The Stovebolt Site Forums The Shop Area Engine Shop Rebuilding 62' 235 for performance

Here's an open invitation to add your $.02 to the next step in my frame-up resto of my 52'. It has a 62' 235 that runs fine, but would like to rebuild it with 2 things in mind: performance AND dependability. Now having said that; what would you do to build this motor right? Interior and exterior.
There are 4 things that will probably happen on the exterior. Dual intake,pair of Rochester or Carter single barreled carbs, dual exhaust; possibly Patrick's SS dual exhaust system. . Not sure what ignition system though. What kind of ponies are doable in a performance rebuild? My rear end will have 3.55:1. The tranny is a 3-speed Muncie.
Thanks ahead of time

In So Cal, I'd give Beck's Machine and Tool a call. These guys are in Santa Maria, CA, have been building Chevy sixes for a long time. 1 805 925-7411. http://www.inliners.org/becks

848 head, ported and shaved. Trick is to check the valve clearance on each cylinder to determine how much to remove without having to sink the valves. Full race cam. For carbs, avoid the rochesters. If you really want some performance, go with dual Holley-Weber progressive 2 bbls. Ignition makes a huge difference. Best that I've seen is the Mallory Uni-Lite distributor with a MSD-6 spark box. The spark box spreads out the ignition over a longer time, which really smooths out the idle.

With this ignition, you will need more power. My friend's 60 amp alternator doesn't keep up when he really stomps on his 261. I would go with an 80 or 100 amp.

What is a 848 head? Where do I find one? I have a 235 from a 55 Chevy that I also will be rebuilding soon to replace my 216 in my 1951 Chevy 3100. The engine had a cast iron powerglide which I will not be using, but I understand that means I probably have hydraulic lifters which is fine with me.

An 848 head refers to the last three casting numbers found on the head just above the intake. There were various different heads made for the 235. The 848 head had a more desirable combustion chamber design, was made of a better alloy that is less prone to cracking and creates higher compression in they cylinders and thus more HP. It may also have had better valves from the factory but since you'll have new valves and valve seats installed to run unleaded gas, the factory valves might not be so important.

Here's my thoughts on building a 235/261:

1. Valves and seats to run unleaded gas.
2. High tension springs for a higher lift cam to avoid binding etc
3. 848 high compression head milled UP TO 100 to get higher compression (check valve clearance or recess the exhaust valves)
4. Deck the block for more compression (valve clearance is still an issue)
5. 4 BBL carb and 4bbl intake manifold or 2 2bbls and a dual carb manifold.
6. HEI ignition
7. Dual Exhaust with hedders or split cast manifold.
8. Drill the block for full pressure oil filtration and install a modern spin on oil filter using a remote filter mount.
9. 3/4 cam (Cliffords, Langdons, Howard's from Patrick...)
10. Drill the front bearing cap to install the two lower timing cover bolts from the outside so as not to have to pull the pan to change the timing gears or cam.
11. Drill and tap the crank and pulley to remove and replace easier.
12. PCV valve from draft tube to intake manifold
13. 4 core or aluminum radiator with fan shroud and auxiliary electric fan to keep that beast cool.
14. Chrome rings, they don't seat as quickly but stand up to overheating better.
15. Really overbore the engine (90 +) and then use v-8 pistons, see Langdon's Cadillac set up.
16. Balance pistons and connecting rods
17. Balance the crank (though may not be really necessary on an inline six depending on who you talk to)
18. Got money to burn? Fuel Injection
19. Wanna go fast, think about the transmission/rear differential, brakes, steering and suspension carefully.

Rattletrap 52,
I built a hot rod 235 in 1963. Here was my recipe; Bored .030 over, McGurk domed aluminum pistons. Offy 3 carb manifold with ?? BXVD carbs. Isky medium race cam with chilled iron lifters, tubular pushrods, inner/outer valve springs, cool red anodized aluminum spring retainers. Cloyes aluminum timing gears. Mallory dual point distributor. Lightned flywheel. Fenton headers. I ported the head myself with carbide burrs. The engine was balanced.

This was in a '54 Chevy hardtop which I ran at the dragstrip in F-gas class. The upshot of this tirade is that the main bearings would fail after about a year. I got pretty good at changing them. I was told this was because these engines had a skimpy lower end...too few main bearing and small ones at that. The bearing failures were blamed on the forces created by the high compression pistons. I don't know if this was true but I know I spent many hours staring up at the oily bottom end of this stovebolt.

There is a great book called "how to hotrod the Chevy 6"..out of print but available.
There is also the in-print book on how to hotrod
the 261 engine. The latter is hard core. To end this novel, research your parts availability, watch your pocketbook and above all, have fun!

Stuart.

Fred,
I've got the 848 head. What kind of compression ratio should be desired? Will a full race cam place additional stress on the bearings? Or will I give up too much by using a 3/4 as NM51 suggested?
As far as ignition, I like the suggestion for the Mallory with the feature of a smoothing things out. As far as the alternator, I would very much like to replace my existing alternator with a rewired generator for 12 volt(the look). Can 80-100 amps be acheived in a rebuilt generator?
And where is a good place to go for the Holley-Weber progressive 2 BBLS?
NM51,
Wow! Sounds like you've been here before. Maybe daily. OK. Quite a list.
Would you agree with Fred on the Mallory ignition? How bout the 3/4 cam vs. the full race?
Would you say that a new replacement radiator would not be adaquate?
Overboring the engine 90+ is three times what I've been hearing. Will this add any unstability?
Don't really care if I go fast, but if I need to get on it, I'd like to have something behind my foot. I'm keeping the original trans (Muncie 3-speed) but rebuilt and the rear is getting the 3.55:1 from Patrick's. And the brakes will remain stock but all new or rebuilt.
I like the look of the dual intake and will take you up on the 2 bbl carbs.
Thanks for the comments. I'm really looking for the 'personal' experiences as opposed to a reference manual.

Rattletrap 52-

It sounds like Fred has more experience with this than I do!

I can't tell you much about Mallory v. HEI ignition. I chose to go with HEI 'cause there aren't any points to be adjusting, it puts out a very high voltage spark and because HEI was something that come as a production option on later model chevy 6's so you can pull the HEI set up from the boneyard and modify the distributor a little to work, or you can buy one somebody converted for you and then in the next 20 plus years be able to find replacement/maintenance parts at your local parts house rather then having to buy them from an aftermarket speciality builder. Don't get me wrong, malloy makes great stuff that I've used on other cars, I'm just building this truck for a differnt purpose. So, I guess what you should do is decide what you want in terms of cost, availability and performance.

With regards to the radiator, I'd go with at least the four core one and if you are planning on getting radical with the engine the aluminum one might be worth the money to insure that your investment in the engine is protected from overheating and damaging something important, like bearings, rings, valves, gaskets...

Overboring the engine 90+ is more than what I would do, though people like Tom Langdon have said that it works pretty well. The reason I didn't do it, after considering it long and hard, is that the more modern engine blocks are manufactured to more exacting specifications so you can rely on the cylinder walls uniformity in size. The casting on these older engines was not as precise, so you might get five cylinders that can take an overboring of that amount and one where the cylinder wall would be too thin. So, instead of spending lots of time measuring it, etc... I just went 30 over. I also chose to sleeve one cylinder rather than take it 60 over. If you are really tied to this engine and looking to build it radically or its already so worn that you don't have a choice, the major boring approach might be worth looking into and talking to Langdon and others about. While you are at it, what about stroking the engine?

3/4 or full race cam? A full race cam requires a lot more carburation, head work, etc... I went with 3/4 because I'm not building a car to race, I'm building it to drive every day that has some power and gets decent gas milage. For me a 3/4 cam was a good compromise for those things. Thats also the reason I went with the t-5 overdrive tranny, so that when I'm on the freeway at 75 I'm not redlining the engine. You might have that covered with the highway gears in the rear differential and the 3-spd, though I'm not sure.

As far as dual carbs goes, that's what I'm running. I've recently read some posts here by someone who tried all the different carb combinations on their engine and discovered they all get about the same gas milage and a single 4 bbl on a clifford's intake peforms better and is more reliable. I went with dual carbs for the sexy look, and I'm not ashamed to admit it!

Anyhow... I guess the answer to your questions all come back to the same thing: What are you trying to build, a race car, a weekend cruiser, a show car/restoration or a daily driver? Once you decide that you can figure out how to build the engine.

Just read a thread on timing that linked to an article on setting points which had this to say about the difference between HEI and points:

MYTHS:

There are many myths surrounding dual point ignitions, here is a list of the most popular.

Dual Point ignitions are better than electronic? Absolutely false. In many cases a point ignition "may" be more reliable if your electrical system on your vehicle keeps killing electronic ignition modules, but points are definitely not better than electronic. Electronic triggers offer better coil saturation, better RPM, no need for adjustments, and smoother running at all RPM levels.

http://www.centuryperformance.com/point_settings.asp

NM51 in your list of suggestions above I like #10 which is something I should do. Dropping the pan is the reason I've delayed changing that front pulley seal. Appreciate more info, here or via email. Thanks.

NM51,
I'll heve to wait until measurements can be taken of the existing bore. Who knows what has been done to it in the 40 years before me.
Are there any considerations in the relationship between a HEI and a rewired 12V generator?
Weber only has one progressive carb 32/36 for my application. Any comments? They do not have a dual linkage for the pair, but have a generic which they say can be tweeked to work???
Oh, this will be a daily driver. Just want some omph when needed or desired!

olblu49-

There are two bolts that go from inside the oilpan through the front bearing cap into the front plate/motor mount the timing cover mounts to. To get the front plate or front bearing cap off you'll have to pull these two bolts. The holes in the front bearing cap the bolts go through can be threaded so that when you put everything back together you can the front plate/motor mount from the outside.

Rattletrap 52-

HEI will require 12 volt.
Here is an auction for an HEI distibutor you could easily modify with a file or 4" angle grinder (appx. $20 at harbor freight or $30-$40 at Home Depot).
Auction Number 8003298443

http://cgi.ebay.com/ebaymotors/NOS-...690QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

I'm using Carter-Webber progressive two barrel carbs on my offenhauser dual intake manifold. I got them from Tom Langdon's Stovebolt Motor Company for a decent price. If you search the threads here on Carbs you'll find the car they originally came out of and might be able to find them cheaper. Langdon also sold me the linkage, which works nicely.

If you are considering dual exhaust, which is reccomendable if you are going with a 3/4 cam and dual carbs, think about Fenton cast manifolds versus tube hedders. Tube hedders rust internally a lot quicker where the cast dual manifolds will outlive you and I. If you go with Fentons Patrick Dykes of Patrick's Antique Auto is in the process of producing the Fenton Dual Intake Manifolds, which nobody has made for a long time. They bolt right up with the Fentons as opposed to when you use Offenhauser you've got to grind both the mount tabs and the tubes on the Fentons to get them both to bolt up to the engine.

NM51 - thanks. I have pulled the cover off after dropping the pan (which can create more leakage problems) and have removed the bolts from the front cap. Always thought the holes in that cap would be threaded but now realize that the threaded part is that reinforced section of the timing gear cover at the bottom. Thanks.

Stuart

In your post on 9/27, you mentioned a book called "how to hotrod the Chevy 6". I have looked and looked but can't find that one, either in print or out of print. I did find and order one from Amazon.com called "Chevrolet Inline Six-Cylinder Power Manual". It should be here on Oct. 11. Is this the book your were referring to?

I have started looking for a head to start use on the 235 block that I have.

Thruwurkin

Thruwurkin,
No, that is not the book. I purchased that one, and although it's interesting, it is not relevant to the 235. It is too specific to the 250 engines and real hardcore race focused. I had the other book as a teenager, and used it as a blueprint to build my 235. I went through my old books several years ago, and my wife said "toss that old thing", you will never use it again...WRONG! It did disappear, although I can't believe I dumped it.

I searched for a copy online and actually found one. I don't know where I found it, but I will search again and let you know. Lots of the stuff in the book is neat. Some of the items used for hopping up these engines are not available anymore, and others have been replaced with newer technology. If for no other reason than to look back into hotrod time, this is a great book to have.


Stuart.

Thruwurkin,
As usual, I had the name wrong..try this!


http://www.themotorbookstore.com/hopup.html
http://www.themotorbookstore.com/cabichgmcbus.html

Stuart.

Okie Doke...I just ordered "California Bill's Chevrolet, GMC & Buick Speed Manual 1954 Edition"

My Son is a High School Senior this year and will be joining the Military at graduation time. I would like to have this engine built before he goes.

Thanks for the help

Thruwurkin

Hmmm.

Repro Fenton Dual Intakes from Patrick's. Glad to hear that somebody is reproducing them.

NM 51,

Did Patrick say when they will be available? Put me on the waiting list. No more Offy/Fenton grind...fit...grind...fit...grind...fit problems.

Spoke with Patrick's son. Those Fenton's won't be out for a while. If you're like me, I want to turn the key within the next several weeks, so will purchase the Offy's and grind off the interference.

Grinding the Fentons wasn't a big deal, it was just time consuming. As Jon Arnett said:

Grind, fit, grind, fit THEN PAINT.

I had to grind the Offys on the bottom to get the Fentons to clear and then had to grind the mount tabs on the Fenton's to get them to the same level as the Offy's so I could use the mount bolts/hold downs. I also had to grind 'into' the Fentons to get the hold downs to fit. If I hadn't they would have been at an angle and might not have held down the manifolds too well! Fortunately there's lots of 'meat' on the Fentons to grind into when you need to.

Also, without thinking I painted the fenton's before grinding them... No big deal to repaint 'em though!

I actually got a real sense of satisfaction from making the Fentons and Offy work together! However, the time and dust in my garage were a pain.

As far as heating the Offy goes, I got some 'tees' from Napa to put into the 'Thermostat to Heater outlet' and 'Waterpump return from heater' and ran solid brakeline using inverted flare fittings and 4 brass 90 fittings. Turned out real nice and no worries about melting the waterline against the header/exhaust. Exhaust gas might have been easier but I wanted to keep the exhaust closed and reduce the possibility of CO2 leaks.