hotrod Chris Craft Hercules flatty - need advice

General engine tech -- Drag Racing to Circle Track

Moderator: Team

dave brode
Expert
Expert
Posts: 679
Joined: Sun Sep 28, 2008 11:06 am
Location: Frostburg, MD

Re: hotrod Chris Craft Hercules flatty - need advice

Post by dave brode » Sun Jul 14, 2013 1:49 am

PackardV8 wrote:In theory, a flathead boat engine should really love a turbocharger. Plumbing's on the same side, RPM range spread is low, the prop acts like a high-stall converter to allow boost to build and hold,
thus helping overcome the inherent breathing problem and it all happens within the safe operating RPM.
Stupid question of the week. Main bearing spacers are commonly used. Anyone seen them used in a rod? I ask because there are affordable H beams sold for slant sixes. 7.005" long, BEW is ok, but they are for a 2.18785" journal [herc has 1.988"]
Once again with the rods. Just what is it about the Hercules rods that has you wanting to replace them?

jack vines
Jack,

I must admit that my sick mind thought that an adapter to fit a turbo to the manifold outlet would be cake. A drawthrough from a 231 came to mind too. The heat under the box from the turbo would be hateful though. I guess one could water jacket the turbine housing. I'm not learned enough to say how the water in the exh would effect it though. Other silly thoughts included driving a centrifugal or even an oem Eaton driven off of the flywheel. Not sure how the Eatons take to fuel though. blowing through the Zenith might be a challenge.

I'm not hellbent on replacing the rods, really. Just thinking out loud. I admit to being less than nuts on the pinch bolt wrist pin end, not to mention the split skirts. I cringed when the owner said it would wing up past 4K in neutral. Am I over paranoid?

Thanks.

Dave

Keith Morganstein
Guru
Guru
Posts: 5308
Joined: Sun Feb 19, 2006 10:19 am
Location: MA

Re: hotrod Chris Craft Hercules flatty - need advice

Post by Keith Morganstein » Sun Jul 14, 2013 5:56 am

Automotive Machining, cylinder head rebuilding, engine building. Old school shop, semi-retired moonlighter. Can't seem to quit #-o

Dan Timberlake
Guru
Guru
Posts: 1377
Joined: Tue Jan 15, 2013 8:10 pm

Re: hotrod Chris Craft Hercules flatty - need advice

Post by Dan Timberlake » Sun Jul 14, 2013 11:51 am

Not saying that supercharging is not the best way to get more power/speed, but that Winnepesaukee supercharged boat article mentioned the project was financed in part by the Prince of Siam. My personal bucket of mixed emeralds, diamonds and rubies is running pretty low these days.

If you have the "wrong" prop then switching to the "right" prop is worth several mph.
http://img.photobucket.com/albums/v682/ ... iser_3.jpg
The above curve is for a boat that starts to plane above 20 mph or so.
I have no idea if you boat planes or not.

These curves show the different drag (related to power requirements) of basic hull types.
http://www.tadroberts.ca/pics/resistancecurve.jpg

Keith Morganstein
Guru
Guru
Posts: 5308
Joined: Sun Feb 19, 2006 10:19 am
Location: MA

Re: hotrod Chris Craft Hercules flatty - need advice

Post by Keith Morganstein » Sun Jul 14, 2013 2:39 pm

It is a planing hull. IDK the HP required to plane, but prob not that much. These were the high class speedy runabouts of yesteryear.

I agree with Dan, the wheel needs to be sized/adjusted so that you can make rated HP RPM. With a supercharger, you wouldn't have increase RPM, just add some wheel.

If they could do it in the late 1940's/early 50's, it shouldn't be a problem today.
Fortunately in these times, you don't have to be the Prince of Siam to afford a supercharger either.
Automotive Machining, cylinder head rebuilding, engine building. Old school shop, semi-retired moonlighter. Can't seem to quit #-o

dave brode
Expert
Expert
Posts: 679
Joined: Sun Sep 28, 2008 11:06 am
Location: Frostburg, MD

Re: hotrod Chris Craft Hercules flatty - need advice

Post by dave brode » Sun Jul 14, 2013 8:54 pm

Gents,

I can't argue about the prop, except perhaps 3200 is about as good as it got with the boats with the 237"? It's as it was delivered, and perhaps they spec'd it for skiing. It will pull an adult up pretty well. I was surprised that it was a spunky as it is. I'll study what was offered.

Thanks for the supercharged engine pic. That's an M [the middle engine family, as big as 339", iirc], but I'd still love to see the other side. A 4-71 would suit a 4000 rpm 237" well, would it not?

Thanks again.

Dave

Tuner
Guru
Guru
Posts: 2115
Joined: Sun Apr 01, 2007 5:26 am

Re: hotrod Chris Craft Hercules flatty - need advice

Post by Tuner » Sun Jul 14, 2013 9:09 pm

I think a ‘screw-charger’ like this one Innovate makes for Subaru and similar engines. Isn’t there one such on a Ford?

http://www.innovatemotorsports.com/prod ... er-frs.php

Image

dave brode
Expert
Expert
Posts: 679
Joined: Sun Sep 28, 2008 11:06 am
Location: Frostburg, MD

Re: hotrod Chris Craft Hercules flatty - need advice

Post by dave brode » Sun Jul 14, 2013 9:20 pm

Eaton blowers are used on a pile of vehicles, but from what I've read, they don't take well to fuel [dry only]

http://victorylibrary.com/supercharger/ ... a.htm#data

I've seen more than one drawing air/fuel, but who knows if what Eaton claims is true: [bearing seals and rotor coating suffers]

Here's a thread showing one on a flatthead of some sort, and one on a slant;

http://www.jalopyjournal.com/forum/show ... hp?t=66333

PackardV8
Guru
Guru
Posts: 5408
Joined: Sun Jul 30, 2006 2:03 pm

Re: hotrod Chris Craft Hercules flatty - need advice

Post by PackardV8 » Sun Jul 14, 2013 11:34 pm

Magnusson sells a model for street rods with a pad for a top mounted Holley, so evidently running fuel through them is no problem.

Image

jack vines
Jack Vines
Studebaker-Packard V8 Limited
Obsolete Engineering

crazyman
Expert
Expert
Posts: 976
Joined: Sat Oct 27, 2007 4:53 am
Location: Yorkville, Illinois (60 miles SW of Chicago)

Re: hotrod Chris Craft Hercules flatty - need advice

Post by crazyman » Mon Jul 15, 2013 2:20 am

dave brode wrote:but who knows if what Eaton claims is true
Does any manufacturer say that using their product in an unintentioned manner is approvable? If you would have told the guys that designed the 265 that there would be 1000+HP 434's, they would have laughed.

dave brode
Expert
Expert
Posts: 679
Joined: Sun Sep 28, 2008 11:06 am
Location: Frostburg, MD

Re: hotrod Chris Craft Hercules flatty - need advice

Post by dave brode » Tue Jul 16, 2013 12:03 am

Understood. I'll look into the Eaton stuff. I need to get to the boat [hour away] and do some measuring.

And degree the cam, cc it all etc.

Thanks all.

Dave

dave brode
Expert
Expert
Posts: 679
Joined: Sun Sep 28, 2008 11:06 am
Location: Frostburg, MD

Re: hotrod Chris Craft Hercules flatty - need advice

Post by dave brode » Tue Jul 16, 2013 8:51 pm

Fwiw, here is a pic of one of the KFL dual carb lumps. Cast iron Zeniths. Not the boat I have worked on. it's pretty, and still has the single carb'd KLC.
You do not have the required permissions to view the files attached to this post.

dave brode
Expert
Expert
Posts: 679
Joined: Sun Sep 28, 2008 11:06 am
Location: Frostburg, MD

Re: hotrod Chris Craft Hercules flatty - now cam spec

Post by dave brode » Mon Feb 24, 2014 5:42 pm

Hello Gents,

Finally got to fooling with it. Looked like a decent old engine until water damage occurs. Someone has been in it, std bore, .020" rods, don't know what the mains are, crank still in.

I put a wheel on the cam, these numbers are reading right off of the tappets [no lash]. Duration at tappet rise of .020", .050", .100" and .200".

Intake = 258, 237, 212, 165*
Exhaust = 254, 235, 211, 164*

LSA is 112*, intake/Exh C/Ls 117/107. Lift at TDC overlap is .058"int / .080" exh. Max valve lift is .353/.349". Again, these numbers are with no lash. Factory lash setting are .010"/.014".

It could loose a little from the base circle before the tappets would drop down into the block too far. Anyone think that there is much to gain from a regrind? I'm surprised that it has this much cam. I kinda expected a tighter LSA too, as peak horse is rated at 3800. Then again, I know squat about flatheads.

Thanks for any advice.

Dave
p.s. - valve springs look like rev kit springs!

p.p.s. - I'll take pictures of the chambers and post tomorrow.

dave brode
Expert
Expert
Posts: 679
Joined: Sun Sep 28, 2008 11:06 am
Location: Frostburg, MD

Re: hotrod Chris Craft Hercules flatty - need advice

Post by dave brode » Tue Feb 25, 2014 4:30 pm

The ports have some sharp edges on the short turns, but they don't look too bad to me. Siamesed intakes, but they look fairly nice. It appears like there are seat inserts in the exh, but I could be wrong. I'll clean it up and get a better look.

Anyone want to comment on the chambers? I need to search for more info on flathead air flow. Area above the intake valve, etc. I didn't think much air went over the valve, but I was wrong there. I'll post chamber and port pics in next post. The heads shown are two different [of three that I know of] casting numbers. I haven't cc'd them, but I see no difference. The "O" mark is ad a dip in the chamber, the depth at the int/exh valves looks to be same. The .450" and .800" numbers are from the gasket surface.

Should I sink the valve seats to allow for a top cut? Stock valves are 1.645"/1.45" or so. I was looking at using modern s/s valves. Tulip is a no-no, correct? I want a flat valve?

Dave
Last edited by dave brode on Tue Feb 25, 2014 4:45 pm, edited 1 time in total.

dave brode
Expert
Expert
Posts: 679
Joined: Sun Sep 28, 2008 11:06 am
Location: Frostburg, MD

Re: hotrod Chris Craft Hercules flatty - need advice

Post by dave brode » Tue Feb 25, 2014 4:44 pm

I should have washed it first, it really isn't as nasty as the pics make it look.

Attempt to cut a trough above the intake valve into the chamber, like the heads here?:

http://www.beautyofspeed.com/gallery/he ... _index.htm
You do not have the required permissions to view the files attached to this post.

dave brode
Expert
Expert
Posts: 679
Joined: Sun Sep 28, 2008 11:06 am
Location: Frostburg, MD

Re: hotrod Chris Craft Hercules flatty - need advice

Post by dave brode » Wed May 30, 2018 8:54 pm

Hello All,

After almost 5 years, I finally got the ok to work on it [belongs to my employer]. I'm posting to ask for valve spring recommendations.

The stock springs, probably from 1957, have 21# seat, 41# open! I found springs from a 1.6 Honda that I think will work well. Sealed Power has stock Honda replacements, Crower has what looks like a nicer spring for the Honda about the same money. Both are 212 lb/inch. They are less than .900" diameter and pretty tall, there are not many choices.

The cam was reground [using the correct master] by CamCraft. The tappets were also reground and are 1.200" diameter. With lash set at .010"/.012", seat timing is 265/263. At .050" rise [no lash allowance] duration is 234/236. Lift is .353 less lash. Depending on what retainer and lock I use, I can get anywhere from 50-80# seat and 120-150# open. The combo that I'd like to use would give apx 70/142#, but I will vary from that if I should.

I look forward to any advice. I'll post with other info on the "build" [did I say that? LOL]
Thanks.
Dave

Post Reply