what would be the results if i took a 350 rotating assembly and put my 305 heads (with some porting and polishing) and tpi system (with a little work, port polish bigger injectors etc.)??????
im looking for a faster engine but on a college students budget. could this get me good amounts of HP and what would i be looking to spend? i was thinking this could get me a good amount of power for cheap since i would be reusing most of my 305 parts and accessories

im sick of getting dusted by preludes etc. i need some great input, i know someone has to have done this before.

EDIT: id also get a new cam for the 350 block and have the heads ported to match that??? would that help out a lil more?

 

lot would depend on what 305 heads you use

 

id like to know this question too, im in a similar situation in my boat it has a 305 with 416 heads and im having the heads rebuilt because they are shot if the block is bad how will they work ona 350 shortblock

 

416 heads, when done up right are a very potent street head. Do a search for Sittting Bull and F-BIRD'88. Both of them have some really good advice on how to get the most out of some 416 heads. Theres a link at the end of Sitting Bull's sig. Click on it. You can port and polish them. Let him show you how.

 

well ive got a 1991 LB9 in the car now. i wouldnt have a clue what heads were on it tho.

i just hope many of you guys have a lot of input here......if all goes well i plan to build my engine from this thread

 

Those 305 heads (081 castings) would be as good as any for the purpose at hand, IF (big if) they're the original ones. Pull a valve cover and check, because it's pointless to try to plan anything around them if you don't know what they are. For all you know, somebody might have stuck some useless TBI heads or something like that on there.

Make sure your 350 short block has dished pistons; specify about a 12cc dish; that will put your compression ratio somewhere in the mid 9s, which is about ideal for a stock TPI setup. Use a cam specifically designed for a stock TPI: not a generic carb cam, not a "RV" cam, etc.

There are a few things you will need to do in order to support a 350, which you can do now, and improve your existing motor. The first is to get rid of the exhaust manifolds. They choke a 305, and REALLY strangle a 350. You will be basically wasting money on a short block if you change that, but leave that exhaust on there. Get yourself a QUALITY set of chassis-specific headers for one of these cars, not some generic Flowtech or other cheapies; SLP, or Edelbrock, would be far better choices. Get a new high-flow cat to match. A cat is about $100 from Summit and such.

I can't imagine a 305 5-speed car, even one with TPI, getting "dusted" by Preludes. That car should have near twice the HP and less than 50% more weight. It should be an easy second to a second and a half faster in the quarter. Is it running right? Has somebody been inside the motor already and modified inappropriately, like slid the wrong cam in it, or downgraded the heads? It really sounds to me like the car has issues beyond just the motor CID.

 

You don't have to get a 350 shortblock to outrun the Preludes (assuming they aren't sprayed). What's required to wake up your 305:

Exhaust - If you don't start with headers and a properly flowing system all the way back, the 350 isn't going to help you any.

TPI - The system is restrictive to a 305, if you don't get aftermarket runners and port the plenum & base, the 350 isn't going to help you any. Adjustable fuel pressure regulator is another must.

Cam - The available aftermarket grinds blow away what the factory attempted.

PROM Tuning - Go to that forum and learn, learn, learn. If you don't do that, the 350 isn't going to help you any.

Heads - Definately port what you've got and install 1.94" intake valves at least (1.60" exhaust valve optional). Reading in the latest issue of National Dragster, I see they allow larger port volumes for 081's than they do for 416's. That surprised me a little, and since we're talking what the NHRA allows for stock classes, it probably means the 081's have slightly larger ports (however, after thorough porting, there may not be much difference). Besides, porting what you've got will allow your base to bolt back on, while 416's would require modification (admittedly slight) to the base. Don't forget valve springs to handle your new cam while you're at it. Screw-in rocker studs are a very good idea, too.

Bottom line: All of the above would have to be done in order for the 350 to work, so if budget is a driver, why spend money on the 350 shortblock? At least for now. Do all this stuff first, see if that humbles the Preludes any, if not (or they're not humbled enough), then go for the 350.

 

Dang, RB beat me to it again!

One reason a 305 TPI 5-speed could get dusted by Preludes is single-cat. Why, oh why did they put 2-1/4" on these poor cars?

 

as of now im running with a gutted cat and aftermarket catback by Ravin. my pipes arent mandrel bent however still look to be bigger than stock. i would plan to put a good set of headers and y pipe on the 350, bigger injectors, port and polish the heads intake and tpi system, get a cam to match everything, invest in some 1.6 rocker arms, maybe a 52 or 58 mm TB, then finish it off with an adjustable fuel pressure regulator, and a custom chip.........hopefully this would happen on a budget (or at least cheaper than an lt1 swap) and give me some serious power

am i wrong?

the reason i suggested this combo was because i read up on a few that have done the 305 heads on the 350 and got good results.......since heads are the most expensive part of an engine theres about a grand saved

 

as far as the preludes...............my friend has a 97 SE (i think) with the si engine (non vtec) and a few mods such as a header, CAI, exhaust, and carbon fiber hood. i know his is more lightweight and is probably pushing 180 HP (im pretty sure 170 stock minus some HP for engine wear) but it feels like he can absolutly dust me when i ride in his car. he chirps all the way to fourth (or has before) and i cant even chirp into second literally. i figured my torque would make up for the lack of HP and more weight (my 1991 came with only 205 hp instead of 215 for some reason)
we havemt run um yet but im afraid to........all my friends think my car is incredibly fast but i know its not......

however this sint about my friends prelude by a new engine for me i just wanted to give everyone the rundown

 

Maybe he's better at typing than he lets on eh?

 

Find out what heads you've got before you start planning anything around them. If you're getting beat by Honduhs, something isn't right, and there's a good chance it's the heads. Until you know for sure what heads you've got, it's all useless conjecture and hypothetical guessing and may or may not have anything to do with the real world. I for one won't waste any time on it.

As long as that TPI is on there, you won't get what I would call "serious power"; but you should be able to make it easily put about 10 car lengths on a Prelude in the 1320, with the 305 still in there. You might get that up to 15 car lengths with a 350. There's just no excuse for getting beat by those things, unless they're running quite a bit of nitrous. Your car should run about a 14.6 quarter mile in showroom stock condition, as compared to about a high 15 or low 16 for the Prelude. A second looks like it's not even a race, the 2 cars should be so far apart (just about 100 feet... or about half a zip code).

OBTW I just have a real fast keyboard.

 

Never assume with your ***. He chirps tires that are probably a third the width of yours. Run him to see what you need, then come back here and follow the advice given. You have given it a good tune right?


Dammit RB! I preview my post and you already posted!! I'm gonna send the Kid over to your house to yank that bloody keyboard!!!

 

I'll just mod another one....

I'm one of those guys that will mod and race ANYTHING.

 

Oohooh!! I got a Tecumseh powered mini-rider that I'm willin' to run on!! If it doesn't blow the rod I'm good to go!!!


I had a neighbor that just could not fathom why I tore apart my Dad's brand spankin new (2 days old) taurus 3.8 (back in '90).
Dad comes back from vacation... 'Gee that cars pretty fast for a six, glad I bought it!' (in Greek though). I still don't think he knows what happened. I even toyed with my brothers dinky escort! I just can't help myself. I even screw with my lawn and garden equipment. It's too fun! I need to enter Wrencher's Anonymous!!

 

Oh yea RB, BTW, I got a 30 cu. in. four banger in the shed... any ideas what I should do with it? Go-cart maybe?

 

Ya you should own his xxx little honduh, like somebody said before hes chirping through **** probably cuz his tires are 1/3 ur size and cheap as **** plus if im not mistaken that gay car is front wheel drive

 

I'll 2nd that.

I bought an '87 LB9 engine complete, was supposed to have been "stock", found out it was bored .040"-over and had one 081 head and one swirlport!

RUS, it would be interesting to know exactly what size this gutless cat is. If you could, measure the OD of the pipes leading into and out of it.

 

i can go measure the cat later tonite however lets say i do have the "good" heads (i dont even know which ones are the good ones or why) will this setup give me some power over my measley 205 hp now? also, if i were to take a set of 350 heads instead of the 305 heads i was planning on using would that produce more power or due to the higher compression will the 305 heads produce more power............if both had some porting done to them?

 

The "good" '87-later 305 heads have a casting number that ends in "081". You have to take the valve cover off to see it.

All other things being equal, including compression, the 305 & 350 heads will produce the same power. Build it for the proper compression, based on which heads you use. As RB said, if using 305 heads on a 350, use dished pistons. If using 350 heads on a 350, use flat-top pistons with valve reliefs.

 

well my casting on the drivers side head was 14101081.....so i guess its a good one!!! as far as the cat........the best measurements i could get were approx 2 1/4 in and 2 1/2 out. however the in could have been 2 1/2 and the out could have possibly been 2 1/4. i was hard to measure, i dont have one of those caliper gauges or whatnot.

heres a pic of the cat from the ypipe, note my horrible exhaust man

 

and heres the cat going out

 

Suspicions confirmed. It's primarily the exhaust that is holding you back.

Suggestion (all p/n's are Summit): Hooker HOK-2055 headers, Catco CTO-9118 direct-fit cat. If your cat-back isn't 3", then get one for the '86-'90 TPI single-cat application (basically whatever you want to get). That alone is going to make a big difference, and unless/until you do that, no other modifications are going to do you any good.

 

so is that whats really holding ALL my power back????? i know the exhaust is a very important aspect however i didnt realize going from 2 1/2 in non mandrel pipes to 3 in mandrel bent pipes would make such a difference. i plan on headers and a new y pipe anyway since that can be interchanged to my 350 but just last year i (my father) spent like 350 bucks for this cat back exhaust. if i do go with a new exhaust can i get away with just the pipe from the cat to my muffler? the ravin muffler is in great shape and flows excellent.....

 

Looks like your exhaust is a complete mess.

Incidentally, that's a perfect pic of why I always recommend buying complete aftermarket exhaust systems and installing them yourself. Maybe take them to the shop to get tweeeked and welded afterwards. Yerbasic "custom" exhaust usually ends up being a hack job; they figure you can't see it and wouldn't know what you were looking at even if you could, so they just stick whatever crap is easiest on them in there.

I don't know about "holding all your power back", but it's definitely a restriction. Especially if it has a 2¼" inlet to the cat. That's TBI/LG4 stuff, has no business on anything resembling a performance car.

I don't think you realize how big of a difference there is, going from 2½" to 3" pipe. So let's run the numbers.... Flow is proportional to cross-sectional area. Cross-section is the diameter squared, times pi, divided by 4. The pipe size number is the outer diameter. So, assuming the pipe is 1/16" thick, the inner diameter is 1/8" less than that. For a number of reasons, very little gas flows right up against the pipe; about the outermost 1/8" is useless. So that's another ¼" off of the effective diameter. So: for the 2½" pipe, that leaves an effective diameter of 2-1/8"; squared, times pi, divided by 4, it works out to about 3.55 sq in. For 3" pipe, it would be 2-5/8" effective diameter, which works out to 5.4 sq in. Significant, no? Then look at all those dimples in that weenie pipe, and figure out how much diameter those eat up, which looks to me like near about another quarter inch, plus all the turbulence they introduce; a 2¼" pipe made like that would therefore have a cross-sectional area of about 2.76 sq in. About half the flow capacity of a 3" mandrel-bent pipe. Plus the effect of the turbulence, which reduces the flow capacity even more.

Like I said, go get a set of headers and a high-flow cat; the better headers such as SLP and Edelbrock (I don't know about the Hookers) will come with a Y-pipe that bolts up to a stock exhaust if you get good ones, and the Y-pipe will be MUCH larger than that drinking straw you have now. Same for the I-pipe. If your I-pipe and muffler inlet are 2½" or smaller, then those need to go to, regardless of what brand or age they are. They're a bottleneck.

 

whoa.........i think i got it lol! i plan to get some headers and a y pipe, apparently soon but i have no cash but as far as my cat.....would i need to get a high flow cat? or can i just butt the i pipe up to my y pipe? we dont have emissions testing here (it may come back but not likely) and wouldnt that flow even better? after gutting my cat i noticed an immesnse difference in the tone of my exhaust and i love it, id hate to get rid of that sound

 

I know a lot about the Hookers personally, and have heard and seen what I know about the Edelbrocks and SLP's here (as well as a couple of magazine article mentions about the TES). The Hooker y-pipe is superior to them all, and I only have one nit about the headers (collector ball flange opening - easily fixed).

They are direct-fit for the '86-'90 TPI single-cat application.

You can't butt the cat-back to the y-pipe, but you can put a piece of 3" pipe between them. From a federal law standpoint, that's an "off-road only" modification. For ~$120, you can have a great high-flow cat that will bolt in. Personally, I haven't gotten any vehicle out of an exhaust shop for less than $120 for several years, regardless of how simple the task was for them (just a short piece of 3" pipe cost me $15, and they didn't install it even).

There's an outfit (Mac, I think), that makes a cat "test pipe", that's still over $50 IIRC.

 

get a carsound cat, they are great and new for $39 on ebay

 

I didn't have any problems with the preludes with my LB9. Fix your exhaust, then you can teach them something. As for the 350, I just finished mine. It has the stock 305 TPI and the stock LB9 cam in it. My heads have the same CC, but they are aluminum. I also threw on some cheap headers while I was at it. If you do get around to building one, you won't be disappionted. Good luck,
FBird

 

Here's a pic

 

CamarosRUS, that is one ugly exhaust. The shame is that your cat-back is hacked now as well. In fact, what I'm going to guess is that either your cat back was wrong, or someone put in a much smaller cat trying to mickey-mouse the exhaust. Does the pipe diameter change from one side of those welds to the other?

For what you are trying to do, the edelbrock stuff won't be bad either. Just coat whatever you get for headers or you'll have top replace them sooner than you would have thought.

The setup I usually use for daily drivers or commuter cars would be the edel TES headers, cat-co cat, and then I try and get the dynomax cat back pipe and a flowmaster muffler. The dynomax pipe is 3" till the end. They conveniently make a clean neckdown which is axcellent for cutting off. Likewise with the flowmaster, so if you cut correctly you have a smooth 3" all the way into the muffler.

But for no cash, I would cut to the outside of each of those welds and pipe it for now. If you were closer, I'd help!

Now once thats done you really need to do a good tune up as well. I think this is where you'll find a few more problems. Don't be afraid to use the autopart store's brand wires and stuff. The cheap stuff works as well, as we have concluded in another post, "Electrons are notoriously non-patriotic".

 

ok well im on a budget especially right now so say i were to buy the hooker headers out of jegs (part no. 520-2460) for $150 would those be good enough and would they come with a y pipe??? if so then ill purchase soon and get a new cat to go with the setup. then have a new 3" mandrel bent i pipe to fit to my muffler......now a few more questions

will the ypipe i get/need bolt up to a high flow cat? and would the cat have a 3" out to hook up to my new ipipe?

 

Wrong ones. You need 520-2055. Nobody makes a bolt-in y-pipe for the 2460's, including Hooker. You'll have to have a y-pipe fabricated, then you're right back where you are now.

The 520-2055's will do all that I said. Don't try to skimp here, it'll just end up costing you either performance or more money. Save up for the right stuff. The "direct fit" cat is just that - fits directly without any modification for the '86-'90 TPI single cat application headers, cat, and cat-back. And it's 3".

 

ok those are defenitly noce however ive gotten rid of my AIR system and dont really want the air tubes stuck on my headers but i still need the oxygen sensor mounting location........any other alternatives?

 

The $150 Hedmans and their $100 y-pipe.

 

thanx five7. thats what i was looking at and wanted to be sure they would work out for me and the 350.

i think ive got everything i ill need do do the swap. ill list it in purchasing order and things with an asterisk i want to buy and perhaps throw on the 305 until i get the 350 shortblock rebuilt.

headers and ypipe w/new i pipe*
AFPR*
1.6 rocker arms*
valves to match*
port tpi and intake and runners*
port and polish heads*
then rebuild the 350 short block and transfer everything over
get a cam to match my heads
get a chip burned
bigger injectors
new ignition
then nitrous!!!!

am i leaving anything out?

also, would my stock runners ported be worth it or would it be wise to buy new higher flow runners?

 

TTT

 

I must put two cents in.

The 2460 Hooker headers are sold on Summit with the offroad pipe for about $200.00. I ended up getting it because I had the headers sitting in my garage forever. the part number is:
HKR-16767HOK

 

Your two cents are about 16 months too late. Check out the date of that last post

 

yea lol. well to at least update everyone ive learned so much in a year and a half. like cars always feel faster in the passenger seat. and good clutches and smaller tires will enable a front wheel dirve car to chirp 4th.

since the exhaust was a big part of the thread ive put the headman headers and y pipe on with a full 3" mandrel exhaust, no cat. weve raced a ton and its not a race really. as soon as i get traction in 2nd im gone. ive put my car to a best of 9.17 @ 78 hes done like a 9.6 somethin (which isnt bad at all for that car). hes since then ported his head, gutted his car with a test pipe, and got crower cams for the car. i still walk him but top end he pulls a little more than he did.

and as for the topic of the thread...im building a forged 383, trickflow heads, custom comp cam, and a HSR pretty much right after this thread i started buying and saving parts for the new motor, now i just gotta build it!

 

Still in college?

Oh, the 2460 y-pipe came out after it was last discussed in this thread.

 

shoot, i didnt notice the dates on the thread till someone pointed it out. good thing it was dug up though, its helped me pick out what headers and y pipe to get.

 

yup, still in college.