390 Holley Jetting

[Hot Rod Todd]

Hi,

I have a 302 Windsor engine in a 26 T coupe. The engine has around 260-275 hp, so its just a bit more than a stocker. I have 8 pipes with baffles in each one ( no collectors) and an old Accel coil. its all 70s stuff - down to the bad flake paint and the red & turquoise velour upholstery. But its way different & I like it.

The engine now has a Weiand tunnel ram with a pair of Holley 390s on it.

Can anyone suggest suitable jetting, plug gaps etc or any tricks to make it run better. The car has fenders & is longer than most - hence I needed to fill up the engine bay with the polished tunnel ram. I know it would be a lot easier to get a dual plane manifold and a 500 Edelbrock carb, but it would look bit "empty" in the open engine bay.

It wont ever be raced, I have my bucket and some other projects for that.

Thanks
Todd

 

[one finger john]

Hi,

I have a 302 Windsor engine in a 26 T coupe. The engine has around 260-275 hp, so its just a bit more than a stocker. I have 8 pipes with baffles in each one ( no collectors) and an old Accel coil. its all 70s stuff - down to the bad flake paint and the red & turquoise velour upholstery. But its way different & I like it.

The engine now has a Weiand tunnel ram with a pair of Holley 390s on it.

Can anyone suggest suitable jetting, plug gaps etc or any tricks to make it run better. The car has fenders & is longer than most - hence I needed to fill up the engine bay with the polished tunnel ram. I know it would be a lot easier to get a dual plane manifold and a 500 Edelbrock carb, but it would look bit "empty" in the open engine bay.

It wont ever be raced, I have my bucket and some other projects for that.

Thanks
Todd

 

[one finger john]

Just sounds like a recipe for no bottom end (small lo po engine, tunnel ram, individuel pipes). Perhaps trade for Edelbrock low rise dual quad set up with tall velocity stack/ air cleaners, progressive linkage.

John

 

[ellis8500]

Read this:

For maximum performance in normally aspirated competition applications, Weiand Hi-Ram Tunnel Ram intake manifolds are the manifold of choice. They're designed primarily for drag racing, truck/tractor pulls, and performance marine applications where high rpm is required but bottom-end torque isn't. With their patented D-shaped port runners and large plenum chamber, they provide optimum thrust of the air/fuel mixture to the intake ports. They mount either single or dual square-mount carbs and, depending on the application, have power bands that run from 2,500 rpm to as high as 9,000 rpm. Separate tops and runners are available for some manifolds.


Note the RPM range. In order for a Ford 302 to work well with this intake, you will have to change the camshaft, heads and pistons. Stock cam and heads will not flow with enough air velocity at lower RPM. The pistons will not have a deep enough valve relief for a higher lift cam. Even with all of this, the engine will not idle at any normal idle RPM. The Weiand Ram Tunnel is an intake for racing engines. You will also need a high ratio rear end; probably 4.25 or higher. This will not be a good street driver.

Do some more research and learn that you cannot just add one high performance part to an engine and expect great results. The intake, cam, heads and exhaust all have to be matched for a specific RPM performance band.

 

[railroad]

Sounds like the guys have a lot of experience, but there is nothing like a challange. Leave the jets, probably 50 or 51s in the front. If you have a front only metering block (4160 model) you probably have
a 6.5 to 8.5 power valve, if it has a front and rear metering block (4150 model) it probably has a 3.5 power vavle, which will probably be good. Run as much intial timing as you can, vacuum advance distributor is good also. Get your idle speed set. If you do not have any chugging or severely rich running, your power valves should be OK. If not take a intake vacuum reading with the car in gear, if automatic. Drop you power vavle rating by 2 numbers from the intake vacuum reading. Do not try opening the idle SPEED screw too much. If it will not idle at a low enough speed due to richness go to the power valves.

 

[72442conv]

Sounds like the guys have a lot of experience, but there is nothing like a challange. Leave the jets, probably 50 or 51s in the front. If you have a front only metering block (4160 model) you probably have
a 6.5 to 8.5 power valve, if it has a front and rear metering block (4150 model) it probably has a 3.5 power vavle, which will probably be good. Run as much intial timing as you can, vacuum advance distributor is good also. Get your idle speed set. If you do not have any chugging or severely rich running, your power valves should be OK. If not take a intake vacuum reading with the car in gear, if automatic. Drop you power vavle rating by 2 numbers from the intake vacuum reading. Do not try opening the idle SPEED screw too much. If it will not idle at a low enough speed due to richness go to the power valves.

It can be made to work adequately but you need quite a bit of experience with Holley Carbs. The timing is critical. I would run 16-20 inital with 16-20 mechanical for a total of 36 degrees total, all the timing in by 2500-3000, as long as it does not detonate. The 390's should be vacuum carbs which is good for what you have. Get some 50CC accelerator pumps, you will need them because of all the plenum volume you have, you may also need larger squirters, and you need to experiment with the accelerator pump cams. Check your idle vacuum and make sure you power valves are at least 3 numbers under that. Jetting will be trial and error. Best thing would be to take the car to a very experienced holley carb tuner that has a lot of experience with tunnel rams.

 

[Screaming Metal]

Railroad and 72442 have given you solid advice.....In my younger days I ran a old shoebox Nova with a 283, tunnelram with 2x4's, ran it one the street about 10 or 15 years....no problems....but it didn't have alot of lowend....but it wasn't undrivable.
With tunnelrams, you have to run a mild cam or a cam with variable bleed lifters, and the exhausts....with the individual pipes without collectors....your not gonna scavange as well. Timing is very important also....more so than with a regular intake.
When your tuning your motor....look at your lower runners just before the flanges....when you have everything set pretty close to right....you'll notice some sweating of the runners.
Just as you were told... the jets are best kept as small as possible because with the tunnelram....your dropping alot of fuel straight down into the cylinders.

On startup, you should be able to pump your pedal about 3 times while cranking and she should light right off...more than that and you might flood it.

 

[one finger john]

Hey Screamer, nice to see ya back. Your input is always welcome.

John

 

[72442conv]

Also get a good 2500-3000 REAL stall converter and low gears, 3.73-4.56 (will vary depending on tire size). If you can get a 3000 stall converter with the right gearing for the tires you have, no matter how bad the low end, it will run hard. Worst thing on tunnel rams is below 3,000 RPM, beyond that they work descent from 3500-5000, and they run like gangbusters over 5000 RPM. On a light car like a T bucket, with a 3000 stall converter and low gears, when you floor it you will basically be out of the tunnel ram bad spot almost immediately, and from there on just hang on :guard:

 

[Screaming Metal]

Thanks John...trying to recover from Christmas....hope everyone had a great holiday....Tunnelrams work really well for the larger motors that have heavier recipicating and rotating assemblies, so down low if you let out a little too fast on the clutch....the motor won't die....

On a smaller motor...even with a stock cam, you'll have to blip the throttle some to come away clean from a redlight. With the gears and converter getting your rpm's up a little will make a world of difference...

But one good thing...because a bucket is so light, it doesn't seem so bad, when you get it set up correctly. Some of the econo-altereds, they work really well....

 

[Screaming Metal]

As far as plugs...platinums resist fouling...which is a bad habit of tunnelrams. Those 'forked electrode plugs' also help tremendiously. Like I said...tunnelrams have a trendency to dump fuel straight down into the cylinders, which is one of their benefits in racing...Gears help out cause it gets your rpms up fast, and the stall converter helps with that also. One of the worst things you can do on the street is run a radical cam and a tunnelram. These setups are made to start pulling @ 3500 or 4000. Its OK for a hot street setup which doesn't see action but a few days a month....they're really hard on parts...take it from someone who knows. Mine was a 283, with a full on roller dirt cam ground to come out of the corners really well...it'd strat pulling @ 3000, at 4500 things got exciting, at 5800 you'd better be hanging onto something good, because it'd redline befoer I could get off the gas. But, I also had a aluminum flywheel, really low gears, and a .700 lift cams.....it was more or less a race car tuned as well as could be expected to run on the street.

Keep the carbs tunes kinda on the lean side, run good plugs and find out where the motor likes the timing set at. I had ran mine everyday, but it went to work, to the grocery store, to the drug store, then around the cruise circuit a couple of times on Friday and Saturday nights....then it just sat there looking awesome the rest of the time

 

[Hot Rod Todd]

Well we took it out today for its first ever drive.

We have a big hot rodding event on down here this weekend, and Im helping out the local drag racing club with promotion of our mational series event next weekend.

Car was a bit light in the rear and the carbs needs some more tuning. The biggest problem was the 8 zoomies - they just arent quiet enough to be either legal or pleasant. So we will have to get something sorted out there.

And its wise to bolt the seats in before the maiden voyage!

We only went around the block, but the trans is good and the brakes are fair. Will rebleed them and see if we can get some extra pedal as it got a bit soft.

Still, its always a good time when you are on that first run in a car when its finally driveable.

 

[RPM]

Congratulations on that first drive. It is something you will always remember.

 

[railroad]

Glad to hear the great news. It's just like therapy. I worked on one windshield post, most of the day.
After fitting it to the bracket, it was polishing time. Had a great day. Sounds like you are real close
on running the 2 fours, tunnel ram.

 

[Mike]

Before you get real carried away tweaking on the carbs, look at the throttle lever. You will see where a small screw passes through the lever to attach the accelerator pump cams. There are two holes. Look at your cams (likely red cams) and try moving them to the other hole. You will be able to see what you're doing with accelerator pump timing. If it bumped up the pump shot and the car likes it, then you might try a slightly larger squirter to see if the car wants to deal with more pump shot coming in faster. Maybe it wants a smaller squirter, to run the pump shot out over a longer duration. Holley will have you in the ballpark with respect to jetting. You will want to concentrate your efforts on the power circuits and the accelerator pump circuits.

Exotic exhausts always catch people's eyes, but a naturally-aspirated motor really needs a collector on the headers. It will help the carbs work and the motor will pick up a bit of throttle response as a result. If the motor is forced induction, there is little need for a collector, as you are artificially creating the flow conditions.

Remember, an engine is nothing more than an air pump. And the air tract each cylinder is dealing with starts at the top of the boosters in the carbs and ends at the tip of the exhaust. Your job is to maximize air flow throughout that entire length, whilst ensuring adequate fuel delivery to provide a proper stoichiometric ratio.

What can drive you crazy is minor physical differences in each intake runner can leave you with cylinders that have different timing requirements. And if an intake change is absolutely necessary, you can usually count on the fact the exhaust side of things will have to be tweaked as well. The Comp car I was associated with has always been one of the fastest naturally-aspirated cars in the country and it uses an odd-fire V-6. My forehead has scars on the scars, from beating my head against the wall trying to make that wee motor happy. You might think it was two 3-cylinder engines connected at the crankshaft, but they were connected at the intake manifold plenum too. You have no idea of the stuff nightmares are made of, until you've played with one of those tuning monsters.

The fellow that thinks an intake is just a box with some tubes leading to the intake ports is lost. He is likely also the fellow that thinks he merely needs some tubing at each exhaust port to move the exhaust away from the motor.

 

[Hot Rod Todd]

Thank you all for your help.

Having had a tunnel rammed bucket in the 90s I pretty much knew what I was up against before we ran the engine. I want to hear the stereo in the coupe, so we are going to modify the pipes to a collector and muffle it down properly. We did wrap the inserts in "wire wool cleaning mits" to muffle it, but that was a big fail. The engine barely ran and the soap in them leeched out. Still, we had a laugh & figured it was time for Plan B.

Because the car has an exagerated rake on the body and we want to run valances and running boards, we have to run the existing pipes from the motor to the running boards and hide the collectors and mufflers underneath them.

The engine looks good with the tunnel ram, twin holleys and K&N flower pots on top. Fills up the engine bay really well. We will print out Mikes reply and go out to the shed and give it a go.

Cheers
Todd

 

[railroad]

Try to post some pictures of your project. I feel like I have an interest in your success.

 

[Screaming Metal]

Thank you all for your help.

Having had a tunnel rammed bucket in the 90s I pretty much knew what I was up against before we ran the engine. I want to hear the stereo in the coupe, so we are going to modify the pipes to a collector and muffle it down properly. We did wrap the inserts in "wire wool cleaning mits" to muffle it, but that was a big fail. The engine barely ran and the soap in them leeched out. Still, we had a laugh & figured it was time for Plan B.

Because the car has an exagerated rake on the body and we want to run valances and running boards, we have to run the existing pipes from the motor to the running boards and hide the collectors and mufflers underneath them.

The engine looks good with the tunnel ram, twin holleys and K&N flower pots on top. Fills up the engine bay really well. We will print out Mikes reply and go out to the shed and give it a go.

Cheers
Todd

HRT, Try what Mike said...I also believe its gonna be the powervalve and squiters your gonna have to jack with. If you've got any Holley 'track-pacs'...get the ole crows foot squirter out and install them....that and tuning your pump cams will help....but those collectors not being there is gonna kill your low end....and your running a smallblock...and they're not torque boxes to start with.

If you can get the 'Zoomie' baffles that have the 3 rings and the center tube..., you can wrap them with fiberglass mat or asbestos, tie the really tight with stainless steel wire....put them into each of your pipes...and you might get enough backpressure to tine it 1/2 way decent.

I believe your gonna have to kick to timing down some, too... when she comes on the pipe...she ought to be a haulin'!

 

[Choctaw Bob]

Try to post some pictures of your project. I feel like I have an interest in your success.

Stay with it Todd. The setup you have looks cool and it can be made to run smooth.

Todd, the carbs are vacuum secondaries so they won't demand any more air than they can pull. Tuning idle air can be a problem but if you concentrate on the back carb only and you can work it out. I would even think about some progressive linkage and blocking off a power valve. Power valves frequently get blown out with back fires and then leak gas that will make it run rich.

There are some good books, Holley Carburetors by Dave Emanuel, S-A Design Books, is the best one I have used for years.

I have 2 Edelbrocks on my BBC but would rather have Holleys because of their ease of tuning.

by the way, you can change out the metering plates on the rear if you meed some top end tuning. I have a box of parts and a complete set of jets and cams left over from my racin days.