Hello Gang.

I was wondering if you might direct me about some possibilities for my 70 coupe, specifically about some changes for the engine.

This coupe doesn't have its original heart, and while a heart transplant is likely something for the future down the road, I'd like to keep the small block it has in it for at least a couple years. It ran strong when I got it, feels like its been cammed up a bit, and appears to be all I need for now.

This engine is a small block Chevy with numbers designating it as a 1969 Camaro, Chevelle, Nova, etc. It didn't leak at all when purchased, but has since developed a few minor leaks. So, I plan on changing some gaskets and cleaning up the engine bay.



I've already put in a new fan and it came with a new radiator that I had out for the frame off I did last summer/fall. I've cleaned up the brake system and wiped down the AC... the easy stuff.





What I'd like advice on is what changes can be done "while I'm at it" to improve performance. My wise mentor suggested not to change too much to the topside when it's hard to say what kind of shape the bottom of this engine is in. I follow that logic. But I'm curious about what this expert panel would do in giving this kind of engine a makeover. It has a Holley carb and a functional stinger scoop hood.





The air cleaner has to go. Would you go open element? What about manifolds? How would you look to improve this engine's appearance and performance without pulling the block?





I was considering this kind of air cleaner assembly:
http://rickscustom-com.3dcartstores....-PKG_p_74.html

What else?

As always, thanks in advance for your time and expertise.

 

You could buy a chrome open air cleaner for a lot less than $99 at your local auto parts store.

The old air cleaner doesn't take advantage of the open stinger hood and draws in air from the 2 snorkels only.
So I would not say there is much of a power improvment to going open element.

 

The best performance bolt on’s without really tearing into the engine would be:

1. Tune up with proper timing and advance curve: you would be amazed how many engines do not optimize spark timing and advance.
2. Headers (will require exhaust work to connect them properly): 1 1/2”-1 5/8” primaries to a 3” collector then reduced to your exhaust diameter which ideally would be 2 1/2”, but is probably smaller. Also, remove any exhaust restrictions.
3. Performance intake manifold: the idea is headers let more flow out and the intake lets more air in, but you are limited by head port flow and that would require more surgery.
4. Higher ratio rocker arms: gives more lift which lets in more air and fuel, but be careful as higher lift require valve clearance. Typically, you can go to a 1:7 roller tipped but you don’t know what work was done to the engine prior to your ownership.
5. New carb: I’m a Holley fan, don’t really care for Edelbrock, but either can work. If you go Holley, stay at 600-650 cfm and keep the vacuum secondaries

Your current dizzy can be tuned for performance, so I wouldn’t waste money on a new one, but I would tune the mechanical and vacuum advance to perfection. You can do cam, heads, etc., but for a “few years” I wouldn’t go past the list above and many of these items can be used on your new engine unless you go crazy. Good luck and post pictures and seat of the pants results!

 

Oh, unless that stinger is open at the cowl, it is doing nothing for you. Test after test shows that an open hood scoop must be 12” or higher from the hood to catch any air. No air is flowing through the front scoop. However it is letting heat out and if you are open at the cowl, you are drawing air in so an open element air cleaner would be your friend.

 

It is open at the cowl. I think I had a picture in there showing that, if not I should have.

 

Thanks very much, Factoid.

 

Headers may be in the works. I am doing new exhaust this spring, so that could happen too.

 

As already mentioned above, recurve your dist'r and use manifold vacuum connected to the vacuum advance canister. Curve should be 36* total advance (initial + mechanical) all in at 2500-3000 rpm. Try initial advance of 14-16*. Once that is done, move onto the carb. Can you tune a carb? Nothing wrong with an open air cleaner but some guys are die hard cold air intake. You have a dual snorkel already but if you can't use at least a 3" tall filter element then find something that can.

 

All the things Factoid said except I would like to add:
1) You can't go 1.7 rocker ratio on a small block as the slot in the heads won't handle it......and it doesn't make sense as the lift is increased disproportional of the duration and the heads don't flow well anyway. The Comp Magnum roller tip 1.6 and a set of one piece pushrods is worth some power but you need to check the slot in the head again.....it can pull the pushrod out and rub. Just adding 1.52 rockers is a good upgrade as the stock stamped steel stuff is pathetic...ratios all over the place.
2) Use a 2101 Non-Egr performer manifold with 1204 Fel Pro gaskets.
3) Keep you Holley Q-Jet replacement carb.....they work very well.
4) Ceramic coat headers are strongly recommended to reduce heat under the hood
5) If you do go for a cam....the Comp 268H is an excellent mild street grind for this engine.

Jebby