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Topic Review (Newest First)
02-25-2013 08:02 PM
F-BIRD'88 install the head gaskets clean and dry on clean dry oil free surfaces.

New GMPP head bolts are only $20. Coat the threads on the new GM head bolts with black Permatex.
02-25-2013 05:55 PM
71fj40guy Well due to a really crappy bonus I could not get new aluminum heads. So I dropped off my cast iron heads at the machine shop for a full clean up and valve job.
When I put the heads back on do I need to use a gasket sealer or do I just bolt on the heads with the new head gasket?
02-11-2013 11:21 AM
71fj40guy
Quote:
Originally Posted by oldbogie View Post
Probably yes, the static compression ratio even with 64 cc chambers, with the original pistons, a .025 inch stock deck clearance, and a .020 thick gasket only generates 8.4 to 1. For a Vortec style chamber in cast iron this will easily operate on regular unleaded especially with the stiff gearing you've got.

You're far away from compression requiring premium unleaded with this engine and its original cam. To get into compression ratios requiring premium fuel you'd need to change to a flat top piston along with small chambered head.

Bogie
Thanks for the info, that puts me at ease no matter what route I take.
02-11-2013 10:02 AM
oldbogie
Quote:
Originally Posted by 71fj40guy View Post
If I mod the heads and raise the compression ratio or get new 64cc heads will I still be able to run normal 87 octane unleaded?
Probably yes, the static compression ratio even with 64 cc chambers, with the original pistons, a .025 inch stock deck clearance, and a .020 thick gasket only generates 8.4 to 1. For a Vortec style chamber in cast iron this will easily operate on regular unleaded especially with the stiff gearing you've got.

You're far away from compression requiring premium unleaded with this engine and its original cam. To get into compression ratios requiring premium fuel you'd need to change to a flat top piston along with small chambered head.

Bogie
02-10-2013 11:03 AM
71fj40guy
Quote:
Originally Posted by F-BIRD'88 View Post
it has a crappy torque curve thou.
When in 4 low combined with the gearing in the 700r4 transmission it crawls like a champ.

I'm basicly looking to just get it back to the way it was at this point. If I send out the heads for a full valve job I will be down for a week. If I buy new heads I will be down for just a weekend. That's really the reason I'm considering getting new heads.
02-10-2013 01:29 AM
F-BIRD'88
Quote:
Originally Posted by 71fj40guy View Post
This is in a 71 Toyota Land Cruiser 4x4. I drive it daily and the factory 290 hp is more than enough power.
it has a crappy torque curve thou.
02-09-2013 08:37 PM
71fj40guy This is in a 71 Toyota Land Cruiser 4x4. I drive it daily and the factory 290 hp is more than enough power.
02-09-2013 04:02 PM
F-BIRD'88 if you are using this in a truck or 4x4 and want to use 87 octane keep the cr 8.8:1 or less.
if you are using this in a truck or 4x4 you got the wrong cam for the job.
02-09-2013 03:43 PM
F-BIRD'88 if what you really want is a more torqey engine overall. replace the 350-290 cam.
Its a bad choice in a low compression engine .. Keep the cam choice mild.

but you can combine a mild cam with headers, head porting and a better intake etc, to good effect.
87 octane will only allow so much practical compression ratio.
The thickness of the new gasket is the primary concern. thicker than the original will lower the compression ratio.

Keep the real measured cr less than 9.20:1 for 87 octane. the mild compression ratio limit dictates a mild/moderate cam.
pretty much any all mild moderate cams will be an improvement over the 290hp cam.
The 290hp cam is not a bad cam, its just a bad cam in a low compression ratio engine. (unless you got a blower or a turbo)
But advanceing this cam by about 7-8deg helps, as the intake valve closes sooner.
Degree it first. then adjust its installed position. "cam phasing"

if you want to juggle the engine compression ratio yet stay using 87 octane gas then being accurate matters.
So first you must measure the real compression ratio of your assembled engine using all the critical factors.
The adv cr is 8.5:1. the real cr is probabily lower than that.
Measure what you got , first. Now you will know how much to change the chamber volume.
keep it 9.20:1 or less for 87 octane.

If you are willing to run 92 octane gas you can run a 10:1cr.
02-09-2013 11:04 AM
F-BIRD'88 No, a high compression ratio engine will not work on 87 octane.

87 octane gas is for driving back and forth to work.

A engine cannot be a low compression and a high compression engine at the same time.
There is no free lunch.
02-09-2013 09:46 AM
71fj40guy If I mod the heads and raise the compression ratio or get new 64cc heads will I still be able to run normal 87 octane unleaded?
01-30-2013 07:02 PM
oldbogie
Quote:
Originally Posted by 71fj40guy View Post
So I am pulling my heads to send them out for a 3 angle valve job and I need recomendations on what is the best, longest lasting head gasket I should get. This is a stock 290hp gm performance crate motor with cast iron heads, a 4.00 inch bore and 0.028 inch compressed thickness.
I've been reading that I should look at MLS style gaskets.
Do I need to stick with a 4.00 inch bore gasket or can I get one thats a little larger so my choice of brand/style is better (if I can go a little larger then how much is too much)?
X2 for both F-BIRD'88's and cdminter59's comments.

The 290 horse crate engine has a serious miss-match between the camshaft and the heads. A lot of cam duration with a late closing intake valve against low (really low) compression ratio. These leaves a lot of power and a lot of fuel economy on the table.

A set of L31 Vortec heads makes this a 330 horse motor with no other changes. Certainly milling the heads you have say .030 inch and using a Fel Pro rubber coated .015 shim gasket part number Q1094 will help some by bringing the CR up. This doesn't bring the better combustion chamber, spark plug location and porting of the L31 so it isn't going to gain anywhere as much with just increasing compression with the heads you have, but it will be noticeable.

This engine doesn't need fancy head gaskets like MLS or copper. These are things for very high compresion ratios and/or the use of aluminum heads where the gasket needs to deal with being sandwiched between metals of quite different thermal expansion ratios.

The stock bore gasket like the mentioned FelPro use a 4.1 inch bore, this is plenty. You're walking a line where you don't want the compressed gasket hanging an edge into the chamber, nor do you want a large space that increases chamber size thus reducing compression ratio and traps a lot burnt gases that contaminate the fresh charge with unburnable fumes.

The rubber coated shim will work just fine as long as the mating block and head decks are flat, clean and undamaged, and you take care to chase the female head bolt threads in the block and clean the bolts themselves. Assembly requires a sealant that prevents coolant from getting into the threads, it will corrode them and leak coolant along the bolt shanks into what ever cavity the bolt passes. The bolts also require a lubricant on the threads and under their heads to get proper torque readings which are essential to getting even clamping forces on the head that don't cause it to warp resulting in the head gasket leaking. The answer here to both needs is found at the home improvement center as plumber's pipe thread sealant with Teflon. This stuff doped on the bolt threads and I like to paste it into the female threads of the block so the entering bolt pushes the sealant/lubricant ahead of it such that the bottom of the bolt is sealed against the coolant even getting a little way up the threads. The Teflon sealant also has about the same lubricity as engine oil that is specified for torque values of the factory head bolts (aftermarket bolts like ARP use a different alloy in the bolts that require a proprietary sealant and lubricant thus they use torque values differnt from the OEM bolts) DO NOT CONFUSE THIS. Factory OEM or OEM replacement bolts get Teflon Plumbers Sealant, speciality bolts like ARP get that manufacture's recommended most likely propietary sealant/lubricant. Getting this wrong most certainly will result in at least leakage and at most damaged to even destoryed castings.

You don't need to worry about plumber's Teflon thread sealant being pushed into the cooling jackets, unlike other curing compounds this stuff will remain soft and the action of the water pump will beat it into a fine suspension with the coolant so it will not plug cooling passages, unlike RTV.

Bogie
01-30-2013 03:11 PM
cdminter59
Gen 1 Small Block Chevy 350 Head Gasket Question

Before you dump money into them worthless 76cc chamber heads that come on the 290 hp crate engine I would look for a better set of 64 cc chambered heads. These Summit Racing aluminum heads would be ideal for that 290 HP engine. Like was said you might want to change the camshaft too. It is a 11:1 compression Corvette camshaft from the sixties. you would see a big difference with this camshaft from Summit Racing.Summit Racing® Camshafts SUM-1103 - SummitRacing.com. Be sure to run the parts thru a compression calculator before you buy anything.
01-30-2013 12:18 PM
F-BIRD'88 A .015" shim style gasket will get you a bit more compression ratio. and is as durable as any.
The thickness of the head gasket has no real bearing on wether the head gasket will fail.
The heads either seal or thye don;t. Detonation and overheating will blow out any gasket.
A smaller chamber cylinder head really kickes up he compression ratio on that motor to good effect.
The cam in that motor needs compression to work.
You can degree that cam too and adjust its phasing ( advance it) for more engine torque too.

Adjust the cam timing so the intake valve closes @ 38deg BTDC @.050" insterad of 46deg BTDC.

You can shave those heads down to the intake valve seat edge to get compression but a 58 to 64cc head really gets it done ( especially with porting)

if you have not ported those heads then most of a 3 angle valve job gain will not be realized.

Get the cr up as close to 10:1 as possible and port the heads and move the cama bit and it will be a whole different motor.


That cam was designed for a 11:1cr and a 4 speed transmsision (1969 corvette 350-350hp L-46)
It is a dud with low compression. GM phased it 1deg retarded 115-113 centers 114 LSA
advance it for 107-121 centers and 38-39deg intake closing point (.050" lifter rise)

Degree the cam and you will see what I mean.

A ported 4416 heads with 1.94 valves installed with a shim gasket (felpro 1094) is a favorite low cost hop up on that motor.
More flow+ more compression ratio.
Don;t be shy with the porting on either of these stock heads. You got to lean on that die grinder to wake them up.
Then a nice 3 angle valve job pays off.
01-30-2013 09:52 AM
71fj40guy
Gen 1 Small Block Chevy 350 Head Gasket Question

So I am pulling my heads to send them out for a 3 angle valve job and I need recomendations on what is the best, longest lasting head gasket I should get. This is a stock 290hp gm performance crate motor with cast iron heads, a 4.00 inch bore and 0.028 inch compressed thickness.
I've been reading that I should look at MLS style gaskets.
Do I need to stick with a 4.00 inch bore gasket or can I get one thats a little larger so my choice of brand/style is better (if I can go a little larger then how much is too much)?

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