caboose1988

Hi Everyone,

I recently purchased a 1984 trans am with a 305 ho. After reading some articles and hearing everyone rip on the 305 i decided to build mine up. So i just wanted to get everyone's opinion on these parts with the 305. To be honest i do not understand a lot about cfm, comparison ratio, port size or anything to technical. I understand the basics of a car and how to work a wrench. Any help with these parts or what i should buy would be very much appreciated. Thank you.

http://www.jegs.com/i/GM-Performance...060K1/10002/-1
http://www.jegs.com/i/Comp-Cams/249/CL12-242-2/10002/-1
http://www.jegs.com/i/Hooker-Headers/520/2460/10002/-1

mickeypatches

not bad parts, could save up some more and drop a 350 putting out 300+ horse but if thats what you want go for it. be sure to get the y pipe in the accessories of the headers, otherwise you will have problems.

caboose1988

Ok thank you for the tip i appreciated it.

mustangdmurder

iTrader: (3)

I don't think that cam will work with a stock carb. The duration is too long, it will throw off the carb. Look at a good cam for the stock carb on this furom there are a bunch of threads about it. Also the rpm range is 1600-5800 which is good for a race car, but hurts the take off speed. You want to get a cam with a duration of idle to about 5500.

mustangdmurder

iTrader: (3)

Oh and don't let people on here scare you away from building your 305. They are good strong motors. I am actually consider trading one of my 350s for a LG4 305. I like having correct motors and such. haha

caboose1988

Ya i was thinking of a different carb. Not sure witch one to use. Figured a holley carb would work they seen the most popular. As far as the cam is there specs you would recomend.

caboose1988

Haha ya i figured if i got a good 305 why not use it. If i ever blow it then im hoping the parts get will swap over to a 350

mustangdmurder

iTrader: (3)

Yeah I believe all their parts are interchangeable besides the pistons and maybe the rods. As far as cam gos I don't think it matters if you are changing the carb but I would still stay with one in the rpm range of idle to about 5500rpm.

caboose1988

http://www.jegs.com/i/Edelbrock/350/7516/10002/-1
do you think this intake would be any better than the jegs one. Thank you

caboose1988

Thank you for the input. This is why i come here everyone seems like they know what they are talking about

mustangdmurder

iTrader: (3)

No the rpm range is 1500 to 6500rpm, again good for a race car that goes in circles but hurts low end torque which you want for take off speed. Also it won't fit under a stock hood. A performer intake would probably be better.

midias

That manifold range is fine stick with a performer RPM or an air gap stay away from a regular performer you will be much happier.

The regular performer is not much better than stock

mustangdmurder

iTrader: (3)

Those won't fit under stock hoods will they? Plus doesn't that RPM range hurt low end torque?

midias

The rpm and the regular are the same size.

It might hurt low end a little but with any decent cam I would rather get the RPM. Totally up to you just my experience with the 2.

Also if you end up going 350 you are really gonna want the RPM.

InfernalVortex

iTrader: (4)

I have a Performer RPM. I have plenty of low end torque. Car will even highway cruise at 1200 RPMs without complaining (T56 double overdrive!). I also run a stock hood. Clearance is tight, but I'd rather give up filter size than give up power band. For a stock car the stock intake is plenty. The intake is one of the things I would change after doing exhaust. But if you're doing a cam swap to an xe268, that cam will probably pull to 6500+ RPMs in a 305 assuming the rest of the engine can handle it. A regular Performer intake will choke it badly.

caboose1988

Hmm i guess i am kinda confused by this you say a stock intake is fine but yet you would change it out?

mustangdmurder

iTrader: (3)

I believe he means with the stock set up, but unless you are making a race car I would recommend idle to around 5500.

cheddar89

So what your sayin is he needs an rv cam a intake to match and a 600 cfm edelbrock to get a little more grunt out of it

mustangdmurder

iTrader: (3)

Also a 305 can't really handle RPMs above 6000 because they are 2 bolt mains. They red line at about 5500 so having idle to 5500 parts is a lot more logical than 1500 to 6500. Parts that are in the 1500 to 6500RPM and up range are made for 4 bolt mains. If you push an engine to RPMs its not made for it can completely tear apart your engine. Meaning it would impossible to rebuild because the block itself would be busted up. If you don't know what a 2 bolt and 4 bolt mains it is referring to how many bolts hold the caps that hold on the crankshaft. If you push an engine to RPMs it can't handle it can rip out the bolts and you can imagine how much damage a crankshaft coming loose could do. It would ruin every part of the engine.

midias

The 305 can and often does spin to 6k. The l69 spins to 6k and enjoys it. Any decent aftermarket build for a 305 should spin to about the same. Getting whatever you want but I cannot reccomend the regular performer for any decent cam.

paulo57509

I could be way off base, but stock 305 heads have combustion chambers around 58cc's, yes? Those Vortec heads have 64cc chambers. I would think that this would lower the compression ratio enough to hurt performance.

InfernalVortex

iTrader: (4)

If your engine is stock, a performer RPM intake wont help you because you'll just lose low end torque without being able to regain top end flow. THe engine cant take advantage of the increased plenum/runner size of the performer RPM if it's mostly stock. If you do exhaust and cam mods, then you're wasting your money by NOT putting a Performer RPM.

I can let an edelbrock carb slide (hard to find a genuinely fast car with one though...) but the RV cams have long since overstayed their welcome. If you want a dog of an engine, put an RV cam in it. If you want something that's actually quick, go with a newer grind.


I really, really disagree. Having some nice aftermarket rod bolts is far more important than the number of bolts in the mains on the engine block. I wouldnt spin a two bolt past 6500, but I've seen then hit 6500 regularly with ease and never seen one come apart because the main caps failed. ARP rod bolts make a big difference high RPM longevity.

midias

Yes he should have them milled down.

mustangdmurder

iTrader: (3)

Or he could just have the stock ones rebuild with bigger valves but I'm not sure how much his machine shop would charge for that

midias

Those heads are designed to be milled up to .040. They will also outflow stock heads by quite a bit. The big issue is they will not handle over .475 lift so that cam is out.


Personally if I were you I would get the same heads bare have them milled to 58cc else you will loose about .6-.7 compression. Then have them set up for larger lift and studs. Have a shop do all the work and assemble them.

InfernalVortex

iTrader: (4)

If he were to switch to beehive retainers for a Gen I sbc and some LS2/LS3/LS6 GM Yellow (now blue) springs (part number NAL-12499224/ ) he would be good to around .500+ lift. They do need some attention as far as making sure the installed height is correct to get the right amount of seat pressure, but they actually match up REALLY well for a medium sized flat tappet cam. With the right installed height in the 1.75-1.8 range you're at 90-105 lbs seat pressure and just shy of 300 lbs open pressure. That's excellent for a flat tappet, and there's a little less seat pressure than the larger 986 springs, which is probably BETTER for cam wear long term and better for break in than running 130ish lbs seat pressure. 981 springs are also recommended for hte xe268, but are much lighter. Less seat pressure puts you at a risk of some slight valvetrain issues, but I dont think flat tappets really hit ramp rates for that to be an issue. The reason you end up with a spring with 130 lbs of seat pressure is because with conventional springs, to get enough open pressure the seat pressure necessarily goes up - hence the other advantage of beehive springs.

Just my thoughts on it.

85gulstrandTA

That cam in a 305 will blow by 6000rpm easy.
It does 6000rpm in a 400 sbc.

I would use it but I like DRIVING my cars. Each person has their own street driving level of difficulty. If you have a stick then use it if you have an auto you'll need a converter to get into the power band.

Vortec heads and performer rpm intake are a great combo and would match the cam well too. Have the heads milled to take advantage of the cam and vortec heads to 9.5cr, you could also use a thinner head gasket to aid in cr. 1.94 intake valves a fine. I seen guys running 12second in the 1/4 mile thinking they had 2.02 to find out later they had 1.94's

when doing this type of upgrades make sure the motor is worth the investment regardless what it is. what are the miles on the motor, does it leak oil, is the cylinder pressure good and even across the board? ect, ect,..

Then work on the cooling system as the stock one may not be good enough to support the extra 100hp of cooling needed in the heat of the day.

Then see if the rearend is hearty enough to live behind it all. which brings up your rearend gear ratio? Higher gears will make this cam a better choice.

when your done most will have a hard time when you tell them it's a 305.

I'm rebuilding a 305 currently for my daughter, but will replace the LG4 with the newer 305 roller cam block for many many reasons... current oils, cheap hp, mpg, build one motor taking my time getting parts then replace old one in a day, ect,ect,...

Dakota W.

Ewwww flat tappet cam, but it's numbers do look good though.

Ron U.S.M.C.

http://www.hioutput.com/tech/343hp/343hp.html

UnderCover89TBI

iTrader: (25)

but build a 350 and have more hp...soo...anyway sounds like a fun build have fun. I have nothing useful to share.

sgtmac

Having bought my 87 Formula with the LG4 305 back in 86, I began bumping the power with mostly simple add-ons:a set of 1.6 rockers which were a direct replacement, a 1/2 inch carb spacer, K&N air filter, a Gale Banks 3 inch exhaust system, a 3 inch diameter cat/con, a HyperTech chip, a Q-Jet electronic carb tune, one step leaner spark plugs to go with the tune up, a B&M shift kit(probably the hardest to do), a 185 degree thermostat, and other things I have probably forgotten. 220,000 hard miles later, still barks 'em off at the 1-2 shift. As I am now restoring and upgrading the car, I will definitely go for more cubic inches, but the stock motor has never had the heads or oil pan off since new. I am guessing all of these additions were a $1000 over the first ten years I owned the car, with the exhaust system being the most at around $500, still using the stock manifolds. The one time I had it at the strip, it ran 15.06 with the 2.73 rearend. Highway cruising buries the 85 mph tach and runs out of steam at about 5500 rpm, so I am not sure how fast it has gone. My two cents worth on the 305...

johnf123

dont waste money on a box cam. get a custom cam and some aluminum heads, headers to a straight pipe, open element with a K&N. consider a cheap junkyard turbo (: i drive a 305 and my friend with a 350 and a 455 always rip on me so ik whats up

Phenom-1

The 305 is practically a guaranteed loser vs the 350, 400 and 455. But just because it can't make power like its bigger brother the 350 doesn't mean its crap either. I plan to get a '89-'93 chevy 1500 pickup and they have a 305 tbi and have thought about swapping in a used 350 but I can always beef up the 305 to make an acceptable 280 hp and 310 torque

Phenom-1

It's not gonna be a Race truck just my work / Daily cruiser Truck to Enjoy, gonna paint it dark teal metallic to match my Maro and for A Race truck to take to the track I'll get a 454 SS truck !