Total 308 overhaul. What would you do?

gearheart

I have just completed removal and tear-down of a 308 twin H. This car has sat for 25 years and it turns out it popped a head gasket and sat with water in the cylinders and oil pan. The bore is .030 over currently with Jahns Pistons. I am looking for a good running street driver. (I also know there are potentially thousands of combos, just looking to avoid some pitfalls) So do you have a recipe for standard Hudson machine work/rebuild?

The main bearings look in good shape, the cam shows a bit of wear on the lobes, the pistons look decent but the motor has sat for so long the rings have quite a bit of rust. I probably would have run it as is except I found some pretty ugly rust grooves in the cylinder. A mechanic friend says they "might" come out at .060 but he was not sure if that would effect the running temp significantly.

So I am all in for machine work at this point. What all would you have done or checked? If .060 causes too much heat, I am probably going to sleeve 3 or maybe all 6 cylinders. Align bore on the mains and cam shaft? Do 7x valves help driveability on the street or just at WOT? What is the 7x relief? What else? How much undersize on the crank is allowable?

Current plan includes the twin roller timing chain, Clifford cam and possibly full pressure oil system (if available) but just looking to get the machine work going now.

Thanks for helping a new guy.

Mike

 

 

DavidC

I recommend you follow the KISS principle.
First thing get block cleaned and checked for cracks- useless to do more until this is done.
Sounds like you need to clean up the cylinders- go as little as possible, make sure the machinist has the strongest, sharpest cylinder bore machine, as these blocks are tough. No problem going to 040 or 060 over on the 308.
Have block decked- as little as possible
Have head planed- just to level, and check head thickness- want 2 inches
Have crankshaft ground- polished.
Align boring is considered unnecessary in the 308- and can be royally screwed up by the machinist
Got to decide whether to put in hardened valve seats- the debate on whether the 308 benefits from this rages on. I did it on mine as I plan on driving thousands of highway miles, and don't want to need lead substitute every tank full. I did exhaust only. Took a lot more shimming to get spring pressures correct, so expect extra work.
Based upon the bore and crankshaft grind, you have all the numbers you need to know to get a proper rebuild kit from Dale Cooper. Bearings, gaskets, pistons, rings, valves
Double roller from R Maas will go in easy
I doubt there is much benefit to enlarging head bolts to 1/2 in- and the machinist can royally screw this up as well- ask me how I know...
No cams, 7X, etc will improve driveability, can only detract. Plenty of power without it. So I would leave well enough alone. Mild cam is well tolerated. But if you want to build a racing engine, Mr. Maas and others can show you the way.
Chamfer all sharp edges on block and head to avoid future cracking. Enlarge and smooth oil drain holes, especially the one that drains the timing cover- helps get oil back to pan.
Unless you have all the necessary tools to check clearances/tolerances/end plays before reassembly, you are better off leaving this to the machinist as well. As are con rod bearing install.
Full pressure oil system? You already got it. If you are referring to 100% filtering, it would have to be carefully designed. If you drop oil pressure for sake of filtering, that engine is done. Try not to re-engineer too much. Enjoy the old straight six for what it is.
There are many other rebuild issues to discuss, but these were the major lessons I learned last year.
Hudsonly,
Dave

EssexAdv

My 54 is .080 over with no heating problem,  When I spoke to Jack Clifford (Hudson Motor Guru) he said they could be bored to .125 but that was the max.  He also said, don't go over .80. so I didn't Motor has been run all over the place for more than 20 years and 50K miles. 

The downside.  It is a bit noisier than a standard bore motor... I'm not talking exhaust, I'm talking motor noise

But then again, it could be the 56 mechanical cam I put in it... I hate that thing.

Ol racer

Mike

Ive bored my Hornet Blocks .125 in the past without heat problems, However, these days.090 is the Max you should bore and 030 on the crank...Be sure to discard those pistons & bearings. Hudson's usually dont need Line Bored.Replace the Cam, Brgs, & Chain.... 2" Intake valves alone adds more power from Idle up... Relieving out to the gasket edges and matching Intake Ports to the gasket, Mill the top of the block & head slightly for more compression and power... Use a BEST  Head Gasket and suggest pitch the head bolts for Studs..Headers adds a lot more power too.
Local Machine Shops can do all that work but some take forever maybe because their unfamilar with flatheads. Best Bet is talk with Randy or Steve Maas about a stock or slightly modified motor all assembled to just drop in your chassis .

Glowplug

Experience is talking in the previous posts... there is more of the same at my website.   Use this URL

http://www.hudsonrestoration1948-54.com/  to gain access.  Click on the OK button in the NOTE BOX that first appears.  After the front page loads ... find the word ENGINE on the left side of the page... click it and you will be taken to a page full of information about Hudson engines.   

Personal experience... I have yet to have a 51-56 Hudson engine run hot due to actions taken during rebuild.  Aside from following the good advice given..I add that the cooling system on the engine MUST be in TOP shape.  rotten water distribution tubes or poorly preforming water pump/plugged radiator will ruin that engine quick!

Good luck and keep us posted on your journey to getting your Hornet purring.

RL Chilton

Can't add much to the above, all the very best advice from loads of experience.  Only thing I would add, after the quote above from David:

"Got to decide whether to put in hardened valve seats- the debate on whether the 308 benefits from this rages on. I did it on mine as I plan on driving thousands of highway miles, and don't want to need lead substitute every tank full. I did exhaust only."

I agree, do the exhaust valves.  Yes, it's true, the Hudson block does not need it. However, it's one of those things that can't possibly hurt and very possibly might be of help, so why not do it while the engine is torn down and you are already there.  A little expense for a lot of peace of mind.   

48Sed

Russell

Does it depend on how many times the valve seat was ground and how good a job was done the last to determine if a new seat is required?

Jay_G

My only comment is, if you are building a performance motor don't forget about changing the electrical to 12 volts.  I did the cam, bored over 0.060, and a new head (Clifford), and I get one revolution to start the car when it is warm.  After that it has to cool down and then it starts fine.  The 6V system does not have the poop necessary when you get crazy with a few upgrades and the engine is tight.

Jay

Chris Smith

I did not go with hard valve seats when building my engine as the blocks are said to be of high nickel content already. Big valves will work if you include tube headers. Think about going half inch head bolts while its at the machine shop. for sure deck the block and head. Nothing wrong with cutting a larger that 7x sized relief especially on pre 54 blocks, the better breathing more than makes up for the loss of compression.

53jetman

The engine in my '54 coupe with a 1954 block was bored .060 over and 2" intake and  1-3/4" exhaust valves installed with no heat problems.  Runs just under 160^ on long trips, even in the mountains.  Regularly gives 20 to 22 mpg on trips.l

Kdancy

Jerry,which tranny and rear are you running?

LHudson

All the things mentioned are very good advice. One thing I really like is the hardened exhaust valve seats. One reason is the unleaded gas and also it helps prevent the cracks that may appear in exhaust seats. If one has small cracks in exhaust seats ,  the cracks can be cut out to put the seats in. One other thing I have become a great believer in, is the balancing of the rotating assembly. To me it makes everything run so smoothly.  It will also make the engine last longer.  My 2 cents.  L Hud

53jetman

Kerry  -  Hydramatic with a 2.62 rear end.  This higher speed rear does not seem to bother the 308 (318 as bored).  If anything, it seems to put the torque curve in better perspective for a car the size of the Hornet Coupe.

Lee ODell

Jerry

Where did you get the 2.62 rear end? I like the possibility of getting 20-22 MPG. What MPG around town.

Lee O'Dell

gearheart

I am blown away with all this great info. A BIG thanks to all. I now have alot more to consider.

I forgot to mention that the block already has 1/2 in headbolts but thinking about going with studs. Is the 7X block relief I hear about the same as "port matching" between the intake and block or something else?

Old Farmer, there is a treasure trove of goodness in that link!

I will update as soon as I have one

Mike

TwinH

Steve Maas has been sharing a pictorial 308 build on the Hudson Essex Terraplane Club facebook page.As far as I know it is not spoken for yet and will be available for purchase when he's finished. So there is a "plug and play" option out there too.

 The old Jahns pistons in my prior 308 had worn out ring lands. Just for grins could you you stick a feeler gauge between the compression ring and piston ring land and tell me how much side clearance your Jahns have?

Ol racer

FYI

With 1/2" bolts you may have a '55 - '56 block, which is an advantage, or someone enlarged them to better hold head gasket...With old Jahns Race pistons someone may have already relieved the block some  in the past,  The motor apparently was hopped up so if unsure how it was used, I would have the crank magnfluxed..

BillUSN1

In my thread here.

http://openforum.hetclub.org/discussion/165555/project-creep-valve-guides-valve-job-etc#latest

I show the port matching on the manifolds.

I asked Steve Maas about the relief cut and he said he used 7* on it.

It's like the old beach boys song, it was ported and relieved and stroked and bored.

That little deuce coupe......

The relieved is removing block material between the valves and the cylinder to increase the flow.

gearheart

Bill, I read your thread with interest recently and plan on speaking with you soon about some twin FI (but first things first) I also have a 72 Scout so I am familiar with your work!

Twin H, as good as buying a completely done-up motor sometimes sounds, I am in it to learn on this one. But will still be talking to Steve very soon for a couple goodies and some knowledge. I will try to remember to check out those old pistons and report back.

Ol racer, this block does not match the car VIN (52 Hornet, 4 door, Dual-Range) but checks out as an early 52 anyway. (I was kinda hoping for hydro lifters but no such luck) It has a stock cam, unless it has been reground. I can't tell by looking.

I mis-spoke when I said full pressure oil, I meant Franks Full Flow oil filter system. I checked his website recently but am unclear if these are in production or on the shelf and ready? I would love to break this in knowing it has all clean oil... I might even run a bypass filter with that cause I like to catch even the little chunks!

I hope to get it off to the machinists this week. I certainly have a much better idea of what I need after those great responses.

Mike

Frankvintagefullflowcom

Mike,
Thanks for the correction.
It's true my site needs a major overhaul. Unfortunately, I'm much better at machine work than I am at computer skills, although some may argue otherwise.
I am producing/selling them and have some units on-hand with another casting run in the works. The set-up allows for addition of a by-pass filter as well in the event you wish to put a "polish" on your oil beyond the effectiveness of the typical full flow element.
You are correct that initial start-up and break-in is the most important time to filter oil before it enters the oil gallery.
Frank

DavidC

Very nice discussion.
Let me add, re the replacement of the 7/16 head bolts with 1/2 in bolts/studs, make sure you use a reputable machine shop that uses a drill guide and sets up your block carefully. 21 head bolts, even slightly out of alignment, leads to disaster. Mine were apparently drilled and tapped by hand. They were angulated any where from 1-4 degrees. All 21 had to be replaced with threaded inserts. Wasn't worth it.

53jetman

Lee   -   The 2.62 rear gears were installed by the former owner of the car, Hedley Bennett of London Ontario.  This is more or less the standard procedure when Hedley gets a car I was told.  Like I said above, driven under normal conditions, the engine acts like the rear gears weren't  changed. 

gearheart

1. Does anybody have a photo showing the 7X relief between the valves? Not sure if I want to do it but I would like to see what it is all about.

2. Any good suggestions on how to get the sheetmetal water thingy out of the block? how 'bout a pic or link showing what this thing looks like?

Thanks again

Mike

maasfhcenturylinknet

This is a photo of an ongoing relief on a block we are doing and hope to complete the assembly in next 10 days.  Steve did the relief.  I finished tapping for 1/2 inch bolts today.

Randy

maasfhcenturylinknet

My project for the day.  Reaming and tapping for 1/2 inch bolts.

Randy

DavidC

Gearheart, if you are referring to the brass water distribution tube, there is a tab that can be temporarily bent straight forward, and you can attach a carefully placed vice grip to. Pre-spray penetrating oil and let sit for a while. Pull gently but firmly, and you can remove it without damage. If you pull like a madman you can destroy it, as did my machinist- I had to get a spare. So, take your time.

Randy, above, demonstrates the right way to move up to 1/2 inch bolts

Dave

gearheart

Dropped off the block, crank, main caps, pistons/rods, head and flywheel today. (forgot the balancer) First up, hot tank and magnaflux!

Thank you Randy and Steve, for the generous offer and the photos, I would LOVE to have a pro built motor but I am looking forward to assembling this myself (with the help of a good friend and his giant snap-on chest of toys)

dougson

What year is the block? From '54-56 the valve reliefs were nearly identical to the 7X. '55-56 already have 1/2" head bolts. Be sure to balance the entire assembly (with flywheel/flexplate) as well as the individual connecting rods. Machine the nose of the crank to accept a Chevy fluidampr balancer and install timing mark (after market) and aluminum pulley. Engine will run much smoother.

Smaas1949

FYI...We (21st Century Hudson) sell complete master engine kits (pistons, rings, bearings, lifters, guides...etc.)/Gaskets, and, of course, True Double Roller Timing Chains...All in stock.

Nevada Hudson

Lester Harris has everything in stock too, and he has been in the HET for over 40 years! (775) 267-2559.

Kdancy

Never heard of Lester, might give him a call and see how he is to deal with.