Thinking of putting in a performance Camshaft in my 305 TPI auto IROC-Z motor is rebuilt not long ago only about 20,000 miles on it.

What are some of the recommendations and what kind of HP am I looking at. Hopefully looking to get at least 30Hp from the cam swap. Want something that will perform and have good driveability without a stall converter.

I will also most likely get Hooker headers for the car. Possible to get 70hp increase with these 2 mods? Will most likely also have to tap into Prom as I am running MAP.

1986 Cam specs as listed on site are

Lift: intake .350 exhaust .385 Duration: intake 307 (crank) exhaust 311

What should I look at getting? Pros & Cons any?

Thanks,
Michael

 

70hp? Highly unlikely.

I ran 2 different cams aside of the stock peanut on my 86. Now theres a 91 engine with stock roller cam in there. First cam I ran was a 204/214 .422/.444 112LSA and its the one I have the best timeslips for. Part of that I think is due to the track I ran at, it was at sea level right next to the ocean, and always at night. Very nice conditions. The ecm had some fits with that cam, and it had a little bit of lope to it. Little. Later, I was running a 212/212 .444/.444 112LSA from comp cams. It idled better with this cam, and got better mileage, but for some reason the ET's just werent there. I dont know if it was the motor dying, or the track (800 feet, inland, daytime (read:hot) and generally bad conditions), but it just didnt put down as good of numbers. I think it could have done better. It also seemed like the intake with that cam was becoming a hindrance. Now I have the stock 91 roller, and its pretty nice. I havent had it to the track yet, but I like the cam. Nice power across the range. Its a 202/207 .413/.428 116LSA (as measured). My instincts would tell me its going to be slower, but who knows right now. I think any of these would pick up a fair amount of power over whats in there now. Theres other cams out there now too, I'd stay under 218 duration and around .420-.450 on the lift or thereabouts.

 

A stock LT1 camshaft would be a nice upgrade from the peanut cam and you can have one relatively cheap (when compared to aftermarket cams).

Keeping it under 218 duration would be the best for the stock setup (plenum, runners, PROM).

 

Thanks for the input. I'd agree with the LT1 cam being a cheaper alternative then an aftermarket but the only problem is that I don't live in the USA. So finding a LT1 or Comp Cams here in Australia will be the same price roughly.

Yes sometimes it is a PITA living outside the US for parts, but what can you do.

Mike

 

There's no good junkyards around you? Melbourne is pretty big.

The ductile steel that street hydraulic rollers are made up of is very tough and can be re-used. So a used one is definitely an option if you can find one.

 

I had a look at a australan place that makes performance Cams if anyone is interested you can have a look at www.comeracing.com

Anyway a guy from C.O.M.E recommended me this Cam

This cam gains at least 25% over stock.

HYDRAULIC: Smooth idle. Strong low down and good mid-RPM torque.Compression ratios 8.5 to 9:1/9.5:1 max with super fuel. Up to 10:1 plus with LPG mild performance profile for otherwise stock engine. Ideal towing. 4 x 4 pleasure ski boat, highway use. Works well with mild modifications, ignition, intake 4-barrel carb. RPM Range idle - 4500.

Cam is $297.00 and lifters are $99.00 a set

Advertised Duration
Intake - 250
Exhaust - 265

.050" Duration
Intake - 194
Exhaust - 201

Cam Lobe Lift
Inatke - .258
Exhaust - .273

Valve Lift 1.5.1 Rocker
Intake - .387
Exhaust - .410

Valve Lift 1.6.1 Rocker
Intake - .413
Exhaust - .437

Lobe Seperation - 112


I saw another Cam on their web site with the following specs and this is supposed to give you maximum street performance without hurting driveability.

These are the most popular grinds in our street range. They are fast acting lobes with maximum cylinder filling design and relatively short duration. You achieve absolutely the most power and torque without sacrificing true daily street driveability. Optimum results require improved induction and exhaust systems. Compression rations over 9:1 are vital with ported heads and retention of stock valve sizes providing maximum airflow velocity as proven in our S.T-2 Streetmaster engine families. Aftermarket dual-plane intake manifolds and extractors will optimise the torque and increases available from these flexible yet powerful grinds

Advertised Duration
Intake - 278
Exhaust - 280

.050" Duration
Intake - 205
Exhaust - 214

Cam Lobe Lift
Inatke - .279
Exhaust - .291

Valve Lift 1.5.1 Rocker
Intake - .419
Exhaust - .437

Valve Lift 1.6.1 Rocker
Intake - .446
Exhaust - .466

Lobe Seperation - 112

HYDRAULIC: Very slight lope. Excellent torque and great mid range power gains. Dual pattern version of HVH 308. Especially suited to Chev & Ford V8's with stock heads & stock compression around 9:1. Good in Holden V8's with less than 9.5:1 compression. Good LPG Grind. RPM Range 1200 - 4800.

BTW will lifters be necessary to change too?? They are $99 a set.


What ya think guys which would be the better option?

 

Max

Is there a reason for the lower lift limit that you suggest? You are the third one that I can think of that says this?

 

He's running stock heads, which dont really flow well at high lift. If they are ported, different story. He's also running an 86 block, which means he cannot use a factory roller cam. Its either flat tappet or aftermarket roller.

I found a book that has Comp cams listed (finally) and they have a 212/218 .447/.454 Thats about as far as you want to go on stock heads... IMO. I dont know what they have on the other side of the world, but I'm sure you can find something in that range to stick in your car.

 

Yes, you must change the lifters. Flat tappet lifters get matched to the cam they are on, if you reuse old ones on a new cam its just a matter of time (minutes) before you can throw the new cam away.

I'd pick the cam I quoted above, of those 2. Looks quite similar to the first cam I ran after the stock one.

 

Maybe try the ZZ4 cam.You might have to change the springs though.

 

That is their XE 256 and is precisely the cam they recommend for a relatively stock 305 with headers and intake. It is worth a good 30 hp over the peanut cam.

 

Wow, that much huh, so going from my .390/.410 lift cam to a Comp 268XE should do me quite some good huh?

 

OK..let's say that the heads are ported and it is a roller cam.

How would the specs differ?

 

Yeah, I'm about to port heads on my 86 and I'm curious to know what would be the best cam replacement. I'm thinking of using summit's TPI cam. It is a flat tappet but they claim to get 40 horses out of it in an 86. Also, should I go with larger valves when I get my heads done?

 

He can't cause it's a roller. I didnt realize that he was running a 86 block til madmax mentioned it.

 

If you have a 350 then the XE 268 will work well. If you have a 305 it will produce a dog, until the rpms get up around 3500. You want a good street car, from what I can see, so phone Comp and tell them what you have a where you want to be.