'87 IROC VERT

iTrader: (4)

My project '85 T/A needs a motor. The 305 is tired, has high mileage, one bad cylinder and leaking oil, so I thought I would rebuild it.

I priced out rebuilds in the Los Angeles area, and for $700 a shop is willing to trade me a newly rebuilt 350 for my 305. The car is a 5 speed, and the swap should be (hopefully) uneventful. I hear that everything should bolt up the same.

So, my question is (yes, I do have one) - without spending a lot of money, what are a few things I can do to bump up the power a bit before dropping in the motor?

It's a stock, high mileage 5 speed, so I don't want to go too wild. No NOS, or blowers. I was thinking more like a cam, aftermarket intake, headers, head porting, etc. I'm not going to race it, or beat it to death. Just want to have fun, and be able to smile when I nail it in second gear.

Since I'm getting a rebuild, I'm fairly sure I can make reasonable requests to the shop building the motor, such as 'please swap in this cam' or 'please port the heads this way' or 'use these pistons'.

This won't be a daily driver, just a weekend car. I have a mint interior, and plan to paint the car the original silver and grey two tone, and enjoy it. But I do want a bit more power to make it fun. Although it would be nice to have it CA SMOG legal, it isn't a deal breaker. I can work that issue out.

The car currently has a 305 with a 4bbl carb. The carb is brand new, and if it fits in to the equasion, I would love to keep it, as I hear the stock carbs work well.

I would like to keep the total cost of the motor and mods between $1000 and $1500 if that's possible, while getting, say, 300hp.

Is this possible?

Thanks for any advice you guys can give me.

Rob

five7kid

iTrader: (14)

$700 for a rebuilt 350 raises flags. I'd want to know what heads they're talking about - most likely large chamber smogger or truck heads that won't support any power upgrades.

Step 1 has got to be headers. C.A.R.B. certified becomes a problem, because LG4 exhaust is terrible, and any LG4 certified aftermarket exhaust, including headers, will be similarly terrible. Carb'd engines have an EFE valve, and the only EFE system worth a hoot is the L69 - so L69 headers with L69 EFE valve (Edelbrock TES is the only headers I know of that retain the EFE valve - and they don't provide the valve, they expect you to reuse yours). A sharp inspector will see the difference between L69 & LG4, but that's less of a probability than not having the EFE valve at all.

So, know what heads you're getting, replace the entire exhaust system, and then you can start considering what else to do (like cam).

Dyno Don

iTrader: (7)

Upgrade to TPI make it all later model equipment take it to the referee to certify, and plan on spending about 4-5K....or sell it buy what you want.

'87 IROC VERT

iTrader: (4)

I'm glad I asked about this motor idea.

I knew there were different version of the 'same motor' (350), but I wasn't sure what to ask the shop.

I want to avoid getting some garbage vintage from, say, a 1981 Caprice Classic wagon, or whatever the slowest 350's came in.

As for smog and being CARB legal, I'm not concerned with that. It will be registered in a part of CA that does not require a SMOG check. It was a 48 state car to begin with, if that makes any difference.

So, should I specify a certain year for the block and/or heads? Or certain casting numbers?

five7kid

iTrader: (14)

Truth is your 305 has some pretty decent heads. Most any 350 block is fine, '80-'85 would be easiest, some 70's blocks were poor quality (casting flaws, machining errors), '86-up will have one-piece rear main seal (not a biggie, just need a different flexplate).

Have the 350 rebuilt with slight dish pistons (on the order of 12cc); have your 305 heads rebuilt with 1.94" intake valves, new springs & positive-type valve stem seals, a nice cam (I've had good luck with Comp cams, many around here say the Summit cam kits work well), and replace all of the exhaust, and you'll be fine.

Non-California car, back when I lived there, meant a $300 "fee" (really a fine), plus certain things had to be there regardless and you had to pay to have them installed (couldn't do it yourself). Maybe things are different now - most likely worse, but that qualifies as "different".

'87 IROC VERT

iTrader: (4)

Anything else I should specifiy with regard to the pistons, such as compression ratio? I don't mind running premium fuel if need be.

Also, cams seem to have confusing specs. Any particularly known part number that's not too expensive, but will really bump up the power?

And what do you think about retaining the stock 4bbl carb? I have seen a few people really suffer with aftermarket Holley's and the like. Not saying they are all bad, just that if I can get similar power from my new one (stock replacement 4bbl, Rochester Qjet maybe?), I would prefer to keep it for reliability and cost savings.

Thanks!

'87 IROC VERT

iTrader: (4)

Guys, can you tell me what year and/or casting numbers would be good to get hold of for a set of good, inexpensive heads? I don't want to get a rebuild with truck heads, as was mentioned above.

Thanks!

91B2L

You can add 1.6 rockers arms, one way is to buy some world S/R heads or summit brand heads for for rebuilt 350, take the stock heads and sell them on e-bay to get some of your money back.

KrisW

iTrader: (5)

Like 5.7 said above, RE-USE YOUR 305 HEADS! Make sure they get a good valve job and that the intakes are size 1.94" and you'll be good. You can keep your carb, there are guys who even tune them with the computer over on the DIY PROM board.

'87 IROC VERT

iTrader: (4)

Sorry guys, I spaced and forgot about what 5.7 said with regard to using my 305 heads. I'll do that. The idea of buying new heads isn't a great one, because I don't want to spend too much on the motor. I'm already never going to get my money back on this car.

But hey, that's not really the point, is it?

'87 IROC VERT

iTrader: (4)

Could I get close to 300hp with an '80 to '85 block and my 305 heads re-worked as suggested above? Or am I just dreaming?

What, if anything, should I do on the exhaust and cam as fire7kid suggested above?
Does anyone have a part number for an aggressive cam that will still idle? It will have a 5 speed behind it, if that matters.

Also, on the exhaust, I will run headers without A.I.R. - which ones will work best? Which ones tend to look nice in a year or two? Ceramic or some other kind of coating?

For exhaust, I am pretty sure that I need to run a single pipe to avoid scraping the pavement, since I recall the underside having room for only a pipe on one side. Should I just run a 3" pipe to a Flowmaster or something?

I was hoping to retain my stock carb, unless that's a really bad idea. I like the idea of a smooth Qjet.

Thanks for all your help, I really appreciate it!

gary sanders

I can see 300 horse out of the 350,its not that hard.One of the big things will be pistons,you will need a flat top piston,NO DISH,compression will be a little high,so might not be able to run power adder ,maybe Nitrous(but you said no nitrous).You will need a cam in the 460 to 480 lift range,take in to account you have a 5 speed,so you can run a cam with up to 230@50 range durration.Even bigger if you want,just watch stock valve spring hight,but throw in some new springs in the heads up to 500 lift in those heads,and your set.,If you go carb,stay with vacume secondary carb with a Edelbrock RPM intake,carb size 600 or 650 cfm,no bigger,unless you want to drag race it,then go 750 cfm,the bigger carb is not always better .Headers,go with the 1 5/8 size tubes,you wont need but 1 1/2 tubes,big for latter on up-grades.
As far as heads(and this will wake up the dead,lol) I would not try 305 heads on a 350 PERIOD!!! Yes it will start,and run,yes it will make a few ponys,but it will bottleneck a 350,because the 305 heads have small chambers,the 350 has larger chambers,so if you use a 305 head on a 350 and say pull 299 horse out of it,350 heads on the 350 motor will make 325 horse,and more is always better(THIS IS COMPAIRING THE TWO HEADS)IT IS NOT ACTUAL NUMBERS,JUST COMPAIRING.
Many have used the 305 heads with no proplems,and so have I in the past,but after learning about compression years ago,never again,hope that helps
If you want to make power,and dont care about gas mileage(look at my engine)it make gobs of power,but gets 8 MPG,on a good day!!!!
Also,my engine now has a 545 lift cam in it,the 512 lift was great,but I wanted more,and so will you latter down the road!!!
I run a mechacinal secondary 800 cfm carb,open plenum intake,1 in spacer plate,cam duration @50 is 250,so it hits very hard on the EHXAUST note.

Tobias05

keep the CCQJET setup as well. not holding you back any. wish i kept mine, but my buddies talked me out of it. 5.7 had a CC 305 with headers and a cam that made very impressive times.

ACCLR8N

iTrader: (8)

five7, why not switch to Vortec heads? They don't cost much more than rebuilding old heads. If I was keeping a flat tappet block and carb, I'd spend the extra couple hundred bucks for these heads and a Vortec manifold. Then the only concern would be what went into the $700 short block.

five7kid

iTrader: (14)

Why not Vortecs? One word - Emissions. Since he's not in a strict emissions area, it might be a good idea. The sdparts.com upgraded head kit will run you about $1100 plus shipping for heads, intake, gaskets, rockers, & bolts - great deal.

If you use the 305 heads, you'll want pistons with a bit of a dish. 15cc at least, depending upon your head gasket thickness and "deck height" (how far down below the top of the block surface the piston crown is at TDC). About .040" total between deck height and head gasket compressed thickness is considered "ideal" - "quench", they call it - helps to avoid detonation. If you go with the Vortecs and their 64cc chambers, 10-12cc total valve relief and dish will give you about 9.7:1 CR with .040" quench.

300 HP with good heads & exhaust is a cakewalk for a CC carb.

jay_d

They didnt make a garbage 350.....they all sucked from the factory. the motor in my car came out of a 76 model dump truck.....if at all possible i would advise you to look for a truck motor b/c they are mostly 4 bolt mains....for 1500 you should really be able to make it hum.....i built a 400 hp dirt track motor for around 2 grand.....best thing i can tell you is to get a good 4 bolt main block and start from there......line bored, new cam bearings....presure checked.....all that...eagle makes a 355 kit with a crank i beam rods and hyper pistons for a $700.....then buy some vortec heads from jegs for like 500 cam and intake and maybe some roller rockers.....you could have a hoss for around 1800

Dirk Edgewoode

Elimate all the unnecessary parts; smog control, AC/Air. That’ll free up some horses. Always worked on Renegades. =)