Thread: Hemi??

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I have a hemi in my 55 dodge royal.I want it to be loud.Is there any thing I could do beside flowmaster exhaust pipes to make it loud.

The Hemi's in the 55's had a real weak bottom end.
First sign of trouble is low oil pressure,before crank lets go.
(Just thought you may like to know)
There are three engines used in the 55 Dodges - the Getaway Six, the Red Ram V8, and the super Red Ram V8. The flathead six displaces 230 cubic inches and is found only in the Coronet six cylinder models. The Red Ram V8 is a polysphere (single rocker shaft) and is used in the Coronet V8 and Royal series as standard equipment. The Super Red Ram V8 displaces 270 cubic inches (like the Red Ram V8) and has hemispherical combustion chambers. This engine has double rocker shafts and old timers call it the "double rocker" instead of the more familiar "Hemi." The Hemi is standard on all Custom Royal series and is optional on all Coronet V8 and Royal series cars. The two V8s share many internal components, and will accept manifolds and other components from the 53 and 54 Dodge Hemi of 241 cubic inch displacement. The six is a flathead and definitely not state-of-the-art for 1955. I have driven both Red Ram and Super Red Ram Dodges and can honestly say that there is a marked difference in performance. The late fifties were a time of inflated horsepower figures, but the 1955 figures were based on engines with accessories and were even a bit conservative. The Super Red Ram could be ordered with the power package (4 barrel, dual exhaust) which puts it way out ahead of the Red Ram in terms of power.

Dang thunder bucket, where were you when I asked about that 331 a while back.

Check here psilentchild, http://www.hothemiheads.com/ It's a pretty good site with some great links. It also has specs for all of those old dodge, chrylser and desoto hemis. There are some good links too.

Derek

In the fiftires Chrysler did have a bad (and deserved) reputation for weak bottom ends, but that was in their flathead 6 motors. The flatheads had a relatively soft crank that would wear rapidly especially when reved hard.

Actually the 55 or any other Hemi all had a pretty good bottom end (steel crank in a nice rigid block). There biggest enemy is the same as any other engine, lack of oil pressure/oil starvation.

Usually when these engines let loose it was either due to:

1. gummed up oil passages (back in those days the oil that was available was non-detergent), and especially on engines that were used around town and never allowed to full reach operating temperature they would tend to form a lot of internal sludge. Additionally the filter system was a by-pass instead opf full poressure and would often recirulate dirty oil past the filter.


2.low oil pressure (usually caused by excessive wear on the internal componets, or tightly wound cold engine). In the early HEMIs, the oil dain back passages are almost too small. If they are would up tight when they are cold especially when there is excessive wear in the rocker shafts the oil will back up in the heads and result in starving the eninge for oil when the sump goes dry.

If you have an original high milage motor in your car I would strongly suggest you take it easy with it or chances are you will likely find out just how expensive they are to rebuilt. Regardless of the milage on the engine, limit the agressive driving until the engine is fully warmed up (common sense for any engine).

The 55 Hemi motors did not like to be ran at speeds in excess of 90 miles per hour for to long,,,,,strange,,,but the 54 hemi's did not have the same problems,,,and i guess the problem was licked by 1957.

".........The Hemi's in the 55's had a real weak bottom end.
First sign of trouble is low oil pressure,before crank lets go....."

".........The 55 Hemi motors did not like to be ran at speeds in excess of 90 miles per hour for to long,,,,,"

I've torn a couple of the old Hemis down with thrown rods (and ruined cranks) it did/does happen. It was never a problem with the design or materials used in the bottom end, but rather the engine had been starved for oil. Run any engine without oil and it goes boom.

Keep in mind the 50's cars usually had relatively low rear end ratios and short 14"/15" tires resultuing in the engines spinning pretty tight especially at high speed. The cars that the Hemis came in were normally top of the line models with automatics and it is unusual (rare) to find a Hemi in front of a 3 spd/OD.

This is a picture of the oil drainback hole on a 55 331 Hemi head (typical of all the early Hemi Heads). There is one hole in each corner of the head. These holes are the ONLY way the oil that makes it way to the heads has to drain back into the oil pan. Normally when these are clean and the rocker shafts don't have excessive wear (the more wear the more oil that flows to the head) they do fine.

Now add several thousand miles of sludge build up in these holes (real common when running non-detergent oil), a little wear in the rocker shafts allowing a fair amount of oil to accumilate in the head (especially with the oil pump spinning at high RPM). Then just for grins say you starterd out 1/2 to a quart low on oil to begin with and chances are at some point all the oil from the pan is going to end up in those big valve covers. What happens?

"....First sign of trouble is low oil pressure,before crank lets go..."

It wasn't a "weak bottom end", but rather one that didn't get any oil. Of course the results are the same

What I would recommend to anyone who is going to test fire or run an old Hemi is to first pull the valve covers and and insure the drain back holes are clear. If your doing a rebuild, plug the bypass valve and go to a full flow filter system with a quality spin on filter. Keep the old HEMIrrhoids happy

Great history lesson but I'm curious as to how the answers he got, relate to his original question, which was how to make it louder. I'm not trying to pick on anyone, but it seemed like everyone went in a different direction. So to answer your question, besides going with no mufflers at all, flowmasters will make it about as loud as you might want it.

In order of loudness (and legality)

Turbo Type mufflers (the larger the core diameter the louder they are, I personally prefer a 2 1/2 in core )

Glasspacks (yeah I know there are more efficient mufflers)

Burned out glasspacks (the straight through type instead if the type with the seperate inlet and oputlet cores)

Straight pipes.

My personal favorites on old hot rods are the burned out glasspacks or straight pipes (full legnth 2"-2 1/4" .pipes) nothing soumds more period correct if you can stand the noise.

If you can find them the old can type Thrust mufflers or smittys aren't bad either.