I recently purchased my 88 Iroc as a kind of "project in progress" from a guy in the military,and as with such projects, you never really know what you are getting into until you "get into it".
The original deal was for him to complete things, but he ran out of time before being deployed, so we made a new deal, and I am doing the "finishing".

I am not very knowledgable as far as the inner "specs" of the Gen1 SBC, but I do understand how things work. I'm sure ill learn much more as I go.

The engine is a 10k mile gm crate engine, part number 10067353.

(Engine specs http://paceperformance.com/i-6484484...te-engine.html)

It's basically a stock 350 4 bolt main, old 882 style 76cc heads. It has an Edelbrock air gap Perf RPM intake, Demon 650 twin-squirter (double pumper) mech secondary carb, Edelbrock headers, Mallory 8548201 HEI with external Crane Cam PS 92 coil and Crane HI 6R ignition.

Lots of bolt on goodies on a relatively stock engine.

Relatively, because he did install an Edelbrock Performer RPM cam/lifter set.

My concern is the "stock" valve springs with this cam. Is it ok? He did not upgrade the valve springs, and I want to make sure that it is ok and going to handle the more aggressive cam. Here are the specs for the cam:

Operating Range 1500-6500 RPM
Duration Advertised 308° Intake/318° Exhaust
Duration @ .050'' 234° Intake/244° Exhaust
Lift @ Valve .488'' Intake/.510'' Exhaust
Lift @ Cam .325'' Intake/.340'' Exhaust
Lobe Separation Angle 112°
Intake Centerline 107°
Intake Timing @ .050" Open 10° BTDC
Close 44° ABDC
Exhaust Timing @ .050" Open 59° BBDC
Close 5° ATDC

And here is what info I can find on the valve springs:

GM Part #3911068
Description: Single with damper
Outside Diameter: 1.241"
Pressure at Installed Height: 80lbs @ 1.70 "
Solid Height: 1.15"
Average Rate Pounds per Inch: 267
Retainer Part Number: 14003974
Valve Seal Kit: 10132715

Notes: Production spring used with special high-performance 350ci, 300 HP (SP) engine.

(Sourced from http://www.gmpartsdirect.com/perform...CATID=734.html )

The cam has been broken in, has a mean, lopey idle, but I haven't driven it yet. I've just listened to it run, as i had to drop the transmission back out do to clutch engagement issues. I've just finishing up installing a new clutch arm, pivot ball, throwout bearing etc, etc and will be ready to cruise this afternoon, (hopefully) but am uneasy about the valvetrain until someone more knowledgable can shed some more light on the subject. I Don't know if he just ran out of time and just did not upgrade or if the current valve springs are ok.

I'd hate to find out that they weren't ok by breaking 1 and destroying the engine.

 

You are borderline with those springs. Install height of 1.700" with coil bind height of 1.15" means .550" lift before coils crash together. Generally you leave .050" of margin so actual lift capacity is .500". You are at .510" with a 1.5 rocker i believe? Thats cutting into the margin

Other thing is spring pressure. 80 lbs seems abit light for that cam. Rather see closer to 110 lbs like in comp cams 981 spring or even abit more for turning higher rpm. Heads arent great heads so it likely wont take advantage of the cams rpm potential. The cam itself also is abit old school and lazy profile on the lobes. Likely can make same if not more power with a modern voodoo or xe grind with less duration, but they require more spring

 

Thanks for your response.
I agree, not the best cam choice for this engine, however it's what I got so until the funds allow it will have to do.

I guess what I am asking is if this combo is " ok" until I can upgrade? I have a pair of 67cc 2.02/1.60 TORQUER heads in the works, they have 'quote : 1.550 valve springs' unquote, (?) not sure what that means but that is what was quoted. I'll find more info on those springs as I get closer, however, valve springs seem relatively inexpensive in the big scheme of things, so a change isn't detrimental when I change heads.

My plan is to run what I have for 2-3 months, (if it will work ok), enjoy the car for the summer, then install the World Product TORQUER heads closer to fall. I might just go ahead and change cams and get a "matching package" of valvetrain parts instead of playing the guessing game.

What would you recommend as far as cam for my car? It's got 342 gears, manual trans, and will be mostly driven on the street. Maybe a few blasts down the track now and then, occasional attack of the cones and such. Have a t56 in dads shop just waiting on a rebuild, and future may bring 373 gears depending on things, but thats future stuff to keep in mind.
Has to be streetable but I love the sound of an aggressive lopey cam. With the 67cc heads I should be around 9.25 -1 cr (summit compression calc).
Thoughts?

 

80 lbs nowhere near enough for that cam get some springs til you can upgrade
Less cam +better head =big smile.

 

I like the 268 type grinds for 350's doing mostly street duty. Comps xe268 or lunati voodoo versions. All work good.

Basically 220's duration at .050". 108-110 lsa