .

cheers
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Old 11-11-2012, 11:33 AM
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Quote:
Originally Posted by mustang 671 View Post
hi all . had the engine running for a while today . sorted out my brakes but my alternator still isnt charging.

however the car didnt want to start when hot . and i got a back fire through the exhausts ( not the blower - that never happens now ) as i have a wasted spark system im thinking my mixture is too rich ??

am sure this will be sorted when im off to the dyno and they plug in their lambda sensors.

any ideas ? i didnt pump the throttle. went to catch a couple of times but nout . all good from cold . just when its hot

expect the pv will neede to be changed .

cheers
If you wire in an ignition interrupter, that will help the hot start problem.

It works by allowing the engine to be spun by the starter, w/o the ignition enabled. Then after the engine is spinning nicely, the momentary switch is released allowing the ignition to become hot and the engine fires.
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