guys,

I just put hydroboost on my 67 Camaro and man what a difference. took it for a 20 mph drive last night, did ok. took it to get gas today (2.69 premium!!!!!) and some lady in a suburban around a turn pulled out and was blocking the road. i was only going about 35 mph, but had to slam on the brakes.

WOW. locked these brakes up with almost no effort at all. i had manual brakes before and its a million times more capable now.

My problem is that the car stopped so well, that it killed the engine. i had to restart it right there in the middle of the road.

So is this just my float bowls being too high? or is it something about the load on the engine that the HB is adding??

It seems like when im idling in the drive, that when i push on the brake, the RPM drops about 200 rpm. right now im idling about 1050 rpm (big cam 540)

do i need a pump off of a HB truck with 1400 psi? or will my 1 year old 67 Camaro pump do the job?

or, is it just the float bowls? which didnt look too bad to me...

thanks guys
jeff

does it kill it when you slam on the brakes when sitting still? if not, then it's not the hydroboost.
it's probably carb related.

it doesnt kill the car when sitting still, but does drop the rpm a little bit when i really jump on the pedal. i think it is adding a load to the power steering pump. and its that reason why i think i might need a HB pump... the 1400 psi job.

it could be carb related too. maybe a combination of both.

just hoping someone had the same thing happen to them...

thanks!

Maybe fuel slosh. I'd try an offroad 4x4 carb.

for slosh effects, the only place that fuel can come out is the vent tubes right? i ordered new sight plugs today

Get those little tubes that extend the jets. When you slammed the brakes, all the fuel sloshed to the front end of the forward bowl and exposed the jets to air. That used to happen to my 69 if I hit the brakes hard.

i have these little brass things that stick up past the main body about 1". arent those the jet extenders? or do i need longer ones??

thanks

Those sounds like the vent tubes. This is what you need.

http://www.holley.com/122-5000.asp

You take the bowls off and screw these in where the jet are, then screw the jets into these.

Those sounds like the vent tubes. This is what you need.

http://www.holley.com/122-5000.asp

You take the bowls off and screw these in where the jet are, then screw the jets into these.

Don't you also need to replace the floats when using the jet extenders?

Yes, the Holley part I linked mentions using a notched float and gives the part #.

"Requires the use of special “notched” float to achieve proper clearance and to operate properly. Notched float number 116–11 Or Kit with float and extensions 116–10."

Although, I think I remember seeing other companies that make them a bit different so you don't have to change the floats. Either way it sure beats stalling under hard braking :hurray:

Your main jets aren't the problem. When you hit the brakes, you've already taken your foot off the gas, and the main circuits have shut down in the carb. Your problem is fuel sloshing out of the rear bowl through the vent. What you need in this case is a vent extension, a.k.a. the whistle vent. It's a rectangular plastic piece that snaps into the metering block in the rear bowl, and vents from the rearmost point in the carb. As the fuel is sloshing forward, it never makes it into this vent now, instead of hitting the vent opening and climbing up the vent tube and out, as it's doing now without the extension.

http://holley.com/26-40.asp

I had those in my carb too, and it still stalled under hard braking. I'm not sure why fuel sloshing out of the vent would cause the car to stall. That's really all those vent extensions are for - to keep gas from blowing out the vent. Although that may be happening in the rear bowl, at the same time the front bowl is sucking air as the fuel moves forward. Seems to me that is a more likely culprit that fuel going out the vent, and I know in my case it was exactly what caused my car to stall.

I added the vent extensions because I was getting fuel on top of the carb - still stalled. I added the jet extensions and problem solved. These carbs don't transition instantly.

Are you saying you added jet extensions to the front jets?

Yes, and the rear - since they are designed to fix this problem when braking or accelerating.

Wow, okay, good luck with that. I guess it'll be fine when cruising, but I wouldn't want to try to win any races with 'em up front.

do you have a link to the companies that make the extensions without the need to go to the notched floats?

thanks!

Wow, okay, good luck with that. I guess it'll be fine when cruising, but I wouldn't want to try to win any races with 'em up front.

I believe he'd rather have his car not stall in the middle of traffic that have issues racing. You may want to talk to Holley engineering about their product design though, since you seem to know they don't work. They only extend the jet enough to keep the fuel in a properly adjusted bowl from uncovering the jets, not enough to cause the reverse problem to happen under accelration in the front bowl. They move the pickup point to the middle-ish of the bowl. I'm trying to help Jeff since I had this problem and fixed it, not argue with you. Have you had this problem?


Jeff - sorry but I don't have link right now, I can look when I have time later today.

much appreciated .. everyone.. thats why its a great site. and not having to do new floats would be great... thanks Kyle

I believe he'd rather have his car not stall in the middle of traffic that have issues racing. You may want to talk to Holley engineering about their product design though, since you seem to know they don't work. They only extend the jet enough to keep the fuel in a properly adjusted bowl from uncovering the jets, not enough to cause the reverse problem to happen under accelration in the front bowl. They move the pickup point to the middle-ish of the bowl. I'm trying to help Jeff since I had this problem and fixed it, not argue with you. Have you had this problem?


Jeff - sorry but I don't have link right now, I can look when I have time later today.

Hey, I'm not arguing with you. If it works for you, then roll with it. He's running a 540 though, he might want it to go when he stomps the gas pedal. That 540 didn't just wind up there from the factory. :noway:

And as a matter of fact, I did have this problem after putting 4 wheel discs on my Firebird. With a Demon 850. Some tuning, and a whistle baffle, and things are good now. The baffle has to be trimmed a bit for use with the demon, as the slot where it mounts is rounded on the ends, but it'll work. I used a bit of epoxy on the ends to make it stay.

Actually, the 540 is factory. it was a one of a kind in 67 :)

Barry Grant makes flattened jet extensions, but how do they screw into the jet or metering block?? do they just "push on"?? i dont like that....

http://www.jegs.com/p/Barry+Grant/743578/10002/-1

what do you guys think?

Sorry Darren - didn't mean to come off rude - just wanted to make sure that if extensions weren't the ticket, then Jeff had some info to back up the claim so he could make a good decision. Glad the vent extensions solved your problem. :yes:

Jeff - looks like they do push on. I'm with you - not nuts about that but maybe call BG and ask about how they actually stay there.

How can it be the carb when it drops RPMs at idle when you push on the brakes. I would be looking at the power steering pump to see what kind of load its putting on the engine when the brakes are applied..

ok, an update. i had to replace the sight glass in the rear bowl. well, the old one was brittle and cracked off as i was turning it. so i got to take the rear bowl off. there is a notched float and jet extensions already there. i didnt check the front. shoulda but didnt think of it.

i took a piece of fuel line and connected the vents and cut a hole in the top just in case there was sloshing. that didnt seem to help, the car still died under hard braking.

i adjusted the front fuel level up (as it was only at the very bottom of the sight glass) and it seemed to help a little. right now, its about half way up the glass. ill move it up more when i get a chance and retest.

im wondering if by chance my PS pulley is too big... underdriving the pump and making it under perform?? can you guys measure your PS pulley diameters?? thanks!

another thing... how do i determine the load the PS pump is putting on the motor at any given time? does a hydraulic system like this only give so much all the time or does it try to give more when called upon... and put a huge strain on the motor, killing it?

just trying to play both angles here...

thanks!!

so after reading this: http://www.freepatentsonline.com/6152106.html

it seems like the pump very well could be exerting such a load on the engine that it creates a snow ball effect...and the engine wants to die.

same thing happened with my electric fans.

so im looking at maybe getting a pump made for a hydroboost application... 1400 psi instead of 900. but my concern with that is ... will that be too much pressure for my 3rd gen camaro steering box? or does the pressure drop inside the hydroboost (from 1400 psi at input to 900 psi at output) so that by the time it reaches the steering box, its at "safe" pressure levels...???

thanks guys

Maybe you can modify your existing valve:

http://jeffd.50megs.com/Pump_valve_mod_page.htm

ok, so doing those mods will increase pressure, but by how much? from 900 to 1400 psi? 25 bucks for that mod vs 60-70 for a new 1400 psi pump?? if it works, im game, but do you have an idea on what the new pressure will be?

thanks

check out page one... the pics. maybe all i have to do is remove the shims and that will put me at 1350-1400 psi?? will the 91 camaro steering box take that pressure? or does the hydroboost output lower the psi to something acceptable for the box?

http://www.pirate4x4.com/forum/showthread.php?t=708701

thanks guys

Do your brakes and steering work well now with the 900psi pump? I can't see it being a plus to crank up the pressure, which only increases the load on the engine. What is your timing set at, and how well is the carb tuned at idle?

Timing is locked at 34 degrees. Carb is set for about 13.5 AFR idle. its not perfect, but pretty good.

The brakes work great. but theres something about the HB that makes me think more psi might be a good thing. pedal is a bit mushy. steers ok.

i was under the impression that if more psi as available to HB to bring it into optimal range, that would be allow it not to put such a load on the engine when called upon....using a pump that could put out the 1400.

if my pump now has to strain real hard to supply a load to the HB, wouldnt a pump that puts out more psi draw less of a load when needed?

that didnt come out right...

so i talked with the good folks at Lee Manufacturing in Sun Valley and they told me that the 91 camaro third gen iroc box requires 1400 psi and that the hydroboost unit requires 1600 psi. They also told me that my stock 67 Camaro pump puts out 1400 psi as is???

Im skeptical about that last point, but ill take their word on it for now.

I described how i have the HB set up and they dont like the fact that ive got the returns teed together. they are telling me that the tee is creating backpressure on the pump and causing my rpm to drop. Tehy tell me that if i had an extra return fitting to my pump, that my problem should go away??

Can someone explain that to me? Is the HB return line to the tee at the pump somehow a lot more pressure under braking than when not braking?? Does the backpressure go all the way back to the pump making the pump work harder to fight the backpressure? and therefore increase the load on the pump and motor??

thanks

According to my 1968 Chevrolet Chassis Service Manual the Camaro power steering pump pressure relief is set at 900 to 1000 psi. I would think that the 1967 Camaro pump is the same. However, with the car stopped, brakes applied, can you rotate your steering wheel all the way to full lock? If you can, then your pump is putting out adequate pressure. If you find that you run out of assist and the steering becomes very high effort before reaching full lock, then I would consider removing a shim in the pump flow control valve to increase the pressure relief setting.

I would tend to agree with some of the comments on the forum that your problem is not hydroboost related because of the fact that with the car stopped, engine at idle, and you really apply the brakes hard your engine drops a couple hundred rpms but doesn't stall. I can't believe that the hydroboost unit would cause your engine to stall when traveling down the road at even higher rpms.

One thought that could be hydroboost related. In a panic situation or under hard braking, is it possible that you are not getting your clutch disengaged in time? Could it be that the hydroboost is locking the rear brakes so quickly that it is stalling the engine?

The majority of fluid returning to the pump reservoir comes from the power steering gear. You want the fluid from the gear passing straight through the T in a straight line. Let the small amount of return fluid from the hydroboost come into the T from the side branch.

Jim

thanks Jim!

the one thing that i found out through some testing is that when the brakes are applied, the HB return line (that goes to the tee) is a decent stream. not just a trickle. the guy who built the unit says something is wrong with the HB. he says that the HB should only release a little bit out of that line when i left off the brakes.

do you think this could be messing with the pump flow/psi and causing a huge load/strain on the motor?

as for doing the test while driving, i push the clutch in and then wait a few seconds and then slam on the brakes. thats when it wants to die....

i appreciate any help you can give me... even in explaing the various flows/paths etc.

thanks

I am sure that the hydroboost unit has some sort of priorety valving in its design. That is the hydroboost would never redirect anything near 100% of the pump flow through its valve and into its return line. This would starve the power steering gear and you would notice a lack of power assist and actually it would be very difficult to steer if oil is not available to the gear valve.

It would seem that a large quantity of oil flowing through the low pressure line from the hydroboost must be a clue as to a hydroboost problem.

Jim

Curious if you have a homebrew HydroBoost? or if it's from a vendor.