Inliners International Forums General Discussion Hi Performance Clifford vs Offenhauser rehashed, 292 4 Bbl

Ok, Clifford calls theirs a High Torque manifold and comes set up for water heat plus on their site says good for street use also, but in a discussion on here so many pick the Offenhauser. I found a possible deal on the Clifford, and plan on using Langdon's iron exhaust, everything topped off with a Holley 390cfm carb or Weber 38. So is this a mistake to go with the Clifford "deal", or should I pony up the bucks for the Offy?

Hi. Iam in the process of doing a rebuild on a 1957 235 engine I just purchased to put in my 46 coupe. I have purchased the Clifford dual intake with the two 2 barrell Webber carbs to put on this newer engine.

What you need to check before purchasing either the intake or exhaust is that the Clifford is much taller in bottom to top height as well as thicker front to back in the water chamber as well as the upper chamber above the water chamber & will NOT work with the stock exhaust cast iron or the cast iron fenton headers. Clifford reomends using their shorty tube headers as this offers a lot of clearance between the two manifolds. These shorty clifford headers is what I purchased.

My engine should be ready to install later this week unless something unexpected pops up & I can have more info then.

I chose this set up as well as the Clifford 264 grind cam as my Coupe will be strictly as a street & Hwy daily driver.

I will have to trailer it to the exhaust shop for them tobuild the pipes.

Jimmie

Thanks for the advise. I wanted the Langdon exhaust because I've never had luck with thin tube headers lasting, and I'm trying to stay away from multiple carbs because I just don't want the headaches of tuning.

I understand on the single carb. On the clifford intakes they are all made to take the 4 bbl carbs & use an adapter plate for all the different mounting bases of the different carbs. Beause of this the top to bottom & front to back measurement of the water & fuel/air chambers likely should all be the same size.

You should contact Langdon & ask if their exhaust will fit with the Clifford intake for your engine as they should know. Clifford could also tell you but they may or may not be more interested in selling you their exhaust.

I would have prefered to use the cast iron fenton exhaust but there was no reasonable modification that would have made those compatable with the Clifford intake manifold short of totally butchering up both manifolds so I took the easy way out with the tube headers.

Jimmie

The Offy will bolt right up to most anything w/out having to modify/cut/grind brackets, headers you name it.

I personally like the OFFY better for low RPM & better throttle response.

The Clifford intake runners are HUGE as compared to the OFFY & IMO, the OFFY gives a better signal to the carb. I also got better mileage w/an OFFY over the Clifford.

My testings were all done on a 250 CI engine, so I would think a 292 could get away with the larger runners, but for a daily driver & concerned a bit about mileage, IMO, I think the Offy is a better choice.

There is a member here that did testing on the two different manifolds & carbs & the Offy did squeak out on top over the Clifford, performance wise.

That is what I like to see in testing, real street/race cars, testing on real streets or tracks, not just engine dyno testing.

MBHD

I'm Just building a clean street truck. It doesn't need to put out huge power, just look good with nice throttle response, and drivability.

Heavy Truck, someone on here put on a 390cfm Holley on a stock 292. The comment made was that the engine only "wanted" about 300 cfm or so. With that 264 cam the 390 carb should be just about perfect. Myself I am more of a Carter fan or a possible Q-jet. Manifold choice? Don't have a clue I have no experence with either. I would probably go Offy for clearence reasons. Whatkind of pistons are you going to run? stock? LP? Jay 6155

Everything in the engine is stock. I think it's looking like Offy, and Holley.

Ah I misread, Jimmie Price is running the 264 cam. Sorry about that. Still the 390 Holley front 2 barrels are very close to the stock 292 carb. From my LIMITED understanding of Holleys they do best when opened up enough in normal driving to "work" the main metering systems at part throttle. A 292 should need enough airflow to do that and provide decent mileage. My only experence with a Holley is the 2bbl on my boat. As the throttle is about half open at normal cruise speeds the carb is just fine. Jay 6155

Hi again. Just to add a bit on my build. Everyone has different paramaters & reasons for the spefic way they choose to do a build. My engine being a 1957 year 235 with a 0.060 bore & a 264 grind cam, Clifford intake with 2 two bbl Webbers & tube headers, stock 3 on the tree & converting ring & pinion to the 355 ratio is an attempt to make a good safe daily highway driver with no intention of a race car.

The brakes & front end have been rebuild stock for now & I will soon be adding a new set of 600/16 radials for better, safer driving while keeping the original stock exterior look of the car. Keeping this stock interior - exterior look is important to me but may be immaterial to others. I just want the look & performance of the cars I drove as a teenager into my early 20's in the 50's - early 60's. The only thing on the car interior & exterior that will not look stock original will be the dual chrome tips under the rear bumper. The difference in look & performance will only be visable with the hood raised and the Vintage Air cond thin vents under the dash.

I am trying to come out with enough HP & torque to be able to drive my 46 Coupe 70 MPH on the hwy without being an obstruction to traffic and be able at low speed & RPM in town have enough oomp in the engine to easily pull an air conditioner compressor in this 100 + degree Texas summers.

I think this will be a good set up for me with what I am wanting to end up with. But I am still open to suggestions but I have already purchased all the above engine & rear end components so I am locked into those. I will look at the clutch when we pull the old engine next week & most likely will make an upgrade there. I have no clue what clutch is there until then. A I will not be popping the clutch while revved up hpefully the 3 speed original transmission will hold up but will deal with that if & when necessary. I prefer the 3 on the tree for me.

I have tried a couple of time to post a photo of the exterior but an just doing something wrong. I will not have any engine photo's until at least late next week.

Jimmie

You probably should determine what RPM your engine is going to be needing to run 70 MPH and base your parts combo to optimize the useable RPM range required to do that. This will help determine which parts will better suit your needs.

Hi. In light of CNC-DUDE suggested on determining rpm needed from the parts I will be using I have a question on figuring this out. I should have the info but it escapes me right now.

Using the following setup on the Coupe lets see if we can figure the RPM needed at 70 MPH.

Stock 46 Chevy 3 on the tree transmission, 355 rear end and with variables in tire sizes for the sake of seeing what each tire size would result in RPM needed for 70 MPH as I will be purchasing new radials anyway. Stock tire size of 600/16 or with 650/16 or 700/16. Would include 750/16 but likely my 4"-4.5" original rim width would be a bit narrow for the 750's.

What do you guys think on this?

Jimmie

So much of what is discussed here has so little to do with how many of us actually use our engines. I'd like to see data for building strong every day work horses that pull from a dead stop to highway speed( 70-75) never going over 4000 rpm and crusing between 2,000 and 2,500. These are actually wide RPM ranges and could be held closer with gearing. My interests are more about drivers than racers.

I think if he can determine where his engine is going to be running as far as RPM range goes, he can make a better selection of parts based on that.

Wow a formula that I know! 336x mphx axle ratio /tire diameter. In this case 70 x336 x3.55/28.3=2950.3. This is with the 600-16 tire from another post. I hope this helps with finding the RPM range. Jay6155

I'm Building a street/show truck. !983 C20, lowered, stock internal 292, TH700R4, and 3.73 rear. I won't be pulling a trailer, but I still want enough power to cruise 65mph and run a/c

Jay that is a great formula. It came really close to what my pickup does after I factored in the overdrive. What does 336 represent?

Heavy, You will have no problem running 65 with the AC blasting. At 65 you should be right at 2000 rpm if the 700R4 OD is about 28% like the old BW.

Beater I honestly don't know what the "336" repersents except that it is part of the forumla that does not change. I also know that this assumes no tire growth or slippage ( think top fuel drag slicks when doing a burnout how much the tires slip and grow) and a solidly connected drive train i.e. a stick shift or lockup converter. Every car or truck I have tested works perfect with what the formula says. Non-lock up automatics with a stock converter add ~200 RPM at 60 mph. For first gear speeds just multiply the trans gear ratio with the axle ratio. In my case 2.52 X 2.73= 6.8796. I am told that to run good that number needs to be close to 9.0. That is why I asked what would happen if I put in a th200 trans with it's 2.74 first gear. Would it be worth doing? Jay 6155

It is probably a constant that is part of the formula. Many of them have them as part of their calculation process, and is a shortcut to keep from having to use a bigger formula.

The hidden constant in the calculation is PI - the coefficient 336 comes from the scalars in the formula: miles per hour, revolutions per minute and tire diameter in inches. The number can be backed into with a thought exercise.

Imagine a 1" diameter tire.
There are 5,280 feet per mile or 63,360 inches per mile.
Circumference = PI * diameter
So for a 1" tire we have 3.141592654 inches in circumference (or inches traveled per revolution)

Arithmetic leads us to:
Revs per mile 20,168 (60,360 / Circumference)
Revs per min per mph 336.1352398 (20,168 / 60)

Or 336 inches per minute per mph.

The value can be also derived in the following way.
There are 60 minutes in an hour and 63,360 inches in a mile
60/63,360 = 1/1056th mph.

1056/PI = 336.1352398 inches per minute per mph.

but I find the thought exercise easier to get my head around.

Thanks Stock 49. I have used that formula for 35+ years and never knew what the 336 was for, just that it worked! I just wish there was a way to predict what would happen to my 1/4 time/speed if I put in that turbo 200 or dropped my gear ratio to 3.23. Jay 6155

Stock 49, Thank you for that explanation. It is good to know that something works and so much better to know why.