My 365 That Isn't

[George C.]

Re: My 365 That Isn't

George, John, Joe,
Thanks to each of you for all of your input and information. I have used the calculator located at the link below, and using a .020 head gasket with the average .030 deck clearance numbers I am coming up with a bout 9.5:1.

http://www.csgnetwork.com/compcalc.html:

Now if I go with a .15 gasket available from Fel-Pro, I could get to 9.77:1
I have another decision to make about shaving the heads. The shop that has the heads wants to shave them a little to insure they are flat, to date I have said no, as the seal to the gaskets was perfect everywhere so I don't think it is needed. But if I do have them shaved that would lower the chamber volume a little and also add to the final CR. I don't know how much change could be gained by shaving .010 off the heads. If it changed by 2 CC's I could get to 10:1.
I think any of these things I do, coupled with the pocket porting I am having done to the heads and ditching the .041 head gaskets I should see some improvement, as it looks like I am starting with about 9.20:1.

Thank you all,
George

[Duke W.]

Re: My 365 That Isn't

Heads don't have to be "shaved" unless they fail the flatness test. Do these morons have a machinist's bar and a .0015" feeler gage? That's the trouble with these guys. They never want to measure anything - just chuck it up in the mill and take a cut.

Go with what you've got with the .015" gasket unless you want to redo the whole engine. Set the total WOT spark advance at 38-40, and it should be okay with 87 or 89 PON fuel. Post a photo of the piston crowns, and we might be able to get you an accurate volume for the valve notches.

I recently evaluated a local chapter members 365 HP - rebuilt by a PO - thick head gasket - probably has a 30-30 cam. I suspected it had low compression - checked the spark advance map and set the total WOT advance at 39 and went through the idle speed-mixture adjustment procedure to eliminate some start up stumble and ended up 1.5 turns out on the mixture screws and 900 on the test tach. Other than that it ran fine, pulled without protest from 1000 revs in top gear (3.70 axle) - just not like a locomotive, but he's not racing it. He just likes to cruise around.

I suggested he try some 87 PON. He did and there was no detonation. He's a happy camper.

Duke

[George C.]

Re: My 365 That Isn't

Duke,
He left the shaving decision to me, I was just trying to ask if shaving .010 off the heads my get me another little bit of compression. Do you have a suggested head gasket manufacturer at .015"? I am looking at all the sites and see some are pricey.

Here is a photo of the pistons, I used a -4 for the relief cuts in the calculator.
IMG_0009 (800x600).jpg

Glad you brought up the the spark advance, I want to have the distributor setup while it is out. Looks like the book calls for total cetrifugal advance of 24@ 2350 RPM and total Vacuum advance of 16.5@8.2". I was going to search the archives for a good curve map to take with me.

Sounds like your local chapter member has a good coach, I wsh I had the 370 gear around town, but I do like the 336 on the highway.

Thanks again,
George

[Duke W.]

Re: My 365 That Isn't

You can't beat the OE spark advance map. It just needs more initial. Download my convention presentation - look at the "sticky" at the top of the page. The timing tab is not accurate with the big balancer, so total WOT timing should be set at 2500-3000 with a dial back light.

It's common to replace the OE pistons with the Speed Pro forged L2166NF, which have the same crown configuration as the OE 300 HP cast pistons. The catalog says the notches are 5.4 cc, and the 300 HP OE pistons are about the same.

Ask the guy for his machinist's bar and a .0015" feeler and measure the head surface for flatness yourself. I can't believe these guys! The heads have probably already been shaved once. Don't remove more material unless absolutely necessary... and it's so friggin' easy to determine.

Look at the Felpro 1094 head gasket.

Duke

[Joe C.]

Re: My 365 That Isn't

The pistons that you show in posts #1 and #33 are Sealed Power W310NP, the replacements for OEM flat cast pistons:
http://www.fme-cat.com/Application.aspx?year=1967&make=CHEVROLET&model=CA MARO&engine=V8 5.4L 327CID&subm=BASE MODEL&cat=Engine&subcat=Cylinder Block Components
If you click on the part number shown in the link, and then click on "specifications" you'll see that the net crown volume is zero (0.00"). Assuming a chamber volume of 64cc, piston to deck clearance of .030", 4.030" cylinder bore diameter, and head gaskets of .015" compressed thickness and 4.100" bore diameter, the static compression ratio (SCR) of the proposed engine calculates to 10.240:1.

[George C.]

Re: My 365 That Isn't

Joe,
Thank you for the additional information, and identification of the pistons. I went to the suggested website, and yes that is them. I don't completely understand why the reliefs do not affect total chamber volume, but I can live with it. With the headwork, detailed below, and a .015 head gasket instead of the .041 that was in it, I am expecting some kind of power improvement.

I talked with the machine shop tonight, and the heads will be ready tomorrow at noon, all machining is done. He just needs to clean them up and do final assembly. Pocket ported, screw-in studs, multi-angle valve job, hardened exhaust seats, and a small mortgage on my house.

Now I am struggling to find the Fel-Pro 1094 head gaskets. NAPA can't get them Advance Auto has 1 at the hub. I'll try CARQUEST and Oriellys tomorrow, but have a backup set on order that won't be here until Tuesday.

Thank you again,
George

[Timothy B.]

Re: My 365 That Isn't

The information on that web site also shows 0 for the weight of the piston.

George, Have you given any thought to replacing the pistons with the correct dome pistons. If the bore is good, have the machine shop run a hone down the cylinder and match the new pistons to the best cylinder. Get some moly lined rings so they seat easy and do the job right.

[George C.]

Re: My 365 That Isn't

Tim,
I guess doing the job right is a subjective discussion. From what I have read, if I go back to the correct domed pistons, increasing the compression ratio back to what it was from Flint I won't be able to drive the car on todays gas.
Interesting point on those website specifications. Ithought everything one the internet was accurate.
My current goal is to correct the valve train issues and be able to drive the car. While the heads were off I went ahead and had the poket porting done. Long term I can continue to research the options for higher compression, a fully restored 365HP motor, and maybe an airport connection for higher Octane fuel.

I am always interested in current stories of people running 365 & 375 HP motors with pump gas.

Thank you,
George

[Clem Z.]

Re: My 365 That Isn't

The pistons that you show in posts #1 and #33 are Sealed Power W310NP, the replacements for OEM flat cast pistons:

http://www.fme-cat.com/Application.aspx?year=1967&make=CHEVROLET&model=CAMARO&engine=V8 5.4L 327CID&subm=BASE MODEL&cat=Engine&subcat=Cylinder Block Components

If you click on the part number shown in the link, and then click on "specifications" you'll see that the net crown volume is zero (0.00"). Assuming a chamber volume of 64cc, piston to deck clearance of .030", 4.030" cylinder bore diameter, and head gaskets of .015" compressed thickness and 4.100" bore diameter, the static compression ratio (SCR) of the proposed engine calculates to 10.240:1.

most flat top pistons with 4 valve reliefs have a negative -5.4 cc volume when calculating the CR

[Joe R.]

Re: My 365 That Isn't

George,

Duke has often posted that the actual compression ratio of Flint engines is about a half a point lower than advertised. Octane is rated differently now than then, but the octane of today's gas is roughly equivalent to what it was in the sixties. So if it didn't detonate then, it shouldn't now. I agree with Tim, you might as well go back the original type pistons since that you've come this far. I would recommend studying Duke and John's compression ratio article. Here it is, scroll down to page 5:

http://stlouisncrs.org/news_files/St_LouisNCRS_ChapterNewsletterSummer2012.pdf

Duke also covered many of these topics in his excellent seminar at the San Diego convention. But I don't know if it's online.

Joe

[Clem Z.]

Re: My 365 That Isn't

if the piston you now have in the engine are cast they would be heavier than the forged ones and you would need to rebalance the rotating assy if you changed them out.

[Joe C.]

Re: My 365 That Isn't

SCR using 4cc for the volume of the valve reliefs is 9.764:1, which yields a very anemic 6.397:1 DCR when used with the 30-30 cam.

I have experience with 327 engines with 30-30 cams. None of them ever detonated on 93 PON gas and one had verified SCR of 11.3:1. 91 PON gas will make a marginal difference but I can tell you that I couldn't induce detonation on the 11.3 motor even with the timing jacked up to 18 initial and using the factory spark advance program. (24 centrifugal all in by 2350 plus 17 degrees vac advance).

Be sure the machine shop pressure tests the exhaust seats, in your presence, before handing over the $$$.

[Duke W.]

Re: My 365 That Isn't

The previously referenced pistons have a compression height of 1.654". The OE 300 HP pistons are 1.675". Given your measured deck clearances the implication is that your block was decked somewhere near. 020", which is a lot.

It's easy to measure the notch volume. Fill them up with some modeling clay or plumber's putty and then drop the forms into a suitable sized, calibrated burrette.

There's a link to a pdf of my PowerPoint presentation in San Diego up in the "sticky" section of the first TDB page.

Send me an email (not a PM), and I will send you and engine prep paper that you may find useful.

Duke

[George C.]

Re: My 365 That Isn't

Guys,
I picked up my heads today, and I am continuing to be educated. He pulled out a couple of valves, and showed me the pocket porting, in comparison to another set of heads he hadn't started yet. He also showed me the multi-angle valve grind, more education. The screw in studs will insure no more issues, as I stated in the original post I had a couple that were moving. He also changed the valve guides; the originals had been knurled and were sloppy
Obviously it's not going to be a rocket ship with the flat top pistons in it and a 336:1 gear, but it’s still a blast to drive, and I am expecting a little improvement with the changes I am making. I will put it back together and decide while I drive it, what the longer term plan is for the lower end. Maybe OEM style domed pistons, and or a new modern grind cam with some additional lower end power.
Again thank you all for your input, and education,
George

[George C.]

Re: My 365 That Isn't

Guys,
This update doesn't include any good news; in fact it looks like I am starting over.
I reinstalled the heads with .0028 head gaskets, trying to improve the compression ratio a little bit. I installed my restored 65 FI unit, and it fired right up. It didn't run well, and was only providing about 7" of vacuum at about 900 RPM's.
After checking plugs, and wires, and timing several times, I started looking for vacuum leaks and could not find any.
I decided to adjust the valves again to insure I had them right. When I got to Cylinder #8 I found the rocker arm just barely moving up and down on the exhaust valve. I pulled the FI off the car removed the lifters, and I am pretty sure I now have a wiped out Cam. Pretty hard to take a picture of the cam, but I think the attached photo of the lifters tell the story. Can you pick out the bad one? No telling how long this has been going on, the car was not running well thus the valve job I started with.
So I have some decisions to make. If you have been following this thread you will know it has flat top pistons, now I have to decide if it is time for a complete rebuild with new 11:1 replacement pistons to go along with my new camshaft. I do know that I am going to go with the 30-30 cam again, and probably will replace the lifters also.
All of your suggestions are welcome, many of you have stated that the 11:1 pistons won't be any problem with the fuels we have available at the pump.

Lifters #8.jpg

Thank you in advance,
George