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Hi guys,
I have a 1949 GMC FC102 with a 228 engine. See attached photos. I purchased this from my brother’s wife several years ago following his passing. He had the original 228 professionally overhauled (new valves, pistons, rings, bearings, etc., and bored .030 over. In addition he had Patrick’s do a cam 264 (3/4)” performance grind. He knew the stovebolt was limited in performance improvements but his goal was to keep the original 228 and as he put it, “make it all it can be”. I have read plenty of articles with Hotrod Lincoln, Justhorsenround, and Carbking and many others on Stovebolt about the mostly cons of multiple carbs and or attempting to boost a stovebolt’s performance.

With all that said, my brother located a 4 barrel intake manifold and a pair of Fenton Headers and installed them and it has been in this configuration since the overhaul, not even a first start or break in run since 2010. I’ve been researching carburetors and need some advise.

1. Should I still pursue a 4 barrel carb? As long as he had gotten this far, my thought is to follow through on a 4 barrel carb and his plan, even if there is little performance improvement. Will it run as good or even better than the stock Zenith carb?

2. I don’t know the brand name of this 4 barrel intake. I can find no markings on it and have no purchase records. He stated in some emails that he got it on ebay from a classic parts store in Texas. Do any of you recognize this intake by chance? Would it be compatible with Fenton Headers and a Holley carb, for example?

3. 2 of the 4 intake holes seam a bit course on the machining about 1/2 way down the barrel. Not horribly so, but obviously not a true, smooth machined bore from top to bottom. May that pose any problems with airflow and gas mixture?

4. Holley’s website requests redline RPM data. Should I report the stock 92hp at 3400 RPM or should I factor in the cam performance grind and the complete overhaul?

5. Would it be wiser to install the stock original intake and carburetor for the break in run, then swap to a 4 barrel?

Sorry for the long post. Thank you all for your input.

Moderator: I moved this thread to the HiPo forum because I felt it would get better responses here.

That looks like a Clifford intake manifold, but every one I've seen has their "6=8" logo on it.

The way the manifolds are currently plumbed there is no provision for carb heat.

I agree that most (all?) 4 barrel carbs would be overkill with this engine, even with the warmed over cam. If you wanted to keep the manifold for looks I'd find a 400cfm Edelbrock or 390cfm Holley 4 barrel and disable the secondaries. Either would fit on this "square" manifold.

That is a patricks copy of a howard intake. You could still use it a put a webber with adapter. A 4 barrle on a 228 would not work well.

I also notice the bolts on the ends of the exhaust manifolds. If it was me, I'd replace them with studs and nuts or there will be lots of cursing later when you have to remove them in situ. I made the mistake of installing the manifold setup with the engine on the stand and later had to take the rear bolt out when it was in the truck. It required much quality time with a bench grinder and a Husky brand 9/16 combo wrench.

Welllll- - - - - -here's the problem- - - - -a 228 engine at 3600 RPM can only flow 238 cubic feet per minute of fuel/air mixture, and that's if it's got 100% volumetric efficiency (impossible). 90% is a more realistic figure- - - -214 CFM. The smallest 4 barrel carb I know of is a Holley racing carb that can move 390 CFM. A new one costs around $850.00 or so. That's over twice as much as the engine will ever need to breathe, even at wide open throttle. That intake and exhaust system would be right at home on a beaned-up GMC 302. They're totally inappropriate for a 228 engine, no matter what camshaft or other modifications it has- - - -it simply can't flow enough air. If you can find the smallest 4 barrel that will fit the manifold and disable the secondary barrels, you'll be somewhere in the ballpark airflow-wise, and you'll still be able to impress the mouth breathers with the hotrod equipment under the hood. The engine will run lousy until the coolant is fully warmed up, because the intake has no way to be heated by the exhaust gases. Good luck!
Jerry

Thank you guys for your input. I certainly value your experience on the subject. I would prefer to stay as much stock as I can on the truck and I’m not really after speed or eye candy. My brother liked to tinker with the speed ideas however 😉.

I did dig out the stock intake and exhaust manifold and Zenith carb today. I separated the 2 as the heat riser is seized up. Got it soaking with PB Blaster. The carb has a crack at one of the attach screw areas above the steel attach to the manifold so I’ll need to locate a replacement fitting for that if I can. Maybe a call to Carbking?

What are your thoughts on the Patrick’s cam 264 (3/4)” performance grind that he had done after his overhaul I mentioned above? Just a bit concerned if thats an aggressive grind or will I be ok with the stock 1 barrel carb and single exhaust? Anyone familiar with Patricks Cam Grinds? When he was in business was his process to send one of his cams ground to your request or did he grind and return yours? Concerned about the quality of that process with this full overhaul engine. Will I need to change my valve clearances? I did not receive any data on that from my brother’s records.

Thanks again. What a wealth of knowledge this site and members are. I love reading the posts and learning about these trucks and engines.

PT

Patrick had a bit of P.T. Barnum in him, I believe. The only way to be sure what you have, camshaft-wise, is to do a degree check, which isn't really all that difficult. All you need is a magnetic base dial indicator or two, a degree wheel, and enough common sense to follow the instructions published by the people who make racing camshafts. In very general terms, any cam with an "advertised duration" of over 280 degrees or so belongs on a race track, not the street. That's about where other engine mods like increased compression and improved cylinder head breathing, plus modified carburetion and exhaust becomes necessary to take advantage of the cam's "improvement". That's also where low end torque starts heading for Never-Never Land- - - -never to be seen again.

Ignore the "duration at .050" lobe lift" specification- - - - -it's a fantasy dreamed up by cam grinders to hide sloppy quality control concerning uniformity between cam lobes for a bunch of cylinders that are supposed to be the same near the base circle. A properly ground cam will begin and end the lift off the base at exactly the same point, no matter which cylinder you choose to measure. The first few thousandths of lift are where the "clearance ramp" is- - - -which also just happens to be the valve lash setting. For instance, if the first 16 thousandths of lift happens very gradually, then the lift rate increases dramatically, that's where that lobe needs to have its clearance set with the engine fully warmed up, to account for pushrod and valve stem stretch due to heat. My general rule of thumb is to set the "cold" clearance .002" wider than the published setting on a cam card. It's remarkably accurate, regardless of who has ground a specific cam. Have fun- - - -that's what hotrodding is all about!
Jerry

If all he wants to do is ID the cam to see it it's too hot for his otherwise stock engine then the 0.050 figure would be fine, I think.

I'm running a 220* at 0.050 and it's a bit to long for my current setup, which is 9:1 static compression. I want it to pull well at 2500 and it pulls at 2850. The advertised duration is 252* In. and Exh. A 264* cam is going to be a bit hotter all other things being equal. So it'll pull closer to 3,000 RPM. That duration should have at least 9:1, preferably higher and a stock 228 is nowhere near that. I'd hunt up the stock cam to go with the stock Zenith 228. With a fresh overhaul it'll be a sweet ride.

Put the what what in the what what?

If it isn't in the shop manual, I don't do it. (because I don't know how to do it)

Otto, the Cliff's Notes version of my above comments can be expressed like this: "The biggest mistakes most amateur engine builders make are too much cam and too much carburetor. Doing race engine stuff on a street driven engine is stupidity squared!"
Jerry

Good morning. I agree with you Jerry. I would prefer keeping all stock because thats a proven winner for decades on this truck. I’m not after speed, but I’m really torn here with this engine because of the cam he installed during overhaul and leaving the intake/exhaust and carb all stock.

I spoke with a longtime cam grinder in CA and he felt that I should leave the 264 3/4 cam installed. He felt on these old Jimmy’s, that this grind is ok and in his opinion really needed for these small engines. He also stated this grind is really more mild on these engines vs newer technology (of course he is a well known speed cam grinder for all kinds of engines).

I’m a bit concerned about pulling the cam to have it reground to stock if its really not necessary. I would hate to cause any harm to this overhauled engine (that has not yet been run). But if it needs to be done to make it right, I will.

What are your thoughts on this cam with the stock intake/exhaust and carb? Will I lose power with this non-stock cam installed with a stock fuel system?

Thanks for listening and all the advice. This truck has special meaning to me and I want to ensure it’s right for family generations to come.

PTCT49

Use the stock intake and exhaust manifold and Zenith carb. It is easy to install and may run fine with the cam that is in it. You would be further ahead and you may be pleasantly surprised how will it does run.

Most people have no clue what a "3/4 grind" really means. Back in the dark ages (1930s and 40s) virtually nobody used duration and lift specifications to identify non-stock camshafts. They were called "1/4 race", 1/2 race, 3/4 race, or "full race" cams. The 1/4 and 1/2 designations went away, as they didn't offer a noticeable power gain over original equipment cams. "3/4" race cams stayed in production for people who wanted a lumpy idle and the ability to brag "I've got a 3/4 cam"! I always asked what the one fourth of the cylinders that didn't have a camshaft were there for? 264 degrees should be OK, as long as the lift isn't extremely radical. There will be a slight idle lope and low intake manifold vacuum, and a little loss of low end torque. Gear the rear end and pick a tire size to give highway cruise speed at around 2,000-2,500 RPM.

The only way to evaluate what you've got is with a dial indicator and a degree wheel- - - - -"3/4 cam" means exactly nothing to anyone with even a rudimentary understanding of engine building. I consider any cam with a duration of over 270 degrees to be unsuitable for street use, but "Opinions are like - - - -uh- - - -noses. Everybody's got one and they can be pretty smelly!" All of the major cam grinders publish detailed instructions about how to degree a cam. My first exposure to understanding cam degreeing came from a little soft cover booklet published by Ed Iskenderian in the early 1950s called "Top Tuners' Tips". If a copy still exists somewhere it's a good read- - - - -I highly recommend it!
Jerry

Ok, starting to feel much more at ease with keeping the 264 3/4” cam installed and get back to stock fuel and exhaust system. I have the Zenith carb, but I need a new mid section as it is cracked. Been beating the bushes with Carbking and he has one, but his is also cracked, so watching eBay. I also have the stock intake and exhaust manifolds soaking with PBBlaster.

The intake and exhaust valves have not been adjusted since overhaul. I did not get any Patrick’s valve adjustment specs from my brother’s records, only the receipt from Patrick’s, which I suspect means he never got one from Patrick’s. I do have a Patrick’s catalog from that time period that shows some data (see attached) about their cam grinds, but markets that for Chevy 235/261 engines. He does not have this info in the GMC section of the catalog, only that he offers a “Choice of grinds”.

What does this info mean in the attached chart?

What we don't know from the catalogue sheet is whether those duration figures include clearance ramps. That's why the 0.050 lift figures are helpful, because that eliminates the clearance ramps. I bought a Howard's cam of that era and the data sheet did give the 0.050 figures along with the advertised figures and lobe centers.

FWIW the Howard's grind was indistinguishable from stock on the road but was advertised as a 3/4 cam. When I mic ed the lobes it was so close to stock I couldn't tell. It might have been one of the "stock-class" cams that had the same lift and duration but a higher lift rate so you could cheat and not get caught at the drag strip. But then who wants to go to all that trouble to "claim" a stock Chevy 6? I could smoke most of a cigarette waiting for one of those to clear the traps at the end of the 1/4 mile. (cheap tobacco).

Here's a "shade tree" trick for setting valve lash "close enough to run". With both valves closed and the distributor rotor pointing directly toward the spark plug wire terminal for a specific cylinder, GENTLY tighten the valve adjusting screw until you feel a little drag on the pushrod as you spin it, and then back the adjuster off 1/4 turn. Lock the nut down and move over to the other valve and do the same thing. Turn the crankshaft to the next cylinder in the firing order and do it again. Six times and you're done. The engine will run with all the valves closing completely. If they're noisy, carefully reduce the clearance until they get quiet. Kind of a "half-donkey" method, but it's worked well for me for 50+ years.
Jerry

Hotrod Lincoln and 1Ton_tommy-
Thank you guys for your guidance.

Hotrod- I found the book Ed Iskenderian “valve timing for maximum output”, 1956 on eBay. Apparently the “Top Tuners Tips” is included in this book. Figured I better grab it while I can. The owner says “the outside cover is a bit worn, but the inside pages are good, but hey it’s 65 years old!” I haven't read a book this old since “Sally, [censored], and Jane” days. There are a handful of at public libraries in the US and Australia but nothing remotely close to me. I’ll give it a read and see if I can sort out the details. Appreciate the valve lash tip also Hotrod.

Tommy- Thank you also for the recommendation on the exhaust manifold studs vs. the 2 bolts that are installed. Good catch.

Appreciate you guys!

PTCT49

Since those split exhaust manifolds aren't connected in the center, using a blind pin at both ends instead of bolting them probably isn't necessary. If you convert back to a single piece manifold with a heat riser, definitely don't bolt the ends down. Those end holes are larger than the alignment stud by quite a bit to allow for heat expansion of a long single piece exhaust manifold. Bolting the ends down can, and usually does end up with a cracked manifold.
Jerry

In days gone by..............

There were a lot of 4 barrel carbs that flowed less than 400. The smallest of which I am aware would be the Carter WCFB used by Studebaker on their 259 CID. It flowed about 295 CFM.

Do Studebaker 4 barrel carbs grow on trees? Nope, kind of scarce, and not overly cheap.

Can the 228 use 295 CFM? Don't know. With a big cam, and good exhaust maybe.

Jon

Thank you Jon. You too have been a big help with my decision on the current stock set up. My brother was kind of a speed guy where as I am a bit more reserved. I feel real good about the direction I’m headed now.

If any of you guys need carb parts or advice- Carbking is the way to go. I received 2 carb repair kits from Jon. Very timely, excellent packaging, professional and 100% American! Jon is a wealth of carb knowledge.

All you guys are outstanding! Thanks for what do.

Pat