[BogiesAnnex1]

More lift and more duration to get a choppy idle increases force on the springs and valve guides all of which are already old. Messing around with a hot rod cam is going to get you into spring replacement and likely a head rebuild to restore the valve guides and seats. You can’t do guides without doing seats both head and valve if the valves are salvageable. Valve wear is seat and stem. Stems usually wear a long time as they are hard chromed but the guides in the head take the beating as a result of the harder surface on the stems. The theory here is refinishing guides is less costly than replacing valves but in this engine that’s still based on 1950’s economics which aren’t true today.

Bogie

 

[BogiesAnnex1]

Choppy idle cams are soooo obsolete. The sound of the 1960’s never produced all that much power against the cubic inches. Much was made of getting 370 SAE gross horsepower from the LT-1 350 with 11 to 1 compression. So rather than refining the engine they turned to a cam that barely closed the valves 312 degrees total duration with only .458/.485 inch lift and 242/254 duration at .050 lift. These needed 100 plus octane fuel and a 750CFM to reach 370 Hp. Plus vehicles like this only came with manual 3 or 4 speed transmissions and rear gear ratios started at about 3.5 and went up from there 3.89 and 4.11 being common. Try spending a day listening to your engine spinning at freeway speeds. Automatic transmissions behind performance engines were something occasionally seen as experiments at the race track, not available from the OEMs behind performance engines.

Today the emphisis to make power is preserving compression pressure on less compression ratio since hundred octane plus fuel is not at the corner gas station. So combustion chsmber design has changed a lot to increase the efficiency of the burn. For Chevrolet these Ricardo (heart shaped) chambered heads first show on the 1992 LT1 and the 1996 LT4 in aluminum and iron for the 94 L99 Gen II engines. The 1996 L31 Vortec introduced this chamber to pickups with conventional block first then heads cooling. The LT1, LT4 and L99 are reverse cooled which routes coolant to the head first and returns from the block. Gen II blocks, heads, intakes, ignition, coolant pump are not interchangeable with the Gen 1 engines with the exception of the aluminum heads can be modified back to conventional coolant routing with some welding, remachining and creative external coolant returns.

The aftermarket industry has picked up on the ideas of the Ricardo chamber and manufacture heads from moderately priced imports to very expensive domestics that blow away anything from the 1960’s using much less can duration and lower compression ratios suitable for 89/91 octane E10 unleaded at the corner station. A cam timing like the Comp XE268H with 268/280 overall degrees having 224/230 at .050 and .477/.480 lift through a 1.5 rocker at the valve will easily produce 390 SAE gross crankshaft power using L31 heads and a 650 CFM carb. With a 750 CFM carb and attention to valve train details its almost impossible not to get 420hp from a 350 all on 9.5 to 1 compression. This makes a lot of torque and power under 6000 RPM that is very automatic transmission friendly and does not need a high stall converter, higher than your 1400 but nothing crazy getting into 1700-1800 stall is sufficient. The exhaust note on this cam rumbles but is pretty smooth at idle but in an engine built to todays knowledge base when it comes on it is gang busters to use the old phrase.

If you’re not building like this as I outline above but rather for rumbly idle exhaust sound you will spend a lot of time looking at the other guy’s tail lights. So you need to get out of this 1960’s think and get modern. In the words from my teen years “you gotta get hep man”.

Like I’ve said the devil is in the details, for all the words I’ve used this is still like skipping stones across the pond. Since this an early build for your history you need to talk to us before tearing into things and buying parts. You need to start with a realistic power goal and realize that changes in engine power are sooner or later effect the driveline and chassis. The first issue is getting the power the next is component survival further down the line. Big power numbers especially in terms of torque will make you learn transmissions, driveline and rear axle technology very quickly soon followed by concepts of the suspension, frame and body. You will find that big power numbers have to be controlled or you crash, I’m wishing you discover the former before suffering the latter.


Bogie

 

[BogiesAnnex1]

GM stays pretty much in this zone of 190 to 205 degrees intake measured at .050 lift. They flutter around lifts with a 1.5 rocker in a range of about .390 to about .450 lift. The LSA’s most anchor at 111-112 degrees but there are excursions from 109 up to 117 degrees. This is just dinking around with a mild cam trying to find a spot that keeps the emissions and mileage quotas happy.

In a high 10.5 compression 327 with a 4bbl these type cams will deliver about 290-300 horsepower. In a 9.5 compression 350 set up the same the power is about 290-300 horsepower. All of this at pretty modest RPM. A 305 set up the same as the 327 or 350 you could expect proportionally less power based on the missing cubic inches.

Most of these cams as I said are just the result of engineers dinking around on a dyno playing with combinations that meet emission and mileage requirements in the real world small changes in this zone don’t amount to differences you’d see on a time slip and probably don’t matter much to your butt dyno either.

Not that a 305 can’t be built meaner than it is but lumpy cams want more RPM, more RPM wants more part strength and stiffer gearing. That’s the physics the only band aid around this is a power adder of some sort.

Now I don’t know about your town but when I was young in my town it wouldn’t be long before you get chose off, prove it or park it. Once it was established you were all noise and no go you got laughed off the parking lot.

Bogie

 

[BogiesAnnex1]

A real L69 ran about 9.5:1 compression that’s about .9 ratio higher than the standard 305. Somewhere the L69 cam times at point oh-fifty at 202/206 degrees with lift at the valve of .403/.415 inch with an LSA of 115 degrees. Should idle at 650 revs.

The pedestrian 305 cam times 178/194 with lift at .350/.385 on a 108 LSA it’s idle is 650.

The standard cam is not unlike the timing used for the 87-95 Swirl Port, TBI engines both 305 and 350. This is lower than a the typical GM mild cams which the L69 times like the earlier standard V8 cams.

While we speak of LSA in generalities of tight LSA having the characteristics of lots of overlap and low idle vacuum where a wide LSA is having little overlap and high idle vacuum, in reality you need to calculate a degree scale from this data to figure the actual overlap as that is what really counts in terms of how the cam reacts and sounds.

But either of these cams are mild cams using stock production springs and valve train parts there is nothing amazing going on with the L69 cam. Prior to emissions requirements the L69 cam’s characteristics of timing in the lower zone of 200 degrees and lifts hovering close to .4 inch were standard production cams found in 283’s, 327’s 307’s, 350’s and 400’s. All used the same lifters, push rods and rocker’s.

The L69 cam is no big whoo except when compared to the SMOG heavy LU4 or LO3 engines.

Bogie

 

[BogiesAnnex1]

I want a noticeable idle, but nothing too big. I don't want to have to change my springs or get any longer rods and rocker arms.

 

[BogiesAnnex1]

A noticeable idle comes on with an intake duration of 215 degrees and higher. The lopey idle is a function of more overlap and a late closing intake. This is the engineering and physics there ain’t no way around it.

The idle will be barkier with higher compression and less LSA but again LSA is an indication of overlap and but not an actual measure. Somewhat like converter stall speed it’s dependent on other influences not a direct measure of them.

Like Isaid before more than once the L69 cam is no big whoo. It essentially is a grocery getter cam from the presmog days. It isn’t long enough in duration to create the situation of lots of overlap with a late closing intake valve.

Overlap is in the zone n lauding TDC and several degrees before and after where both the exhaust valve is not yet closed and the intake is opening. This is used to have the exiting exhaust to start to pull the intake charge into the cylinder and to use the incoming charge to scour out the remaining exhaust. With a big cam having a lot of overlap at low engine speeds
thus low intake charge inertia there is enough cylinder pressure to vent some exhaust back into the intake system making a weak and exhaust diluted charge that doesn’t burn well so the idle staggers in RPM and sound. This condition is further enhanced at idle by the piston rising on compression and pushing mixture back into the intake further weakening the idle burn and resulting in the engine staggering to try and keep itself running. This is he reason for big cams needing a fast idle, that is to provide a minimum burnable mixture that the engine will idle on. This is the physics and the engineering, every 4 cycle engine is limited by this period!

Bogie

 

[BogiesAnnex1]

If you want a lope you need to get the duration up and the LSA tighter. But your stuck between not wanting spring replacement and probably don’t want to install a higher stall converter.

Unfortunately even the mildest of cams that stagger the idle without getting into pushing a stall converter and not too crazy on duration tend to push the lift. Cams that push the lift quickly get into springs. They also require you check clearances of retainer to top of guide including the stem seal, coil to coil on the spring and getting up around .5 inch lift the valves to piston. It’s pretty hard to get what you want for an idle without going deeper than you want.

Probably the lowest cost answer is the Summit 1103 with 214/224 at .050 lift having total lift of .444/.466 on an LSA of 112. After that Summit 1104 at 224/224 with lift of .466/.466 on a 114 LSA.

The 305 with small valves, ports and bore diameter will be more responsive to duration increases than lift. This is because the flow in CFM is limited by these dimensions, therefore, the answer is to buy more time which is what duration does.

Three other big helps but require digging deeper than it appears you want to is to back cut the valves, run 1.6 rockers and pocket port the heads. This really helps the 305.

Back cutting behind the valve’s about 30 degrees to blend the seat with the back side of the valve head shape into its seat angle seat really increases low to mid lift flow from just off the seat to about .4 inch. But you gotta take the heads off or this surgery.

Your kind of between a rock and a hard place trying to keep the old motor running and wanting a raspy idle while setting funds aside for a replacement motor. OK technically an engine.

Bogie

 

[BogiesAnnex1]

My response in bold type.

2. February - Oil Pan Innards and Timing Chain Cover:
Procomp PCE2651061 timing cover, Fel-Pro TCS45265 timing cover gasket kit,

Better choice, this allows future entry into the timing case with out disturbing the pan to timing case cover seal.

SB Chevy 2 Piece Timing Chain Cover Kit V8 SBC 283 327 350 383 400 V8 Aluminum | eBay

SB Chevy Timing Chain Cover Set - 2 Piece Design. Applications: 1958-1986 SB Chevrolet 283-400 V8 Engines. (Except LT1). Timing Pointer: NO. Kit: Complete Kit Notes: It will clear most double roller chains, however test fit first for clearance before installation.

www.ebay.com

Melling M55HV high volume oil pump,

Unless running maximum clearance main and rod bearings and or remote oil filters and coolers this is totally unnecessary and is a substantial power consumer.

Bogie

 

[BogiesAnnex1]

Valve guides are a machinist operation. There are several methods used.

First all of these operations proceed a mandatory head valve seat job to insure the seat is concentric with and normal to the stem center. “Normal” being an term for mechanical interfaces that are 90 degrees to each other.

- The lowest cost is knurling. Here a knurling tool which is a thread rolling tool is driven down the guide with a high power drill motor. This rolls what looks like a thread pattern into the guide squeezing guide wall material inward creating an irregular reduced diameter of the guide bore. This is followed by a reamer that is sized to the stem diameter plus a clearance. The remaining spiral reduces guide surface area by about 40 percent and introduces a spiral path for oil to escape around the guide into the valve pocket so this is very dependent on a positive oil seal to keep from flooding the valve pocket. The reduces surface contact area also runs the valve hotter. This is not a particularly long lived process.

- Next is replacing the valves with oversized stem valves where again a dimensionally correct reamer for the new valve stem size plus necessary clearance is run through the original guide. This is a long lasting process.

- Next is a thin wall guide, here the original guide is reamed out to a slightly enlarged size then a thin wall brass or bronze guide tube is driven in followed by a sizing ball that essentially cold extrudes the guide to its needed internal diameter presses it hard into the original guide. The ends of the guide are then trimmed as some material is pushed beyond the original guide ends by this process. This is a pretty good long lasting process. It might increase valve operating temperature as the heat flow across the interface is never as efficient as when the guide is a continuous material.

- Last is boring out much to all the original guide and pressing in a thick wall bronze or cast iron guide. This is most expensive and is very long lasting. This also requires a finish operation of reaming and or honing to set the final diameter and stem clearance.

As I said at the start all of these guide refurbishment and replacement processes require the head’s valve seats be reshot after the stem fix process is completed in order to restore concentricity and normality with the valve to its head seat.

The valve’s only cooling medium especially the exhaust side is seat to seat and stem to guide heat transfer so it is important that these operations be done correctly or the valves will quickly burn.

The cost of this is not insignificant and often drives people to just buy either mass rebuilder refreshed heads or go to the import aftermarket for new heads.

The mass rebuilders just tool up automated machines and run hundreds if not thousands of heads through a production run. This lowers the cost far below what the corner local shop can do the old fashion onesy twosy way as they come through the door. They sweep the recycle and wrecking yards nationally for rebuildable cores which has to a large extent reduces local yard availability to the average guy, this a huge change from when I was young.

One of my best finds when I was young and building Fords is at a local yard they had a crashed state patrol Ford Police Highway Intercepter. No engine in it so I asked at the office as to the whereabouts of the motor hoping it hadn’t been sold. The guy said he sold the heads but the short block was in the junk pile as their scraping mechanic said it blew a piston and wrecked the bore wall. I asked if he minded if I hunted for it he said go ahead so I climbed the junk engine pile and started rolling engines off. eventually I rolled an engine off the shrinking pile till there it was an open bottom FE with cross bolted mains staring up at me. Dug it out rolled it over OMG it’s a just a scratch in the wall. Ran up to the office and asked how much, he said scrap price is 25 dollars, I paid the man on the spot. I mean they even lifted it out of what I turned from a scrap engine pile to a moon crater of scrapped engines and loaded it on my pick up and they replaced the engines I rolled off the pile back onto the pile. If anybody today can imagine being given free reign of a scrap pile today. Oh the liability! The so-called ruined bore cleaned in .015 inch so the ‘gouge’ was just a minor scratch.

Bogie

 

[BogiesAnnex1]

I should add that in my years as a builder of hot rods, racers being motorcycles, cars, boats or whatever along with 54 years of aerospace engineering projects I found that once you have a solid cost estimate multiply it by 2 and you got a pretty good idea of the real end cost.

Bogie

 

[BogiesAnnex1]

Frankly Tynan918‘s proposed 305 fixes estimate are half the cost of parts store reman long block 350. That in stock form is an easy 280-300 horse engine for a little more money. As I expect based on a bunch of decades experience that estimate is half what he’ll spend on the damn events of parts I thought would work don’t. So by the time you wrap that eventuality in your up to the cost of a decent reman if not new Mexican crate motor with a lot more potential.

All this talk about the L69, this is not a real performance motor, it is 99% GM advertising making a stock pre SMOG grocery getter engine sound like a performance motor. The L69 if sold in 1970 would have been an entry level V8 to the 350 just like the 283 was the entry level V8 to the 327 in 1966.

My early on recommendation was just keep the 305 limping along and put his real money into a replacement account for at least a 350. But now he’s into it so we need to help him from where he’s at.

Then this isn’t even at the transmission yet. My experience experience says that automatic transmissions wear at about the same rate as the engine they are connected to. So as the engine looses power as it ages the automatic also looses its ability to transfer power as it ages. So the early surprise you get when hooking a frisky fresh engine on the front of that old automatic it soon pukes whats left of its bands and clutches into its pan. So there you are with another high cost adventure.

Why do I say these things, simply because of ‘been there done that’ and dood it more than once.

Bogie

 

[BogiesAnnex1]

High mileage engines have valve guide and often valve stem wear that is just expected because that’s what we’ve seen time and again. If you work in an automotive repair shop on these engines that is a common repair. It’s not that we will it, it’s just something that is.

Same for cylinder bore wear. Though since 1987 it’s less of a problem mostly because these are all fuel injected and fuel injection is a lot easier on the bore walls, rings and piston skirts because EFI is pretty balls on with mixture control where carburetors are pretty sloppy outside of steady state conditions like cruising on the interstate.

Valve guide and stem wear results in stem wobble which causes the valve to roll about its seat rather than instantly closing which offers an opportunity for the hot exhaust gasses to burn the seats. The clearance on the guide is very tight, as that widens oil gets pulled in on the intake due to operating vacuum which forms hard coke deposits on the back side of the valve and in the pocket adding weight to the valve, increasing its operating temperature and reducing port flow. On the exhaust side which sees searing heat and pressure this tends to burn oil in the guide leading to a sticking valve to blown oil black out starving the guide for lube thus accelerating guide and stem wear.

In the cylinder bore the top end lube is really thin and is subjected to combustion flame burning what little oil there is near the top of the top ring so it tends to dig into the bore around its upper travel zone leaving behind a ridge of original bore above the top end of ring travel on the bore. Again this is more pronounced on carbureted engines than those with EFI for reasons already stated about carbs being sloppy with gasoline when cold and or transitioning throttle settings. This gives the travelled bore a taper from the top of piston ting travel (especially top ring ) to the bottom of the bore which sees piston thrust forces. Piston thrust is against the cylinder wall opposite the direction of crank rotation. Looking down on the bore this gives the bore an egg shape to its diameter. Needless to say these wear patterns make it damn hard for a piston ring to follow what’s going on with worn bore shapes.

This is what to expect when taking things apart. This is why when you get deeper into the engine when you disassemble things you just can’t put them back as the act of disassembly upsets dimensions for a long list of reasons. A good example is putting new bearings in an old engine with no other work being done. As the engine wears the bearing clearances increase which sits the crank and the rods lower so the ridge making pattern on the cylinder wall moves down. Now a lot of thousands of miles later somebody puts new bearing in the bottom end to restore failing oil pressure reduce rod knock noise or whatever the reason but now the wear clearance has mostly been remove such that the crank and everything connected to it are sitting the pistons higher in their bore. Then you fire it up only to get a bunch of busted top compression rings.

For uncorrected cylinder and piston wear when doing a top end valve job restores cylinder vacuum and pressure depending on which stroke the piston is on. Here without fixing the cylinder bore, rings and piston the engine will suddenly acquire a bad case of blow by and oil consumption as the higher pressure will bleed into the crankcase on the compression snd power strokes while oil will get pulled around the worn piston rings, bore wall, etc on the intake stroke.

Basically we‘re trying to give you a high school to junior/technical college auto shop course one blog at a time. If you have a JC or Tech college in commuting distance I highly recommend you sign up. At some point you’ll be able to use the Monte as your class project. Just buy a POS commuter to get around in the mean time.

There are basically two things we here are trying to do for you by making you aware of how this stuff actually works, save you from wasting hard earned dollars and keep the Monte from going to the scrap heap when you finally have taken enough of a beating from it. Every guy here that isn’t a millionaire has been through this and I wager even more guys have been through this and in the end had to walk away from it far out number those of us still tinkering with auto’s. There just aren’t a lot of Jay Leno’s in the world that can pump the millions of dollars into this hobby. Probably the best way for the average guy to get in it is to due the time in school and on the shop floor to see if you have the skill set to open a racer’s studio that attracts the high rollers that want a rod but don’t have the time maybe not the skills but have big bucks. Get really good at this they will beat a path to your door. That also will take moving to the big city to get established once established then you can consider a country estate out of town with a barndominium.

If your not born into a wealthy family then the only way forward is by paying your dues, it ain’t easy but that’s the path.

Bogie