I have a 88 5.0 tpi 5-speed 3.08 gears.
I need opinions think it will be a beast, not concerned about gas milage lol !!
I want this car to fly, so here's whats getting done !

Port and polish heads
shave the heads
port match intake, and intake runners and throttle body
Mill for 1.94 valves
bored 30 over (310.3 ci)
Flat top pistons
hedman 3" headers with 3" full exhaust with flowmaster 80
Drill heads for 1.65 roller rockers (5.26 lift with 1.65 rockers)
Comp roller cam (Part # 08-305-8)
rpm 1800-5800
lobe center angle 114
intake center line 110
Duration 276/290
Duration @ .050"lift 220/230
Valve lift .510 .510
Fuel pressure regulator

 

I don't want to make this a 305 vs 350 thread, but if you're going to pull the engine and have machine work done to the block and buy new pistons, the best and cheapest power adder you can do is get a 350 block. That's an instant 50lb/ft of torque for an extra $200 or so.

Also, the 80-series Flowmaster for these cars is probably the worst performance muffler you can buy. The actual muffler is only about 5" wide because a large portion of the back half is used for the "cross flow" tube. Their single in single out muffler is a MUCH better performance muffler. If you want a single in with dual outlet pipes, this was the best muffler I could find, the Dynomax 17227
http://www.summitracing.com/parts/WLK-17227/

How much are you going to have in the old heads with the porting, machine work, and new parts (1.94 valves, springs, locks, retainers)?

 

thanks for replying so quickly. im not sure about the heads im not doing it myself im using a performance shop that someone recommended, i just know hes port and polishing and port matching everything. But do you think with this setup the car will have a nice idle and pretty good performance. his dyno sim said 308hp and 410 tq he guarenteed me its within 4 percent.

 

"Drill heads for 1.65 roller rockers (5.26 lift with 1.65 rockers)"

I assume you meant to say you are drilling and taping for the rocker arm studs. If new I would go 7/16" studs.

I agree with BadSS assessment of the situation. Buy a 350 block seeing as you are getting new pistons. Use everything else from the 305. Don't use a Flowmaster if you want performance.

 

that seems highly optimistic, but if he guarantees it, then go for it.
if it doesnt live up to the dyno program, then get your money back

 

Yep,, 410TQ looks a little high,, however,,, 308 uncapped is very possible depending on the head work. That would be about 250 - 260 rear wheel depending on the exhaust and tune - which is a few HP better than a stock 350TPI with headers and a tune.

The cam is a pretty good choice for this build. It should pull about 16" of vacuum around 700rpm in a flat-top 310 with mildly ported heads. It will have a noticable bump at idle, but it should be fairly easy to tune with the MAF system.

 

what Quarter mile time do you think it will be capable of with the 5-speed and 3:08 rear gears. if not will the rear gears make a good improvement ??

 

Sorry for breaking the ***** but would the car be fast or is it that much better to get a 350 block. if i were to get the 350 i wouldn't get as many upgrades done to it.

 

High 13's low 14's.......

305's just do not move enough air period. They can not breath like a 350 because of their small bore size. You need at least a 4 inch bore. Find you a vortec truck motor that needs to be rebuilt and start with that.

305's small bore size shroud the valves to much and impead air flow. Going with larger valves on a 305 can actually hurt them because the valves get closer to bore making the problem worse.

 

i see what your saying, im not looking for pavement ripping performance and im on a budget. i want the originality as well lol. but do you think the car would go good and possibly a 13.7 with rear gears??

 

It can be done but you will probably spend more money making a 305 go that fast then you would if you started with a 350. Just save up a few extra 100 bones or so and find a 350 on craigslist. Then you can drive your car while you are building your 350.

Hell I just sold a good 350 roller block, a good crank that probably just needs polished, and a set of GM 350 rods already reconditioned with ARP bolts for $150.00

 

13.7 is a pretty good guess on what it would run. A friend's 305TPI 5-speed back in 88 ran 14.2's on street tires and one 13.999 or something like that at the track in cool weather with slicks. That was with 3.42 gears I think,, K&Ns, modified air box, thermostat, and bumped timing - not much. With 3.08s, the cam, mild port job, headers, 13.7s seems about right. That's about the same ETs you can get a 350TPI automatic to run (back when they were new and in good shape) with 3.23 gears and basically "free mods".

You could run faster than 13.7,, 13.2s probably, with the same cam and everything else in a 355 without porting the heads (which should be less money).

 

Wont i need to change my computer? right now i have the jet stage 2 chip would the cam be better with or without it ? I have pretty much made up my mind in the beginning i just wanted a rebuild, but the guy for almost the same price will do a performance rebuild and i just wanted opinions on if the motor will have some decent power, and now everyone wants me to get a 350 lol. i know it will be faster but i think the 305 will get the job done and i dont want the t-5 to explode. i will probly throw 373's in the rear and should be happy with that. you think a 13.5 is possible with 373's??

 

can you please show me a link or send me a clip of what you think my idle will sound like ?? i am dying to know lol.

 

what is your opinion on the power it will make ? do you think it sounds right

 

88 iroc josh,

Keep the 305 only if you want to keep the car as a numbers matching car. Otherwise, you are going to make power cheaper with a 350.
Having said that, I don't think that your power goals are unrealistic. The 305 can make power, just not as much as a 350 for the same amount of money.
Stock 081 heads can be made to flow well with enough port work. However, I would consider the cost of doing that work vs getting a set of aftermarket aluminum heads.
I would recommend that you test the ported heads on a flow bench, it will help you select the lift of your cam a little bit better. Stock lb9 heads don't flow much past 0.5" lift, meaning that you are not going to be making power past that with a cam that has a higher lift. Also keep in mind that staying with the TPI setup will limit RPM, thus you need to take that into consideration when selecting a cam. It is always better to err on the side of a smaller cam, rather than a larger one. I think that something like the comp 08-501-8 will be more suitable for your application. The rule of thumb is that for every 10* you go up in duration, you are going to raise the power band by 500 rpm. Keep both compression ratio and proper quench in mind.
One of the biggest restrictions on the stock TPI intake are the runners. They can not be ported, but can be upgraded with larger aftermarket ones. Port match your intake base and plenum to that.
I would also recommend that you upgrade the injectors, especially if you are still running the stock 19lbs units. I personally went with the 22lbs bosch design 3 with the modified bases from FIC.
You are definitely going to need a nice wide band tune to make this work well. That means that you need to find somebody that can tune your car under load on the street. No mail order chip and definitely throw that jet chip in the garbage. Having said that, you are not going to need an adjustable FPR.
You are going to need to upgrade your gears with the bigger cam. 3.42s would be a good choice. If you go higher, you are going to spin out of the TPI's power band too quickly. Remember, these are torque monsters.
You can make that little 305 into a screamer if you do your homework (read) and plan things right. High 13s/low 14s should not be a problem at all.

 

Like he said if you are set on using the 305 the 081 heads are the best ones to use. I had a boat with a 305 and the 081 heads factory from Mercruiser. I ported the snot out of those heads, drilled them for studs, cut the guides down for more lift and to fit new style valve seals. I also worked on the chambers to unshroud the valves. I put a factory LT4 cam in it and 1.6 roller rockers. The boat picked up almost 10 mph because it would rev higher. The only reason I kept the 305 was because it was already in the boat and there was nothing wrong with it. It started from a leaky intake gasket.....when I pulled the intake I saw that it was a roller block and I just happened to have a LT4 cam and valve terrain laying around.

 

Oh and I put fuel injection on it.





sorry for all the pics just showing off a little....

 

nice looks good.... the heads concerned me but i have some clarification now that the heads wood be good with good port work. How much torque do the think the 305 will put down?? with my mods?

 

I dont know what i was thinking...its impossible to port the intake runners.lol
Anyways i think that the cam should be good(im hoping). i can trust the guys at the shop that would do the port and polishing. they do race motors so i hope they know what they are doing, and they have been recommended by a good friend that gets them to do stuff like this all the time. what is your guess on the hp and torque you think it will have im trying to get different opinions to see if it will have atleast 300hp and 380torque or so. with the setup i have posted what would the idle sound like would it have a nice rumbly idle or a crap smooth idle.?