Inliners International Forums General Discussion Engines Heads & other Q's for a 235ci rebuild

Hi,
I need to build (2) 235ci engines for our daily drivers. I have 3 848 heads with the following numbers:
1. 3836848 E77 , GM14 intake is 1 15/16”.
2. 3836848 12J3, GM3 intake is 1 7/8”.
3. 3836848 C162, GM25 intake is 1 7/8”.

Which would be the best 2 heads, assuming they are not cracked?

What would be a good street grind for a camshaft?

How much can you mill the head, with 0 block deck, and be safe for pump gas and have adequate piston to valve clearance?

Does anyone make aftermarket (upgraded) rod bolts?

Thanks,
Ken

Any of those heads will work fine.

try to keep the gross duration at or below 260 degrees. The Howard M4F or one of Langdons Bulldog cams would be what most people use. What you use for a tranny and rearend gear will be a factory in how well one cam works compared to another. You have to consider the whole package not just one thing...

.060 would be the max to take off a head. Be sure to shim the rocker shaft stands the same amount. Recessing the intake valves may be necessary depending on the amount of lift you are running. Try to keep about .090 daylight between the two.

You will not be able to take enough off of the head or block to build up enough static compression to not be able to run on pump gas.

Nobody makes new rod bolts that I'm aware of, but I believe some people have taken rod bolts from a Ford 351 and made them work. (ARP)

Der Ken;

Brian is correct. However; I would save the one with the larger intakes for future.

You can take off as much as .125, but DON'T. You use pistons to raise comppression & you won't need a lot more for "daily driving". Surfacing the head is for "clean up only" unless #1 & #6 vary a lot in CC volume.

The M4-F cam is only an improvement for the 'early' 216 & 235 CID engines. The 'later' (1955 and newer) have that or better from the factory.

Here again, you need to look at the 'whole thing' as he points out.

Good luck.

The only 235 to use a cam like the M4F was the Corvette. The M4F is actually slightly bigger than the 261 cam, which works well when used in a smaller displacement like the 235.
There are dozens of people out there using this camshaft, mostly in the later 235's, and I can't say I've ever heard anyone complain about it. Ken, I would suggest that you talk to someone who has actually used it and see what they have to say about it.
Generally, as displacement goes down, the engine will run rougher per a given cam spec.

K;

The M4-F cam was made to 'upgrade' the 40s engines in the 50s. By 1955 the 235 engines stock had more horsepower than the (upgraded) 40s ones and the 261 even more.

The 54 Vette cam had different specs, but used Hyd. lifters where the M4-F was/is a solid lifter camshaft. Totally different usage and MFG for that Corvette only (one time).

You don't have to actually 'use' a product to know what it does and doesn't do.

If you want to upgrade a 55 or newer 235 or 261 CID engine you need a F-290 or F-298 unit. These are used for Hot Rods & racing and not really good for "daily driving" etc.

It's just that simple!

Do these intake numbers refer to the valve head diameter?
I only ever heard about standard or the larger ones for engines with powerglide trannys.

I have a NOS 848 head I like to use with a late 261. The head is factory with guides and has never been installed or milled.
I like to tune for street and mostly freeway driving at 2500-3000 rpm average and 3500 max.

How much if any should I mill this head?

Will porting & polishing make a difference for this average rpm?

What kind of pistons and rings shall I shop for?
I heard about forged and cast ones.
...I got this 54 Chilton's motor age magazine with ads presenting the latest chrome rings, but also heard to stay away from them...

This will be my first rebuilt, if you can't tell already...

THE CORVETTE 235 AND THE 261 USE THE SAME SOLID LIFTER CAMSHAFT. IT IS THE LARGEST CAMSHAFT CHEVY USED IN THESE ENGINES PERIOD.
THE M4F IS SLIGHTLY LARGER THAN THAT CAM, SO THAT MAKES IT AN UPGRADE TO ANY OTHER 235 OR 216 BY SIMPLE ARITHMATIC. PUTTING IT INTO A 'VETTE 235 OR A 261 WOULD BE A WASH, BUT NOT IN ANY OF THE OTHER ENGINES. IT WOULD BE LIKE BRINGING THE OTHERS UP TO 'VETTE SPECS, RIGHT?

GOING ANY LARGER THAN 260 DEGREES IN THESE ENGINES WILL REQUIRE ATTENTION TO TRANNY AND REAREND GEARING, AS THESE CAMSHAFTS LOOSE SOME OFF THE LINE TORQUE. ACTUALLY TALKING TO SOMEBODY WHO HAS USED THESE CAMSHAFTS AND WHAT THEY USED FOR GEARING, ETC... AND FINDING OUT HOW WELL IT PERFORMS IS THE ONLY SURE WAY TO GET AN IDEA IF THAT COMBINATION IS RIGHT FOR YOU INSTEAD OF LISTENING TO SOMEONE GUESS ABOUT SOMETHING THEY HAVE NEVER DEALT WITH.

SO, IF BY YOUR OWN ADMISSION THE F-290 AND F-298 ARE TOO BIG FOR THE APPLICATION, THEN WHAT DO YOU SUGGEST? HMMM, LETS SEE... I GUESS THAT LEAVES US WITH THE M4F OR SIMILAR CAMSHAFT PROFILE, DOESN'T IT?

Thanks for the input.

I called Howard's cams and they don't stock the M4-F. In fact, the new owner isn't even sure what the actual specs are for it. He'll grind anything I want, if I spec it out. I'm not a cam expert, so I'll pass on that at this point. Patrick's carries 254* and 264* duration cams with about .440" and .445" lift respectively.

I'll need to keep as much low rpm torque because one engine is going into a '51 coupe with 3.55 rear gears and a stock 3 speed.

Again,
Thanks for the info.

Apparently they have discontinued the M4F?Patricks used to sell them. Or at least they were selling one labeled as such.
If you can get a stock 261 grind, that would be nearly identical.
The 254 sounds like the way to go if you want to keep the torque. Or just reuse the stock camshaft.
I don't know what the specs are for the F290, but I know the F298 is a 268 degree cam. Way too much for what you're trying to build.
Clifford and Tom Langdon also have camshafts available.
Delta cams can grind one also.

RR,
Do you know what you want to run for a cam? Do you have a target compression ratio in mind?
For street use cast pistons and rings are fine.
Bowl porting will help more than the slightly larger valves would.

Thanks for your time and help gearhead and all the knowledgeable advice and info - I love learning.

Good question about the cam.
I know I only ever go 2500-3000rpm and only rarely higher.
I probably go with the next step up from the stock 261 cam and see if Delta can regrind or recommend the right cam for me.

I like to tune for freeway driving and will have a 47 3-speed and 3.55 rear.
I know this works quiet well with my other daily driver, same driveline but with late 235 and stock cam.
The 261 will have more power/torque but the coupe weighs 1000lbs (25%) less than my truck and I like to keep the simple column shift.

I think I like 9-9.5 compression but maybe I should go higher.
The only prior experience I have is my late 235 with lower comp 1955 head, using 87 octane pump gas.
I definetly don't want to use higher than 91 octane.
I have a dual intake and dual exhaust already.

Donny Johanson can still grind a few cams. I'm sure he still has all the masters. The new "Howards" is not the same. If he is not in our Inliners membership list. I can put you in touch with him...Good Luck on your project.JD

The've been discontinued because there of no value for the post 1955 engines and totally obsolete today.

If he's going to "cruise around" under 3,000 RPM, no cam change is required.

An upgrade (for higher speeds) would be the F-290.

I ran a Clifford 264 in a 235 with a 3spd and 3:55 it my truck the first time around. I didn't really like it much overall. I had to slip the clutch a little on takeoff, and the performance was blaaah when going from 2nd into 3rd. I put in a 4:11 and that helped (4:11's can hide alot of sins), but of course, it had no top end anymore. I put the 3:55's back in and got a T5 from an S10. That was the best solution, allthough one with a 3.50 first would be better than the 4.03 like I was using.

If you are set on using a 3spd and 3:55's, you will be better off with the 254* cam or something similar. If you're not going to wind her up much past 3500, then you won't get much out of a larger cam anyway, except for the rumpy sound. If you can't stand the idea of running the stock cam and you just gotta have something different, then the 254, M4F, or stock 261 style cam would be my recommendation. It's real easy to overcam these things. Under 3000 rpms you really don't need to do anything more than that.

Thanks for the insights. I always wondered what would happen if I just upgrade the stock 235 cam slightly.
Like you said earlier - best to always check with somebody who ran the same setup.

I have always stayed below 3500rpm with original tranny and torque tube for the past 11 years and never had any desire to wind up these cast iron 4 main bearing blocks higher.
To me it's about keeping them on the road every day. I really enjoy the non-synchro double-clutch column shifting. Can't imagine driving without it.

With a slight cam upgrade I was hoping for better breathing and a cooler running engine, during long hot desert freeway trips in the summer.
But sounds like I should just stay stock.

What is the stock cam degree and lift with a late 235 and late 261 anyway...?