305 is not really a 305! Its a 350, need suggestions

[celeryman22]

Hi, I was always under the impressiont he my engine was a 305. Yesturday I took a closer look and under all of the oil and dirt I found that it is a 350. And it is the original block from what I can tell. The block numbers start 140 or something like that. They have replaced the intake manifold with a different one. So now I have decided to keep the motor!

My question is this, if I wanted to get a little more power can I replace the heads with a new set? I was thinking of replacing the head, intake, exhaust, carb, fuel pump, cam, etc.

What sort of combinations work the best? Should I use trickflow, edelbrock, ...?

Should I strip the engine and have the block rebuilt while I'm changing these?

I have rebuilt the head of a 305/350 before back in high school. The problem I have is I don't know what parts are good and what I need to change at the same time.

The engine seem to run excellent before I ripped it from the vette, it just lacked power?

One thing I did notice yesturday when I pulled the exhaust manifold off is there was an oily residue in the port. Not sure if that means a leaky valve, or if it was oil from somewhere else. And the exhaust manifold bolts where only "finger" tight!
Is there a package for jegs or summit I could get?

Please let me know your sugestions.

 

[Stingray6974]

Need a lot more info first:
4-speed or auto?
rear end gear ratio?
style of driving: cruiser, street/strip, autoX?
road conditions: mostly hiway/some city or?
what are you looking for: low/mid torque, mid/high?
rpm where you spend most of the time
how much do you want to spend?

Mike

 

[celeryman22]

Need a lot more info first:
4-speed or auto?
rear end gear ratio?
style of driving: cruiser, street/strip, autoX?
road conditions: mostly hiway/some city or?
what are you looking for: low/mid torque, mid/high?
rpm where you spend most of the time
how much do you want to spend?

Mike

Automatic turbo 350
gear ratio is 3.55 or 3.07 I believe
just a cruiser
mostly city
rpm where you spend most of the time, this doesn't matter to me but probably 2500rpm
Ahh, the infamous question... I was going to buy a new rebuilt 350 from www.enginefactory.com. So, I would be will to spend that, 3500.00us. But if I can do it cheaper I would like to. Would 1200 be to little?

 

[Stingray6974]

Interesting website. Sounds good but I haven't seen any feedback on them. If they do everything they say then it's not a bad price. Not great but not bad. Going by your description you are wanting a mid-range engine with comfortable drivability.
First you need a better set of heads. Yours have poor flow and are prone to cracking. Edelbrock, Dart Iron Eagle, and AFR (my personal favorite) are good choices. Your main concerns are intake runner size. For mid range the runners need to be in the 180-190 range. 200 is too much. The exhaust to intake flow ratio needs to be near 75%. Match this with a single pattern camshaft (Crane 272). You need a better set of pistons. The factory pistons have a small quench area. Go with a good set of Hypereutectic flat top pistons with four valve reliefs. You will have to adjust the compression ratio to match the heads. Aluminum heads need 9.5-10.0. Cast iron heads 9.0-9.3. A set of headers and a good flowing exhaust system will be needed.

Mike

 

[I_R_DA_ONE]

Hello Celeryman
I have rebuilt a lot of Corvette motors........It is like StingRay..Mike...was saying...
The frist thing you want to do is figure out what you want to do with the Vette...
but always keep in mind that the more original the car is, the higher the value.....and if you make a lot of modifications it will make the value of the car go down...
Next if you rebuild the motor yourself...DO NOT CUT CORNERS....they will come back to haunt you in the end.....
Machine shop work and parts kit on that motor and heads to rebuild should be about $1500.00
This does not include reassembly of the motor....
I always have the motor computer balanced...this is one of the easyest ways to get more horsepower....
Do you have a way to check the compression.....ON a good motor the compression should run from 160 psi to 170psi and not vary to much from that...
I would check the compression before I disasembled the motor.... You can still check the compression by hooking a starter up to the motor and just spinning it over with a pressure gauge in each cyclinder....do it one cyclinder at a time....record your findings for each cyclinder...this will be helpful if you have to disassemble the motor....
WHAT ever you do do not get rid of the original heads or intake....if you change them to something else, KEEP the old stuff.....This is very important because when you decide one day to sell the car, you will have the correct heads and intake for the next owner....This will keep the value of the car from falling to the bottom....
Now for the heads.......have your machine shop do a three angle valve job on them... Make sure they check the spring tension on each valve....
I normally use a TRW tow and go camshaft...this is the best of two worlds..
If you use to wild of a cam ,,,,,your mileage will go down the drain and the motor will not last as long.... and the automatic trans will take a beating......
Speaking of which.....are you sure that is a T350 tranny and not a T400.....A T400 will have a kidney shaped pan on it and the T350 will be square....Most of the corvettes that I have worked on have had a T400.....The reason I ask this question is that the T400 would take all the horsepower that that motor can ever put out....and the T350 maybe kinda Iffy....
As for the carborator,,,,,,I have found that the 1967 Corvette 427/390HP will bolt on your intake with no modifications.....change the primary jets to a smaller size and it will give you pretty good mileage...around 19 mpg
If I were to have someone else assemble the motor,,,I would be looking for someone that has built a lot or racing engines and has a very good reputation for his work.....and not just someone that built a motor every once in a while....A good builder will not be afraid to give a very good guarentee on thier work....100K or better..

I hope that some of this helps
Mike

 

[celeryman22]

Well, heres what I found on the net so far... Can you let me know what you think.
jegs.com
cylinder head partnumber 350-60909
intake 350-27012
carb 350-1400
cam 270-100052
pistons 648-h3437.std or what ever it ends up being.

or should I buy this kit so the intake matches the cam and the carb. 350-3701pk

I'm trying to find my chevy small block rebuild book so I can see exactly whats involved.

Do you need to replace the crank, and rods, pushrods, etc. I know you should, but is the crank something that wears out?

mike

 

[I_R_DA_ONE]

Celeryman

the crank does wear out....have your machine shop mic. it to see how much wear is on it .....then buy bearings to offset the wear....If the crank is not as slick as snot,,it may have to be ground and polished....If they have to take off more than .0015 you will start loosing the case hardness on the crank....then you will possibly have to replace it....they make oversize bearings just for this purpose...

the rods sould be fine unless you are going to beaf up the HP.....then you may want to look at what is know as pink rods...they are of a higher quailty..
I hope this helps
MIKE

 

[celeryman22]

Im going to pull the heads off tonight and see what kind of shape the cylinders are in. The price of a crank isn't that bad I will probably just get a new one. I've contacted summitracing with a list of parts. Does anyone know where i can get a ball brush to hone the cylinders if need be? I read these are easier then the 3 stone type.

Thanks
Mike

 

[goingballistic]

I'm gonna throw in my 2 cents for what it's worth at this point.

I am building a 383 stroker and decided to keep the original matching block in tact for the next owner ( should there be one) I started with a 74 Nova 350 block. I toyed with the crate approach and priced it all out including building my own and it appeared about an even $$ amount for each so I decided to do it myself rather than buy a crate.
Now with that said ( as someone pointed out in a previously) DON"T cut corners, I did not and it is costing me quite a bit more than I originally spec'd for the motor......I'll be over $6K in parts and maching by the time it's all said and done. Now you ask...........why??

Two reasons 1 ) it's a great project with both my boys, we have spent several late nights researching parts and have bought just about the best of everything and employed experts to guide us in the selection, so far I am real happy with what is transpiring 2) The original intent was a street drivable muscle car with some "Oooommmmphh" when you stand on it, that changed in about 12 seconds ( I hoping closer to 11) flat.

By the time this is done it'll push close to 490HP, 10.9CR. I figured if I was going to do this I was going to do it right the first time and I didn't want someone else deciding what parts to put inside without asking me or me deciding because it is my money afterall.....actually my Wife's . I chose AFR 195 heads, Edelbrock carb ( 750 CFM) and manifold, bored 60 over, 6" rods, forged pistons and on and on. I am planning to drop it in after dyno which should take place this spring and yes I plan to race it.

So you kind of have to ask your self some questions. What do you ultimately want to do with the motor and the car and above all............spend countless hours researching if you are going to do it yourself. I wasted over $500 in parts I can't use for various reasons ie an external balanced crank ( when I really should have gone internal), ate the cost of the crank, actually have it up for sale. Things like that weren't decided or understood prior to starting but of course the entire agenda of the car changed in the process.

These guys on these boards have been and remain a wealth of knowledge and some of the combos of parts have been great, just ask and they will help educate you, they have helped me tremendously ( you know who you are )

 

[celeryman22]

Well all I want is a motor with around 300HP and I will be happy. The car right now has little get up and go, drives fine idles fine, but when you punch it, it dies out then goes. In the end I want something I can drive on weekends not at a track, but I want a car that won't get beat by some mustang. I also don't want to get it back together and find out in a few months the motor needs rebuilding, since I have the car totally ripped apart now. I've got a friend here at work that used to rebuild engines in a previous life, he will be able to help me out if I get stuck. My problem is getting parts that will all work together to produce a great running machine. Hopefully Summit will come back with suggestions.

 

[goingballistic]

Summit is a great place to start your parts quest.

Part of the reason I started my build was my wife bought a 90 Mustang 5.0 with an oversized cam that blew my socks off................not for long sweetheart
and now I never hear the end of it. My son and her are both Ford fanatics.

I started with a clean block and can certainly give you part numbers and makes if you want them.

Paul.

 

[tomtom72]

Hi All, Just 0.02 more...IMHO save the original motor, maybe rebuild it later when things allow it. In the mean time why not just get a crate motor? If around 300 hp is good for you the ZZ4 or whatever GM has that's close or dosen't Summitt still offer complete motors? My reasoning is if you don't need a motor with over 350 to 400 hp why bother making one yourself, especially if racing is not the aim? Most of the time 300hp crate motors are nice to live with... gas & all... and they are reliable & come with a warranty, I'm fairly sure GM's does. One reason I said crate motor is when you do it yourself it always costs more than GM, unless you re-use the original motor as a starting point. But if you do that you may alter the ultimate value as a collector car. I had a 72 LT-1 A/C cpe, I rebuilt a 71 lt-1 junk yard motor to fac. spec. to use and kept the #'s motor on the side for later. I should have just bought a crate motor to use in the car & kept the original, it would have been cheeper. At least that's how the $ worked out for me because I wanted the driver motor to be reliable and work on availble pump gas in the late 70's & early 80's. Just my thoughts on the subject if the rarity value of the car is to be maximized. Tom. Happy holidays to all!

 

[celeryman22]

I really appreciate everyones help. The value of the car really means nothing to me in the end. Since this was my dads car I will probably keep it forever. I also paid nothing for it, he gave it to me because he was sick of fixing it. I am going to start with the orignal motor and rebuild it.

Is the crank in these motors steel or cast? Should you use new bearings if you are keeping the same crank or replace them?

How do you know how much HP you are going to end up with?

Mike

 

[vette-dude]

Before you consider buying anything it is important for you to make some decisions as to the following:

1. What are you going to use the car for-street. strip, crusing, etc.

2. What RPM range do you want the power band to be in, (i.e, on the cam at 3,00RPM or ????? rpm.)

3. Cam selection dependent on where you want the power band to be.
(Keep in mind with an Automatic large cams will require you use a stall convertor.)

4. Rear End ratio and tire size (will determine rpm range for power band).

5. Compression Ratio desired.

6. Airflow management, (Heads,manifold, carburator and headers should all work with each other. In other words don't get smog heads, a single plane manifold, put a 1000 CFM carb on in it and then use small tube headers.)

Research all the parts and decide where you are going to get the biggest bang for the buck. If it is a street cruiser and you want power and torque, then go with a mild cam (no more than 270 duration) with a power range from 2,500 to 6,000 or so RPM, a dual plane manifold, 1 3/4 max size headers, and a 650 vacuum secondary Holley or Edelbrock 650 carb. Get a new set of Dart Heads (72 cc size) and flat top pistons with 4 valve reliefs. (This should keep your CR around 9.3.) Recurve your distributor to have it all in by 2,000 to 2,500 RPM. Upgrade your primary ignition components. I'm sure thare are those out there who can add to this and help you along. Competition Cams has a program that you can input different scenarios and it will direct you to what parts are needed to acheive the results. You will need to give them specific info and I think they have the questions needed on their website. Lunati can do this also. I find many of the guys that try to build engines listen to alot of wannabee racers that think because you have a 750 DP carb and headers on a stock 350 you should run in the 11's and have 300 HP. These same guys seem to gravitate towards alot of chrome on their engines and things that look good but don't necessarily make any power. It is good to listen but always ask why the guy that is giving you the advice is driving a 10 year old Datsun pickup and why is not building racing engines. Anyways, I don't drive a Datsun and my last racecar was a 1954 Chevy Bel Air with a Balanced 383 chevy, 3,500 Stall, Ford 4:11, 31 spline, 9" w/ Auburn posi,Modified turbo 350, Tubbed, 4 link SWR rear suspension, Pinto FR with discs, 292 Cam, roller rockers, ported and polished 64 cc aluminum heads, 8 point rollcage, and it was streetable and ran in the high 11's and low 12's dependent on the dragstrip. It was a handful on the street but loved eating Mustangs and Camaros. Hope this helps a little.

Randy

 

[celeryman22]

OK, so I think I found the kit I am going to buy. Its part number TFS-K314-350-400 from summitracing.com
Now I need to come up with a set of pistons. I was told 4 relief valves flat top pistons. Is it possible to get these is a floating wrist pin design? Are there and negatives to getting floating wrist pin, should I stay with pressed fit.

 

[Tom Bryant]

I used these. SilvOLite H1279030 They are Hyperautectic and press pin. Just the ticket for your mild street engine. The part number is for a .030 over and I got them got for $86. from my machine shop. You can find them a little cheaper at Summit and some other places but I didn't have shipping and mu guy cut some other prices lower to make me a good deal.

Check out this thread for a complete review of my low budget mild build. There is also a complete build summary at the end of the thread.

http://www.corvetteactioncenter.com/forums/showthread.php?t=24476

Tom

 

[Jack]

Measure block before ordering major parts

OK, so I think I found the kit I am going to buy. Its part number TFS-K314-350-400 from summitracing.com

Now I need to come up with a set of pistons. I was told 4 relief valves flat top pistons. Is it possible to get these is a floating wrist pin design? Are there and negatives to getting floating wrist pin, should I stay with pressed fit.

Yes, you do not need floaters for 300 or even 500 hp. To fit as floaters you MUST have "bushed" connecting rods. Your stock rods are not bushed ... having bushings retrofitted or buying bushed rods is an unnecessary expense. Many off the shelf pistons can be fitted as either press fit or floater.

Here's a coupla Speed-Pro hypereutectic flattop pistons, both with 4VR, both -5cc dome volume:
P/N H669P w/ 64cc heads & w/ 30 overbore CR about 9.7:1, fit pressed or bushed, 590 grams.
P/N H345NP w/ 64cc heads & w/ 30 overbore CR about 9.3:1, fit pressed only, 546 grams.

With two (2) valve reliefs you'll get a more even burn across with fewer hot spots. I recommend this 2VR Speed-Pro hypereutectic flattop piston that also has -5cc dome volume:
P/N H631P w/ 64cc heads & w/ 30 overbore CR about 9.7:1, fit pressed or bushed, 567 grams.

FYI, if replacement pistons don't weigh very close to OE pistons ... you'll need to have your motor balanced (about $125-$200). Stock cast dished 350 pistons PROBABLY weigh between 500-550 grams.

FYI, many times a motor will need to be decked (machine material from block's surface where head lays) in order to restraighten it. The compression ratio always increases when block is decked. CRs quoted above are for standard deck of 9.025".

Floaters' primary advantage is in their ease of disassembly/assembly on rods ... time is important when freshening race motors on a routine basis. Floaters do have a tiny bit less friction ... but not enough to matter in a street motor.

I strongly suggest waiting to order heads/pistons/rods etc until AFTER old motor is disassembled and measured-inspected by auto machinist. If it needs decking you'll want to closely revisit piston-combustion chamber volumes ... and you can't know what oversize piston is needed until bores are measured. G'Luck.
JACK:gap

 

[celeryman22]

I do plan on waiting, I have my micrometers in the mail to check it for myself. The block is mostly stripped and then its going for a caustic bath to clean it up. I was thinking of swapping out rods anyway just to be safe. The motor only has 100K on it, the pistons are all decent looking and I can still see marks from honing the cylinders. I would like to use floaters if possible, there is just something with me and presses.

Thanks for all the help.

 

[Jack]

Tom's 350 build thread is definately worth a close look ... his piston choice is a good one too. Heck ... if you want 4VR flattop ... I've got a deal. From a project I abandoned ... I have a brand new set of Badger hypereutectic ... equivalent to Tom's silvolite H1279030 or Speed-Pro H345NP ... 30 over ... professionaly heat-pressed onto freshly resized rods ... all 8 piston-pin-rod assemblies yours for $175 + ship. Again, just my 2 cents ... it's spittin' in the wind to float pistons in combo you've proposed. Of course, mike the bores ... but if you can feel a ridge at top then it probably needs boring. Frankly if the bores, journals & decks are OK ... I'd stick a set of rings & bearings in it, new op & timing set, new vortec iron heads, new vortec intake, a comp X262H or X268H cam and let it rip ... for a whole lot less $ than the TFS setup. But, if you're certain to get all new internals & heads ... about same money will build a long-rod 383.
JACK:gap

 

[celeryman22]

Do you need to replace the cam bearings when you swap out the cam. I would think you should, but I cant seem to find any cam bearing kits.

What do you guys normally do.