New to thread. Seeking advice.

J

Josh69

Member
I have built a 454 bored 30 over with a cam of .601 lift and 285 duration. Trickflow 280 aluminum heads, Weiand tunnel ram with two holley street avengers 470’s on top with vacuum secondaries. I had faith in the tunnel ram but am constantly told to lose it. The combination worked well in my head but I’m not getting the performance I was hoping for. What did I overlook and what should be changed?
 
Josh69 said:
I have built a 454 bored 30 over with a cam of .601 lift and 285 duration. Trickflow 280 aluminum heads, Weiand tunnel ram with two holley street avengers 470’s on top with vacuum secondaries. I had faith in the tunnel ram but am constantly told to lose it. The combination worked well in my head but I’m not getting the performance I was hoping for. What did I overlook and what should be changed?
Click to expand...
Do You have the camshaft profile number ?
The exact cam specs can be looked up then.
What transmission are you using ?
What rear diff gearing ?
What torque converter stall ?
Tunnel Ram is a drag race weapon.
It can be used on the street.
 
welcome too the web site!

yeah we need more info, like
whats the compression ratio,?
whats car/truck weight and tire diameter?
and

and as previously stated

"Do You have the camshaft profile number ?
The exact cam specs can be looked up then.
What transmission are you using ?
What rear diff gearing ?
What torque converter stall ?
Tunnel Ram is a drag race weapon.
It can be used on the street."

AND
"I’m not getting the performance I was hoping for. What did I overlook and what should be changed?"

give us some idea as to both current performance and what your trying to achieve with the engine combo,
it would also help if you let us know what your fuel pressure is, and post clear, detailed color pictures of your spark plugs ,
and what your ignition curve is set at and what are the rpm, or power band the engines operating under.
you might have a reasonable combo and just need the tuning tweaked,
but if the compression's to low,
the fuel/air ratios not both consistent and well dialed in,
or if the drive train gearing is not well matched,
if the exhaust is restrictive, or the turnings off, it won't run well.

have you recently done a compression test?
\properly adjusted the valves?
done a tune up?
checked the ignition advance curve?
lots of experienced members but we need info to base suggestions on, not guessing
 
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Howard’s cam #121905-11. 3.73 rear end and a well built th350 with a shift kit. 10.1 compression. Low stall torque converter. Thinking about 3000 maybe 3500 with this particular cam. I did have a couple disagreements with the machine shop as I was advised to have the rear carb fully open just after the the first, and with the tunnel ram, I’ve always been told they need to function identical and also be jetted the same. In all honesty it feels as if the motor is starving. My attempt at describing its power output. It can leave hard, I’m assuming the lower end torque with that particular converter. In this forum, I consider my knowledge novice at best. I’m sure you guys have forgotten more than I will ever know about this. I’m constantly told to lose the tunnel ram, but I’ve seen them shine and have faith in the system. Part of it, I believe, is most people nowadays don’t know or want to mess with a tunnel ram. This was my fathers car I helped him build, holding flashlights and utilizing my small hands at the time to thread bolts and retrieve tools. It had a 427 with smaller chamber heads but spring shims had wore out causing metal shavings to end up in the head. So, I got a new block, as the older one was getting oblong cylinder wear as big blocks do, I did keep the stock crank and rods. This decision was made because I wanted to keep it naturally aspirated and the research done on both the rods and crank showed it could stand up to what I was doing. Hypereutectic pistons were used. The car was originally built to run stoplight to stoplight. My growing up always taught me nothing beats American muscle. So, I enjoy punishing imports that claim to be ten second cars. Even running like it does I get them off the line and into third. But the top end doesn’t perform as I would like it to. Which worries me I made a mistake somewhere. I appreciate you guys taking the time to address any issues and couldn’t thank you enough. Constructive criticism is fine as I work in the oil field, believe me, I’ve heard worse. I will hold you’re opinions to the highest regard. Thanks again.
 
pictures of the car would be nice?
the combo is reasonably well matched ,
but I don,t see anything regarding the headers and exhaust system?
what rpm are you launching and shifting at?
BTW if you kept the stock 427 crank and rods you have a 427, or a slightly over bored 427 version, not a 454, a 427 has a 3.76" stroke the 454 has a 4" stroke crank,
and a 496 is a .060 over bore and 4.25" crank.. usually with longer 6.385" connecting rods with matched pistons
so it looks like its partly a tuning issue, but thats a fairly mild cam that limits the 427 upper rpm potential a bit ,
we can work with it for now, Ive used those oval port heads in the past they provide decent power .
what oval port tunnel ram intake are you using?
whats the ignition advance curve?
whats a compression test showing?
what headers and exhaust system?


https://www.competitionproducts.com...01-111-LS/productinfo/121905-11/#.XENQV1xKi9I



http://garage.grumpysperformance.co...he-bore-stroke-displacement.14906/#post-83901

http://garage.grumpysperformance.com/index.php?threads/tuning-a-tunnel-ram-intake.5175/

http://garage.grumpysperformance.co...-potential-dream-bbc-combos.14607/#post-77976

http://garage.grumpysperformance.co...ket-race-not-transportation.14229/#post-72282

http://garage.grumpysperformance.co...in-height-compression-height.5064/#post-66240

http://garage.grumpysperformance.co...gine-to-match-the-cam-specs.11764/#post-55651

http://garage.grumpysperformance.co...g-block-head-comparison.319/page-2#post-61658
 
When I rebuilt this particular engine I kept the stock internals. So it is a 454 crank. I Apologize for not making that clear. I have hooker competition headers
  • 2" x 27" Primary Tubes
  • 3.5'' x 10'' Collector
  • intake is a Weiand 1981 hi-ram
  • Mallory unilite mechanical advance as it was the only one at the time I could find to fit between the firewall.
  • As far as advance curve and compression test, I will have to get back to you on that because I don’t currently have the car with me. I moved for work and the garage here is to small for two cars in my opinion and it hails in Colorado so it’s in my brothers garage about two hours south from me. I know. I’m a pain in the ass. I also wanted to go more aggressive with the cam but since I run a break booster Jay (the machinist/engine builder), suggested I get as much vacuum as I can for the breaks. Last I checked 13 pounds which was higher than I thought it’d be. I vaguely remember timing as I messed with it. I don’t want to throw out numbers, however, 32 degrees initial timin sticks out and I want to say total advance was 46. Take this information with a grain of salt because it’s been awhile. The last obstacle I was trying to hurdle before leaving was setting valve lash. Damn lockers wouldn’t hold after fiddling with it three times. I also can’t seem to upload pictures, I think the file size may be too large. I’m currently doing this on an iPad and can’t figure out how to get them on here.
 
Figured it out.

index.php
 

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back in the day ...in a galaxy far far away...,I'm just an old (70) now retired HOTRODDER and mechanical engineer ,whos been building cars and engines, helping my friends on a semi constant basis fo r well over 45 years,
here,s a picture of me in 1970 (49 years ago) with a 1969 camaro I installed a BBC-496 with a tunnel ram https://www.summitracing.com/parts/hly-0-9377-1/overview/

into, then later CROWER FUEL INJECTION
paulscamarobw.jpg

crowerin1.jpg

Crower_Injectors.jpg


just a couple years ago
garage25.jpg
 
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That’s amazing. I’m sure I’m not the first to say thank you for laying out your wisdom and taking the time to do so. In retrospect, I should have built a 496. I might still do it if this doesn’t work well enough. Completely start over with a brand new block, forged rotating assembly, sniper jr. intake manifold and a 1270 cfm carb. A 4.5 inch bore and 4.375 stroke...okay okay...I’m getting carried away. I suppose I should keep it streetable or I’ll be forced to take an Uber for the next five years.
 
Ok.
I don't think the Holley Street Avengers are a good choice for a Tunnel Ram.
470's are small.
Its a 4150 carb with a single accelerator pump.
Works great on single carb dual plane intakes for street performance & daily driving.
Also works nice on vintage Offy intakes.
I use a 770cfm Holley street Avenger on my 1963 Pontiac Grand Prix. Know the strengths & shortcomings.

Tunnel Rams want a Huge accelerator pump shot of fuel in when you hit the gas pedal.
Holley Double Pumper 4150's wanted.
660's at least.
Beating a dead horse with the 470's.

Need $$$$.

If this is your daily driver you need another car for work.
Its a Street Toy the 1969 Camaro 454 with the Tunnel ram.
 
What about volumetric efficiency? The machinist said I should start with 750s with those heads but could take it to 1000...each
 
Josh69 said:
What about volumetric efficiency? The machinist said I should start with 750s with those heads but could take it to 1000...each
Click to expand...
I would not worry about Max VE today.
You want to drive this 1969 Camaro on the Street.
Use the Tunnel Ram.,
I have to look up the Howards Cam this morning but you said the engine is pulling 13 inches of Vacuum.
Its No True Race Engine.

Race Engine has 1-2-3-4 inches of Intake manifold Vacuum only.
Hit the gas & 8,000 RPM Right there right now.

Can try 750's.
Pair of 660's .

You can stagger cfm sizes also.
 
yes the carbs may be rather restrictive,
especially if they don,t fully open , but properly adjusted to open fully, and properly tuned to provide the correct fuel/air ratio, and with a 100% functional fuel delivery system, they should be functional, if not ideal.
but until you take the time and effort to measure both the fuel/air ratio consistency and plenum vacuum you really can't rationally assume thats your major issue.
look at it logically a 454 cylinder has an intake stroke every other revolution, engines rarely exceed 100% volumetric efficiency ,and most hydraulic roller cams won,t maintain valve train control at over about 6500rpm


if we take 6500 rpm and a 454 displacement at 100% volumetric efficiency....



carburetor cfm = (14.22)(max rpm)(number of cylinders)(stroke)(bore)2
67547.4

= Volumetric Efficiency

Theoretical CFM
in your case with a 454 and a max rpm near 6500 rpm, thats 790 cfm MINIMUM
your two small carbs might be a bit restrictive , but properly tuned they should work
4 barrel carbs are rated at a vacuum of 1.5 inches of mercury increase the vacuum and flow increases

the quick short hand version
454 x 6500 rpm divided by 2 divided by 1728=854 cfm

http://www.wallaceracing.com/carb-cfm-vacuum.php

http://www.wallaceracing.com/intakecfm.php

http://www.hipermath.com/engines/carburetor_cfm

http://www.wallaceracing.com/Calculators.htm

http://www.enginebasics.com/Advanced%20 ... ooler.html

http://www.summitracing.com/expertadvic ... Calculator

http://gottafishcarburetors.com/CFM Formula.html

http://wallaceracing.com/intakecfm.php

related threads

DON.T guess!
calculate the correct answers and ask , detailed questions,if your research hits a dead end

http://garage.grumpysperformance.com/index.php?threads/how-big-a-fuel-pump-do-you-need.1939/

http://garage.grumpysperformance.com/index.php?threads/dual-quads.444/

http://garage.grumpysperformance.co...le-that-don-t-use-resources.12125/#post-58374

http://garage.grumpysperformance.co...alculating-engine-volumetric-efficiency.6254/

http://garage.grumpysperformance.co...-calculators-and-basic-math.10705/#post-50173

http://garage.grumpysperformance.co...ing-parts-and-a-logical-plan.7722/#post-26314

http://garage.grumpysperformance.com/index.php?threads/bypass-fuel-pressure-regulators.12776/

http://garage.grumpysperformance.com/index.php?threads/tuning-a-tunnel-ram-intake.5175/

http://garage.grumpysperformance.com/index.php?threads/setting-up-your-fuel-system.211/

http://garage.grumpysperformance.com/index.php?threads/holley-carb-power-valves.1639/

http://garage.grumpysperformance.com/index.php?threads/tuning-carb-with-just-vac-gauge.14932/
 
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Take a picture of the upper air horn where the Choke is .
It will have the Holley LIST #.

I don't see a Holley 470 cfm street avenger listed.
Smallest is 570 cfm.
Largest is 870 cfm.
Looking at Summit Racing.
 
You guys are just great. Looks like I have some work cut out for me. I can’t tell you guys how much I appreciate your guidance and helping a simpleton like myself. I was convinced the carburetors were the issue once I got it up and running. I will be heading down to Colorado Springs today and see if I can’t make some headway. I will try to take more pictures
 
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