Inliners International Forums General Discussion Engines Mild 235 build

I need some tips on a mild 235 build for my 56 210. This is a powerglide car and I'm leaving the rear end gears alone, 3.55's. I run 225/75/15 which are about 28" tall.

What I am interested in is this collective's opinion on what things to improve on an otherwise stock 235 for more performance and reliability.

This car is a sunny weather cruiser and I'm interested in any thoughts. I like the vintage speed parts look and am considering the following setup.

1. Dual carbs
2. Fentons and Smitty's
3. Heated intake - I live in Houston - how important will this be?
4. Electronic ignition

I will keep the manual brakes and steering. I do not plan on adding A/C. I like the 'glide and gearing it has now.

My guess is, based upon my research, that half a point more compression and a short duration cam barely hotter than stock is what I want for this combo.

However, which cam is best and how much compression is enough? What pistons should I use?

I don't plan on a bunch of head work other than some mild pocket porting and cleaning up of the exhaust ports.

I don't want a Bonneville car or Top Sportman contender, just something vintage looking and a bit more interesting than stock.

I've located a decent core so as not to trash my original running motor. The tranny is fresh from a rebuild. The front end was just completely rebuilt and I've got Praise Dyno Brake's entire setup including shoes, wheel cylinders and trick kit on all four corners. I also added KYB's all the way around too. Basically, I took care of all the things that make the car safe and driveable. Now I want to have some fun.

Get as technical as you want. The more detailed the better. Thanks in advance for all your help.

Everyone else tells me to junk the six and stick small block in it, but I'm not interested in the easy way out.

This will be my first engine build. After 30 years of reading just about everything I can get my hands on about engines I'm finally going to out the magazines and books down and pick up wrenchs.

Dear Zeke;

Well dual carbs & exhaust will work okay.

You won't need an ignition change as your 12V already in a warm climate with a low RPM application. You can do without the manifold heat too because of this.

A +.125 overbore will give you 252 CID & a Howard F-290 cam from Patrick's should do it nicely for a low cost.

Check with Phillip (520) 836-1117 there for all the details/prices.

Good luck.

What kind of power can be made with a 235? You mentioned a cam swap? Do you need to go to the dual or triple carb set up to get added power? What would be the most cost effective mods?

I did almost exactly what Zeke asks about. I have a 56 Chevy 210 sedan. 235, patricks mild cam, dual exhaust, and I put his early dual point distributor in it. I have 3.36 gears, a TH350 trans and 235/75/15's. I had the head ported exactly as you suggested Zeke. I like it with the exception that the TH 350 trans has strangled the car in 1st gear - but it is a ton better than stock. Once it gets going it is fine, but right off the line it is a dog. I would do this combo again. I would consider an overdrive tho for better gears. I'll never have a bent 8 engine. I would keep the manifold heat though. this is a good combo for a driver. Give Patrick a call - he helped me. Dual carbs, dual exhaust, mild cam, good trans/rear combo and this is hard to beat and its FUN

Gentlemen;

You will need the extra manifold heat in colder climates. An HEI ignition will help there (freezing weather) too.

A 252" (235 engine) with the F-290, headwork, dual carbs & exhaust will be around 200HP.

Don't run them over 5000 RPM unless you ballance everything.

Good luck.

The only .125 over pistons on Patrick's site are forged. Is there a cast alternative? What compression will I end up with?

Does anyone know the specs on the 290 cam?

6inarow,
Do you have your kickdown cable hooked up?

Zeke,
I believe it's F-298 and no, you don't want to use it in a "mild" 235 with a stock automatic. It will want to idle around 800 rpms which would require an increase in stall speed to operate properly. Run the M4F or even a stock 261 cam instead. You should stay below 260 degrees gross duration when using a stock automatic. I believe Tom Langdon offers a split pattern camshaft that would work well also.

As for pistons, etc... I'm in the camp that tends to just bore it enough to make it "new" again. Considering the costs of 235 pistons that are bigger than .060", you need to ask yourself just how much am I going to gain by going much farther than that. I would like to see some performance numbers from somebody that can justify the extra cost of going from .060" to .125".
My last 235 was bored .060" over and it was pretty close to being too big for the head gasket. If you do go bigger, you may need to get a 261 head gasket.
Having the block decked to level with the top of your new pistons, combined with milling an "848" head, will help alot with how well it runs and responds and will give you the most compression you can get without popup pistons.
HEI is always a good idea as it will alow you to run a hotter spark for a more complete burn, wider plug gap, less/easier maintinence, longer plug life, etc...
I have run both balanced and unbalbanced engines, and I will never do a full rebuild on another engine without getting it balanced. It is soooo much smoother all the way through the rpms and it doesn't cost that much more to have done.

But that's just my opinion...

Dear Zeke;

You have the piston MFG make the compression you want based on the size of your heads combustion chamber/bore size etc. Stock is about 40cc with the "848" a little smaller & you will need to measure this.

Ten to 1 is about all you need go with the forged pistons and 252" displacement.

The M-4F/261(grind) cams are great for the pre- 1955 engines which were 85 Hp. but won't do much for the later (55-62) ones which is why you need the F-290.

"Stall speeds" are of no concern here as the SBC V-8 engines idle at 8-900 RPM+/- from the factory using the Powerglide transmission.

Ballancing this engine is a good idea as Bryan points out.

Good luck.

hey gearhead, no I do not have my kickdown cable hooked up yet. its one of the million little things to do yet.
Zeke, I agree the f298 cam is probably pretty aggressive for a mild 235

6inarow,
You may find that it will work better with it hooked up. At least I did on my '66 Chevelle.

Zeke,
I run the F298 in a 1960 261 with an 848 head, and I wouldn't recommend it be used with an automatic unless you "loosen up" the converter. Find out who all the local streetrodders take there trannies to, and talk to them about your proposed setup. They should tell you the same thing. The 200-4R would work out much better because of its shorter first gear and with the overdrive it will allow you more flexability with rearend gear selection. Basically you get a good launch and still cruise down the interstate.

The '56 has a in drive idle speed of 425. You would need to nearly double that with this camshaft, which means the engine would be racing when in park. I have been around a few overcammed automatics before, and it is not a fun driving experience.

Thats 600 in drive, not 800. I doubt that the converters in question are going to be identical. Apples and oranges...

Gearhead, how did the kickdown cable help the trans in your chevelle? I just havent made the connection etc to the throttle linkage yet. What gives?

Dear Zeke;

The engine will be 800 RPM in neutral same as park & not 'racing', just 800. This may be above what the 'stock' 235 was, but well within (600 in drive) limits used by the V-8s.

Now; there may a difference in converters but It's all academic until you try yours on the road. It may "creep" a little, but It's the price you pay for the added horsepower to go on the freeway.

Happy trails.

6inarow,
stock 307 2bbl with a TH350 rebuilt with a shift kit and 3.08 rearend. I ran it without the kickdown cable for quite awhile, and It was a little "doggy" especially when trying to pass or use anything past half throttle. I decided to hook up the cable again, and it became much more responsive and I could even chirp second gear because now it could downshift when needed. I supose you could downshift manually, but I prefer not to do it that way. Hooking up the cable is a bit more idiot proof. Try it and find out for yourself. If you have another vehicle with a TH350, try disconnecting the cable and see what its like compared to having it hooked up.

John,
With this cam, It will need to be at 800 in drive, which means around 1000 in park, which will sound like its "racing". It will probably experience "run on" when trying to shut it off in park when hot. Having to shut it off in drive is annoying and gets old fast.

Its really not that difficult to talk to an experienced tranny shop about it. If they say to go ahead and try it, then go ahead. Otherwise its just a simple matter of loosening up the converter a few hundred rpms to get you to a point where it will behave in a civilized manner and be more enjoyable to drive.

Gentlemen;

Patrick's sells 3 camshafts ground by Howard.

These are: M-4f for the early 216/235 engines. F-290 for the 55-62 235/261 engines (street use)and the F-298 for Hot Rod/racing application(s) etc.

Valve settings determine the idle characteristics on the later models.

Please call the # I posted if you have further questions on this topic.

The years aren't relative to cam selection as the head design and displacements are virtually the same.

Valve settings are important for all engines and the settings to use come with the camshaft.

If the Idle Is higher then what you had for a Stock cam YOU Will need a Losser Stall speed. And as to adjusting the Valves Do what the NEW CAM CARD Calls FOR. If this is a Mech. Esp. a Hyd cam will still remain at Zero Lash. If the Stall speed is to LOW and NOT what it should be for a certain Cams ProFile It will do one of two things It's either going to Stall the Motor OR It will sit there and Jerk The dog out of it Because It's going to want to PUSH the car Just Like doing a Brake tork.

None of this is relevant as the F-290 idles at 700+/- in neutral/park and 500+/- in drive, with the valves set properly.

This will all work just fine with a 1956 (stock)Powerglide if everything else is 'right' in it.

I think were getting "off trac" here again gentlemen.

I do not have one of those motor Nor have i ever Running that is. Nor do i know much about that cam. Just nearly Stating facts about most Cams IF KEY WORD (IF) anything Other then stock One should follow The cam Cards Spects

I understand.

This guy's building a 50s 'street machine' using 60s style parts, is all.

Different in "your world" with 7,000 RPM (250/292") +/- engines for todays Drag Strip etc.

Happy trails.