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Another random question. The guy doing the work said he would not reuse my chrome valve covers (non-original for a 435 but I like them). Will a ZZ502 accept my valve covers or is there something different about the newer heads that won't accept the older valve covers?
I have noticed the internal vs external balancing difference. Does the harmonic balancer sit behind the crankshaft pulley or is the pulley somehow balanced. Would that be an obvious difference between the two types of balancing? Can you get these long blocks in either internal or external balanced?
As for an upgraded cam, the guy putting all this together said the engine he has found has a mild cam with a smooth idle. I don't have any specifics but I would like better than "smooth idle"
The balancer has a weight on the hub. The pulleys are the same for 427 or 454.
As for bigger, if you go that waybe sure the biggun is built on a standard deck block (9.8 inch from the crank centerline). It's certainly possible to use a tall deck block, but lots of things would need to be changed to make it work. Fit under the hood would be very tight as well.
Another random question. The guy doing the work said he would not reuse my chrome valve covers (non-original for a 435 but I like them). Will a ZZ502 accept my valve covers or is there something different about the newer heads that won't accept the older valve covers?
the bolt pattern is the same. but since the 502 will have roller rockers the polly locks won't clear the short valve covers. you will either need to run spacers, shorter polly locks or thicker double gaskets
Thanks to everyone for the feedback. I'm not into these crate motors so I don't know the differences. The reason for not going bigger is cost. A ZZ502 is freaking expensive and the cost only goes up from there. Sounds like a ZZ502 will look quite similar and be a massive upgrade. I'm not trying to race anyone here, only frighten women and young children. I have a high degree of confidence in the person doing this work for me and he has an inside edge on a ZZ502. He's recommending a cam and valve spring swap for a nice lope.
just go buy a goodwrench 454 gen 4 longblock ,for a mid 70-80's gm truck,bolt it in and everything fits
the bolt pattern is the same. but since the 502 will have roller rockers the polly locks won't clear the short valve covers. you will either need to run spacers, shorter polly locks or thicker double gaskets
Not true, I used Comp Cams rockers and chrome short valve covers and they fit with one gasket. See photos of my 496 engine build. If needed you can buy shorter poly locks, these are standard what came with the rocker arms. I have also used these same rocker arms on a 468 build with the short cast aluminum I and doing now for my 1970 truck.
One more thing to think of. The 427 was internally balanced, the 454 blocks were all externally balanced. You will want to know what you buy so you can have a matching harmonic balancer and flywheel. I can't say what the new GM blocks are but I bet it states in the add if it is internal or externally balanced. Most of the new blocks run a one piece rear crankshaft seal rather than the old two piece design. The one piece is a much more reliable rear main seal but again, this type crank needs a matching flywheel, the bolt patters are not the same as the two piece seal flywheel.
Just a heads up, GM bbc with 1 piece rear main seal, whether 454 or 502 are both external balance flywheels BUT (and it’s a BIG but) they are not balanced the same and even though they will both bolt up to the crank, they are not interchangeable.
Just a heads up, GM bbc with 1 piece rear main seal, whether 454 or 502 are both external balance flywheels BUT (and it’s a BIG but) they are not balanced the same and even though they will both bolt up to the crank, they are not interchangeable.
And the Gen 6 engines have a cam thrust plate and use a different stepped front nose cam. Makes using a hyd roller cam simple as they are already setup for it.
Lost my 427 when dealership burned down and it was hauled off as toxic waste before I could get to it.
Installed ZZ502 w/Tremic and have never been happier. Being in northern Michigan the car winters unheated
seven months, in the spring I don’t even get in. Stick my arm in window make sure I’m in neutral and turn the key.
Cranks about three to four seconds and vroom! I’m especially pleased with the additional torque and the low throaty
rumble of the 502 vs 427. Note that I installed electric fuel pump due to the fuel injection and a hydraulic clutch.
I cannot see any upgrade in power due to the stock suspensions inability to hook-up.
St. Jude Donor '09-'10-'11-'12-'13-'14-'15-'16-'17-'18-‘19-'20-'21-'22-'23-'24
Originally Posted by Kelley
I'm not trying to race anyone here, only frighten women and young children.
I'm a firm believer of do whatever you want to your own property. I gotta wonder just where all these various fire-breathing beasts are going to get their exercise. Fastest car I have owned was a 427/400, and even if I still had that I'd never do 3/4ths of the stuff I did back then. I'm older and hopefully smarter, and the radar and other such stuff the cops have today is FAR more "deadly" than back in those days. Not long ago I watched a C-7 get on an on-ramp, and whatever gear he was in took him from slow to out of sight and probably well over the posted limit in the blink of an eye without even shifting. Having 500 or 600 HP is impressive, and I would have killed for that back then, but what do you DO with it, to justify the extra $$$ it costs?
Again, it's YOUR cars and I don't care what y'all spend or do. I'm just not on the same page.
UPDATE:
I have the car back and I can make one suggestion to anyone contemplating a ZZ502 swap. DON'T upgrade the cam! I drive my cars regularly and this thing is hard to drive at low speed. A more mild cam would be a blessing. Plus, it's so damn loud I'm going to have to address the exhaust. I'm very happy with the work done on this car but in hind sight I should have never replaced the cam that came in the engine.
Just out of curiosity, can you list the cam specs for the one in the motor? I have a couple of 427’s and one has a 230/236 @.050 roller on 112 lsa and one has a 224/236@ .050 roller on 113 LSA and both are fairly mild in terms of “hot rod cams”
The 230/236 cam is a Comp Marine grind which by its very nature can’t be too big to be able to shift and prevent reversion in wet exhaust.
UPDATE:
I have the car back and I can make one suggestion to anyone contemplating a ZZ502 swap. DON'T upgrade the cam! I drive my cars regularly and this thing is hard to drive at low speed. A more mild cam would be a blessing. Plus, it's so damn loud I'm going to have to address the exhaust. I'm very happy with the work done on this car but in hind sight I should have never replaced the cam that came in the engine.
Looks great, Was this a long block or a short block and you reuse the Promaxx Aluminum heads from your previous motor?
You can always take a day and put the other cam back in, it is not a fatal mistake and might get you where you want it to be. You are invested now so make it the way you want it.
Not true, I used Comp Cams rockers and chrome short valve covers and they fit with one gasket. See photos of my 496 engine build. If needed you can buy shorter poly locks, these are standard what came with the rocker arms. I have also used these same rocker arms on a 468 build with the short cast aluminum I and doing now for my 1970 truck.
The older Comp Cam rockers will not fit, the ones you show are the modern design with a little revision in design that allows them to fit.
09-09-2022, 06:50 PM
