online170

When i bought my firebird, it was a running driving vehicle (still is). However, its a 1987 formula, with an early 70s truck engine in it thats been built up. It has 0.30 11:1 TRW pistons it. My question is about the spark-plugs.

Whenever i buy a car, i do a complete tune-up on it, regardless of when the previous owner did it. While doing so, i can examine how the car WAS running, by looking at the filters, the plug wires, reading the spark plugs, examining oil etc... and i start off with a clean slate.

Well, after going through a few small blocks, i know what spark plug they use. This one has HEI ignition, still carbureted, so i knew i had to change the gap. So i went down and bought the regular R45TS or something to that effect spark plugs from AC-Delco. Pardon my memory, but they are the regular small block plugs, for a 78 corvette 350 lets say.

Anyways, when i went to swap it out, my 5/8 socket wouldnt fit, i had to use the 13/16 socket. Turns out the plugs in there were R45 AC-Delco plugs.

So incase you dont know the difference, this is the major one. The R45 electrode sits quite a bit higher up in the combustion chamber, where as the regular R45TS sits in much deeper.

I thought maybe the builder had done this, to avoid clearance issues???? So i turned the engine over by hand, just to make sure i wasnt getting contact, and everything seemed good. Then i started the engine, it seemed to run fine, then i brought it up to temperature and went for a 10 minute drive, still everything ok.....


Well i was still not 100% satisfied, so i went and bought 8 new R45 and put those in, just to be safe, because i dont know why the builder had done, but i figured he had a good reason. However, im beginning to wonder, if i keep the regular plugs in there, it will probably up my compression a miniscule amount.

So my question is...

Why would the builder have put in a plug that sits much higher in the combustion chamber???

-Clearance?
-Heat dissipation?
-Earlier ignition since the electrode is closer to the valves?

Id like to hear from people running 11:1 or higher pistons. And id like to know if its safe to go back to the regular plugs?

Thanks.

Sonix

iTrader: (1)

11:1 pistons are probably big domes eh?
The S in the R45TS refers to extended tip, so yea, the R45TS would be longer, maybe too far to be comfortable. I believe this also has an effect on the heat range, since it's further into the combustion area. F-bird'88 recommended I use R42T in my 10:1 iron headed SBC over the R42TS, I believe for this reason.
Is the motor actually 11:1 CR, (or does it use big chamber heads and drop the CR?)
Reason being, R45 is still a rather hot plug, I think if it's got a high CR, you'll want to drop the heat range of the plug a few steps. Do you know how to read the heat line on a plug? Look for the discoloration line on the ground electrode. Halfway to the tip is just right, too far towards the threads means its too hot, go to a cooler plug, and vice versa. I think you need a colder plug, IMHO.
I've attached the bosch letter definition chart as well.
Hope that helps.

online170

No the motor is not actually 11:1 CR, its just 11:1 TRW pistons. They are not domed either. The builder had dropped one piston before installation, and gave the guy the piston with the engine as a souvenir, so i have itnow, and its not domed.Atleast not outwards.

Also i dont know how to read the heat line. I understand you explanation. Im assuming ill have to pull the plugs out. Also, wats a good time to do this? I installed the plugs near the end of winter, and the car has been driven roughly 300 kms since.

Also worth mentioning, it has iron heads, i dont know whats been done to them, but i think they may have been machined (or possibly the block decked). When the startor turns the motor over, it doesnt sound like an excessively high compression engine, so im guessing effective compression is close to, if not below 10:1

Sonix

iTrader: (1)

You don't know the CR of the engine?? Uh oh.
Well, do you know what heads they are? Casting number, or aftermarket part #? Can you find the chamber size? Pistons, what part# are they? Can you find the dish size? I guess it's a flat top with 4 valve reliefs?

You can check the heat line whenever, it permanently discolors the metal, so it's colored by now.

Supervisor42

If this is a 350 (you never actually said) can you post a picture of the "souvenir" piston? The engine I built for my GTA used the TRW LF2304 forged "11:1" pistons. They have a slight 1/8" dome and a deep slot for valve reliefs. Depending on the year of cylinder heads on your block will have more to do with the compression ratio than the pistons. After '70 the combustion chamber size increased yearly until unleaded gas showed up and then they ballooned.
About sparkplugs and high compression: Short tipped plugs are used to prevent any detonation leading to preignition (which is 10 times worse).
Later engines use extended tip plugs for better flame propogation to help with emissions and mileage since detonation isn't a problem.
As far as the plugs in your engine go: If you had to use a 13/16" socket to remove the plugs then the heads are old enough that they use gasketed not tapered plugs. Using any tapered plug (5/8") will ruin the heads. (like a R45TS)
My '68 model heads on my engine use a gasketed champion RJ12YC.
Resistor plug, 14mm, 3/8" reach, 13/16" hex head, standard projected core nose, copper core design.

online170

Ok, yea guys sorry i should have been more specific.

It is a 350 engine, bored 0.30 over, to a 355. Ill take a picture of the piston, but the head numbers will have to wait. The car isnt in my driveway right now.

You are right the plugs in there now are gasketed plugs, the R45TS are tapered, and i tried both. The R45TS i didnt tighten enough, so they were very lose, but the car still seemed to run ok. Obviously i had exhaust leaks everytime those loose cylinders fired.

Ill get you the numbers soon. However, i trust that whoever built this engine did it right, because it goes like stink, and has been very reliable thus far. Its been driven hard for most of its life, although it was rebuilt not too long ago, and no problems yet.

So i would assume the builder had a good reason for putting in those plugs. Just would be nice to know why. But because it runs so good, i never bothered to calculate the CR or anything like that, the only number ive chekced is the 3970010 at the back. WIll get you the rest shortly.

Supervisor42

Sounds like the engine I built. The "other" news is if the heads use gasketed plugs they don't have hardened valve seats since they were "pre-unleaded gas". You will have to use "lead substitute" unless the heads have had exhaust valve seat inserts put in them. It's not expensive, available at Walmart.
About the plugs: depending on the dynamic C/R of the engine and how prone it is to ping, you could probably use a projected tip plug. The R45 was used
from '55-'66 on the 283 and 327s.
Do the heads have factory accessory bolt holes?
If they do then they are 69 or 70's. '68=no holes '71=tapered plugs.

online170

Yep, i use lead substitute every other "fill up" because i never actually fill up all the way. So one bottle is usually good for 2 half tanks.

As for bolt holes, maybe this pic will answer your question. The only factory option not installed is A/C, and the alternator bracket doesnt quite line up, but otherwise everything works.

Like i mentioned before, ive used both plugs for roughly 10 mins of run time, much more for the R45, so i dont know if they are bad for heat dissipation and such just yet. I still dont have my car, will try to get you those numbers, and plug reading next week.

online170

And heres the pistons. The one with the connecting rod, is one of the originals taken out, the "cleaner" looking one is the souvenir piston that was dropped.

Supervisor42

Yep, that's a forged 11:1 350 piston alright, same as mine. I bet that thing does haul a##. Looks like that driver's side valve cover will be the easiest to pull off to get that all important head casting number. If the heads have the gasketed plugs AND have the accessory holes then they have to be '69 or '70. Of those years only 2 castings were 74 and 76 cc chambers. All the rest are 64's. I think the guy that put those TRW slugs in it didn't put heads with big chambers or 1.72 valves on top.
That engine is looking more like mine by the minute.
Of course, we'll never know what cam is in there...

online170

Good to know, i wish my transmission wasnt shot, the engine loves to scream on high revs, but my tranny isnt up to it. It wants to chirp the tires even in the 3-4 shift, but the clutches are pretty fried and it wants to shift "smoothly". Used to be a tunnel ram setup on it, the previous owner "downgraded" for driveability.

Anyways, i just bought an Air-Gap RPm and holley 750, and some chrome valve covers, so they need to be changed anyways. Will get you the numbers soon.

As for the cam, the guy who got it built, didnt know a whole lot about it, he just said make it fast, but the builder told him it was a 284H cam (whatever that means) and 194 heads (what ever that means). I had posted a thread about the cam a while ago, because the seller claimed it was a real mean cam, meant for high revs. The car shakes quite a bit at idle, but its hard to tell with the quite factory exhaust. Also it has a super nice idle, probably the nicest ive ever heard. When the revs get below 1000 to 800, you can kinda hear the back fire of a lumpy cam.

I concluded, that it was a 284H cam from crane cams, and 284H was the advertised duration. If you look at their specs for 0.050 lift, its something like 228 duration only, which would explain why its such a nice idle, and can still be mean up top. Of course i wont know until i tear it down, but atleast we can figure out the chambers of the heads.

Supervisor42

This is getting scary. My cam is a 280 with 224@.050 108'LSA. My heads have 1.94 valves. If you pull off that valve cover and see fat double springs, I'm gonna crap my pants...

Sonix

iTrader: (1)

haha, that's funny, that's a very similar cam to supervisor. But I would think the comp284 has a 110LSA, vs your 108 lsa right? 194 heads sound very familiar.. I don't know the stats offhand, but I'm pretty sure I saw a build vizard did using them.. Double humps I imagine?

Mileage is pretty dismal I imagine? haha, hope it's got a big enough stall speed.

11:1 pistons with 64cc heads would probably be close to 11:1 then. That big cam will bleed off some pressure, but (you probably already know this), keep it full of super premium fuel eh? And keep a close eye on the timing. I'd want to be sure it doesn't detonate.
And yea, after you have it running around, check out the heat line, I have a funny feeling you'll want to jump down a few heat ranges actually.

online170

Oh man, supervisor where were you when i posted my cam thread????? I was all confused because this car when turning over to start doesnt sound like it has monster compression, that may be just because of a good starter though. Also, it idles super smooth, unless you dip into the 600-800 rpm range, then you hear the cam a little. It shakes quite a bit also. The one thing that pretty much confused me the most was, it got close to 17" of vacuum. A good running engine will produce 14"-22" so mine is on the high side.

Ive tried a few different fuel suppliers, and i only run sunoco's 91 octane, but ive been itching to try the 94. I dont think the heads are double hump, just judging by the accessory holes. Maybe you guys can tell with the pix, or ill see if i can post some better ones.

As for timing, well dont get mad but, the distributer is kinda loose enough so i can "tune" it by ear if it feels out of sync. Gotta get it into a shop or get a timing light and fix that. Luckily i dont drive it often, so its ok for now.

By the way, i still dont know exactly what the cam is, i just know its a 284H, but your guess is as good as mine as to what company. What kind of timing are you running supervisor? Also how did you decode those piston numbers? I couldnt find them anywhere.


Oh and lastly, the reason my transmission is shot is because its still factory, with the 900 stall. Yes thats right, 900 stall. So when i have to REALLY brake hard to keep it still when in gear. And when you shift into D, the front end pretty much lifts off the ground. So this tranny is gotta go. However im picking up the tranny that was built for this motor in a few weeks, it a TH350 to the eye, but has 700R4 internals, so APARENTLY it can shift into 4th. We'll see when i get it in.

Sonix

iTrader: (1)

Weird, 4 gears in a TH350... ok...

When you get a timing light, and setup your timing curve el perfecto, you'll probably want some 94 octane to be safe.

I think supervisor just eyeballed those pistons. They're domes, and you said TRW, so there isn't much selection with that criteria. They look to him like what he used... Also 7051P is probably the part number no?

Yea, that low of an idle speed, and 17" vacuum is crazy. You must be doing something right... Damn! I'm jealous.
Double humps had accessory holes for a few years IIRC. '69-70. I'm not sure on that part # , 194. but one of the old experts here will recognize it

online170

yea cant wait for that transmission. I know nothing at all about trannies, but the builder was a serious offroader, and so he knows what he was doing. His career is fixing mining equipment in the field, so i figure he was talented.

I may have exaggerated a bit on the vacuum, i like to keep my idle at 1k on the dot. At that point the vacuum is 17" or so. But around 600-800 the vacuum drops to about 10-12"

Supervisor42

This should be your cam here: Crane 284H12
That 228'@.050 look familiar???
Anyway, the LSA of the cam is not listed per-se but the numbers are there for the opening and closing so a little math can come up with the LSA. (I'm guessing the H12 means the LSA is 112') This will have a bunch to do with the idle vacuum etc and timing. The cam I'm running is 108' LSA and it will have different charachteristics than yours. Remember the LSA is measured in CAM degrees so 4' difference is a bunch.
You can hear it idle HERE with the timing (retarded) set to about 6' with 15' of vacuum advance. Total of 21'. If you turn up the volume you can hear one snap when it fires that tells I had 87 octane still in it.
How did I decode the piston? I toted 8 of those bastards around for 18 years waiting to build an engine. Cost me $249.00 for 8 in 1984. They do have a very distinctive look too. They were patented by GM and licensed to TRW.
So they were either TRW pistons in a GM box or TRW pistons in a TRW box.
Throw the box away and it's a choice of 1.
Back to the timing: I don't know if your distributor has been recurved or not so if it has the factory weights and springs it will have to be set very differently. How fast it should rise with RPM will depend on the shape of the combustion chamber of the heads and the actual static compression ratio.
Best way to time it for now is like they say: advance it till it pings and back it of until it don't. If you can't restart it when hot, retard it some more.
When do you think we'll get to see that cylinder head casting number?
I still haven't finished tuning mine because I haven't built the exhaust yet.
Timing is still set in the "safe" zone. On the dyno with turn-downs only.

online170

Wow that helps alot. I remember the guy i bought it from, always complained he couldnt quite get the timing right. Thats why its "loose" the way it is. If you look at the picture, you'll see the engine USED to look like that. At that point, it was not an HEI distributor, that was a later conversion. The seller thought it was probably because the engine wasnt getting enough fuel, but im willing to bet that distributer isnt curved right. So those points will need to be fixed to get the engine running just right.

As for the numbers, im one of those ppl that has more cars than parking spots, and my garage is being used to strip a Van that weve had for ages, and cant seem to sell, so now its time for it to go to the scrapper. Also, the road in front of my house is being repaved, so we cant park on our driveway.

So my car is at a freinds house 20 highway minutes away, until i get more space. however, valve covers, are no biggie, so ill see if i can go down this weekend and take some better pictures to figure out if its a camel hump heads, and what the numbers are.

online170

You can hear mine here. It sounds similar to yours in the 600-800rpm range, but any higher than that,and its probably as smooth as a newer fuel injected car. Ofcourse with the stock y-pipe and factory CAT, breathing through only a 2.5 in or so dynomax muffler, you really gotta listen. Those vids are mostly of me revving, ill see if i can record it just idling for 30seconds or so when i go to pick off the numbers.

http://s111.photobucket.com/albums/n...rebird%20Vids/

online170

Ok, i got the numbers, i dont think they are camel humps, but from what i read, they decoded to be 69-70 heads w/ 76cc chambers. To me the numbers look like 3932441 with a 26-9 at the bottom. Also, no fancy spring work in there.

Also, i tried to get a sound clip of the car, but all it recorded was the vacuum leak, and the carb sucking in air, didnt get the bass sounds very well, thats where you hear the cam. I ran the car at 1000 idle and 700 idle, if interested i can post those clips. Also thats the best picture i could get of the heads. So whats the verdict?

Supervisor42

I liked the "in your face Ben" video.
Man! you have got to ditch those cast iron manifolds.
I hate to sentence anyone to the pain and agony of installing headers but that engine needs them BAD!
You said you already bought a RPM air gap and a holley 750. If you haven't actually ordered the holley get headers first. That Q-jet ain't as bad as you think, it's probably a 750.
Forget any tuning until that is changed because it ain't gonna mean a thing.
Picture for encouragement:

Sonix

iTrader: (1)

Does it have a Q-jet on it now? I thought it had something else, edelbrock or something?
Either way, yea, i'd put my first dime (dimes, many) into headers and Y-pipe.

online170

The in your face ben is a good one, he was making fun of me when the car only laid down one tire line, so i got a little excited when i saw both.

Yea no worries, like i said, i dont drive it very often, and my budget it tight, so all in good time. I have shorty headers, i just got the holley 750 mech secondaries. I know the Q-jet is an awesome carb, but you gotta tune it just right. The holley is pretty well bolt on performance, i bought it from a member here, and its gonna have that "quick" fuel advantage. This q-jet is a later CC model, so im not thrilled with it.

In a couple months, depending on my budget, im gonna go down to speedy muffler, and have them fabricate a 3" Y-pipe for me, which will dump into a 4" cutout just before the cats. Thats gonna clear it up alot. After this year, my car no longer needs emissions, so im ditching that stupid 40lb cat as well. That'll clear it up alot.

Also, i spoke with the guy i bought it from, im trying to buy that distributor off of him. Maybe i can figure out its curve, and have my HEI recurved to that. So i got all the parts lined up, just need to install, and tweek. With a 9-9 schedule though, its kinda tough, so weekends are my only time to work on the car. (i work in the day, classes at night).

So back on topic, did you see the heads? What spark plugs do you recommend? I beleive you said 69-70 were the non-tapered ones right?
Also, with the 76cc chambers, my compression is probably more around 10 or so, and even less DCR, so would it really hurt to get an extended tip? Crap, speaking of tip, i just realized i forgot to read the heat range on the plug. Will have to wait on that i guess.

Supervisor42

Yours are indeed one of the 2. Atleast they are "thick" castings. We don't know how much they were milled or if they were.
They couldn't be milled enough to get close to 64 and still have the intake still bolt up.
Atleast we know now why the dual carb setup wasn't that hot.
That engine should still be 9.6:1 depending on headgasket if it hasn't been milled. That isn't that bad.
The first pictures you posted showed a Q-jet or a edelbrock "clone" of a q-jet, same thing.

online170

Sonix, the very first picture in this thread, is the car in its current state (mehcanically). SO yes the Q-jet is on there now.

Supervisor42

Hey, hey. Easy there. Unless my vision is going bad it's not CC and not even a late "emission" carb (my personal favorite).
Your carb, if it's a 750, will support 425 HP.
Does it have idle mixture screws under the front corners?

Sonix

iTrader: (1)

Gotcha, I missed that for a sec.
That's a non-cc one isn't it? If my eyes aren't fooling me?
If you go to the holley, you'll need to swap to a different bolt pattern intake manifold (or do you have that on the shelf too? I have a bad memory now).
I hope you have a good speedy muffler there, I went to a shop who claimed to do muscle car exhaust, (so I assumed they could handle 3", mandrel bends, etc), and they told me there was no possible way to make a y-pipe fit my hedmann headers. So I bought the one off the shelf . Anyway, you might be better off (cheaper) buying the y-pipe meant for those headers, and adding the cutout right after that, before the cat (singular right?)

And wait a sec, holley is bolt on performance, but the Q-JET needs to be fiddled with? Where on earth did you hear that?!?

Summit has a distributor curve kit for $5. Comes with springs, weights, and bushings (i'm not sure if that allows you to limit your mechanical travel or if it's for something else), but that, with a good dialback timing light, or a normal light and timing tape, and you could set up your timing curve to whatever you want. I have a funny feeling it's about what most small blocks tend to like.

Supervisor42

Oh, sparkplugs. AC R43S or Champion RJ12YC.

online170

Ok first off, doesnt CC stand for (computer controlled?) And if so, thats what this one is. The mixture screws are capped off, it has an electric choke and a sensor hooked up to my dash, it also has that plug connector for the idle mixture controls.

Secondly, i think we can all agree, that the iron intake manifold has got to go. SO i figured if im replacing it, lets do it right. This car is built for high rev performance, BUT i wanted to get some low end out of it too, to be a street warrior kinda car. The RPM Air gap is the perfect compromise. Best value for $. Now the RPM air gap has a square bore application.

SO, i figured, if im adding some bling why not a new carb too? I gotta say, im prolly the biggest fan of Q-jets, but lets face it, its not the easiest track side tuning. The float level is hard to do, you gotta get everything just right, and its very hard to get to. So you basically take the air horn off every few seconds. Holley has got the mechanical secondaries, so thats gonna give me that quick fuel , and no lag of the vacuum. Conversly, im gonna hang on to the q-jet, ive got a square to spread bore adapter, incase i decide to go on a long trip, and dont wanna burn a whole in my wallet for gas.

Next up, the speedy muffler. Yes these guys are good, they are located in Hull quebec, and i live in Ottawa. Not the closest muffler shop, but they are tried and true. JUST ONE GUY there. My freind tried them, he was getting a whole exhaust done on his F-150. Mandrel bent, new mufflers, headers, the whole deal. They even went through a few heat cycles, and retorqued the headers. So i think they will do my exhaust alright. And yes you got it right, its goin y-pipe to one outlet. Ive read about the 2 outlets, but not many ppl do it successfully. So, i just gotta decide what measurements im doing, its gonna be something like 2.5in y-pipe and 3in cutout, or 3in/4in. We'll see.

And thanks for the spark-plug recommendation. Will pick those up.

Forgot to mention: The speedy did it for like $200, so i have a feeling they will do the whole job, for close to the price of a new off-shelf y-pipe.

online170

Heres the best video i shot of it idling. Sorry for the poor quality, blame it on photobucket.

This is exactly what it sounds like when its in gear, but instead of putting it in gear and having someone sit there holding the brakes and frying the tranny, i just turned the idle down. The vacuum reading is around 10 at this point

http://s111.photobucket.com/albums/n...ent=Pix704.flv

Supervisor42

Nice Idle. That's 284' alright.
Don't forget to tell Santa that a 2200-2400 rpm stall converter makes an excellent Christmas gift. That will fix the lunge when you put it in gear.

online170

Hey Supervisor, time to revive this thread. Im getting some work done on my car in a couple weeks. Going to install the shorty headers, and get a 3" y-pipe with a 3.5" cutout in there. Also throwing on that RPM air gap manifold, and my 750cfm double pumper. Need your help with picking out a recurve kit. I was looking on summit and they have one with a few different springs. How do i pick the right one?

Supervisor42

First things first: Get the carb/manifold/headers dialed-in before you touch the distributor.
If we go by the calculated compression ratio of 9.5 - 9.6:1 you shouldn't have to move the curve much from stock. The main thing is to not advance the timing based on rpm too soon that the engine pings. But if you have it advance it higher in the rpm range than the engine "likes", the engine won't make full power. This is the all important "tuning" that you hear people talking about. It's best if it can be done on the dyno or at a track that you can measure ET. We'll change things to make the car accelerate as fast as possible without pinging and still be able to start the engine.
The main thing is that we pitch the factory heavy weights and light springs that advance the timing way too early for a performance engine. They are usually "all in" (fully advanced) before 2500 rpm for gas mileage. We want it all in around 3000-3500 (or more) rpm, but the engine will tell us what it "likes".
I would start with the lightest springs.
The vacuum advance also affects the timing. I would suggest an adjustable advance if your cam likes a lot of timing lead to idle smoothly. (mine does)
I like to refer to it as a vacuum retard because it retards the timing as the manifold vacuum drops. The adjustable advance lets you limit how many degrees it retards the timing when when the throttle is popped open or when the engine is being cranked or lugged. Then there's the big debate over using ported or straight manifold vacuum to connect to the advance...
The total timing should end up around 36-38 degrees before top dead center not including the vacuum advance, depending on combustion chamber shape.
Timing tape (perferred) or a dial-back timing light will be needed.
Goog luck.
EDIT: The weights & springs and adjustable vacuum advance are in this one
KIT.

online170

ok that makes sense. But by get the carb/ manifold/ headers dialed in, you mean installed right???? Ive always been told you cant tune a carb until the timing is done. But yea thats obvious, obviously i wouldnt tune the distributor and then go change the combination.

Thanks for the help!

Supervisor42

I meant don't change everything at the same time then if it runs like crap, you don't know what to tune, ignition or carb. Right now the ignition runs good enough if you spot the engine and mark the distributor you can drop it back in and dial in the carb.