I finally got my engine together and took it out and it runs great. I still have some timing and carb adjustments to work out but the throttle response is amazing. I've gotta thank cutlass efi for the cam recommendation it pulls good and has a great sounding idle.

 

Let's see/hear a video! Congrats.

 

What all was done to them? Either way a point higher compression and a much better cam will go along way.

 

The heads are 7a's. I milled them .015 and had 2" intake valves installed that's about it. The cam is a erson viking.

 

Would you mind sharing your build specs with us? The cam specs especially? Looking at a similar build. Thanks

 

403 bored .030 7a heads milled .015, 2" intake 1.625 exhaust valves. Erson Viking cam 222/222 @ .050, 476/476 lift, 110 lsa. It runs good, I was dissapointed when I dynod it but that was before my custom built carb and before I recurved the distributor, I'm pretty happy with it overall.

 

Looks like the cam came from Mark. I have the same one for another build.

 

Yes it came from Mark. It's a decent street cam, it's got a really good sound as well.

 

I am also doing a mild 403 build. i am looking to do it on a small budget and get a little more hp and make it sound good. I am going to start with 7a heads, I have been told I can just use the valves it has. Is that true? I am going to have to bore the block because there was a broken piston ring. Will I need to valves springs? Going to try and keep it small as possible. What are suggestions for Pistons? Suggestions on intake, carb, and cam would be nice too.

thanks

 

With 7A heads, you need cast replacement dished pistons. You can reuse the valves, if they are in good shape but 2.07" intake and 1.625" exhaust valves with the bowls opened would be better. Get the matching valve springs to go with whatever cam you go with, Cutlassefi is a good source and vendor. A cam like the Lunati 217/221 .485/.485 on a 110 lsa should work OK but Mark(Cutlassefi) knows better. A Performer RPM intake and either the stock 800 cfm Qjet reworked or a Street Demon 750 carb would be good choices.

 

Mine was a budget build as well so I used the factory springs and ex. Valves but put in 2" intake valves. I had smi induction build me a custom quadrajet and I recurved my distributor. If I were you I would deck the block to about .010 and use the .027 shim head gaskets. With dish pistons you should be around 9.8-1 compression. I would've run headers on mine but it's a T/A with a 4 speed so I doubt any headers would fit decent.

 

Actually the cast replacement with around the 20cc dish will give right around 9 to 1 compression, perfect for an street cruiser. Thosse pistons are short on compression height, cut the block at least .010" and the expensive .027" head gaskets will help quench.

 

He would probably be around 9.1 without decking the block to .010 and using fel pro head gaskets. But with a .010 piston to deck, shim gaskets and milling the heads .015-.020, he should be right around 9.8. I'm at .020 deck height, .040 fel pros and my compression is 9.3. IMO olds seem to handle higher compression better than other old, iron engines.

 

Here is something I read that had a big impression on me... Decided there to just put the heads on as is. Not taking this car to the track.

Performance Modifications
It should also be noted that small valve heads can easily be machined to accept the big valves since both small valve heads and big valve heads came from the same casting.

Large valves can be installed in the small block heads or any heads in general. My number 5s were machined for 2.072" intake and 1.710' Ex. With this combo you can't put hardened seats in the heads, but with stainless steel valves you shouldn't need them. The largest ex. valves you can use with 2.072 int. and still put in the hardened seats is 1.68".

This brings up a good point regarding the difference in actual valve size, \ and any performance advantage. I realize that the bigger the valves, the more airflow typically you can get in the cylinder (disregarding any MAJOR differences, and looking at the basic type of intake tract). But how much is it really worth to have the larger valves? Is it worth extra HP, or is it not a valid need until higher RPM. My contention would be this. With a normal street motor, running typically at 3000 RPM, and occasionally up to say.... 5500-6000 range, I'd bet there isn't much of a difference in the basic overall view of things. It may be down a bit on HP when buzzing the redline a bit (with the big valves), but face it, how many people here spend any considerable amount of time at that RPM?

In fact, I'd say that for people that really like the "grunt" of the bottom end of these motors, you may be better off with the smaller valved heads (yep, you heard right...). Typically you will make better low end power with the smaller valves than with the bigger ones (the same thing can be said for carburetion also, in that a smaller size carb will give better low-end power, and a bigger carb tends to lose bottom power, but gain top end).

Is it worth "ditching" your small valve heads for a pair with a bigger valve (considering you're staying within the same year, and not comparing the smog heads to non-smog). I'd say no. Keep the ones you've got, and spend the money on getting them ported if you have money to blow. There's better things to spend the money on than this. There are alot of other things in your powertrain that will NEED to be worked on before you get into things this far to make a big difference.

 

I am trying to ditch the 4a smog heads. but this read is implying there is no need to switch the valves in the 350 heads. Thanks for the help guys sorry to hijack your post. Any more information would be great. Thoughts on an intake and is there any suggestion on brand of pistons.

 

If I may, here are some suggestions:

If you are replacing pistons (or not!), measure some stuff before final assembly.
Measuring is important, shoot for the .040 quench (top of piston to flat of cylinder head) distance. So cutting the block deck will probably be needed to square it anyway, but first install the new pistons, measure how far they sit in the hole. Cometic makes many different thicknesses to make a lighter cut give you .040-.045 quench.
From my experience, quench is important on these 403's. I had terrible quench, like .060-.080 in my low 9:1 403 and it pinged, my 10:1 403 has .040 and it runs with no pinging now.

Also measure piston dish and head chamber cc, MEASURE! Published #'s are a ballpark. Then plug your numbers into a calculator and find your actual compression ratio. This will help with finding a range for cam selection.

Just throwing #'s around: With .040 quench, 23cc dish .024 over piston (my assumption), and 66cc heads(typical as cast chamber size), it puts you at 9.43:1. Remember, a little variance on one of these #'s goes a long way.


Also, general oldsmobile build info, make sure your bore and hone is done with a tq plate. If the machinist doesn't think he needs one, walk out. You will wind up with an untrue bore.
Also, with a 403, setup piston to wall clearance a little loose in the acceptable clearance range.

 

With small block heads, normal oversize pistons are normal oversizes like .020" with a 20 cc dish. In most cases the block needs decked a lot to hit 0. I do get 9.7 to 1 with .040" quench and .020", it would require a fairly aggressive cam. Why would anyone want to use tiny valves, other than cost? 2.07/1.625 valves with bowls opened up and no other porting should do wonders. I think quench is important, more so than I thought on the Olds V8. My 350 is right at 9.5 to 1 but has .065"+ quench and a small cam and pinged. Another thing pointed out to me is oil entering the combustion chamber makes pinging issues worse. I have no baffles in M/T style Edelbrock covers, I plan on adding blind grommets and only a limited opening. I plan on dropping compression slightly bigger cam and improving quench with my other fresh #6 heads.

 

Lots of things could be causing the pinging besides lack of quench. I'd look elsewhere first.

 

I got rid of the pinging. I had to slow down the timing curve, run really cold 5670-8 plugs and remove the choke plate. Overall, even though it ran faster, it just wasn't as fun on the street. I need to measure guide clearance and access the valve job on these other #6 heads, see how good a deal they were. I just need to buy the measuring tools this week. I will post what I find, not sure how much a half point of compression and a heated crossover will change the cam selection.

 

Hey Guys would you suggest 7a heads or #3 High compression WG Olds 330 cylinders heads that have had quite a bit of work done to them. Larger valves 1.995" Intake and 1.624" exhaust

 

Not to nit pick but the compression will be slightly lower since 66cc is NOT the typical as cast chamber size but rather 68-69cc is. 1967 #4 heads are 64 cc. Carry on.

 

My 403 built by Mark
For Sale-Tampa/st pete Florida

Built by Mark Remnel- Cutlassefi(here on classicoldsmobile.com check him out) Look under 403 Cutlassefi post in the small block section. He will answer any questions about this.

.039 over 403, KB 6cc piston, .020 in the hole
N crank
4 main halo
Stock rods
455 C heads, 2.07/1.68 Built by Champion Racing Heads
221/228@.050 on a 112, in at 107 Custom Lunati Hyd Roller
5/16 one piece restricted pushrods
HS 1.6 rockers
9.0:1
QF 750 Slayer
Performer RPM intake matched to the heads
Accel HEI 30* Timing

Melling HV pump with purple spring

451hp@5600/512tq@3600. Run on 91 octane pump gas.