Another Advice Post

[RogerK]

First I want to thank everyone who has responded to my posts and answered my head and cam questions.

Here is what I'm planning. The engine is running in the car with all stock parts right now. I have a 318 V8 from 76 to 84 Casting #4006730-318. Its .030 over with stock flat top pistons. I do not know how far in the bore the pistons actually set at TDC but most of the info I have found puts them at .081. I will measure this when I pull the heads.

The planned upgrades include a pair of closed chamber heads from a 66 273, casting #2658920. I CC'd them at 66, so i'll get them cut .030. That should get them down to 61 CC's and up the compression a bit. The heads will get 1.88 intake and 1.60 exhaust valves. I will polish the chambers and do a mild port to clean up the casting and smooth out the runners. The heads will get hardened seats. I'm sticking with the stock stamped rockers and shafts.

An Eddy Performer will go up top. I will stick with the stock exhaust manifolds and single exhaust for now, but a dual exhaust is in the future. The rear end is stock 7 1/4 for a slant 6. I don't know the gears. The 904 has as mild shift kit and the stock converter.

The cam is the variable. I want improved performance over the stock cam and good mileage. I'm not racing this car and drive it from CT to Carlisle. I do want to burn the tires if I want and feel like I'm being planted in the seat when I take off.

I've seen a lot of cams recommended and I think I'm going with the Comp Cams XE262H. http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=626&sb=2 New valve springs are a given.

Anything I should worry about with these specs? Will I need to shorten the push rods? Anything I forgot?

Thanks. :cheers:

 

[RedFish]

Have you priced harden seat install ? if not, be prepared for sticker shock.

 

[Hebrews10:26]

Hardened seats will up the cost another 90-120 depending on shop.

With a 1.88 in those heads, you are gonna be doing a lot of bowl and short turn work 'for one who doesn't do this professionally' to get them to flow as good as a bowl blended 1.78 valve.
As the turn gets steeper, the flow becomes less..and that's what that larger valve will do.

I'll be posting a thread to help you, read it.

 

[krazykuda]

Hardened seats will up the cost another 90-120 depending on shop.

Yes, but hardened seats are necessary. I bought my formula S with an "already rebuilt" engine - no hardened seats. With less than 6k on the rebuild, when I removed the rocker arms the #8 exhaust valve stem stuck up 1/4"higher than the intake valves. The seat had been beat to hell and the valve would no longer seat. :-x


Hardened seats are a must... Pay me now or pay me later.... Which would you rather do??? :dontknow:

 

[rumblefish360]

That cam is a good cam for mileage and decent pep on the road.
Skip the polish on the heads. Just run them stock to bowl ported and you'll be fine.

 

[318willrun]

Your going to spend a lot of unnecessary money. First of all, being bored .030 over will automatically help raise the compression. So, by the time you do all that work on the 273 heads (bigger valves, hardened seats, porting, milling), why not just use a set of 302's, or even 308's?? The 302's are very easy to get (85-91) 318 and are close chambered heads. The 308's are found on 360's from 88-91. They are not close chamber but have the bigger valves/ports.
My suggestion is this: Because you don't care about performance/high horse power, but all you want is bottom end "stomp" and a good cruiser, I'd forget bigger valves. Just use 318 heads (new enough to already have hardened seats). These are inexpensive. If your not using headers, not racing it, then big valves and porting do you no good. Big valves/ports take AWAY from low end torque. Big cams, valves, ports want high rpm. You said you want low end, so stick to a 318 head and save some money. What you can do for the 318 head is mildly open the intake ports a little to match the intake ports... and this is free because you can do it yourself at home.

 

[RogerK]

That cam is a good cam for mileage and decent pep on the road.
Skip the polish on the heads. Just run them stock to bowl ported and you'll be fine.

Your going to spend a lot of unnecessary money. First of all, being bored .030 over will automatically help raise the compression. So, by the time you do all that work on the 273 heads (bigger valves, hardened seats, porting, milling), why not just use a set of 302's, or even 308's?? The 302's are very easy to get (85-91) 318 and are close chambered heads. The 308's are found on 360's from 88-91. They are not close chamber but have the bigger valves/ports.
My suggestion is this: Because you don't care about performance/high horse power, but all you want is bottom end "stomp" and a good cruiser, I'd forget bigger valves. Just use 318 heads (new enough to already have hardened seats). These are inexpensive. If your not using headers, not racing it, then big valves and porting do you no good. Big valves/ports take AWAY from low end torque. Big cams, valves, ports want high rpm. You said you want low end, so stick to a 318 head and save some money. What you can do for the 318 head is mildly open the intake ports a little to match the intake ports... and this is free because you can do it yourself at home.

Thanks for all the comments, appreciated as always.

Rumble, thanks on the thumbs up on the cam.

318willrun, I understand the 302 heads already have the hardened seats and have considered them.

At this time I've spent nothing and committed to nothing. I want to keep the intake ports on the small side, intake manifold and heads will get a gasket match. So that I understand, staying with the smaller valves and this cam with a mild cleanup of the ports and no chamber polish will give me what I'm looking for without breaking the bank, right? This is with stock heads not milled .030.

My current heads have the small valves but are open chamber. Lest assume I keep these for now while searching for a set of 302's. Even though they have a larger open chamber, will I have the gains I'm looking for by swapping the cam and intake? I mean, the valves and guides have about 10,000 miles on them. I could pull these heads, disassemble them, port them a bit and call it done. The only thing I would be giving up would be the increased compression ratio.

 

[rumblefish360]

You'll be down a little on power. Go for it.

You want to get away with this as cheap as possible. I understand. When time and money allows, upgrade later.

 

[Hebrews10:26]

Roger, what i mean to say is that if you leave the short turn steep/vertical, the flow will not be good. 1.88 valve will make the turn steeper without porting them and without a good throat cut will also leave a big ledge just under the seat.

If one were to cut for a 1.88 valve and do no porting, it will flow less than a stock 1.78 as is from the foundry.

 

[RogerK]

Roger, what i mean to say is that if you leave the short turn steep/vertical, the flow will not be good. 1.88 valve will make the turn steeper without porting them and without a good throat cut will also leave a big ledge just under the seat.

If one were to cut for a 1.88 valve and do no porting, it will flow less than a stock 1.78 as is from the foundry.

Thanks for the explanation. I think I will stick with my open chamber, stock small valve 318 heads and just swap the cam, lifters and springs for this year with the performer intake and see how it goes. I'm going to port the 273 heads if only for the experience, whether I use them or not.

 

[Hebrews10:26]

Thanks for the explanation. I think I will stick with my open chamber, stock small valve 318 heads and just swap the cam, lifters and springs for this year with the performer intake and see how it goes. I'm going to port the 273 heads if only for the experience, whether I use them or not.

Sounds like a good plan, good luck!

 

[moper]

I'm with Hebrews - nothing really needed in terms of head work and kep the 1.78 intakes. Have a good performance valve job done with the throat cut and you're good.

 

[RogerK]

Thanks Again Everyone. I'm learning a lot about the differences in building engines for different performance levels.

AS Always, FABO Rocks! :headbang: