The Stovebolt Site Forums The Shop Area Engine Shop Hopping up the GMC 270 in the firetruck?

Does anyone make the aluminum side cover and valve cover to fit the 1950 GMC 270 with "H" head. I'm trying to fix mine up some. Also looking to buy the Fenton duel exhaust and aluminum 4 barrel intake from Patricks but I always get their message machine. They still in business? Looking for a TBI throttle body and ECM , harness and accessories to set it up with fuel injection. I'd like to get it where I can use it for my hauling truck more frequently. Thanks. Jim

Gonna call Patricks tommorrow. Hope they answer.

Are you just doing cosmetic improvements?

Already put in the Pertronix II ignitor and coil, converted to 12 volts with Alternator. Looking to put dual Fenton exhaust and TBI to replace the carb, let it breath easier. And hope to find an overdrive 5 speed for it. The engine internals appear to be in good shape, so I'm not going to mess with that until necessary. It only has 15,300 miles, plenty left as is. Will replace all seals and gaskets when I do the above. And clean and paint it. Thanks. Jim

Try [censored] Larrowe in Sandy,OR. He does a lot of GMC items. I think his son has taken the business over now. He advertises in the Inliners club mag.

http://www.34-chevy.com/

Ordered the Fenton duel manifolds from Patricks today. They didn't have the intakes, so I might try my hand at making a stainless TBI manifold. If I can find a decent TBI setup local.

The phones at that link for Larrowe say disconnected, no longer in service. Plus, the links on the website are dead.

Found that out myself too. Sorry about that. He did sell some really nice stuff. Odd, their ad still appears.

I had looked at their website before about a month or 2 ago. Never could get links to work.

Patrick's 'instructions' for using the Chevy manifolds on a GMC suck. Here's how I made 'em fit.

I shouldn't have to do anything to mine, they're supposed to be for a GMC.

You are in for a surprise.

Please say it ain't so. Why wouldn't they tell you it needs modifying to fit before they sell it to you. ?

On the 270 GMC in my 450 series truck, should it have vacuum advance on the distributor. Mine doesn't. I've been told by a friend that it should. ThAnks. Jim

I don't think a 450 has one. You might ask in the big bolt forum.

Thanks Cletus. My manual just says some do, some don't. Wonder if it would benefit from having vacuum advance. I'm not used to vacuum advance that rotates the whole distributer either. At least that's the way it looks in the manual. Still waiting on exhaust manifolds to show up.

Just a guess while I have coffee... if the 4xx series is a heavy duty rig for large loads, would it use heavier cent. adv weights and be 'all in' to accomadate the load?

Yeh, I haven't the slightest idea. I'm hoping someone will tell me the answer. Patrick at Patricks Vintage said he'd never seen one without. Maybe I didn't emphasize enough that this thing is Big. Think I'll get some of that coffee now too. And start reading up on ignition timing. Thanks. Jim

Picked up a 4.3 TBI and harness and all the sensors, relays, ECM and crap to get started. Pick and pull in LR Arkansas. Nickel and dime you on the small stuff, but that's life. Hope to get started at least on the mount plate for the TBI tommorrow. Then build the rest of the intake.

Anybody have a spare distributor for a 270. Looking for just the part for the points cam lobe, The shaft part that has the points cam lobes on it and the advance weight springs attach to it. Thanks. Jim

The main reason for having a vacuum advance is for fuel economy. At light-throttle cruise speed with the manifold vacuum high, the vacuum advance cranks in about 8-10 degrees more timing advance. It goes away as soon as a load gets applied to the engine again. Since the really big rigs were seldom if ever run without a heavy load, there would be no reason for the extra advance. If you're not planning to work the truck like it was intended, swapping a dizzy from a lighter-duty truck shouldn't be a problem, but I doubt if there will be a noticeable improvement in gas mileage with the gear ratio and gross vehicle weight you're dealing with.
Jerry

As Jerry stated, the distributor on my 54/55 GMC 350 (2-ton) came with no vacuum advance. It starts and drives fine.

Thanks Jerry and TC. I'll be experimenting a little with TBI and letting computer control the timing. Gonna learn how to reprogram TBI chips here soon. Used to doing my 68 with 5.3 with HP Tuners. Something new to learn. Jim

TBI was designed as a Band-Aid fix to transition from carburetors to port fuel injection 30 years ago. It's marginally better than carburetion, but it's hardly worth wasting a lot of time trying to adapt it to an engine with siamesed intake ports that can't be readily adapted to any sort of cylinder-specific sequential port injection. I think I'd rather spend my time designing some sort of intake manifold modification that might get a port-type injector aimed at the back of each intake valve if my intention was to upgrade to computerized fuel injection and ignition timing. At some point, it's sort of like putting lipstick on a pig- - - -not very practical for the effort involved.
Jerry

Ehh, gonna try anyway. Already bought the TBI parts. Looking for a spare distributor points lobe shaft to machine down for a reluctor ring to fit on. Anybody got one that will fit a Delco Remy distributor in a 270 engine? Also, does anyone know who would have a 4 barrel manifold in stock that will fit with the Fenton dual exhaust manifolds? Thanks. Jim

Use a Chrysler 6-cylinder reluctor and pickup coil for a slant 6 engine to trigger a GM 4-pin ignition module. I'm in the process of building a Triumph Spitfire 6 cylinder distributor that way, and the reluctor and trigger coil are a good fit in the Delco distributor for the Turnip engine that's almost a clone of the Chevy, just CCW rotation. a guy on Ebay sells the whole reluctor/trigger coil unit, new old stock, dirt cheap.
Jerry

Thanks Hotrod Lincoln. Been looking on Binderplanet at Bill USN1 a sight for FI info. Lots of good stuff there and Bill must live on his computer, cause he's real fast with answers. Jim

I picked up two 1958-59 270s. The one from a 1/2 ton has vacuum advance and the one from a 2 ton does not. I've been told the large truck usually did not have vacuum advance.

So I wonder if a dizzy from a Chevy six can be used in place of the GMC non vacuum unit, or if parts from a Chevy vacuum dizzy can be used on a GMC non vac. unit.

When converting to EFI with fuel and timing control the vacuum adv makes no difference. It's only there to maintain the stock appearance. For carb use it's always good to run it on a daily driver.
The 4 pin GM module is good for an electronic conversion for use with a carb. For EFI it needs to be a 7 or 8 pin module to allow timing control. Then the mech and vac adv is locked out.

Hot Rod has made some interesting remarks and I would like to have a new thread to discuss them vice going off topic here.

I've done a lot of research on siamese ports and would like to hear more on the subject.
TBI as a "Band-aid", not exactly how I remember it, but it works quite well for our 50+ year old engines that were designed prior to a concern for efficiency. Much better than a carb.

I have done dual 1bbl TBI on a stovebolt. Here's a link with pics. Dual 1bbl TBI on a 261
Single TBI with DIS-distributor less ignition on a 1275 mini.
Dual SUs converted to dual injectors in the SUs on a 59 Triumph.
And now converting a pair of dual SUs to injection for my mini.
The IH 6 is almost a mirror image of the Stovebolt 6.
I have run 1 and 2bbl TBI on it.
Working on a MPFI system for it now and already have the parts side worked out but debating on making my own log manifold or using the stock one. But anything I do for it should cross right over to the Stovebolt.

The price point or ROI-return on investment goes way off when you start talking MPFI over TBI on these engines.

But it could be another good talking point for another thread.

The whole point is to make them a more efficient and reliable driver so they don't set in the driveway.
Having retrofitted TBI and MPFI on these old engines, my personal experience is the only real thing you gain with MPFI is the shock and awe or wow factor when you pop the hood to show your buddy.
Nothing wrong with that...I have MPFI on 2 of my IHs.

Thanks Bill. Like your thinking. Love my 68 Chevy C20, couldn't afford to drive it with 327, T400 and 4.56 gears. I drive it everywhere now with 5.3, 4L60e and 3.54 gears. Love the looks of older trucks, love working on em, but I want to use mine all the time. Tow a 68 Airstream all over the country for my job with it. Would love to get my 50 GMC firetruck to that point. This time wanted to play with the old engine and modernize it. TBI was an appropriate way to do that. Especially after going to your sight and seeing how easy it is. Very simple, affordable, works great and I can do it myself. Again, thanks for sharing. Jim

Got a few parts ready to put on the 270.
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Started disassembly today. Got all the interference items off intake. Hydra vac lines, gas lines, carb, throttle cables, choke, horn, PVC.... Had to cut the exhaust pipe, couldn't get enough leverage to remove 2 bolts. All bolts on intake and exhaust are now loose. No stuck bolts there. Tommorrow hope to get the new stuff on. Jim

Got the old off and the new on. Little bit of grinding and porting and modifying and fabbing and the Fenton duals are on with the military 302 intake. Vac lines were in the way the whole time. Broke the vac hose to the hydra vac booster. The fitting coming off the intake for vac lines was in the way of the throttle on the TBI. Will have to move to lower port. The fender braces are where the air cleaner wants to be. Fun fun fun. Nice hot, humid day today. Two of the bolts on the manifolds are dang near impossible to tighten. Next time I'll pay extra for the Nicson manifolds. Jim
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Pretty much my experience as well. Granted the tbi might be better than feedback carburetors, but that is like stating a headache is better than an upset stomach.

Will state I have never had any experience with aftermarket tbi's but have had MANY customers that transplanted these engines with o.e. tbi into older vehicles trash the tbi in favor of an old-fashioned carburetor, always significant improvement in both power and economy.

O.E. tbi's were a dime a dozen at the local swap meets back then.

Programmable aftermarket units may be different, like I said, no experience with these.

Jon.

Is the plug behind the hose at the top rear of the head engine coolant or oil passage? Need a place to install an engine coolant temperature sensor for TBI ecm. Thanks Carbking. I kind of like making everything in my life more complicated than necessary. If I don't like the single 2 barrel TBI, I'm going to try 2 1 barrel TBI's . If that doesn't do it for me, I'll do the small 2 barrel Holley. Jim
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Got the distributor converted for HEI today. Looks pretty good. Everything was in spec as far as condition of distributor.
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Jim, I just read your build thread and enjoyed it very much. Don't let the comments from Hotrod Lincoln and carbking discourage you. They have obviously not driven a properly installed and tuned fuel injection system. If you're like me you don't do this stuff because it's easy you do it because it's hard. I like a challenge. Good luck.
Ron

Subscribing to the thread for updates. Liking where this is going. Nobody makes any performance valve cover or side cover that I know of....only for the chevy 6's. You could have yours chromed. TJ

Kind of stalled right now. Learning about tuning the chip. I have it running for about 5 or 6 minutes. Need to get exhaust installed. Need to get throttle linkage designed and fabbed to drive it to exhaust shop. Short on available time right now though. Need to perfect the tune. Right now running on V8 tune, little ruff. I read all posts, regardless if they're to my liking. Most folks on here are full of good info and tips, and are very helpful. I like tinkering, so I do things how I want them anyways. Thanks everyone. Jim

Guy used MSD's quick tune injection on a 235 and had to tune it as a 350 tune. lol Anything smaller was running to lean...they say that because the manifold is mounted on the side and there is only 3 ports that that is why tuning is more difficult....I've noticed it as well...outer cylinders 1 and 6 run leaner...cylinders 2 and 5 run a little richer and 3 and 4 run rich...so..the old hotrodders used to run cooler plugs on the outer cylinders and run them hotter as they came to the center...just an example...1 and 6 would run NGK 6es...2 and 5 NGK 5es and 3 and 4 NGK 4es. It may help with tuning as well...never done it myself...but am thinking on it for my hotrod engine. TJ