I have been a member for over eight months, and this is the first time I feel the need to post. The search button has been awfully wonderful to me. I knew nothing about these or any other cars, but thanks to you and only you, I have installed spohn weld in subframe connectors, spohn front and rear sway bars, spohn wonder bar, poly bushings, bilstein sports, sportline springs,and complete front end rebuild kit. I have never driven a car that has handled so wonderfully.
SO to the point. I bought a complete racecar (a stripped down nova) from this guy that I work with for $3000. All I wanted was the engine and tranny so I am currently selling off the parts that I don't want and have collected $500 for the rims and rear end so I'm only in for $2500.
The engine has all forged internals with iron eagle heads ported, polished and shaved down to 55cc combustion chambers coupled with srp forged 11cc domed pistons (jegs #867-140678) and a really aggressive cam, he said it produced 590 horses at the crank. He also has a nitrous extreme kit with a 100 to 200 adjustable shot that was included. My problem is that the combo produces almost 14:1 compression.
All I want to do is get this engine streetable on pump gas and into my car with as little additional investment as possible. If I get new heads and cam I would like to spend about $1500 to $2000 because I don't want to put crap in my car.
Jegs sais that the pistons with 76cc combustion chambers will produce 11:1 compression and with aluminum heads, this should be doable. I would think something like afr 74cc aluminum heads with a big gasket would get me there, or would changing to a flattop or dish piston and keeping the same heads I have on there now be better.
I don't want the fastest car around but I would like 375 to 400 at the crank for this car (92 rs 305 tbi) so I think I will switch to carb Because I don't want to tune the tbi.
PLEASE HELP AND CRITICISE ME (but forgive my ignorange)

 

Both components of your compression ratio (combustion chamber size, and piston) are made for higher compression (which is why it is rediculously high now). So either way will get you lower compression ratio...the heads being the easier of the two.

Although I find it kind of hard to believe that these numbers were acheived on a 305 TBI.

 

No the racecar and engine was a nova. the camaro has been mine for over a year and is still bone stock in th engine department and is ready for a transplant. Sorry for the confusion, I now have a tired 305tbi in the car, and an awesome engine in the yard, waiting to be dropped in.

 

I'm so sorry I forgot to mention that the engine I'm going to swap in is a 350 carb. I now have a stock 305 tbi with 170,000 miles and all original. I tried not to be too long winded.

 

Ohhhh, so you are swapping in the race engine. Well, like I said, that CR will not do for street (obviously). The cheap route would be to replace the pistons, but requires most work. The expensive route is the heads, but will be easier to put on.

Either way, I'm not too sure that car will be very streetable. You might get it to run on pump gas, but don't expect good mileage. What are the specs on the cam?

 

the car never was and never will be an everyday driver, just a weekend driver. I really don't care about mileage as long as I can get at least 10 or so. The cam he has in there is huge, the only thing I can remember is .690 lift. No matter what I do I will change the cam to something milder. If I would have built the engine from scratch I probably built a 383 but I came by what I thought was a deal, just not exactly what I wanted. Could I possibly run dish pistons with the iron heads and change the cam?

Thanks in advance

 

I'd say you can safely do that. If he had valve clearance with a .690 cam and dome pistons, then you will have plenty of room with a smaller cam and dished pistons.

 

Hey thanks alot guitarjunki17. DO you think a dished piston would be the most sensible way to approach this. The car will almost never see track use and is only used about 20 miles a week, but I would also like to be able to drive in city traffic without overheating. How low do you think I should take the compression? Oh yeah I would still like to run 150 shot of NO2. Should be OK right?

 

Sell the motor and pick up a 350 and put some vortec heads on it, with a XE274 cam and you will be very close to your 400chp mark. If you want something a little tougher, Scat 9000 crank, scat rods, probe forged pistions.

I just hurts to see a nice motor like that be reworked into something milder. Im sure you could start gathering parts, and meanwhile find a buyer for that monster you have now.

 

I did think about that, but its kinda hard to sell the engine when I don't know exactly what the cam specks and such are. Besides it already has headers, trany, nitrous, carb, starter, and radiator hooked up to it. And I'm only in for $2500 so far. I may put it up for sale on the boards here because I know some of you hardcore guys may consider what I'm trying to do sacreligious. I am in south Louisiana by the way if any of you guys are interested. It was professionally built and only has 2 miles on it.

 

For 20 miles a week, put race gas in it and call it good

 

I did think about that, but would much rather the convience of pulling up to the pump or tanking up at some ungodly hour for whatever reason. After all I will only take the car to the track once so when somebody asks "what does it run?" I can honestly answer.

 

Well, it's running fine at the high compression with NO2 correct? You said it's already hooked up. You can take it down in the 9's and still be safe I believe. I mean, I know that there are cars that have forced induction and are on the juice. In order to run boost safely, you need a lower compression. Ask around in another thread to get more specific answers.

If you are content with ripping out the rotating assembly to change pistons, then that is fine. It will be cheaper too. You might just consider a whole rebuild while you are at it..bearings and piston rings and whatnot. Looking at around $500 there. Just make sure you check for clearance beforehand. No doubt you will have issues if you don't change that cam to something less mild. Do your research first before sticking everything in and starting her up.

 

Thanks again guitarjunki17. I love my car and would never just stick something in and crank her up. I'm talking to a guy with a race shop down here and he says to go with the 76cc chambered aluminum heads and bring the compression down to 11:1. The reason I posted here is I have learned so much here just by reading other peoples posts that I wanted for you guys to take a stab just to see what you would come up with. I hope I don't sound dumb, but I won't do the work myself either way. I will prolly get him to do it for me. He owes me a favor and says he'll do the swap by himself without me turning a wrench for $550 if he doesn't have to take the engine apart. I think that will be best because I could get some cash for the heads and cam that are on there now. Thanks you guys.

 

swap to dished, forged pistons. Have the rotating assembly rebalanced. Go for 10.5:1 CR or so. AL heads right?

That cam is useless to you. I'm guessing solid roller. Get something in the 23x intake duration @.050 range. A solid roller again. Lashing valves isn't hard. You can probably re-use most of your valvetrain.

Going to a 76cc chamber will still have too high of CR IMHO.

 

The heads now are iron eagles so 10.5cr is probably too much. I was going to get aluminum heads with 76cc chambers. I also feared that 11:1 would be too much. Are is there anything else I could do to bring it down a little more without ripping apart the rotating assembly? Oh and yes it is solid roller.

 

you could port open the 76cc heads a bit probably.
Maybe a thicker head gasket.

Hard to say what your CR is until you measure it all up and do the math. Piston depth, bore size, head gasket size that you will use.

ok, maybe 10:1 then with your current heads. I think you can do that with pistons easier then with heads. 15cc dish type piston would do it, with a 0 decked block, and .039" gasket.
With heads you said you can only go as low as 11:1 you say?. With AL heads, and a decently large cam, that's not unheard of.

 

I don't have the time or the tools to do the work myself which is what was making me lean to the head solution. I just posted another thread on my aluminum head solution. Maybe I should have waited until this one ran its course.
Anyway, How thick is the thickest head Gasket you can get? Is there any way that I could get it down to 10.5 or 10.6 static cr? The iron heads on there now have been extensively worked, maybe I should just have the engine rebuilt. Or maybe I should sell the whole thing and spend the 7-10 grand I was thinking of spending on having a stroker and tranny built. Sometimes this hobby is so confusing!!! But cmon, how many of you guys would have passed on a sub 10 second racecar for 3 grand?
sonix, what brand of pistons would you suggest if I were to rip apart the rotating assembly?

 

I woulda kept the nova, and drove that around

ok, you can probably sell that motor for some big coin. That's probably the best course of action. However I think selling a used racing motor is quite difficult to do. So lets say that's not possible.

Take off the heads, and measure the piston depth, a feeler gauge and straight edge is needed for this. Well, to whoever is going to do it, i'm guessing you have no engine stand to work on this with?

Anyway, I was assuming it was 0 decked, since it was done up as a race motor, that's a fairly safe assumption. But i'd want to be sure.
You can get über thick head gaskets, but they kill your quench. Having high CR, and no quench is a recipe for detonation.

You have 6" rods (as per the part # on your current pistons), so new pistons to mate with 6" rods would be needed. Those are expensive.

I'd seriously think about selling the whole engine and using the cash to get a more sensible motor.

 

Yes the rods are 6 inch(jegs#356-crs6000b3d). Also I love novas too (when I was younger I had a 70) but when I say stripped down it was nothing but a custom made tube frame and some sheet metal with a seat, a wheel, rims tires and rear end.
Still I'm thinking if I change the rotating assembly I'm still doing good because for 2500 bux I still have the iron eagle ported and polished heads, complete nitrous express system, hooker headers, seasoned block, turbo 350 tranny with transgo shift kit, mds complete ignition system, carb, starter, aluminum radiator, edlebrock performer intake... I really ought to sell this thing or at least try to trade but my 700r has 170,000 miles on it so I would have to rebuild it also if I put in a new engine. $$$$$$$$$$$$$
ok... Lets try this.... I get the 76cc chamber aluminum heads, and assuming the block has been decked to zero, how thich a gasket would I have to get to get static cr down to 10.8:! or 10.5:1. and would this "kill my quench" enough to cause detonation? Am I asking a question I already asked? Is there hope for me and my quarter mile motor?


Edit: I don't think the engine is decked to zero because with those pistons, a static cr would be around 15:1 and I don't think it was that high.

 

ok, so if you aren't gonna sell it, then take off the heads and find out what the piston depth is. With domes it's a little harder to do, but not impossible. Find out what it's been decked to, then you can find out what your CR is.
You can go to a .050" thick head gasket, I think if it's a decent quality one, and you torque down your heads right, you shouldn't worry about blowing it out.

 

Thanks a million sonix. That's exactly what I was looking for. You guys are so helpful. If I were to change the rotating assembly, what would be a good set of dished pistons to go with for maybe the $500 range. I am a little flexible. Also, where is the best place you guys think I Can get them?

Thanks a bunch guys

 

I've just been kind of watching where this thread would go and thought I'd throw something out there. The bottom end of this motor is obviously built pretty stout and as said before, it would be a shame to compromise what's already a good combo. I think and easier way would be to go with an aluminum hear(say an AFR 200 to a 210....a 220 would be too big for that cubic inch motor) with a 76cc chamber. The fel-pro standard permatorque gasket is plenty thick to lose a little more compression so what you'd end up with would be a still-streetable 10.5 to 11.5 to 1 ratio. The aluminum heads would keep the heat low and if it still seemed to much a cam swap to me would still be better than destroying the bottom of a good motor. Go with a stick that has some more overlap and duration(a good nitrous cam will do it every time) and it will bleed enough cylinder pressure off to keep detonation at bay while still keeping the motor a crisp compression ratio that can be driven on pump gas. Heads and cams are an easy swap compared to tearing into a bottom end. Hope it works for you and if it gets bad enough I've got a whole ls1 combo that will work.......... lol

 

If your friend owens a shop have him do a leak down test to the motor first make shure you have a good short block.I would then remove a cylinder head and find the part # to the pistons to see there adv comp ratio.Or just cc one cyl for real comp ratio. I would not use dish pistons in a 350ci motor Flat tops are great even with iron heads. If you can get the comp down to 11.0 or 10.8 you will be ok on pump gas with the right cam choice.Do the AFR 195 with the 76cc chamber and a smaller cam you also wont have more money tied up in having the motor re blanced.

 

Ok bygblok, with that fel-pro gasket what size aluminum head would be a good choice if 76cc is too big? And what exactly does "too big" mean? I'm not being sarcastic, I really want to know the best way to get this combo running. Most people I talk to around here will do it with me and charge only a case of beer, but I hate people who take perfectly good vehicles and modify them half @ssed.

Oh and I also have the MSD ignition system that was hooked up to the engine. Can I use this box or do I have to modify it? I don't know much about MSD except that the people who have like them a lot.

 

the 76 is not too big in chamber size...what I said would be too big would be the AFR220. Too big was the reference in port diameter or "flow" which means 220cfm per intake port. That large of a port would kill a small motor like a 355 but would work very well with a 383 or larger motor that demands more volume and has the size to keep port velocity up enough so the head is efficient. With the setup you have a 195 to 210 port size would be great.... the smaller 195 would probably be a better street head since you rarely see above 6,000 on a street motor and generally it is much lower than that. I wouldn't touch the bottom of the motor but it was suggested that you at least pull a head(if not both) and find out exactly what it is you have as far as pistons, chamber size on the heads, etc, etc. Even things like deck height come into play when you're talking about this kind of motor since it has a huge affect on compression ratio as well and can also make you wonder about things like have the heads been angle milled, how much of the block deck was milled, will a standard intake work on it.......... a million different variables can come into play when you're talking about not knowing "exactly" what you have. I'm not trying to burst your bubble about your motor at all. As a matter of fact if it's that nice I wish I had it here because my ride would be rolling this weekend!! Then again, I'd probably tear it down unless I knew the history of it and who built it anyway. The right heads, the right camshaft and you'll have a good streetable combo. Then again, keep it as-is, throw a flying toilet on it and use alcohol..... sounds like it would be a good candidate for some duty at No Problem dragway in LaPlace to me!!!!

 

Hey thanks for the explanation bygblok. I had to read it twice, but you did educate me. So my best bet would be 195 port size with a 76cc combustion chamber, and one of those fel-pro permatorque gaskets, right?

Don't worry about bursting my bubble. I really didn't know what I was getting into here, but I'm learning every day. When people at work used to talk about cars, they had just as soon be talking about quantum physics to me. Thanks to you guys I can now follow them, and even declare BS sometimes.

Does anyone know about the MSD box though? Can I use that if I change heads and cam to a pump gas combo?

 

Ok how about this.....

If the engine hasn't been decked at all (I believe I read here stock deck height is .025) then 74cc heads with my pistons and a fel-pro .039 head gasket (jegs #375-17030) should give me a cr of around 10.5:1.

If the engine has been decked down to zero then my pistons and 74cc heads and a .061 fel-pro (jegs #375-1144-061) should give me a cr of 10.6:1.
This all according to united engine's cr calculator.

The 6 inch rods and everything else can stay right? anything else to change? Should I be good or am I missing something? It can't be really that easy can it?

 

You're on the right track you will also need to change the cam. And dont be afraid of 11.0 to comp. a cam in the 248-250 dur @.050 and it will run on pump gas I like head gaskets in the .040 range. Also remember you will need about .035 clerance between the piston and the head.You're MSD ignition will work fine. It may need some tunning for the new combo.

 

you can run 11.1 with the aluminum heads with no problem since they dissipate heat better and generally the chamber design is a tad better. They also tend to "absorb" a small amount of detonation since the material is softer(at least in theory it works) The cam specs Ross gave are good but don't go with too short of a lobe center(stay up around 111 to 112 even with the roller) and it should still bleed enough cylinder pressure to make it streetable. Like I said, pretty much any GOOD nitrous or blower cam will tend to give you those results. Oh, and the 6" rods are great. The longer the rod the less stress on the rod itself because the geometry changes to the good side.

 

I think you would whant a cam with 106-110 lobe sep nitrous cams try to eliminate pressure bleed off.

 

Wow, I'm sure learning alot about these cars and engines, but I have no clue about cams. If anyone cares to explain just a little I would really apprciate it, but if not I will do some research on the internet and this site because I know its been asked before.

As for compression and cam, this is all I know; I don,t want an idle like a dragster. I do like idles with a little lope to them though. Will the larger compression numbers make an engine choppy at idle or does this solely rely upon cam choice? That is why I wanted to take it down to about 10.5:1.

How many horses do you guys think this combo could make with a decent cam that isn't too choppy?

thanks guys

 

Am I asking a stupid question, or should I consult the the dealer of the heads that I am going to purchase?

I did some research last night, but couldn't find exactly what I was looking for because this entire setup will be an odd combo. Should I start a new thread for cam choices, or should I allow this one to run its course?

You guys have been very helpful so far

Thanks a million

 

You need to pick you're cyl heads then we can give you a cam choice and like stated before pull the motor apart and see if it has a roller or flat tapet cam. As for the idel its going to be a bit choppy. Look at the AFR 195 heads with these heads and agood came you will make 320-350 rear wheel horse power.

 

I know it is a solid roller and I am going with afr 195 74cc chamber as soon as I pony up the cash. The compression ratio goal for the engine is 10.5 to 10.6:1. The only reason I am not going to the limits with the cr is because I don't want the engine to be that close to its limit just yet. After all 11:1 cr will be only a thinner head gasket away right?

Ross, I know the idle is going to be a bit choppy and I like that. I don't want glass smooth, but I don't want people to hear it and think that I have a top alcahol dragster under the hood.

SO.... How about it guys

-solid roller cam
-afr 195 aluminum 74cc heads
-no dragster under the hood
-350hp at the wheels sounds niiiiiiiice
-150 shot of the juice

 

Ok with a solid roller it will sound a little less racey or at least my soild rollers sounded more tame. As far as comp remember a thick head gasket will lower comp but also you will raise your qwench area wich can also lead to detonation.

 

Ross, would 11:1 with .041 would probably be better than 10.5:1 with .061 gasket? I was worried that I would have to run too large a cam to run 11:1 on the street. Thats really the only reason I wanted lower than 11:1 static.

 

Use the .041 head gasket you will need a good sized cam also remember to go fast it not only takes a good motor but also the right exh. system,gear, converter and so on.

 

Yeah, I know. I've done my research on that part. The hooker headers that are on the car have 3 inch collectors, so 'i was thinking 3" custom y pipe into a single 3 1/2 incher all the way to the magnaflow (which is already on the car) with no cat or highflow cat.

Gears are 2.73 which I know people will say are to high but I have read that the 2.73 may allow me to get into the nitrous off of the jump without spinning the wheels, but anyway they are what are in the car now so they are worth a try. If I don't like them I can always switch later.

The rear end has posi (it had it when I bought the car) so I figured I'ld try to keep the 2.73 because the engine is already mated to a th350 and I don't think my tired old 700r will hold up for a week to that many horses. My plans for the tranny are to install a t56. If I do I wil go to a lower gear ratio because of the double overdrive.

........All that said, what about the cam?

 

with as much camshaft as you'll be running a good(and I mean GOOD brand) converter and at LEAST a 3.42 gear will be needed. The 2.73 will KILL anything you may have to offer off the line. I went from a 2.73 to a 3.42 in my facotry rearend and now the 9" has a 3.90 which has made all the difference in the world. I really want to do a gear vendors overdrive too which will put me in good shpe to do poer tour with it which was the long-term goal the whole build. Take your time, gather the right parts and THEN put it together. You'll truly be amazed at the results. Oh, and the AFR 195's are a super head and if that doesn't sut your needs RHS makes a 200 also that will do almost as well. I'm pretty partial to the AFR's though. Good history with them.

 

I've looked at the gear vendors overdrive too, but man they are like $2400. But not that bad a price for turning a th350 to a close ratio semi auto 6 speed!! I think I will get the t56 though because I like to go through the gears by hand.

I want to get the engine in soon because I don't want it to freeze up or anything. Its covered and all but I just don,t want it to sit up for too long.

 

I have to row the gears on my th350......... manual valve body!!!! The shifter looks cool in the original console too. The gear vendors would solely be used for driving back and forth to the track and doing power tour. I only use a 3200 converter so it's not a huge deal with too much stall. Honestly though, 2.73 gears are gonna take the fun out of it and you'll build a huge amount of heat in the trans with the converter slipping all the time. You'll need a gear........can I interest you in my original with the 3.42's, an auburn posi and a t/a/girdle?? lol The 9" is in so I don't need the stock rear. Gears have a slight whine(I missed a bit on my backlash from what I can tell) but work great. It's a drum brake rear(the 9" also has discs) and it's just taking up room here. I'll make a deal!! lol

 

Do you think it will still be a dog down low with a 150 shot off of the line? I want to keep the stock 16x8 rims.

I sent you a pm

 

Even with the nitrous it will need more gear than you have now a 3.42 or 3.50 is a good compromise.And are you planning on using the headers from the nova?

 

I was but they are really large (primary an collector size) and are not coated. I prolly will unless I find someone who wants them because it will cost a few hundred to ship and coat and for a little more I could get new coated ones. The ones on the engine now are hookers.

By the way I'm really stoked that I had over 400 views on my first post. I was worried that you guys would just tell me I'm in over My head and the whole thing would be over in three posts........cool

 

if you don't have a good gear hitting the spray off the line will only do one of a few things.... It will cause the tires to go up in instant smoke(best) It will drive through the converter until it bakes(bad) It will drive through the converter AND cook the trans because the trans just can't take that much heat(worst) so yes, a gear will be needed if you intend to spray it at anything below say....30mph in low gear with those 2.73's!!

 

Ok is your really for sale or were you joking?

 

I really AM going to sell the stock rearend from my 92. Haven't thought about it a bunch since I'm at a standstill right now on the car. Let me find out what they're going for and I'll deal with you some. It's a stock, 28 spline rear from my 92 RS that now has an auburn posi carrier, a GM 3.42 gear and a T/A braced cover for it as well. Like I said, it has a minor whine to it(my fault for missing on the backlash a bit) but it's never gotten hot or had a problem. I only changed it because I knew my LS motor would end up breaking it and I got a hella-deal on my 9" too. If anyone has an idea of what this rear might go for chime in. Oh, I work in Biloxi too so I can deliver it part of the way to Lowsy-anna if you can meet me somewhere.

 

Ha ha ha ha.. and so many comedians out of work....

Yes get back to me, Biloxi is about two hours from me. If I would take it apart and reset the backlash the whine would go awat right?

 

you could take it apart if you wanted but I don't think it's bad enough to warrant disassembly again. Besides, when I put my spin tecs on I couldn't hear it at all!!