What's the casting number?

 

The only number/stamp I can find on it is the "Z98" between the valve springs that you can spot in the 3rd photo. I wish I could find more.

 

Maybe you'll find something here to help.
http://www.crankshaftcoalition.com/wiki/SBC_cylinder_head_identification

 

Are those spark plug holes straight or angled?

 

give us the casting numbers, or did I miss them ?

 

The plugs are angled. I can't find any casting numbers under the valve cover, side, front, or rear of the heads except the "Z98" in one spot. They are a mystery.

 

Your heads look like this to me.
They are identified as C/n 376450; 350 1987-’94 76 cc 1.94" x 1.5" valves

With the engine out, it is a very quick job to pull one head and inspect the valve size and so on.

With re-reading the crankshaft coalition page, it looks like there were only two iron castings from GM with angle spark plugs. That kind of narrows down your choices unless the castings are aftermarket.

 

blwilliams, that really does look close but I don't think its right. I noticed that casting from the coalition page that RWENUTS kindly linked to. I do think this is an aftermarket casting if for no other reason than the fact that I'm not finding any casting numbers or distinctive markings other than the Z98 mark that doesn't seem to help.

I've been doing a lot of reading and thinking and I think I'm going to put aftermarket aluminum heads on this engine and put these old ones up for sale. I'd really like to know what they are before making any purchases or final decisions. I'll pull them off and take some more pictures and measurements.

Thanks for the replies!

 

If the intake is off can you use a mirror and check the underside of the intake runners?

 

Good idea, I'll be sure to check and get photos of the intake runners when I pull it apart. The intake is still on.

 

Looks like a set of Phase II Bowties. The area between the exhaust ports is raised. The Iron Bowties had that.

 

I did a search for Phase II Bowtie and came across this ebay listing. The casting marks on the front/rear of the heads look just like what I have:

GM Bowtie 18° Raised Runner Aluminum Heads for SB Chevy IMCA NHRA 10134363 | eBay

Those heads in the ebay listing are aluminum and aren't quite the same but do look very close!

Here's another article featuring the bowtie heads, looks like my stamping:
http://airflowresearch.com/articles/article115/A-P1.htm

Now to figure out what they are capable of. I'm almost sure I will be replacing them but maybe I can be convinced otherwise.

Thank you so much, StraubTech! These heads have been a mystery to me for 2.5 years!

 

I take it this is a strong engine not a 160hp stock motor.

Yeah, not stock at all. Car is '79 L48 model and this engine has a 1975 date code with 4-bolt main caps.

Also check for brodix casting numbers they are hard to see and very small. Also not in the normal spot you would think. they have a link on there site to all the heads styles.

I checked the site, and you're not kidding:

Those casting marks are so small that they may have been filled with paint! I'll see if I can uncover those areas.

 

That head will pass tech as a GM casting and in the right hands it can be disguised to pass tech in classes where it is illegal. It is a 185cc runner casting, 23 degree valve angle. In the 80's it was the top GM Performance head. Then then the World Products castings came out an at their price point the Bowties took a back seat.

Extremely good head. Heavy casting.

 

Hmm, maybe I should keep them. I was looking at the Blue Print H8002K aluminum heads as replacements. They seem to flow better. I'll do some reading and thinking before I decide. Any input on how those heads compare to the H8002K heads would be greatly appreciated:

http://www.blueprintengines.com/ind...oducts/bp-cylinder-heads-landing/item/bp-195cc-sb-chevy-aluminum-cylinder-heads

I emailed Blue Print and they recommended the XR282HR cam with the H8002K head for around 400hp with my setup:

http://www.compcams.com/Technical/DynoSheets/XR282HR-10_001.asp

If these GM heads with that cam will only cost me 15-20hp under the Blue Print heads, I wouldn't justify the $900 cost for the new heads even though the aluminum heads are lighter. Not sure what I could get for these.

 

Most of those get under cover port work so what the head looks like in the runners doesnt' tell the story. The head on a compression 355 can make 655HP. I've done it. If you have these and spend the money to get them flowed then you will know. In the 80's people drooled over these in the pits.

Boys at Blueprint are recommending Comp huh.....I'll have to make a call!!

 

Sounds like I need to find a reputable head shop in Las Vegas to take them to and tell me what's up with them. I've budgeted $900 for the blue print heads and have a decision to make.

The passenger side head has two valve cover studs broken off FLUSH into them, one of which I tried to extract with an easy out bit that THEN broke in there. Oops. That needs to be addressed before I'll run this engine with those heads again. Gooping up the valve cover with silicone to get it to glue-seal and still leak a bit was getting really, really old.

Boys at Blueprint are recommending Comp huh.....I'll have to make a call!!

I sent you a PM with the contents of that email in case it helps you out.

 

HBR, Rick Rapp, out at the Race Track in Vegas. Tell him Straub sent you. He will know the heads.

 

Awesome, thanks. I need to get my hands on a leak down tester and see what the engine is doing, and try to ID the cam, and go from there. This is a transmission swap project that I'm trying not to spiral out of control! The engine already runs okay but seems like it could be way better.

 

A leakm down test would be well advised IMO. But having the heads checked and redone would be better. The 'mightas wells' can always add up, but if this was a strong runner that wasn't smoking, then it can't too bad. A valve job, rehone, rings and bearings are going to run roughly equivalant pricing of a new set of heads and cam. Depending on what your goals are, it sounds like this motor in good condition is plenty to rip up a transmission - how much more than that are you aiming for?

 

I think my valve seals might be leaking. When doing a mild engine brake in a high vacuum scenario (20hg+), the car spits black smoke out the tailpipes and it smells like oil smoke. This is easy to recreate when warm and in 4th gear at around 70mph (3,000 rpm) with my foot off the throttle driving down a slight decline. It idles at around 7-8hg so the only time I see that high of vacuum is during decel in gear.

I did a compression test by hand on two cylinders before I realized how ineffective it was, but one of the cylinders hissed out the exhaust valve. I may have a burned valve, or I may have adjusted the valves wrong when I tried to adjust them sometime in 2014.

Lastly, there's the two broken valve cover studs with the broken off easy-out. That needs to be addressed.

I suppose while its out and on a stand I could adjust the valves and do a leakdown test. If it is within spec, replace the valve stem seals and move on. I'm hoping to ID the cam by pulling off the front cover and looking for stampings. I think it has some ridiculous radical cam that isn't working out well for me.

 

Camshaft ID markings are almost always on the rear end of the cam and not on the end under the timing gear....so you'll usually need to pull it to find that info....or degree the cam out and that will fill in the blanks.

Something Strab missed telling you is that the iron Bowties are nothing great in stock form. A good solid casting, but unless they have been ported by someone who kows what thety are doing almost all modern iron and aluminum aftermarket heads outflow them, some by a wide margin.
If they haven't been ground on, then a good port job can really wake them up, or you can sell them without the porting to a circle track racer whose rules prohibit porting. There are a lot of classes that are like that.

I'd follow his advice and have them looked at before you make any plans or buy any other parts.

 

consider the TKO 600 5 speed
The 6th gear in the GM transmission is all but useless and not very strong,
Go back and talk to Straubtech when you have the camshaft out and give him the info off the back of the cam.
Those cars need some serious attention,,,please check out the rear trailing arms very closely,,,they fail!

 

If I go so far as to pull the heads off to have them looked at, pulling the cam out to look at the rear for the stampings isn't a big deal. I thought there might be a stamp on the front but maybe not.

If I had money to burn, I'd like to just buy a set of heads with a matching cam and move on! Sure is tempting, but it isn't the smart thing to do at this stage.

I've heard about failing trailing arms in the C3s. I had Tucker's Performance in Las Vegas do a 4-wheel alignment last year after I installed the VB&P street/slalom suspension and the Steeroids rack and pinion. He had some trouble dialing in the rear toe but didn't notice any issues with the front mount of the trailing arm although he did say I should replace the bushings as a preventative maintenance type thing. We were both standing under the car while it was on the lift looking for anything to address, he was very helpful!

Just for fun, here's a photo I snapped while it was on the lift. I've since junked that exhaust that was rubbing on my monospring and installed side pipes:

 

the trailing arms split/fail,not the bushings. They are only spotwelded from the factory. I see you also have that nasty rear spring to replace. Add any power and the car squats and pees when full throttle is applied. Change the transmission X over and use true dual exhaust. I have 3 inch system on my car

 

Oh ok, I'll look up how the training arms fail and keep an eye on them.

What do you mean about the nasty rear spring? What you're seeing in the picture is a new monospring from the VB&P kit. Its funny you said something about replacing it, since it is longer than the original spring and now my 275/60/15s are rubbing on it when turning hard.

The crossmember is about to be modified for the 6-speed. I have true dual exhaust, as true as it gets!

 

looks like the factory glass mono spring. If you upgraded the rate and stayed with a mono it should not squat. I had a trailing arm failure,not something watch,its something to prevent from happening. At least get them properly welded

 

Its a 330lb monospring, the springs I took out were the old metal leaf springs. Not sure if I have a squat or not.