Batass

I just finished a carb swap from tbi on my 305. Heres the new parts:

Holley 600 double pumper fully rebuilt, jets 64 pri 70 sec
fuel pressure reg set to 5 psi
performer rpm intake
stock cam
rhs stock replacement torker heads 76cc chambers (roughly 8:1 cr for supercharger)
lt4 valvesprings
pro magnum 1.6 rockers
hooker super competition 1 3/4 headers

initial timing is 10

The motor fired right up and revved well. I took it out and the tranny was slipping (700r4). I adjusted the tv cable, and it still has crap acceleration. It will break the tires loose with the brake on, so I know the tranny is grabbing now, the car just doesnt move like it should. I didnt install any shims under the valvesprings, should I have? The motor doesnt do anything funny but it does have a loud hum to it when im cruising down the road, but that could be the open headers. Any ideas?

sofakingdom

iTrader: (1)

I don't know where you're coming up with 8:1 CR; using the most optimistic possible values, I get 7.4:1.

This is why you don't build a great N/A motor, and "maybe slap a blower on it later"; or build a great blower motor, and expect it to run decent N/A.

You've got WAY too much header, WAY too little cam, WAY too little CR, for N/A. All around, a total mismatch.

Reserve judgement until you get the blower on it. That combo is simply going to run like dog poo N/A. You'll find out at that time, that you should have changed out the cam too. But a blower will take care of some of the other things.

Sonix

iTrader: (1)

Yea, that sounds like a DOG of a motor. Low compression, stock TBI cam, 305... Sheesh, a V6 camaro would keep up to you now.

Is the supercharger at home now, or in the mail, or in your dreams? no offense, I just mean is it a sure thing, or a hope? Once you get the blower on, bump up the jets, probably want a better cam, then tune from there.

84z28350

Thats less compression than the 165hp smoggers!

Im surprised its got enough ***** to move the car. But once the supercharger is on there it should really wake it up, but i think a new cam would be in line too.

Batass

Yea I know the cam is ridiculously small, but I didnt want to dig that deep into the motor. Im building a 383 when I get back to the states, and I just wanted to do something with this 305. I figured 350hp would be nice for the autobahn. Its also something to do with my spare time. Yep, I have the supercharger. Its a vortech v-1. I didnt know the compression would quite be that low, but that would maybe explain the unexpected power loss. I want to get the motor running as good as it will and then put the supercharger on, to minimize any surprises. This is the first smallblock ive ever really built, and I wasnt sure what to expect. Here's another thing, when I was setting the preload on my rockers, some of the lifters didnt have any spring to them and I could turn the nut all the way down with ease until it bottomed out on the valve. Any more turning required a wrench and it opened the valve. Could this be because the oil drained out of the lifters? But wouldn't the spring keep it up?

sofakingdom

iTrader: (1)

Yes.The spring in the lifter has maybe - MAYBE - 5 lbs of tension, on a good day. So no, absolutely not, it will in NO WAY WHATSOEVER hold up anything, except the piddle valve.

If you were that uncertain about adjusting the rockers while assembling it, it would be real smart to go back and adjust them with the motor running.

Batass

If I adjusted my rockers too tight, would this cause a hum in my motor? Do I have to adjust them with the motor running to get full pump up? Isnt there a better way? One more thing, could this cam be so incredibly crappy that it is just screwing up my whole motor and with this supercharger I may not even get to 300hp? If so I may be looking at some cheap decent cams. This is just a play motor. Dont care much about the bottom end. Thanks for the replies!!!

Sonix

iTrader: (1)

That '91 305 TBI is a roller motor correct? So you could get a roller cam that would work in your 383. It won't be ideal for both motors, but i'm sure you could get something that would be good middle ground... (assuming you don't use the blower on the 383...)

Or, a cheaper flat tappet cam & lifters, a blower cam. You'd still only be out ~$200, compared to your blower, it's pocket change.

You can do your valve adjustments with the motor on if you like, but don't bother having a shower before
I'd do your valve adjustments with the motor off, simple EOIC method (search on the boards for that). It's pretty easy, and a very reliable way to do it. Jiggle the pushrod up and down, don't twist it, that'll help you find 0 lash.

Don't bother tuning it before the blower goes on, you won't get anywhere, and you'll start back from square one once you put the blower on. Just jet up, bolt it on, and start tuning then. You should be able to use a lot of boost with that low of static CR, but watch your stock bottom end

Batass

I know the ic eo method, just wanted to know if it would still work with empty lifters, or how to pump them up so that I could adjust them. Ill see what kind of power the car has with the blower on. If it sucks, I may buy a decent cam. I plan on putting a big cam in my 383 and I dont want to rev this 305 to 7000 rpms. This may be the wrong board for this question, but how much boost do you think I could reliably push with a mid 7 cr on the stock bottom?

84z28350

With a static CR in the neighborhood of 7:1 you should be able to push around 12psi non intercooled with 92oct gas

stroker_SS

I hate to say i told you so, but i did in your previous thread dealing with low cr heads. Good luck with the blower however.

Batass

I didnt receive the heads I thought I was getting. Thought I was getting 64 cc vortec replacements, but instead got 76cc stock replacement torkers. Couldnt find much info on these heads, and instead of dealing with the bull**** of sending them back, I decided to keep them and see what happens. They were only 400 bucks. Supposed to be a 30 hp rise over stockers. They wont cut it on the blown 383 Im building though.

jimmy_mac

Those heads do suck but will actually work better on the 383 as far as compression goes. But on the 305 with heads that massive and a bore that small I'd hit it with as much boost as I could. You really need to adjust the lifters with it running at this point to be sure. They make doo hickies to cover the holes on top so oil doesnt' go everywhere. From your description of the adjustment you did to them you probably have some to tight and those valves are staying slightly open. It makes a huge difference in how it runs obviously.

anesthes

iTrader: (12)

With 7:1 he should be able to push about 30psi of intercooled. I ran 12psi on 9:1 non intercooled and it ran like nothing else.

7:1 is junk. Min compression for a blower shoudl be around 9:1, or it will just be a stone when not in boost. 7:1 is for a 671 blown engine that sees 9 seconds at a time, and no street driving.

-- Joe

Batass

Perhaps I should have sent the heads back then. They are really going to kill the low end torque that I love so much. I want this thing back on the road yesterday, so Im not changing the heads again until I go home. I have a holley that I adjusted for boost, and the pistons are stock, and Im running a .015 rubber coated metal head gasket. I dont think I can run 30 psi. Anyone know a safe amount? Non intercooled, but I may buy a water/meth injection kit. I should have just kept the stock heads on there and waited.

joe350

Yes, the CR is crap but you still have the issue of an intake and headers that like high RPM and heads and cam that like low RPM. With that kind of combination you actually end up with the worst of both.

Batass

So would you recommend I change the cam and use low boost? Ive never changed a cam, actually ive never done any of this stuff, just read a lot for the past 4 years. Anyhow, I think I would rather throw a cam in than running high boost, but I would have to run one that wouldnt lower my compression and it would have to be cheap because Im only running this motor for another 9 months or so. The cam that Im putting in my 383 will require bigger springs than these heads can handle, so that is out of the question. Got any suggestions?

joe350

Cams have no affect on compression. I'm not sure what to suggest for a cam except don't get one with overlapped intake and exhaust lobes just in case you actually put the supercharger on because some of your boost will just go out of the exhaust.

Batass

The cam affects dynamic compression, thanks for the tip on the blow by. Im wondering how a stock l98 cam would do?

anesthes

iTrader: (12)

Cams affect compression plenty. You're silly.

A little overlap is ok with a blower, depending on how big the cam is. IF you have something upwards of 245 degrees at .050", than 9 degrees of overlap is just about right. The whole combination has to be looked at. Thats what blueprinting is. You'll learn more about motors if you pickup a book and start reading.

-- Joe

Batass

Ill do that on my next motor. I just want a cheap decent cam for this one. Hoping to reach 350hp with the blower. would a stock l98 cam work well with 1.6 rr here? Is my compression loss pushing my peak torque higher in the rpms? I just need something to fix this issue I have, and I really dont want to push more than 12 psi of boost. Thanks for the help.

joe350

How, exactly?

anesthes

iTrader: (12)

All static compression ratio is, is the amount of combustion volume related to the amount of cyl volume.

cam overlap bleeds off pressure, affecting both cranking and dynamic compression ratios.

two identical motors can have a static compression ratio because of identical bore/piston/head, however two very different cams will drasticly affect both the cranking pressure, and more importantly, the dynamic compression ratio.

here: Dynamic CR

-- Joe