63- 327/340 Engine Builder Questions

[Edward J.]

My engine is back from machine shop and re-assy will be starting shortly, I have a few questions for some of you engine builders, First off the car was originally equipped with 2 head gaskets per side, can I just use the Fel Pro head gasket set which has the thicker head gasket? which are of course not the steel shims as the factory used.

Another Question is it still has the factory cam and lifters would like to re use the cam and lifters ,the lobes all look fine and solid lifters appear to have slight dishing on the bottom - seems normal for a 70k engine, Sooo- should I Be able to reuse these lifters? If not can I use new ones with the old cam?

[Duke W.]

Re: 63- 327/340 Engine Builder Questions

You need to provide more information.

What pistons?

What are the deck clearances - all eight cylinders?

What about the heads - what was done? Surfaced? How much? Were chamber volumes measured?

The point is to compute the actual compression ratio range you will end up with when the engine is assembled.

My recommendation for the Duntov cam is to limit it to 10.25:1 true, which should be achieveable with the OE components and a gasket thickness in the ballpark of the double .018" shim gaskets from Flint, but anything less than taking the measurments and computing the CR for each cylinder, which yields the total range, is just guessing.

There was an comprehensive article on this subject in the Fall 2009 issue of The Corvette Restorer.

Duke

[Edward J.]

Re: 63- 327/340 Engine Builder Questions

Duke, I changed the compression to 10.5:1, bored .30 over, I am not sure on milling of heads, the last time I talked to the machinst, all new valves, seats, screw in studs, polished crank, I am getting engine back on monday, not sure if the he milled heads.

What do you think on the solid lifters being re-used?

[Richard G.]

Re: 63- 327/340 Engine Builder Questions

"car was originally equipped with 2 head gaskets per side"

New to me. Are you sure it was original this way?

Don't reuse the cam or lifters. The dish on the lifters means they are shot. It would only be possible if you marked the holes they were removed from so they can go back onto the same lobe they were removed from. Consider a newer cam grind. On can get a modern grind (they have learned a lot in 40+ years). Can get one that will sound the same and give you more performance and less pinging. Plus it will cost a lot less than the copy.
Rick

[Duke W.]

Re: 63- 327/340 Engine Builder Questions

Duke, I changed the compression to 10.5:1, bored .30 over, I am not sure on milling of heads, the last time I talked to the machinst, all new valves, seats, screw in studs, polished crank, I am getting engine back on monday, not sure if the he milled heads.

What do you think on the solid lifters being re-used?

Your reply makes absolutely no sense. Unless you can answer the questions I asked, you can only guess at the compression ratio. Dig out your Fall 2009 Corvette Restorer and read the compression ratio article. Unless you understand what data is required to determine what the CR is, neither I nor anyone else can help you.

Beginning as a running change during the 1962 model year, SHP/FI engines were double gasketed through the end of '63. There is a TSB on the subject, and it's been discussed several times, here.

Duke

[Joe C.]

Re: 63- 327/340 Engine Builder Questions

My engine is back from machine shop and re-assy will be starting shortly, I have a few questions for some of you engine builders, First off the car was originally equipped with 2 head gaskets per side, can I just use the Fel Pro head gasket set which has the thicker head gasket? which are of course not the steel shims as the factory used.

Another Question is it still has the factory cam and lifters would like to re use the cam and lifters ,the lobes all look fine and solid lifters appear to have slight dishing on the bottom - seems normal for a 70k engine, Sooo- should I Be able to reuse these lifters? If not can I use new ones with the old cam?

You may use the same cam and lifters so long as the lifters are matched to the lobe that they originally mated with................................but WHY??? If the lifters are dished, that indicates that there is quite a bit of wear on them, and the lobes as well. If you have photos of the wear patterns on the lobes, especially of those of the lifters showing the most wear, then that would be helpful. Again, why would you do this? Would you go to the trouble of full disassembly of your heater box without replacing the heater core while you were "in" there? Makes no sense..........especially when you consider high-wear items with 70K miles showing considerable wear, with probably no more than another 30K-50K useful life left before wear accelerates to the point where lash adjustment is required on an annoyingly frequent schedule before engine performance deterioration becomes noticeable/measurable. As far as replacement I would use the Speed Pro version of your original 097 cam, complete with their piddle valve lifters.

Don't know what you mean by "changed the compression ratio to 10.5:1" ? If your machinist has already installed flat top pistons, then you ought to have him replace them with domed originals..............or, change cams to the 929 instead of the 097.

[Edward J.]

Re: 63- 327/340 Engine Builder Questions

You may use the same cam and lifters so long as the lifters are matched to the lobe that they originally mated with................................but WHY??? If the lifters are dished, that indicates that there is quite a bit of wear on them, and the lobes as well. If you have photos of the wear patterns on the lobes, especially of those of the lifters showing the most wear, then that would be helpful. Again, why would you do this? Would you go to the trouble of full disassembly of your heater box without replacing the heater core while you were "in" there? Makes no sense..........especially when you consider high-wear items with 70K miles showing considerable wear, with probably no more than another 30K-50K useful life left before wear accelerates to the point where lash adjustment is required on an annoyingly frequent schedule before engine performance deterioration becomes noticeable/measurable. As far as replacement I would use the Speed Pro version of your original 097 cam, complete with their piddle valve lifters.

Don't know what you mean by "changed the compression ratio to 10.5:1" ? If your machinist has already installed flat top pistons, then you ought to have him replace them with domed originals..............or, change cams to the 929 instead of the 097.

The cam and lifters will go into rubbish and will not re-use ,I had marked all the lifters to there prospective lobes, My only logic for the re-use was not knowing if finding a cam to replace the original. As for the engine compression, the engine is not assy. I will be doing the reassy. I had menchined to the machinist that because of the fuel today I would like to drop the compression down a 1/2 point, there was no other mods. to cylinder heads other than to freshen them up, as for the milling of the heads ???? , I will be getting the engine back on monday and report with more. (pistons, milling, etc.).

Joe, I Know the compression is rated 11.0:1 from the factory, so my question is dropping the compression down, for running with todays gasoline, would that mean that the domed pistions would now be flat tops? or can the dome of the pistions be slightly changed? To get a approx. compression ratio of 10.5:1 ? This car is not going to be a race car just a slightly modified engine for the gasoline of today,Driving may amount to about 1500-2000 miles a year, I was relaying on the machinist to do the job right and supply some of the parts since he bored block and fitted the pistons and install the pistions onto the rods.

[Domenic T.]

Re: 63- 327/340 Engine Builder Questions

Edward,
2 gaskets were the gas station mechanics way of lowering compression.
You can beat this to death or just assemble the engine (with a new cam & lifters as advised by others) and do alright.
Most of these engines were cut once or twice in their life and you can't put the metal back.
If you use the perma torque gaskets that come with most gasket kits you will be alright as they are thicker.
Who cares about splitting hares on the compression ratio? The gas you put in varies in octane from station to station, believe me I know.
When I worried about valves touching pistons I would use clay and lightly bolt the head down and rotate the engine to see what the valve/ piston clearance was but I don't think you even have to go that far.
The small block has gone together (in garages) more than any other engine made and if there was a problem you would have had a heads up on where to look.
As long as your going together stock with factory specs you should be OK.

DOM

[Edward J.]

Re: 63- 327/340 Engine Builder Questions

Dom, believe it or not the factory used 2 steel shim head gaskets on this engine. it may have been the only one they did. there is some post in the archives on this engines 2 head gasket use.
Thanks for you input, Ed . And like you said I am not into splitting hairs.

[Stuart F.]

Re: 63- 327/340 Engine Builder Questions

I ran the feeler gauge check on my engine to prove or disprove whether it had the two head gaskets. Some will say I must have done it wrong, but I could never get a reading equivalent to the expected two gasket crush (so to speak). My engine has never been apart, of that I am sure, and if it ever is in my life time, then I will know for a fact one way or another. For now, I will assume advertised compression ratio. It's too late for me to go back and file suit - I think.

Stu Fox

[Edward J.]

Re: 63- 327/340 Engine Builder Questions

Stu, I am not sure why GM had a reason for the install of the two gaskets per side, maybe a clearance problem with the piston to valve, or even a problem with the winters intake manifold ports alignment to cylinder head ? Who knows.

[Michael H.]

Re: 63- 327/340 Engine Builder Questions

Stu, I am not sure why GM had a reason for the install of the two gaskets per side, maybe a clearance problem with the piston to valve, or even a problem with the winters intake manifold ports alignment to cylinder head ? Who knows.

Supposedly, at some point during the early part of the 62 model year, there was an issue with detonation reported by owners. The cure was to install two head gaskets instead of one at the point of engine assembly. I don't know when that occured.

I don't know what changed but, supposedly, the new 63 engines were assembled with only one gasket.
However, there was a bulletin issued in early 63 that instructed dealers to remove the heads and install two gaskets if there was a customer complaint of detonation.

Others claim that all 63 engines were assembled with two gaskets. I don't know if that's the case though. Several unrestored 63's that I've owned or inspected over the years have only one gasket. ??????

If anyone has a 63 that appears to be original with original head gasket(s), it would be easy to measure with a feeler gauge.

[Timothy B.]

Re: 63- 327/340 Engine Builder Questions

Edward,

If you search the archives there is discussion about the double shim gaskets on the 63 model.

With the late closing inlet valve on the 097 camshaft and flat top pistons the low end torque is not going to be as good as it could be because much of the compression pressure is bled off at low engine speeds.

If you read Duke's post about compression ratio that's why he is suggesting to maximize the compression ratio by making engine measurements and head gasket selection so you know without guessing what ratio the enging has.

The 097 is designed for 11-1 compression ratio which is why the small domes on the original pistons. If you want a original running 340hp engine stop now and do some research.

[Joe C.]

Re: 63- 327/340 Engine Builder Questions

The cam and lifters will go into rubbish and will not re-use ,I had marked all the lifters to there prospective lobes, My only logic for the re-use was not knowing if finding a cam to replace the original. As for the engine compression, the engine is not assy. I will be doing the reassy. I had menchined to the machinist that because of the fuel today I would like to drop the compression down a 1/2 point, there was no other mods. to cylinder heads other than to freshen them up, as for the milling of the heads ???? , I will be getting the engine back on monday and report with more. (pistons, milling, etc.).

Joe, I Know the compression is rated 11.0:1 from the factory, so my question is dropping the compression down, for running with todays gasoline, would that mean that the domed pistions would now be flat tops? or can the dome of the pistions be slightly changed? To get a approx. compression ratio of 10.5:1 ? This car is not going to be a race car just a slightly modified engine for the gasoline of today,Driving may amount to about 1500-2000 miles a year, I was relaying on the machinist to do the job right and supply some of the parts since he bored block and fitted the pistons and install the pistions onto the rods.

I don't know for sure, but will bet that stock pistons are solid dome, since weight savings is not generally a consideration. If that's the case, then, yes, the domes can be shaved somewhat, but absolutely not to the extent that they can be "converted" to flat tops. If they were hollow domes, which I sorta doubt, then they would not be able to be shaved. Ask your machinist what he used for pistons, which are probably new 4.030". I doubt that he would have re-used your original 4.000" pistons, unless the motor did not require more than a clean-up honing of a few thou, or so. But, you never know. If he DID re-use your original pistons, then he may or may not be hungry for work, and could have charged you time and labor cost to machine your old pistons. More money in his pocket and you save on brand new pistons. This is not an accusation, but these things are very common occurances.

I believe that 1963 vintage SHP SBC, with 64cc chambers, nominal .025" deck clearance, .018" head gasket thickness, 5.3cc domes (-5.3 in the calcs, for "deficit") were rated at 11.25:1 SCR. Plug the numbers into this calculator and see what you come up with:

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

As you can see, there are more than a few things that can be played with, to adjust SCR. I don't know the piston dish volume for the 327/250 and 327/300 engines. As you know, with these, all other factors are the same, except for piston dish volume (a positive number in the calcs. for "additional volume"). The rated SCR of the 250 and 300 engines was, I think, 10.5:1.

[Joe C.]

Re: 63- 327/340 Engine Builder Questions

Edward,

If you search the archives there is discussion about the double shim gaskets on the 63 model.

With the late closing inlet valve on the 097 camshaft and flat top pistons the low end torque is not going to be as good as it could be because much of the compression pressure is bled off at low engine speeds.

If you read Duke's post about compression ratio that's why he is suggesting to maximize the compression ratio by making engine measurements and head gasket selection so you know without guessing what ratio the enging has.

The 097 is designed for 11-1 compression ratio which is why the small domes on the original pistons. If you want a original running 340hp engine stop now and do some research.

The intake valve closes at the same point as that of the L79 (151 cam): 42 degrees ABDC, which is much earlier than that of the LT1, which is 52 degrees ABDC, and earlier still than the 30-30, which is 58 degrees ABDC.