GM 427 question

G

George4

Member
I have a 1977 Chevy C65 truck with a Goodwrench 427 in it with only about 3k miles on it, just been used very little for years. The engine is the only thing worth keeping and scrap is up so she is getting scraped and I am wondering about keeping the engine. I know it holds 8qts of oil and I am not sure what else is different besides the pan compared to other 427 engines found in street cars. If I keep the engine what would I need to change to get it to fit in other projects where a big block could normally fit? Thanks
~George
 
George4 said:
I have a 1977 Chevy C65 truck with a Goodwrench 427 in it with only about 3k miles on it, just been used very little for years. The engine is the only thing worth keeping and scrap is up so she is getting scraped and I am wondering about keeping the engine. I know it holds 8qts of oil and I am not sure what else is different besides the pan compared to other 427 engines found in street cars. If I keep the engine what would I need to change to get it to fit in other projects where a big block could normally fit? Thanks
~George
Click to expand...
iF YOU KEEP IT, MAKE SURE YOU KEEP ALL THE BRACKETS, ALT., P/S, AND ANY OTHER BRACKETS, KEEP FLYWHEEL IF AUTOMATIC OR STANDARD,DOES THE MOTOR HAVE A HOLLEY, IF SO ITS PROBABLY HAS A GOVERNOR ON IT, DON'T NEED IT, MANIFOLDS MIGHT WORK OF A TRUCK, BUT HEADERS ARE BETTER, DON'T KNOW OF ANYTHING ELSE, JUST TRY AND KEEP MOTOR COMPLETE WITH ALL ACC.
 
George, that is probally the tall deck 427, I don't remember the exact specs but seems to me that the bores where about a 1/2 inch taller than the passenger car blocks,the pistons where taller and used 4 rings instead of 3. Thats not a problem and that motor can be easily built to well over 500 cubic inches.
Any performance build would require longer rods and new pistons. Also any 427 intake will work but will require spacers between the head and intake.also the distributer is longer than the passenger car 427.
That motor in its stock form is a stump puller and will not rev up hard. Also you could run into hood clearence problems because of its extra height in a passenger car.
 
I used the crank out of one of these motors in a 71SS Nova I built. I used a 454 block and if I can remember the rods from a 396. The crank has the same throws as a 396 and is steel. I even used the oilpan and had over 9 quarts of oil to help keep the beast alive.
 
Plain and simple --- if it is a good engine with only 3k miles, it is worth considerably more than scrap and well worth the time it will take to pull it. Call a couple of yards and see what they get for a low mile engine like this.
 
Great motor!! If you dont want it...rather see you put it on ebay or something rather than scrap it. Its worth some dollars for sure. Those are getting a little hard to find nowadays.
 
Thanks for the info guys. I am getting ready to pull it, I am going to try to throw in into a 80s Monte Carlo if I can find one. I am pretty sure it has a Holly four barrel carb on it. What is this governor about?
 
So what do you guys know about this engine, has anyone used the same 427 tall deck BBC for a build? I was thinking I should put a new cam in it and get rid of the stock Holly with a governor on it. What CFM carb should I use, 750? And what kind of luck have you guys had with what cams? I was also thinking of using a tunnel ram intake with single carb, I think I will need some spacers to make it work on the tall deck. Also the oil pan on it now holds 8 qts, will I need a new pan to fit it into any car, thinking G body. Thanks
~George
 
So I pulled the intake off to take a look at the heads, here are pics... I am guessing these are the "peanut port heads" that I don't want. I guess I will track down some new heads, I will try to find some rectangle port heads. Can a machine shop do anyhing with these heads to open them up?


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Those are the normal oval port heads and depending on the combustion chamber can make some very good power with the right work done to them.
 
Well I got the casting numbers off the heads and numbers are 343722, which according to a few different sites its form 1976-1984 Oval Port, Open chamber with 2.06 intake valve and 1.72 exhaust valve. Are these decent heads?
 
I can't find any info on the chamber size. If its the 118 it's a good head if it's the 110 you cant use a big dome piston with it but still will work ok.
 
The deck was made taller on the truck version of the 427 and the nearly identical but smaller bore 366 engines so that they could accommodate a VERY HEAVY 4 ring piston package. The deck height is .400 taller than a passenger car big block Chevy like a 396 or 454. The truck engine is NOT a performance engine and it will not tolerate high(above about 3600) rpm. These engines have heavy duty cylinder heads with very small valves and sodium cooled exhausts which are intended for low rpm truck usage.

The 427 tall deck blocks can be used in performance applications when building a stroker and they can accommodate up to a 4.500 stroke with the right connecting rods.

The crankshaft used in the 366 and 427 truck engines is the same forging as ones used in the passenger car engines of the same stroke. It's forged steel but balanced differently because of the greatly increased piston weight in the truck engine. Rebalancing will make it usable with normal pistons/bob weight.
 
I have been checking on a few machine shops to see how big of valves they could fit in these heads. I was thinking of leaving the bottom end alone and just getting the heads opened up, bigger cam, roller rockers, put a good harmonic balancer in, and a dart tall deck aluminum intake with new carb, and then just other smaller things.

BTW what size intake and exhaust ports should be on the bigger side?
 
Usually we put 2.19/1.72 valves in most of those heads. Stay away from the dart intake and use an edelbrock. The stock bottom end will limit your rpm to about 4000 safe rpm. Don't touch the exhaust port exit and match the intake to a felpro gasket.
 
So since it already has 2.06 intake valve and 1.72 exhaust valve is it really worth pulling the heads off? The reason I said dart is because that is the only one that I have found that is made for a tall deck and I was wanting to try to stay away from spacers needed when using a standard BBC intake. Maybe I need to do some more searching for intakes.
 
If you seeking horses from this motor ...like was said...keep it under 4000 or it wont last. Lots of torque on these motors. You can do some work on the lower end to get high rpms but it will cost you. Thats why drag racers seek these blocks. If your just going to put it together for street use...id call comp or crane cams and ask for a good cam for your application. May have to put different springs in the head....doubt it though since your rpm's wont be too high. Also...get a better intake. That will help out in the long run. Look for edelbrock intake as racing68 said. So...get a good cam....better intake and leave the rest alone. You will be happy with the outcome im sure. Does this have HEI ignition?? Probably doesnt....id upgrade to that as well. Good luck..seems like a cool project motor.
 
Best use for one of these is to use the block and build a larger stroker engine to take advantage of the deck height otherwise it has no advantage over the lighter "car" style block. In order to use normal pistons you'll need to go to a .400 long rod. Keep in mind that something like an 049 or 781 head will produce VERY low compression on 427cid. A closed chamber head would be a much better choice for some sort of street engine.
 
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