[bygddy]

Originally Posted by CHEVILLAC

I honestly have no idea about the heads. The story I was given is " There's an old circle track guy in the Denver Co. area that built these heads for all the circle track guys within at least a couple hundred mile radius, about 15-20 years ago. He wouldn't divulge his source for the bare heads. They have no casting #'s and never did. they weren't ground off, they were never there." My boss had this motor in his 41 willy's, which I rode in, and it ran strong. I can't say it ran right because as I said I'm new to the technical stuff, but it ran strong. He did say that when he first built the motor he had an 850cfm Demon carb that was setup by a performance shop on the car and kept sucking the fuel bowls dry, under what conditions I don't know. He also said it has very little vacuum which creates a problem for my power brakes but I can get an electric vacuum pump for that. Seems there's alot of heresay but I do know it's a strong motor in great shape. If I put my 600cfm edelbrock on there, will it run? I have a Q-Jet on my other 350, but it could use a rebuild. Would it get me by?

Mystery heads, a race car cam that likely needs race car fuel, a single plane intake......with all due respect, your going to hate, or break it. And regret it. If you own it, and can't change that, be smart here, pull the race car parts, sell em, make them garage art, whatever, buy some decent heads, the right cam, swap the intake for someones dual plane, sell your 600 Carb, or trade for a 750, and enjoy your truck. I have done, hell I'm kinda doing now what your going to do, and its a terrible idea.....I'm a moron sometimes, don't be like me.

[CHEVILLAC]

Which would be better for short term (a few weeks max), the freshly rebuilt Eddie or the Q-Jet in need of a rebuild? $40 for a canister, $55 for a pump that provides 16hg and is smaller....? My other motor is getting tired so I'm trying to get this carb thing figured out asap so I can swap motors and be back up and running in a weekend because for at least a couple more months it is my daily driver. I already get 11mpg so how much worse can it get? Ultimately I'm thinking Holley 670vs or 750vs but for some reason everyone in the Portland area thinks those are worth $150-$200 all beat up. Seattle area has fresh rebuilt ones for that price but I'm leary of buying carbs sight unseen.

[bygddy]

Originally Posted by CHEVILLAC

Which would be better for short term (a few weeks max), the freshly rebuilt Eddie or the Q-Jet in need of a rebuild? $40 for a canister, $55 for a pump that provides 16hg and is smaller....? My other motor is getting tired so I'm trying to get this carb thing figured out asap so I can swap motors and be back up and running in a weekend because for at least a couple more months it is my daily driver. I already get 11mpg so how much worse can it get? Ultimately I'm thinking Holley 670vs or 750vs but for some reason everyone in the Portland area thinks those are worth $150-$200 all beat up. Seattle area has fresh rebuilt ones for that price but I'm leary of buying carbs sight unseen.

Mystery heads, mystery compression, doesn't matter what Carb, tired is better then broken, keep the tired motor,sort out the race car motor and install next summer

[CHEVILLAC]

bygddy

He ran it on pump gas for almost 20yrs up until about 6 months ago when he built a 383. I paid $600 for this motor. You don't think it would be worth it to just put a dual plane intake and 750 carb on it? In part, my thinking is... having 170hp or so more than I had, even if it can't perform to it's "full potential" will feel better than what I have. Even if I don't change anything else, as long as it's not going to destroy the motor. If you go from a good running factory straight 6 to a small block v8 smogger it's still going to be more fun.

[cobalt327]

Maybe that's why I recommended the DP to him in the first place, w/reservations. You're preaching to the choir. FWIW I used a 4777/4779 DP on 8 of the 11 engines I had in my DD Camaro.


But what ET's better (WOT) doesn't necessarily make the best all around street carb, either.
The idea that the carb is only about the engine, and is apart from and not affected by the rest of the combo and vice-versa, is a flawed theory IMO. The carb is just as much of a part of the whole combo as is any other important part. The CFM is about the engine as far at max output goes, but when you're looking at the whole picture and not just WOT performance (power under the curve), you'd have to see that there are some carbs better suited to a combo than others. Else why is there different types of carbs in the first place?

[cobalt327]

Originally Posted by CHEVILLAC

Which would be better for short term (a few weeks max), the freshly rebuilt Eddie or the Q-Jet in need of a rebuild? $40 for a canister, $55 for a pump that provides 16hg and is smaller....? My other motor is getting tired so I'm trying to get this carb thing figured out asap so I can swap motors and be back up and running in a weekend because for at least a couple more months it is my daily driver. I already get 11mpg so how much worse can it get? Ultimately I'm thinking Holley 670vs or 750vs but for some reason everyone in the Portland area thinks those are worth $150-$200 all beat up. Seattle area has fresh rebuilt ones for that price but I'm leary of buying carbs sight unseen.

Vacuum canisters are a poor second choice- use a pump or convert to manual brakes.

Use the fresh Eddy and a dual plane.

If you're lucky the CR isn't so high you can't use straight pump gas.

Ideally you'd pull the engine apart for inspection/freshening, and while there see what the cam was and swap it out if it's too big. You can even do that (check the cam) w/o taking the engine apart if the guy can't tell you upfront what the cam is.

Set the distributor up correctly. You'll need more initial timing. Start around 18 degrees BTDC and work up or down from there. Limit the mechanical as needed. More here.

[CHEVILLAC]

I really appreciate everyone's help on this. I'm just trying to make my truck a mean summertime street machine that will be fun at the track, not trying to break any records. I got a really good deal on the motor and figured I'd put a carb on it and see how I like it. If it feels too much like a race car then I'll make a couple changes and have what I'm looking for at a reallydiscounted price. At the most I would change to this Voodoo Hyd Cam Kit - Chevrolet Small Block 276/284 - Lunati Power cam and a dual plane intake like the performer rpm with the same holley 750vac sec carb you guys are recomending and just add a posi carrier to my 3.08 rear end or maybe go to 3.50 or so gearing so I can keep it fairly street [B]and[B] highway friendlyish but still be fun on the strip. The motor came with a 150 shot NOS setup as well. Thanks again for all your help on this.

[bygddy]

Originally Posted by CHEVILLAC

bygddy

He ran it on pump gas for almost 20yrs up until about 6 months ago when he built a 383. I paid $600 for this motor. You don't think it would be worth it to just put a dual plane intake and 750 carb on it? In part, my thinking is... having 170hp or so more than I had, even if it can't perform to it's "full potential" will feel better than what I have. Even if I don't change anything else, as long as it's not going to destroy the motor. If you go from a good running factory straight 6 to a small block v8 smogger it's still going to be more fun.

Ahhhh......OK, some of this I didn't know and I apologize, if he ran it on pump, and you only paid 600$, then absolutely, have at it, nothing to lose but a few bucks and some time. I would still try and swap your 600 for something bigger, and would up the gear and converter, but sounds like a fun, maybe grenade, but absolutely fun.

[CHEVILLAC]

Originally Posted by bygddy

Ahhhh......OK, some of this I didn't know and I apologize, if he ran it on pump, and you only paid 600$, then absolutely, have at it, nothing to lose but a few bucks and some time. I would still try and swap your 600 for something bigger, and would up the gear and converter, but sounds like a fun, maybe grenade, but absolutely fun.

I don't want to blow it up but I really don't have a lot of money to invest in it either. I think I'll rebuild my q-jet, put it on the motor, put the motor in with a 3000 stall and see what it feels like. Then when I can save some money I'll put the 3.73 posi setup in the rear and my 29"x10" pie shell cheater slicks and head for the track. Does that sound reasonable?

[bygddy]

Originally Posted by CHEVILLAC

I don't want to blow it up but I really don't have a lot of money to invest in it either. I think I'll rebuild my q-jet, put it on the motor, put the motor in with a 3000 stall and see what it feels like. Then when I can save some money I'll put the 3.73 posi setup in the rear and my 29"x10" pie shell cheater slicks and head for the track. Does that sound reasonable?

Honestly don't know enough about Qjets to know how its going to run with that much cam, and like is said, kijiji, Craig's list etc, you could likely swap the edelbrock for something more appropriate. And the cam is going to want a 3500 + stall, that being said, find a Carb, through a stall of your choice in it, and go enjoy the hell out of it.

[CHEVILLAC]

I'll give it a shot. 3500 stall just doesn't sound like it would be any fun on the street at all but I can't say I've driven anything with that high of a stall on the street so I really don't know if it's as bad as it sounds to me.

[cobalt327]

Originally Posted by CHEVILLAC

I don't want to blow it up but I really don't have a lot of money to invest in it either. I think I'll rebuild my q-jet, put it on the motor, put the motor in with a 3000 stall and see what it feels like. Then when I can save some money I'll put the 3.73 posi setup in the rear and my 29"x10" pie shell cheater slicks and head for the track. Does that sound reasonable?

If you're going to use a Q-jet, the amount of vacuum the engine makes has a direct effect on what spring to use for the power piston. Too much spring/too little vacuum will have it running pig rich (will be always on the power circuit) anywhere except WOT. Same concept as the power valve on a Holley or the step up springs on an Edelbrock/Carter.

Depending on what the Q-jet carb was originally from, it may need other changes (APT adjustment, jets/rods, bypass air orifice size, more idle fuel, to name a few). I don't say this to dissuade you from using it, just want you to be aware of the possible pitfalls.

Again, for the purpose of getting the engine up and running: Use the Eddy and a dual plane. Use a properly set up distributor.

Once you know what the idle vacuum is and how the cam is, then you can go about tuning it for real.

Also, the cam is the big unknown. It might be any sort of cam. Depending on what class it was built for, it could have a stock lift cam (often they'll have a ton of duration), it could be a cam ground for a vacuum rule, it could be set up to intentionally loft the valves off the nose of the cam lobe to circumvent the rules, could have hydraulic lifters on a solid cam (or vice-versa), it may be excessively advanced/retarded, et cetera.

If you cannot get a straight answer on cam specs/grind number from the guy who owned the engine, you really should take the time to measure it or see if there's some ID on the cam- whatever it takes. Because the way it stands now, you're (and we're) totally in the dark. This makes giving meaningful recommendations a total crap shoot.

3500 stall on the street is not as bad as you may think. But again- w/o knowing what the cam specs are, picking a stall speed is a total guess.

[CHEVILLAC]

Originally Posted by cobalt327

If you're going to use a Q-jet, the amount of vacuum the engine makes has a direct effect on what spring to use for the power piston. Too much spring/too little vacuum will have it running pig rich (will be always on the power circuit) anywhere except WOT. Same concept as the power valve on a Holley or the step up springs on an Edelbrock/Carter.

Depending on what the Q-jet carb was originally from, it may need other changes (APT adjustment, jets/rods, bypass air orifice size, more idle fuel, to name a few). I don't say this to dissuade you from using it, just want you to be aware of the possible pitfalls.

Again, for the purpose of getting the engine up and running: Use the Eddy and a dual plane. Use a properly set up distributor.

Once you know what the idle vacuum is and how the cam is, then you can go about tuning it for real.

Also, the cam is the big unknown. It might be any sort of cam. Depending on what class it was built for, it could have a stock lift cam (often they'll have a ton of duration), it could be a cam ground for a vacuum rule, it could be set up to intentionally loft the valves off the nose of the cam lobe to circumvent the rules, could have hydraulic lifters on a solid cam (or vice-versa), it may be excessively advanced/retarded, et cetera.

If you cannot get a straight answer on cam specs/grind number from the guy who owned the engine, you really should take the time to measure it or see if there's some ID on the cam- whatever it takes. Because the way it stands now, you're (and we're) totally in the dark. This makes giving meaningful recommendations a total crap shoot.

3500 stall on the street is not as bad as you may think. But again- w/o knowing what the cam specs are, picking a stall speed is a total guess.

Cam specs are in my original post but it is a summit cam, k1108. This is setup as a race motor and has very little vacuum at idle but the previous owner was able to drive it on the street. This motor was in an all steel 41 willy's 4 door and clocked 10 flat on the strip with a 150 shot of NOS, several times. I know vacuum secondaries are generally better for vehicles less than 3000lbs or so with automatic transmissions and mechanical secondaries are generally better suited for heavier ace vehicles. I want to take this truck to the track but be able to drive it to a cruise-in or car show too, hopefully without changing anything except MAYBE the distributor and the stall converter for now and add my posi later. Which brings me here asking which carb to run. It looks like a 750cfm is the consensus and I'm guessing mech secondaries since I have very little vacuum. Unless a vacuum secondary carb can be tuned to operate correctly with little vacuum, So because I'm also reading that vac sec carbs are more street friendly and pretty good at the track when a person is not so into racing that they're trying to shave tenths off their et. So I'll put the 600 eddy on there so I can get a vacuum number because the previous owner doesn't remember how much the motor had because he didn't care since he ran with fuel injection. From there maybe I'll have a better idea which carb to use. I do the fab and body work part of building custom cars and truck. This is my personal ride and I want it to be fricken fast and track worthy. I'll upload some pics and maybe that will help some of you understand my perspective a little better, if you don't already. I've never had more than 300hp and never been the driver at the strip but I drive my truck like I stole it.

[cobalt327]

Originally Posted by CHEVILLAC

Cam specs are in my original post but it is a summit cam, k1108. This is setup as a race motor and has very little vacuum at idle but the previous owner was able to drive it on the street. This motor was in an all steel 41 willy's 4 door and clocked 10 flat on the strip with a 150 shot of NOS, several times. I know vacuum secondaries are generally better for vehicles less than 3000lbs or so with automatic transmissions and mechanical secondaries are generally better suited for heavier ace vehicles. I want to take this truck to the track but be able to drive it to a cruise-in or car show too, hopefully without changing anything except MAYBE the distributor and the stall converter for now and add my posi later. Which brings me here asking which carb to run. It looks like a 750cfm is the consensus and I'm guessing mech secondaries since I have very little vacuum. Unless a vacuum secondary carb can be tuned to operate correctly with little vacuum, So because I'm also reading that vac sec carbs are more street friendly and pretty good at the track when a person is not so into racing that they're trying to shave tenths off their et. So I'll put the 600 eddy on there so I can get a vacuum number because the previous owner doesn't remember how much the motor had because he didn't care since he ran with fuel injection. From there maybe I'll have a better idea which carb to use. I do the fab and body work part of building custom cars and truck. This is my personal ride and I want it to be fricken fast and track worthy. I'll upload some pics and maybe that will help some of you understand my perspective a little better, if you don't already. I've never had more than 300hp and never been the driver at the strip but I drive my truck like I stole it.

The idle vacuum doesn't matter as to whether to use a vacuum secondary or DP carb. When you floor it, either way the vacuum drops off to nearly nothing, regardless if it has a small or big cam.

Heavier vehicles and/or higher (lower number) rear gear ratio equipped vehicles are generally easier to drive w/a vacuum secondary carb. Light vehicles w/low rear gears take to a DP like a duck to water and aren't as likely to bog on you.

Either will work (the DP requires a learning curve- think of it as the difference between an AT and a stick shift). But for the street most guys tend to like a vacuum secondary-type carb better than a DP, and the mileage will tend to be better as well.

There's a lot of trickery that goes into a race engine. Glad you know the cam in this engine. I guess it's the heads that nothing is known about and I confused the two. My mistake.

Good luck.

[CHEVILLAC]

Originally Posted by cobalt327

The idle vacuum doesn't matter as to whether to use a vacuum secondary or DP carb. When you floor it, either way the vacuum drops off to nearly nothing, regardless if it has a small or big cam.

Heavier vehicles and/or higher (lower number) rear gear ratio equipped vehicles are generally easier to drive w/a vacuum secondary carb. Light vehicles w/low rear gears take to a DP like a duck to water and aren't as likely to bog on you.

Either will work (the DP requires a learning curve- think of it as the difference between an AT and a stick shift). But for the street most guys tend to like a vacuum secondary-type carb better than a DP, and the mileage will tend to be better as well.

There's a lot of trickery that goes into a race engine. Glad you know the cam in this engine. I guess it's the heads that nothing is known about and I confused the two. My mistake.

Good luck.

Ah yes, I think I got it!