See part one. Copyright © 2006, Allpar, LLC.
Pete Hagenbuch was a Chrysler engine development engineer from 1958 through to 1987. This is from our second interview, of three — the first is posted here. You can read more about Pete here.
I had two questions from readers since the first interview. First, on the slant 6, why was the distributor put all the way down there where it’s so hard to reach?
Because that’s where the cam shaft is.
The second question which I think I also know the answer to was, why did Chrysler go from the hemi head to the wedge head.
That could be answered with a dollar sign. Because Chrysler had a potentially winning engine and for some reason we were too dumb to understand that. So ours was 331 and everyone else’s was up in the high 350s, so we went up to 354 and then everybody went up to 400. In both cases they outperformed the Hemi, because there is no substitute for cubic inches and it doesn’t cost a lot more to build a big displacement engine than it does to build a small displacement engine.
For instance, the small block Chevy started out at 265 and ended up reliable at 350, although the high performance ones were 327, I believe. The Hemi was expensive to build, there was no way we could win the displacement race, we didn’t have the resources to change engines every year, and even if we did it was expensive engine. A 454 Chevy would blow the doors off a 400 cubic inch Hemi in street tune, the way we did them then. That was it, just simple dollars.
You know that the next one was not designed with anything in mind but race. That was probably the nearest thing to a pure race engine that was ever produced by the big three car companies. The thing wasn’t fit to drive on the street and it wasn’t supposed to be. That’s were my group, among others, came in when we worked out the hydraulic cam and lifters which I detailed to you in one of those emails.
Can you describe the conversion of the race Hemi to the Street Hemi?
Not very much, a mild cam shaft, hydraulic lifters, a legal exhaust system for sound which added great gobs of back pressure. I think, but I wouldn’t bet on it, they made some changes in the rocker shafts and the valve rockers to improve oil flow to the valve tips.
I mentioned sometime to you that there was a valve tip wear problem in the race hemi. We finally succeeded in fixing it, but in cold weather warm up operation it, frequent warm up like a passenger car when you go to the store and come for an hour and then go to the dentist, each time the valve tip and the rocker pad run essentially without lubrication until the cold thick oil works its way up, fills the rocker shafts and the end and finally works it way out to the drilled passage in the rocker arm. So that was a big one that was still done by the race group. There was a lot of competition between the groups, especially where the Hemi was concerned. I guess I helped out physically but it was really the race group’s test.
Now the camshaft development was mine but as far as lube was concerned, that wasn’t in my domain. I was way too busy with other projects and the race groups did it themselves. That’s why I say I think they did several things to improve getting oil to the valve tips on warm up because I know it needed it.
We chrome-plated the valve tips and loosened up the keepers, leaving some clearance so that natural rotation would take place — which is not only good for valve tips but essential for the valves themselves, they need to rotate, they cannot sit there dormant.
If you compare our intakes and exhaust valves on any run of the mill engine back then, the exhaust valves had a four bead lock/keeper whereas the intakes just had a one bead — a kind of conical shaped piece that fit inside the valve spring retainer and held the valve. That was very important; they loosened that up and gave it a little clearance because it helped rotation. The problem was so bad, anything you did helped. The problem was the valve stems were only 5/16ths diameter, not 3/8. That’s a big reduction of area on the valve tip.
Was that done because there wasn’t room or to get light weight?
Yes, and to take up less room in the port, giving more room for mixture flow. The bigger the valve stem, the more you reduce mixture flow, the effective valve opening. It also reduced the weight of the valves, increasing the rpm where valve float starts.
The valve tip problem was not a surprise. Everybody was scared to death, mostly about breaking valves down in the radius from the stem to the underside of the valve head and the valves were very lightweight for being huge, 2 ¼ intakes and 1 7/8 for the exhausts, and that never happened.
We examined the 1st and 2nd place engines after the original Daytona triumph, where Petty lapped the field and Jim Pardue was 2nd in another hemi. We tore those engines down and Petty’s looked beautiful, would have gone another 500 miles, and so would Pardue’s except for one thing. He had what we call a rat bite in the exhaust valve, it was a burn through on the OD which had progressed up almost to the stem and why that valve didn’t break none of us could ever figure out but it didn’t. But he couldn’t have been running on eight because it was a big hole.
That started out as a burn, probably started out as a slight flaw in the meeting of the valve and the valve seat, maybe a nick, maybe a flaw in the casting and the exhaust gas starts going through and it’s like a blow torch. Why that engine didn’t fail none of us could ever figure out, but by the time we saw it the burn had gone ¾ of the way around right in the critical fillet area between stem and valve. It looked to me like one more revolution… talk about being lucky!
Speaking of which, another project which has been talked about a lot, there are a couple engines out there the dual overhead cam Hemi. Did you work on that or have any knowledge of that?
We started one back in the 60s while I was still in the valve train group. And before we could even find out if it would run right or not word came down that Bill France was going to cut us off any day now, which of course he did, and you are just pouring money down a bottomless hole, stop!
We stopped and there was no work done on it. I don’t know how long Design spent, but I don’t think we had the engine two weeks.
That was probably a smart decision when you come down to it.
When you look back it was because that was probably the same year that Bill France cut off our water.
He cut off the Ford project as well; they had a 427 overhead cam.
I think Bill France cut that one off. I think he told Ford, “You build it, I won’t let you race it.”
He may have told us that too, but if he did it wasn’t common knowledge maybe it was just common sense.
What would that be doing at Chrysler?
There really was a lot of common sense at Chrysler. It didn’t reach to the highest levels sometimes but yeah, I never agreed with the project. I didn’t like the looks of the design from what little I saw of it. I got to look at it because here’s another guy that knows valve train. I looked it over and saw a few things I didn’t like very well.
They said it was very complicated and expensive.
Well, the two go together, expensive is the key word.
On the far side of expensive we have the LA engines. One of the questions that I have we are looking at the history and we see the A series V-8s and then not very long after those come out we go straight into the LA and then they basically stay there until about 1999 with the 4.7. What made the LA such a good engine series?
Well, I tell you what — if you go to a Chevrolet man about my age ask him what made their small blocks so great, he won’t be able to tell you. It was serendipity, and it was just a perfect design. But if they tried to do it again on a bigger displacement they wouldn’t have hit it. It was just one of those things, everything was right. The port, the valve size the short stroke with big bore, light weight it was, I talked to some GM friends and they’ll admit it [that it was luck] if you back them down a bit.
Sure, we were lucky. It probably would have been a good engine anyway but not like it was. I mean, even considering our Hemi, if you ask me what the most important engine in the 20th century was, I would answer without pause, small block Chevy. It was just a fabulous, fabulous design. Somebody gets a lot of credit but Lady Luck gets a lot more.
They designed it and developed it and it was an excellent engine but Lady Luck made it a fabulous engine. I don’t claim that the 273, 318 eventually the 360, with exception of the 340, they weren't fabulous engines they were ultra reliable, they made commercial power output but they weren't magic and the Chevy was.
You excluded the 340, so what would you say about that?
The 340 it was like the 389, we threw the book at it and most of it worked. But it was still a wedge head, and it wasn’t magical. But it sure did feel good in a Road Runner, I’ll tell you because I had one for a year. I loved that car, 1972 Road Runner.
That car was the nearest thing I have ever driven (that was a normal sized American intermediate) to a sports car. That car with the light engine up front and the big anti-roll bar in the back, you could throw that thing around with the throttle almost. You give it a tweak on the steering and a blip on the throttle and you’re headed in a whole new direction. The thing was fabulous; it was a great, great car. I hated to turn it in.
The 360 came just after the 340, can you tell me anything about that and why the decision was made to switch over?
They wanted to use it in bigger cars. Well, trucks certainly needed it, something better than the 318. But beyond that it would be pure conjecture. It certainly seemed to be the right size because it lasted forever. If I'm not mistaken, it’s still alive and well somewhere and I think it’s somewhere south of the border.
The 340 was dropped at about the time they brought the 360 in.
That was about the same time the high performance 440 was dropped. Between the government and the insurance companies, there was little demand for muscle cars. The 426 Hemi was already dropped. Nobody would buy a car that cost $5000 to insure [at the time, most cars sold for less] and I don’t blame them.
So that’s the main reason you think all those engines were dropped all at once?
Everybody did [drop them], tell me a high performance engine that lived all the way through the 1970s. I don’t know of one.
Now the 318 had a four barrel for a short time. Why do you think that was normally kept as a 2 barrel carburetor in that engine?
Well, the applications that the 318 was used in were not really 4 barrel applications. It was sold to people even older than me who didn’t have need for the 4 barrel, and there was the 360 if you didn’t like the 318. The 383, I'm sure you’re aware, had all kinds of 2 barrel applications but they were all back in the later ’50s and early ’60s when you could buy a 383 2 barrel; either the long-stroke Chrysler version or the short-stroke performance engine.
You told me why they made the two 383s and one thing I have been curious about is why Chrysler, Plymouth and Dodge all had what seemed to all different engines and then even more different ones for Canada.
That was easy. Until the Mound Road engine plant was built, and that came on line in the 1956 model year, each plant, with the exception of Plymouth, built their own engines. They were all different, there were no interchangeable parts, it’s just like Topsy, it’s how it grew. There were DeSoto engines, we didn’t call them Hemis, but we had three different Hemis in the 1950s all at the same time. We had the Chrysler Hemi, I can’t call it a Hemi, we had the Chrysler double rocker, we had the DeSoto double rocker which was a totally different engine. If you look at a transverse cut away of the two I could not tell you which was which but I can tell you that the parts didn’t interchange they had different engine lines, different plants, the whole ball of wax.
Dodge too. Dodge had their little Hemi. What a desirable little engine that was but nobody ever really picked up on. A 4 litre Hemi, a 4 litre Hemi today would pretty much be a world beater for smaller cars. DeSoto started out as FireDome and of course the Chrysler engine was the FirePower 180 when it started. No bean counter in the world could explain to you why it just grew that way.
That was before the Mound Road engine plant, which was new, the first time I saw it was on an SAE tour where Chrysler showed off this beautiful, gorgeous, modern, cutting edge assembly plant. That was the first time I saw it, I was still in the Institute, I didn’t graduate until 1958; by then it had been cranking out engines for two years. The Trenton engine plant came online for the 1958 model year and it built 350s and 360s.
Actually, the original B-engine was called a 360. When the 360 A engine came out the B engine got promoted to the 361. They didn’t change the displacement, but it was used in DeSotos and Chryslers, so it had to be bigger than a 360. Such are the ways.
When you hear the reasons and think it over, it makes a little sense. One cubic inch, and I'm not even sure but that maybe it was rounded down to 360 originally. I'm sure the B engine was bigger than the A engine because they wouldn’t have let that happen the other way; it just couldn’t be done.
Where the B engines completely different from the early hemis and the polys or were they basically the same thing with different heads?
Absolutely, the B engine was an entire new design. I know I have either told you or written you about the weaknesses that showed up in the big double rocker when it went to 392. In fact I think I describe the spectacular explosion that I was not too far away from and got there in time to see some of the parts hit the floor.
Incidentally, we never had a failure in a passenger car 392 and if you think back, the last year of the 392 was also the first year of the B engine, and the only the only place it was used was in the 300 letter series and the Imperial. We were very conservative back then on durability and the fact that failures could happen, if it hadn’t been the last year on the engine there would have been a huge fix program in place; as it was they did a lot of proving ground testing and didn’t find any failures and decided to go with it which I think was one excellent idea, with a lot of hindsight.
It was one of the very few times that I can remember where there was a major flaw that we judged to be limited to severe operation and since there was only a year to go, in fact some of those engines were stockpiled, they took the line out of the Chrysler Jefferson so some of those 392s, especially in 1959, were orphans before they even got in cars.
That brings up a couple of interesting questions — with the 2.2s, did you have any early issues with head gaskets or anything else going on?
I'm inclined to say no but you have to understand that I was in the performance group which by then was almost an entity in itself, we weren't even in the same office area with the rest of the engine development and I just wasn’t that close.
I don’t remember any problems at all on dynamometer power testing. It was another bulletproof design. I think they learned their lesson with the kangaroo and then went back to the bulletproof approach. I tell you if I had a choice of a 100 lb lighter engine or a bulletproof engine I know which one I’d pick.
It says a lot that you were able to get 220 horsepower out of it.
Absolutely, but the 2.5 wasn’t like that, the 2.5 wasn’t bulletproof. Once again, that was an extra inch of stroke. By the way do you know how to recognize a 225 from a 170? There is a very short rubber hose from the front of the cylinder head to the water pump and on the 170 the thing is impossible to replace without removing the head it’s so short. On the 225 you can replace it without removing the cylinder head, it’s an inch longer.
It’s a dead giveaway. That’s just a little thing that we all knew intrinsically, I just wondered if it’s common knowledge. If you got a hose that’s about 2 or 2 ½ inches it’s got to be a 225. If the two nipples, the hose it’s connecting looks like it’s about ½ inch apart it’s a 170.
What was involved in going from the A engines to the LA engines?
You know I don’t really remember any problems, there had to be some but I can’t remember anything serious enough to be worth talking about; even the performance improved by getting rid of the silly polysphere.
A wedged chamber does have some advantages. One of the advantages is that you can build in a lot of what we call squish, where the chamber is just part of the cylinder head surface and the piston has a flat area that matches up with it.
Squish is why you can run 12:1 on a wedge head because without squish you would have to run 9:1. It gets the charge moving and mixed, moving through the chamber at high velocity, which means the flame travel is fast and there isn’t anything left to burn by the time it gets to top dead center where you expect the detonation. Anything that reduces detonation also helps reduce pre-ignitionm which is catastrophic.
Detonation can lead to pre-ignition because of the rise in temperature. If you are in more or less constant detonation, sooner or later you going to hole a piston, its going to become pre-ignition which means it starts burning the minute the intake valve opens which means that the full force of the combustion is working against the piston going up and things get really hot in there, and aluminum melts at around 1200°.
So the wedge would also be good for emissions?
Yes it is, and the Hemi is not. If you look at our Hemi it has squish, a full 360°. That is the feature that a lot of fluff book writers use to jokingly call a semi-Hemi. But I think once they have driven one they don’t call it a semi-Hemi anymore.
Do you mean the current one?
The current Hemi.
The most outstanding thing about the current Hemi is we make money on it. We didn’t make money on the others, they were too expensive.
The foolishness was that here you have this potential super-engine so what do you do with it; you put a two barrel carburetor and a single exhaust on it! And what did you get out of that lovely combustion chamber? Absolutely nothing!
The first good Hemi was in the 1955 300. The engine came out in the 1951 model year, but until the two four-barrel, the one everyone likes to call the C300 which is incorrect, it was just the 300, the letters started with the B, but that thing was a hell of an engine.
GM never copied Chrysler on anything for a long time, I think they just felt it was demeaning, once in a while Ford got a good idea they copied. But it wasn’t long before they had two four-barrels on a couple of engines. They did the same thing with their big modern V-8 and so did Oldsmobile. They came out with a two barrel carburetor and a single exhaust. They also had a wedge head, [but not with] a lot of attention paid to the porting, which was something people didn’t do early.
The Hemi was just a big torquey slug for the first four years, and then the 300 came out. Then it realized its true potential.
I'm sure you know of the fact that Briggs Cunningham raced Hemis at Le Mans for four years in big heavy car with drum brakes. Unfortunately those were the years of the disc brake Jaguars, which beat almost everything. The only race they ever would have lost was the 1955 race against the Mercedes 300SLR, only that was the race where the Mercedes hit a slower car and went into the stands where the magnesium body …. There were 80-some people killed and I think that includes some of the pit crew and the driver of the Austin Healy that got in the way. But the guy that caused the accident never had a problem with it, it was Mike Hawthorne, later to be world champion. He was going into the pits and cut off, I believe the guy’s name was Lance Macklin, who was driving an Austin Healy.
The only reason the D-Jags were so good at Le Mans was because it had such a good surface, because the D-Jags had a solid rear axle just like American sedans, they were not sophisticated except aerodynamically, and they had one hell of a six-cylinder engine. But other than that they were not superior racing sports car design.
On the 2.2, they reportedly switched to a fast burn head in 1986.
Well, yeah, fast burn, that was everything we made. Maybe we did increase the squish area. I honestly can’t remember and that was my area. I was responsible for that but I’ll be damned if I can remember enough to tell you.
I had a turbo III car and replaced my fair share of timing belts. Was there any discussion of switching to a timing chain on the turbos especially the intercooled ones?
No, because it would have to have been a new engine. You can’t run a chain out there where the belt is without lubrication. Perhaps you could cobble up a bolt on front end out of cast aluminum maybe but I don’t think so, I think it would have taken an entire redesign of the whole block and there is no way in the world we were going to do that.
Do you remember switching from mechanical to electronic waste gate actuation?
That was after my time. I'm afraid that’s a little too new for me. I think it’s a great idea because the mechanical ones were reliable but they did screw up occasionally. They were certainly not what we would consider a field problem but it was possible.
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