My 1989 Regal 25 has a 454. As I mentioned in another post, I had the q-jet rebuilt a few weeks ago when we were in Lake Havasu City. The carb guy was talking and mentioned we had a tall block. What is this?

Our chassis is a 1985 but the original owner told us the engine was replaced in 1992 or so. They had nothing but trouble with it since it was new. GM got tired of working out the problems so they put a new engine in. I have all kinds of docs from Barth and GM regarding the original owners getting an extended warranty on the chassis since it was out of warranty before the chassis ever got built up.

Where would I find the engine number on this block? I'd like to know what year engine we have for future reference. If I remember correct, a number starting with CE is a crate engine.

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had a tall block. What is this?

A Tall Block is essentially a complete engine minus the accessory items like alternator, A/C,starter, etc.

A short block is usually just the bottom end of the engine, missing the head, manifolds, and the like.

It is always a good idea to get a detailed description of what's included as the terms are used very loosely.

Truck engine, four bolt main bearings, raised deck

Sorry, I think I confused Tall Block with Long Block

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A Tall Block is essentially a complete engine minus the accessory

Are you confusing long block with tall block?

Another question, when motorhome manufacturers buy a chassis, is the engine included with the chassis? If so, then my Barth would have originally had an 1985 engine.

I was told the mid to late 80's 454s had lots of problems. That might be why my engine was replaced if there is any truth to this.

Bones,

I'm quite sure the chassis is delivered complete with entire drive line. My 97 Monarch is built on a 95 Spartan chassis. I believe RV companies often bought packages of chassis based on their forecasts and projections. They probably had left-over inventory in the form of raw chassis at the end of the year. I have some documentation that bears this out, flyers with "specials" from Barth.

I'll bet my Monarch was built for the original owner as a deal on this left-over chassis. Since my Barth's first owner was in California, it could have been a Cal emissions chassis that sped delivery time up. I recall being in the motorcycle business when any dealer in the country could order Cal emissions, but Ca and Nv dealers could only order Ca emissions.

It was a very interesting time to say the least. Eventually, there were so many states requiring Cal emissions, that the manufacturers made only that version.

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Originally posted by Bones:
Another question, when motorhome manufacturers buy a chassis, is the engine included with the chassis?

Yes, for gassers. .

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I was told the mid to late 80's 454s had lots of problems.

I have had a number of 454s and 502s in different vehicles, including three MHs and several trucks, cars and boats.

The weaknesses I have noted are all minor:

1. Starter solenoid does not work well when hot. This was addressed by factory upgrades, and can be further mitigated by heat shielding and avoiding heat soak.

2. The Q jet fitted to all GM V8s can leak at a float chamber bottom plug. Any good carb guy can fix that.

3. The small fuel filter on the inlet of the carb gets neglected, and the threads can gall. There are repair kits make for that.

4. The small fuel filter on the inlet of the carb gets neglected, and is designed to by-pass by pushing against the spring if clogged. This allows crud in your carb. I use two springs instead of one to prevent the bypassing. I would rather have my engine balk and stumble than dump crud into the carb.

5. The short hose from the water pump to the intake manifold is often neglected because it is hard to change. I use a steel reinforced marine hose.

6. As previously mentioned, the right rear of the engine suffers from poor air flow. This is addressed by a right side air flow director/splash shield on later models. In addition, I use silicon spiral wires and a Nomex and foil boot over the plug boot. There are cable sets with ceramic boots that look pretty good, but no experience here. Accel 9000C, for example.

7. In motor homes, the oil cooler lines are too small and failure-prone. Look at the cooler end of one of the lines and observe the reduced diameter. I believe everyone should have an oil temp gauge just to keep track.

8. The right exhaust manifold can crack or break its bolts. This is addressed by a factory bulletin.

9. Many RVs did not come with a trans cooler. This can result in the trans dumping a lot of heat into the radiator, and the engine is blamed for running hot.

10. Fan clutches can fail, and many folks replace it with a non-GM clutch. Big mistake.

11. Some run hot because they have had second-rate water pumps installed, with stamped steel impellers. The impeller needs to be cast. It can be either cast iron or cast aluminum, but a centrifugal impeller cannot be properly shaped out of sheet metal. I use a high flow water pump on mine. Starts with M. Milodon or Moroso, I can't remember.

You will notice that many of these faults are not particular Big Block Chevy faults, but GM or the MH builder's faults. And, all can be rectified by a competent mechanic or amateur owner.

That's all I can think of right now.

The next time you hear an opinion on how bad those 454s were, question the guy specifically on these issues, and you will see if he really knows what he is talking about. A similar case is Jaguars. I have also owned a number of Jags, and have heard all the stories, but very little specific, accurate information. Having bought all of them used, and done all my own work, I am very aware of the weaknesses of both Chevs and Jags, and find that most naysayers are repeating apocraphal information that gets less accurate and more colorful with each telling.

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Originally posted by Bones:
The carb guy was talking and mentioned we had a tall block. What is this?

The tall block was a big block (366, 396, 402, 427, 454, 502 or 572) designed for truck, marine and hot rod heavy-duty service. The original idea was to allow room for longer (ringed) piston skirts to clear the crankshaft counterweights. The block became popular with HP engine builders because of its strength as well as its room for a longer stroke.

The main external difference is that the engine and intake manifold are a little wider and the distributor is longer. The engine is a little taller. All of this is the result of the cylinder head surface of the block being just under half an inch farther from the crankshaft centerline. The hose between the water pump and intake manifold is a little longer, which makes it MUCH easier to change. It is common to use a regular intake manifold on a tall block engine by using spacers where it meets the head on each side. This is about the only obvious tip-off.

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Where would I find the engine number on this block?

This makes it appear that it might be on the top of the engine, near the back of the driver side cylinder head.
http://www.oltrucks.com/catalog/images/Big_block.jpg

If you find a number, this might help decipher it: http://www.roadsters.com/bbc/#blocks

Matt

Wow, some great info there, thanks.

I already replaced my fan clutch with a non-GM part. Something I'll have to keep an eye on. I'm aware of several of the problems mentioned. Many motorhomes have heat issues and it's easy to see why.

At this point with the recored rad, my heat problems seem to be over. I'll know for sure in July when we head to west Texas.

Again thanks for the helpful replies. Bones

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As previously mentioned, the right rear of the engine suffers from poor air flow. This is addressed by a right side air flow director/splash shield on later models. In addition, I use silicon spiral wires and a Nomex and foil boot over the plug boot. There are cable sets with ceramic boots that look pretty good, but no experience here. Accel 9000C, for example.

Bill, Do you use a straight boot or angled boot plug wires? Do you prefer a specific brand of silicon spiral wires?
Thanks, Ed

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Originally posted by Ed Chevalier:

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As previously mentioned, the right rear of the engine suffers from poor air flow. This is addressed by a right side air flow director/splash shield on later models. In addition, I use silicon spiral wires and a Nomex and foil boot over the plug boot. There are cable sets with ceramic boots that look pretty good, but no experience here. Accel 9000C, for example.

Bill, Do you use a straight boot or angled boot plug wires?

I use straight boots because the Thermo Tec heat sleeving I like fits over them easily.

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Do you prefer a specific brand of silicon spiral wires?

It's hard to say, anymore. With all the outsourcing going on, what I liked a few years ago is likely from a different source today. I can say that the Accel Spiro Pro 8mm silicone wires that I started out with are still good. But they have had heat sleeves since day one, too.

If I were buying tomorrow, I would probably get the Taylor 409 with straight nipples and use Thermo Tec sleeving. Their Extreme Service is the 409 with their own heat sleeving. But their sleeving does not have the reflective layer of aluminum that Thermo Tec fiber glass/aluminum sleeve offers. We found in aircraft that you need both insulation and reflection to get the best heat protection. Of course, a heavy duty foil wrap over the Extreme Service leads would be pretty good, too. The right rear one needs the most attention. I use a Taylor knitted sleeve with my own foil wrap. The foil gets replaced every couple of years, as our humid salt air gets to it.

Despite the heat tolerance of ceramic nipples, it also conducts heat, so the wire inside still gets hot. So I don't know if they would really be worth the price. I guess it would depend on exactly where the heat failure occurred, right at the nipple or a little farther up the wire.

We use header wrap on our big block Cobras and secure them with stainless steel safety wire. Even with the engine on a dyno you can wrap your hand around the header pipe without burning. As extra precaution we sometimes use manifold blankets and then the entire engine compartment only reaches water temperature (185 deg.). The installation is a custom fit but lasts for at least ten years. You can then use standard performance wires and plugs. Not cheap but heat is your enemy and your coolant load is greatly reduced.

Since we're on the subject of heat, does anyone have any experience with Jet-Hot?

Jet-Hot