502 to replace knackered 454 engine

[abridges01]

G'day folks.

Although I appreciate my engine replacement saga has gone on way longer than can really be considered respectable, I feel I am moving toward ending the sorry saga at last.

I had a good chat with my local engine rebuilding guru last week, and during discussions I mentioned I was tempted by having him rebuild my busted 454, but was also seriously contemplating investing in the HT 502 (see example here). Turns out he reckons to build an engine suitable for mounting in Ethyl would not save me any money. He says the biggest problem we 'classic owners' face is the build up of heat in the engine compartment as there is no easy way to duct the heat off.

The HT 502 is purpose built for towing and high torque applications, such as inside an RV, and would, obviously not the excellent GM warranty. So, to cut a long story (if not a long saga) short, this is the route I plan on taking.

My questions to you, esteemed 'Streamers are as follows:
1. What carburetor will I need?
2. Which inlet manifold?
3. Will the standard engine mounts be OK?
4. Will I need change the bellhousing?
5. Do I need change water pump?
6. What's the best source for a HT 502 - I live in Southern California?
7. Any other changes required?
8. Is this enough questions for one posting ;-)?

I plan on switching to a dual electric cooling fan setup (see here)to make sure this beaut does not over heat, and will also switch over to electric fuel pumps - anything to try and reduce the 'drag' on the engine. Any other suggestions I should consider while spending the kids college funds?

Cheers,

Andrew

[RUSSELL]

Hi Andrew,
With the price of 502 I would rebuild the old 454. It is a work horse and it is proven out by being in the service for many years. Do the following.
1. replace water pump with a new one no rebuids.
2.Put decent headers on.
3.Electric fuel pump O.K.
4.Put oil cooler on the engine as well as on the transmission.
5. Install a new fan cluch on your engine or two electric fans.
Your unit probaly has a 4 barrel cvarb. Have it rebuild. This way you save on intake manifold as we as on the exhaust manifolds.
Your trany schoukd be a 400 s speed with straight cut gears for better take of in 1 gear.Good trany.
Regards from Russell in sunny Tucson Az.
P.S. How is your trany?

[elolson]

If you are hard over on the 502 then Scoggin-Dickey has the some of the best prices for GM crate motors. I have bought heads from them and other parts and have always found them to be first rate.

Frankly, I'd go with the 454 you had in it. A good rebuild will be the cheapest route and the power difference is marginal on a good torquey 454 rebuild. It's all in the cam.

Scoggin Dickey at Sdpc2000: Performance Parts, Racing Engines, Racing Engine Parts, Race Engines, Race Engine Parts - SDPC for scoggin-dickey.

[guy99]

Originally Posted by elolson

... It's all in the cam.

Is there a trade-off between power and other desirables and fuel economy?

[Poprivet]

When my time comes, hopefully far in the future, I plan to get a factory rebuild from Nappa or the likes there of. At the same time I will exchange the tranny, carburetor, alternator. and starter. A radiator rebuild and a good set of headers to finish the job right.

When installing your new engine, pay careful attention to the routing of the plug wires. Heat is the enemy!!!

[klattu]

You are right on about heat removal.
Look at the later AS MH, they have a pair of vents to let some heat out.
See it just above wheel opening...


You could add something like that, or one from a Trans Am or Z28.
A spoiler directly below radiator base, angled slightly forward at bottom, will create a vacuum behind it, drawing more air thru radiator.
It would also prevent air flow from bypassing and slipping underneath.
It must be below base of radiator, not on front bumper, or anything with a air gap between it and radiator.
You will be pleasantly surprised at how well air flow works.

[JimGolden]

How about a 496? That is the modern replacement for the 454. Same basic block but enlarged. Look for a wrecked pickup truck. I'd score the engine, the transmission, the computer and EFI system. Just buy the whole thing.

That'd get you a modern engine with electronic fuel injection that would run better than any carb. Get yourself a new aluminum radiator and call it good. Maybe cut some louvers into the fenders as they showed above.

It's at least worth looking at.

[abridges01]

Thanks guys.

Given the difficulty I've had in removing the damaged 454, I am really anxious not to repeat this procedure, so would rather spend the extra cash and get a new/remanufactured engine that will, hopefully with a little TLC, last us many years. The 496 is a possibility, as is a 502 or Jasper's 'purpose built' RV 454 engine.

Having looked under my mattress and confirmed a total lack of a large pile of cash, any purchase will not happen quickly, so in the meantime I am having the three-speed (Hydromatic?) rebuilt, have had the radiator recored and assorted other coolers pressure tested. I will also see about rebuilding the front suspension and steering, rewire the front coach electrics and recore the water heater. All this in the (vain? I hope not) hope of making Ethyl run reliably and smoothly for many years to come... am I niave or what?!

Then there's my assorted electrical woes to sort out as well. Thank goodness I realize this is a longterm hobby and not an instant vacation.

Happy Memorial Day everyone.

Cheers,

Andrew

[GlenCoombe]

Andrew, good to see you back at it.... even if you're not progressing at a rapid rate.

Tranny rebuild: Low RPM lockup torque converter!! Tow and go is the terminology I've seen and heard. Did you ever find out the rear end ratio?

Engine.... how many miles are on the present mill? If the block is sound I'd strip it down and bore it out. Look for deals. Use new parts for all accessories. Start hanging out with the motor heads, they're always buying stuff they don't need and selling off later cheap.

Engine mounts are easy to do and cheap when the motor is out and a real bi%c^ to do later so the choice is yours.

I like the electric fans idea. New core or new rad if you can find a good buy.

You've got time on your side....if not money so hunt for the deals. Those deals will steer your project.

How's the interior coming along?

[ranchmink]

Hi,
I have been looling at upgrading my 79 Excella 454 to something more power. I have found out the following:

1. Torque is more important that horsepower. I am installing a set of Thourley "Y" headers that should add about 30 HP in the low end for torque. These run about $600 ceramic coated to keep heat out of the engine compartment. If you are interested I can tell you my source for buying the headers, but make sure you get ceramic coated to keep heat out. My exhaust geru tells me he gets more torque from both 2 1/2" pipes going into a single exhaust, drivers, side than the dual that I have currently. This did suprise me. I will let you know next week after I get it put on.
2. I have seen you can get more low end torque by adding a Eldebrock intake, cam and right carb to get about 35 more HP in the low end. I am strongly considering this, but you have to add the cam as well as intake to get the full benefit. If you rebuild you can make this change and install a system. Elderbrock has this on thier web site.
3. Beware of 454/502 hot rod engines. I have installed a few of them and they do generate more heat as they run at 200 to 220 all the time compared to running 180 with the old 454's. Make sure you get a truck engine not a car or hot rod engine, different animal. You want your horsepower in the range of 1800 to 3200 RPM for the motorhome, at least that what mine tells me expecially with the Gearvendor overdrive unit. I may install the intake after the exhaust and see what impact it has. What is good is the headers and intake would work on a new engine as well as a rebuilt.
4. My motorhome does not have a snorkle for air cleaner fresh air. I have been told that I can a few more horsepower by running a snorkle tube to grab fresh air for the intake. I will keep you posted.

[Goin camping]

Hey Ranchmink, You joining us at the CalStreamers summer Rally? Its around the corner from you up near Gorman.

Check out the "California Streamers Summer Rally" thread on upcoming rallies page.

Hope to see you there.

[bobkelly]

A great source for GM Crate engines is gmpartsdirect.com. New everything and 50 more cubic inches is 50 more lb-ft of torque compared to the 454.

[Silvertwinkie]

I know it's more costly, but have you considered putting a diesel in it instead of another gasser? Reason I say this is that you seem to want to hang onto this long enough to not want to do it again (at least for some time). A gasser, though powerful enough, mostly gets about 200k on the high end before needing an overhaul...in most cases, even sooner than 200k, whereas a diesel, 100k is really just breaking it in, plus the slight mileage increases, etc.

The 502 is a great engine, but it too has it's share of issues. Piston slap was an issue, as is oil consumption. If you didn't think diesel would be a good option for you, then I might lean toward a rebuilt 454, but if it were me, I'd have bitten the bullet and taken on the drivetrain upgrade to diesel. They can fit, there was a factory 280 turbo diesel out there.

[Taxman]

abridges01,

Whatever route you take with the engine, start looking for and purchase a Gear Vendors overdrive unit. I installed one in my 1990 Land Yacht (three speed Turbo, same tranny as yours), and at 60 MPH, the RPM decreased FRom 3,000 to 2,400. Engine is quieter, runs cooler and 2,400 RPM seems to be its "sweet spot."

You just may be able to get a quality rebuilt 454 and a Gear Vendors for the same price as that high dollar 502. I guarantee you'll like the Gear Vendors!

PM me if you have any questions.

FReegards,

FRank

[JimGolden]

How about a World Products Merlin 632

She'll make 800hp and 600+ ft-lbs of torque. They'll call you The Silver Bullet!

[ranchmink]

Hello,
I have ordered a HT502 today for replacement of my 454 in my 79 Excella. The engine is about $5400 and has the following:
1. 480 lb-ft torque at 1750 rpm
2. 512 lb-ft torque at 2800 rpm
3. 338 HP at 4500 rpm
I will have to replace my carburator, intake and add an electric fuel pump. I am excited to see and feel the gain in hill climbing expecially with the Thourley "Y" headers, Eldebrock intake and fresh air intake for the air cleaner. We should have it back together in about 30 days or so. I will take photos as it progresses. I agree in the above thread about getting hot air out of the engine box area. I will figure this out and make sure it works. I like the twin fans above because when you need cooling the most you are going the slowest and the fan robs HP. The elec fans will pull air all the time or we set it up on a thermostate it can be tied to water temperature with ac override switch.

[str8strm]

Where are you getting the 502? that sounds like a good price

[ranchmink]

Hello,
I have purchased numerous crate motors from Motor City GMC dealership in Bakersfield. You should be able to get most anywhere for around $5400. If have any issues tell them you are a jobber and want jobber pricing. I will keep the forum posted with my progress. I hope to have it installed starting in about a week. It has to come form Michigan. This is not a dealer stock item. They indicated it takes about 5 working days to get out west. I will have to add an electric fuel pump. I had the exhaust done today for the "Y" headers and fitted.
Ranchmink

[remcolent]

for good coolers take a look @ MuscleMotorSports
I have a large aluminium radiator and oil cooler from them for a fraction of the cost new.

[ranchmink]

Update:
I took delivery of the HT502 today and took my 79 Excella to my mechanic who will get started. I had previously installed a gear vendor over drive but still need more power for big hills and towing a trailer. I will post some photos as the project starts.
This weekend I mounted a large trans cooler up front, passenger side behind the grille. I hope this plus a cool tube trans pan should keep the temperature of the fluid below 200 degrees except for short loads. I ordered a elderbrock #3761 intake manifold today that should help give more torque also. This does have the egr connection for California smog requirements.