Holley carbs info
Discussion
Can anyone direct me to some reference material on my carb (Holley 0-4778)? Website, book etc.
I dunno which screw on it does what! Also a bit of clarification on the electric choke business. I've read on here they're more trouble than they're worth, but what are the pros and cons of removing it?
It seems to be humongously rich idling - makes your eyes stream even outdoors.
I dunno which screw on it does what! Also a bit of clarification on the electric choke business. I've read on here they're more trouble than they're worth, but what are the pros and cons of removing it?
It seems to be humongously rich idling - makes your eyes stream even outdoors.
Holley has a fairly good tech info on their carbs www.holley.com/HiOctn/TechServ/TechInfo/FMCTech.html
It doesn't tell you what you need to do only how to do it...but useful none the less.
I tried disabling the electric choke by winding it to full lean. This stopped the choke plate from coming into play. It didn't seem to do me much good at all. The thing was a pig to start and would idle until it was fairly warmed up. I figured the whole setup just needed adjusted properly...or replaced with EFI.
It doesn't tell you what you need to do only how to do it...but useful none the less.
I tried disabling the electric choke by winding it to full lean. This stopped the choke plate from coming into play. It didn't seem to do me much good at all. The thing was a pig to start and would idle until it was fairly warmed up. I figured the whole setup just needed adjusted properly...or replaced with EFI.
BobM said:
....Also a bit of clarification on the electric choke business. I've read on here they're more trouble than they're worth, but what are the pros and cons of removing it?
When I took my engine for a dyno run (with brand new Holley) at Knight racing this was the first thing they removed on the grounds that they were never much good and only ever caused problems. On starting from cold I have to keep the gas on for 30-45 secs to get a steady idle otherwise it dies. Mind you I always warm my engines up (much to the annoyance of the neighbours) so this never a problem for me..
Oh, and I have an HP Books guide to setting up & modding Holleys (which I am halfway through) If you want a few (ahem..) scanned pages, email me via my profile..
Plenty books on Amazon but as Dave F says, Holley website at least tells you what the various screws do. Small screw on each primary barrel near base for idle mixture. Rich idle seems to be the norm.
I've had no problems with electric choke, but you need to make sure it is adjusted properly, (ie choke plate opens when the thing gets hot). My car starts OK.
Only real issue I have is the stalling under heavy braking which I believe can be rectified with careful adjustment of fuel level and using extended jets, anti surge kits etc.
I am saving up for a Holley Stealth Ram EFI kit (would like individual throttle body injection from Kinsler but can't justify cost on my engine spec).
IMHO the carb, as pointed out by Dave Walker when he dyno'ed Stig's car, is just a big watering can pouring fuel into the engine and a fairly crude device whatever you do to it. It is cheap, rugged and easy enough to tune though.
I've had no problems with electric choke, but you need to make sure it is adjusted properly, (ie choke plate opens when the thing gets hot). My car starts OK.
Only real issue I have is the stalling under heavy braking which I believe can be rectified with careful adjustment of fuel level and using extended jets, anti surge kits etc.
I am saving up for a Holley Stealth Ram EFI kit (would like individual throttle body injection from Kinsler but can't justify cost on my engine spec).
IMHO the carb, as pointed out by Dave Walker when he dyno'ed Stig's car, is just a big watering can pouring fuel into the engine and a fairly crude device whatever you do to it. It is cheap, rugged and easy enough to tune though.
gdr said:
Rich idle seems to be the norm.
Yep. That's what my reading seems to indicate. The sort of spec of cam we fit to our engines has quite a lot of overlap which seems to lead to a rich and fairly rough idle. The idea seems to be to tune the mixture for maximum vacuum no matter what mixture that actually ends up with as that will give the smoothest idle.
I'd advise you check the dimensions of the Stealth RAM kit before you lay down any cash gdr. I did some rough measuring on my car the other week and the end of the throttle body gets very close to the rear bulkhead. I believe it is possible to turn the plenum on the Stealth RAM around but you then run into issues with the distributer. I think that it is possible to get a low profile distributer and use a crank trigger with the Holley ECU controlling the spark advance...it would certainly be a fun project but not necessarily straight forward.
Regarding the Stealth Ram.
I've been looking into it quite a bit. Per Holley, the plenum can be reversed. Still the issue with the distributor. It will get in the way. One option is to use a Holley crab style dist with crack trigger. Would work just fine.
Other option is to just use the Holley Commander 950 and don't use the Ram. This would be quite a bit easier and less of a project. I haven't decided if I want to go the project route or not, but it will be one or the other.
I've been looking into it quite a bit. Per Holley, the plenum can be reversed. Still the issue with the distributor. It will get in the way. One option is to use a Holley crab style dist with crack trigger. Would work just fine.
Other option is to just use the Holley Commander 950 and don't use the Ram. This would be quite a bit easier and less of a project. I haven't decided if I want to go the project route or not, but it will be one or the other.
davefiddes said:
[quote=gdr]
I'd advise you check the dimensions of the Stealth RAM kit before you lay down any cash gdr. I did some rough measuring on my car the other week and the end of the throttle body gets very close to the rear bulkhead. I believe it is possible to turn the plenum on the Stealth RAM around but you then run into issues with the distributer. I think that it is possible to get a low profile distributer and use a crank trigger with the Holley ECU controlling the spark advance...it would certainly be a fun project but not necessarily straight forward.
I have a stealthram sitting in my garage ready for phase two (consisiting of Stealthram connected upto MoTec)
It is VERY close in my MK4 (by my meausrement, I haven't whipped of the current manifold for a test fit) and may have to fab an interesting air feed/elbow. However it look fairly straight forward to swap around and I'll be running a crank sensor with the MoTec anyway..
Yep, I thought the Stealth Ram might be a bit tight but I have not got serious enough yet for detailed dimensional checking. Glad to get the response from you guys who have already done some research. To be honest, the dual plane manifold with the Commander 950 probably as good if not better for my engine which will not be operated above 6000 rpm. Just liked the look of the Stealth Ram for same price!
Bogbeast, let us know how you get on with the Stealth anyway.
>> Edited by gdr on Monday 1st December 15:16
Bogbeast, let us know how you get on with the Stealth anyway.
>> Edited by gdr on Monday 1st December 15:16
gdr said:
To be honest, the dual plane manifold with the Commander 950 probably as good if not better for my engine which will not be operated above 6000 rpm. Just liked the look of the Stealth Ram for same price!
I agree that the standard c950 would do the job as well. Sure would look nice though to have a polished Ram sitting on top of the intake manifold. I'm torn between ease of installation over the WOW
effect. I'm still debating installing an LS1 or a 550hp SBC.
From what I've read on ChevyTalk the Holley MPFI intake needs some porting work before it'll flow well on high output motors like ours as the injector bosses stick into the port. Best recommendation seems to be the Stealth for a bolt on solution or a converted single plane race manifold (like a Victor Jr) with blended in welded injector bosses.
Just a thought - could you mount the Stealth Ram throttle body in a remote location and fabricate the necessary ducting to the plenum (like many modern production cars)? The looks would suffer a bit, and maybe not worth the hassle. The Ultima headers tend to get in the way of this type of thing, but interested to hear if anyone thinks it is feasible.
There's a tunnel ram, for sale on ebay:
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=2446338326&category=9903
also, I'm currently converting a edelbrock Victor JR to fuel injection using megasquirt.
See www.mez.co.uk/ms4.html
eliot.
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=2446338326&category=9903
also, I'm currently converting a edelbrock Victor JR to fuel injection using megasquirt.
See www.mez.co.uk/ms4.html
eliot.
eliot,
that Enderle mech injection system on e-bay looks intersting. I'm tempted to bid if cheap as potential for conversion to EFI. Looks a bit radical though and probably not that streetable.
I'd also be interested in how your Victor conversion works and if not too nosey, what the final cost +/- ends up.
Cheers
gdr
that Enderle mech injection system on e-bay looks intersting. I'm tempted to bid if cheap as potential for conversion to EFI. Looks a bit radical though and probably not that streetable.
I'd also be interested in how your Victor conversion works and if not too nosey, what the final cost +/- ends up.
Cheers
gdr
Discovered a couple of interesting things whilst doing further EFI research.... 
Brammo Motorsport has a couple of pics that show how a Holley Stealth RAM might look with the top plenum turned around and the appropriate distributor fitted.
I have also discovered that Edelbrock have released a variant of their Victor E race manifold with mounting points for injectors and custom high flow fuel rails to match. This is pretty reasonably priced at about $310 for the manifold which is about $80-$90 more than the plain Victor E (or Victor Jr) manifold. For Ultimas I'm guessing that the extra plenum volume isn't likely to cause a problem as we're more after top end power. Might have a bit more sluggish throttle response at low revs (no worse than any ram based intake I would have thought).
The folk on Chevytalk seem to figure that this manifold, a DIY on a Victor or equiv or a Stealth RAM is the way to go. For high hp (>450bhp) the Holley MPFI is too restrictive.
I'm currently pricing up a Frankenstein EFI setup with the Edelbrock manifold, Holley throttle body and injectors(probably), Aeromotive fuel pump and regulator and Megasquirt ECU (because Open Source is my bag - substitute Holley C950 if you want an off the shelf proprietary). I'm planning to keep the current low press fuel pumps but feed them into a 1 litre swirl pot and have some sort of switching return line so I can keep the stock tank layout and swap back to carbs if required.
Brammo Motorsport has a couple of pics that show how a Holley Stealth RAM might look with the top plenum turned around and the appropriate distributor fitted.
I have also discovered that Edelbrock have released a variant of their Victor E race manifold with mounting points for injectors and custom high flow fuel rails to match. This is pretty reasonably priced at about $310 for the manifold which is about $80-$90 more than the plain Victor E (or Victor Jr) manifold. For Ultimas I'm guessing that the extra plenum volume isn't likely to cause a problem as we're more after top end power. Might have a bit more sluggish throttle response at low revs (no worse than any ram based intake I would have thought).
The folk on Chevytalk seem to figure that this manifold, a DIY on a Victor or equiv or a Stealth RAM is the way to go. For high hp (>450bhp) the Holley MPFI is too restrictive.
I'm currently pricing up a Frankenstein EFI setup with the Edelbrock manifold, Holley throttle body and injectors(probably), Aeromotive fuel pump and regulator and Megasquirt ECU (because Open Source is my bag - substitute Holley C950 if you want an off the shelf proprietary). I'm planning to keep the current low press fuel pumps but feed them into a 1 litre swirl pot and have some sort of switching return line so I can keep the stock tank layout and swap back to carbs if required.
Here's the response I just received from Holley regarding the ability to reverse the plenum on the Stealth Ram
"The upper plenum can not be turned around. I guess you would have to make a plate to cover the front TBI area. Then machine the back area for the TBI in the back. Then you wil have to modify the lower so it will flow air properly on all cylinders. Thanks WW"
I can get more info if desired.
"The upper plenum can not be turned around. I guess you would have to make a plate to cover the front TBI area. Then machine the back area for the TBI in the back. Then you wil have to modify the lower so it will flow air properly on all cylinders. Thanks WW"
I can get more info if desired.
slangley said:
Have you looked into pros/cons of a TEC3 unit compared to the others you are interested in?
Not really. It looks pretty clever for the money they are asking though. I think that Mark Koch is using it. Full sequential is an improvement over batch fired injection. You need it for getting the best economy and the last little bit of power...its more complex and thus expensive. The distributorless ignition looks great. The fewer electro-mechanical bits flying about the better. It might be harder to tune and/or get support on???
Shame about the Stealth RAM. Sounds like quite a bit of work to make it perform properly...
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