Freshening up my Ramjet 502

[chevynut]

While at SEMA this past week I talked to several companies about parts for my 502. I bought the engine (a NEW GMPP ZZ 502 longblock) from a guy over 12 years ago for a great price and it's been sitting around in and out of my car ever since. The exhaust ports have been covered with duct tape and the intake loosely attached. I sold the intake that came on it along with the HEI distributor. I bought all the parts to make it a GMPP Ramjet 502 with some upgrades. I added new GMPP upper and lower intake manifolds, all new sensors, IAC valve, GMPP computer-controlled distributor, 42 lb/hr injectors with a GM fuel rail and regulator, a Holley dual 58mm 1000 CFM throtlle body, MSD coil, and a Holley Commander 950 PRO with a Wideband O2 kit. This is the way it looked when I bought it and it's never been run...



The engine has been sitting for a long time, in a dusty environment, and has some issues I want to address so I have decided to tear it down completely, clean it up, and freshen everything to get it ready for final assembly of my car. I also want to paint it. I don't intend to replace a lot of parts, just clean everything up and make sure it's put together right. I'll replace a few parts with better ones but try not to go overboard .

Rings-

I know these engines have low tension oil rings and that's one thing I definitely want to address. I don't want this to burn oil like some I've read about. I talked to a rep at the Total Seal booth about his recommendations and come to find out he worked 20 years at GM and worked on the development team for the 502. He said I am on the right track to change the rings, and agreed that I should go to regular tension oil rings. He suggested I buy a complete set of file-fit rings, lightly hone the cylinders with a torque plate attached, and re-assemble the engine. I asked about pistons and he said leave them alone, because the engine is very well built otherwise.

I looked in their catalog and they sell a set of conventional rings, or a set that contains a gapless top or second ring. I like the concept of at least one gapless ring so I think I'll probably go with a set that has a gapless top ring (seems to make the most sense there), a conventional second ring, and a set or normal tension oil rings. Does anyone here have experience with the Total Seal gapless rings?

Cam-

I have been considering upgrading the cam for a while now. At SEMA I talked to Comp Cams about the camshaft and other engine parts. Again, the guy said the engine has some very good parts in it and he recommended that I have the engine balanced since he said GM doesn't do a very good job of balancing them. I really wonder how important that is for my purposes.

He also recommended a slight cam upgrade for me because he said the most often heard complaint about the ZZ502 is the mild cam and lack of lopey idle which most guys like. The stock ZZ502 cam has 224/234 duration @.050", a 110 degree lobe separation angle, and .527/.544 lift with 1.7 rockers.

The cam he recommended is their XR282HR-14 hydraulic roller that has 230/236 duration, a 114 degree lobe separation angle, and .510/.520 lift with 1.7 rockers. The only thing that bothers me about this cam is the lower lift. It seems like with the longer duration I'll get more of a lope, but the performance gain isn't obvious to me at all. In fact it seems like I should lose bottom end torque with the higher lobe separation angle.

The next cam is their XR288HR-14 which has 236/242 duration @.050", a 114 degree lobe separation, and .520/.539 lift.

The stock ZZ502 cam has more lift than either of these Comp Cam rollers, but not as much duration. Which is the better choice for a strong street cam? Will either one make more power than the stock one, and how much? I always thought a short duration high lift cam was better for street use.

In this article they "wake up" a ZZ502 with a larger Comp cam that has 242/248 duration, 112 lobe separation and .566/.566 lift. They gained 80 HP and 27 ft-lb and lowered the peak torque 300 RPM. The weird thing is their catalog I picked up says this cam is for jet boats.

http://www.superchevy.com/how-to/eng...-crate-engine/

Rockers-

I asked Comp Cams if there were any roller rockers that would fit under the factory 502 valve covers that I intend to use..cuz I like them . He suggested to use their roller tip rocker, the Comp Cams Magnum rockers with 1.72 ratio. This seems like a reasonable upgrade even though it's not a full roller rocker which won't fit under the stock valve covers. I wonder why the 1.72 ratio instead of the stock 1.7?

Head gaskets-

I assume I'll have to replace the head gaskets so next I ran into the Cometic booth and talked to them about their gaskets. I asked why their head gaskets are better than others, and got the whole marketing rundown. I have since done some research and read that some guys have water sealing problems with these multi-layer steel gaskets. Plus their head gaskets are about twice the price of others.

So, are head gaskets re-usable if the engine hasn't been run? I think once they've been torqued, they're shot but thought I'd ask anyhow . My block has a 4.466" bore and I've seen head gaskets of sizes all around that number. What size gasket bore do I need to get? Also, what about thickness? I see them from .027" to .070" thick.

After doing some research it seems like a composite head gasket is less likely to cause headaches. I'm not building a race engine either, but I don't want problem with head gaskets. Lots of guys seem to like the Fel-Pro composite gaskets. Now I need to know which one to use. I could just stick with the GMPP 12363411 gasket they originally used on the engine which has 4.540" bore and is .039" thick. I don't know who makes them.

Seals-

My engine has a one-piece rear main seal...do I need to replace it? I have no idea if they degrade with time, even if unused. I have a new oil pan gasket and I believe I have new intake gaskets as well. What about valve seals?

Any other upgrades you would recommend while I'm in there? I don't plan to do any porting of the heads or any other machine work. My plan is to disassemble the engine, remove the oil galley plugs, make sure everything is clean as I can get it, and re-assemble it using the new parts listed above.

[MP&C]

So here's where everyone can make suggestions on how Laszlo should spend his money.... This can't end well...

[markm]

The story goes that OEM steel are not exactly 1.7 some may be 1.65. Rollers are designed to give you at least advertised numbers.

Cam selection depends on use of car. I really do not see you in drag races or cross country runs.
I run a 425hp 427 cam in my 396 244/244@ .050 and .520 lift. It works well for what I do, I like a cam with some duration. My favorite cam is the 30/30 Duntov in my 67 Camaro. I also like solid or roller lifters not a fan of hyd. or hyd. roller. What is the current cam.

The only reason I can think of for using a thinner head gasket is if you are trying to squeeze a little more compression out of it.

[NickP]

At this stage of my life, I no longer see the need to have a near perfect, near race engine in a vehicle unless the specific build requires it for a specific application. The expense outweighs the disadvantages. I am more drawn to reliability than the lumpy cams and fuel mileage than horse power. I know this is a very subjective topic and I know what is involved by going to the extreme with power plants. If it's bragging rights or one just wants it because one can, I fully understand that.

I feel that anything over 350 HP is a waste. There are very few places in the USA one can bust it off and do anything above 75 MPH legally.

Just Kidding!!!!!!!!!!!!! For me, fresh means new. New head gaskets, new rings, new seals. I'd save my money and use the same cam, lifters etc.

[Troy]

Won't all of this work void your warranty?

[chevynut]

Nick, that's essentially what I'm trying to do. Spend money where it makes sense, but not go to extremes anywhere I don't need to. This engine has a lot of good parts in it already and it should make 500-550 HP as-is.

Troy, I think the warranty expired when I bought it. LOL! I thought it was going to be running in two or 3 years.

What do you guys think about the balancing? I'm feeling like it's a waste of money to do that for the type of use this engine will see. If it's good enough for GM to ship that way it seems like it should be good enough for a street engine. I'm not sure I'll see any gain in reliability or anything.

I did some more looking last night and I think I'm staying with the GMPP head gaskets that were made for this engine.

I also noticed the gapless ring set is over twice the price of a standard set of rings from Total Seal. Would that be worth the money? I don't mind spending some money on the engine but I don't want to throw it around needlessly. The honing with the torque plate seems to make sense but it will be a hassle. I just don't want an oil-burner.

Would you do anything to the valves, valve stem seals, or springs? The valve springs have been sitting compressed all this time in some cylinders. I'm not equipped to do any of that myself.

I've considered having a local shop build up my longblock for me but it would be fun to do it myself too.

[JT56]

I have run cometic before...they fit extremely well. Never had any issues with water sealing, but that was before boost. I went back to Felpro MLS and have no issues.

[Rick_L]

Given the oil consumption reptutation of those engines, changing to a "more standard" oil ring makes sense. I personally feel there's no benefit to the gapless second ring - all it does is fool you on the ring condition when you do a leak down test. On the other hand, I just helped tear down a street driven 468 BBC that had them and everything looked really nice. So I don't see a down side to them except for the above comment + slightly more cost. Honing with a torque plate is probably a good thing. File to fit rings aren't something needed for your type of engine, but again no downside. Just slightly more trouble + cost.

On the cam, I think the cam in it would be fine for what I think you'd use the engine for, but the 230 @.050 Comp will probably pick up some power.

I understand why some like cams that idle badly, sounds good in the parking lot, but it's not helping you out except for the "sound" and there's a price to pay.

I don't think that the tiny bit of difference in lift means anything relative to your use of the car and its performance. The performance is in the area under the lift curve, and you gain that with either duration or lift or both. Really good all around engines flow a lot of air at low lift, don't need high lift so much.

The gain with that Comp cam is more about the duration than the lift.

Keep in mind that getting the idle tune and driveability right with the Holley controller will be more difficult with a bigger cam. It probably will like more timing at idle and off idle than the stock cam, but with EFI fixing that doesn't screw with the rest of the timing since it's tables and not analog with springs and weights. There
s probably a Holley tune for a BBC that will get you pretty close for startup.

markm is correct on the stock rockers, they are "not quite" a true 1.7 ratio, the roller tip ones will be.

If I were you, I'd buy a new Fel Pro or equivalent gasket set. It should have a new rear main seal, I'd put it in since it will be on hand. Probably don't need to, but you might as well. There's nothing wrong with Cometics, but Fel Pro is more widely available (you can get it locally), and frankly there's no wrong answer on head gaskets as long as you stay with the typical composition gasket that's widely used and what your engine came with.

Valve springs sitting compressed in storage aren't affected at all. On the other hand the factory didn't shim them at all, there will be no precision or consistency. IF you go with the Comp cam, look at the recommended valve springs for it, they are likely a bit more than the stock spring, and it would be worth a little high rpm performance to get them and shim them to get the actual recommend seat pressure.

Given that you live in the high desert, if the engine has been stored dry and clean, I'm not sure I'd do anything. It's just time and money that might have better return elsewhere. Especially as in it might be done sooner.

[chevynut]

Given the oil consumption reptutation of those engines, changing to a "more standard" oil ring makes sense. I personally feel there's no benefit to the gapless second ring - all it does is fool you on the ring condition when you do a leak down test. On the other hand, I just helped tear down a street driven 468 BBC that had them and everything looked really nice. So I don't see a down side to them except for the above comment + slightly more cost. Honing with a torque plate is probably a good thing. File to fit rings aren't something needed for your type of engine, but again no downside. Just slightly more trouble + cost.

Thanks for the feedback Rick. Total Seal says you can use the gapless ring in either the top or the second groove. I figured the top made more sense, but maybe it doesn't. I thought ALL rings were file to fit rings. If that's not the case, are they that accurate coming out of the box? When I rebuilt my Yamaha Grizzly top end last year I had to file fit the rings. I have a standard bore and don't expect that to change unless I run into some surprises when I tear the engine down...hope not.

On the cam, I think the cam in it would be fine for what I think you'd use the engine for, but the 230 @.050 Comp will probably pick up some power.

I understand why some like cams that idle badly, sounds good in the parking lot, but it's not helping you out except for the "sound" and there's a price to pay.

I don't think that the tiny bit of difference in lift means anything relative to your use of the car and its performance. The performance is in the area under the lift curve, and you gain that with either duration or lift or both. Really good all around engines flow a lot of air at low lift, don't need high lift so much.

The gain with that Comp cam is more about the duration than the lift.

Keep in mind that getting the idle tune and driveability right with the Holley controller will be more difficult with a bigger cam. It probably will like more timing at idle and off idle than the stock cam, but with EFI fixing that doesn't screw with the rest of the timing since it's tables and not analog with springs and weights. Theres probably a Holley tune for a BBC that will get you pretty close for startup.

Yes Doug Flynn sent me a tune for a BBC with close to my setup to get started. I'm not sure a cam change is worth it unless I gain some significant HP and don't sacrifice any low end. That's what was interesting about that jet boat cam.

markm is correct on the stock rockers, they are "not quite" a true 1.7 ratio, the roller tip ones will be.

I agree. But the roller tip ones are advertised as 1.72 ratio. I don't think that will change anything but I like the idea of reducing friction there.

If I were you, I'd buy a new Fel Pro or equivalent gasket set. It should have a new rear main seal, I'd put it in since it will be on hand. Probably don't need to, but you might as well. There's nothing wrong with Cometics, but Fel Pro is more widely available (you can get it locally), and frankly there's no wrong answer on head gaskets as long as you stay with the typical composition gasket that's widely used and what your engine came with.

A gasket set may be the way to go but I'm not sure if that's the case with this engine and I don't see where GMPP offers any complete sets. The GMPP head gaskets for this engine are $79 each from Summit. The only other gaskets I really would need are the timing chain cover, since I have everything else. The oilpan gasket and valve cover gaskets are rubber and are reusable. I think I even have a brand new pan gasket.

Valve springs sitting compressed in storage aren't affected at all. On the other hand the factory didn't shim them at all, there will be no precision or consistency. IF you go with the Comp cam, look at the recommended valve springs for it, they are likely a bit more than the stock spring, and it would be worth a little high rpm performance to get them and shim them to get the actual recommend seat pressure.

This engine redlines at 5800 RPM and I doubt I'll try to push it over that limit. Again, thanks for the advice on that since an engine builder would probably try to talk me into some different springs. The Comp Cams rep said not to mess with them.

Given that you live in the high desert, if the engine has been stored dry and clean, I'm not sure I'd do anything. It's just time and money that might have better return elsewhere. Especially as in it might be done sooner.

That's the issue...it's been dry but not very clean. I think the injector openings have been unplugged this whole time and the intake was only on with a couple of bolts. My shop is really dirty when we work in there so I'm concerned some grit may have found it's way into the engine. I'd rather be safe than sorry, and I feel that I NEED to address the low tension ring issue so it has to come apart.

Thanks a lot.

[markm]

"Would you do anything to the valves, valve stem seals, or springs? The valve springs have been sitting compressed all this time in some cylinders. I'm not equipped to do any of that myself. "

Really, KD sells several affordable valve spring compressor options, this is easy compared to some of the stuff you do on suspension. I do have to agree with you about doing it yourself. That is why I will never have a crate moter.