First off, you post a search comment and I'll slam your butthole good. I've been here long enough to know that.

With that comment out of the way here is the sitution. I have 350 L98 Heads, paid 100$ bucks for them, thought I could put them to some use.

I spent the weekend helping my friend to dismantle his 350 for a build up and learned alot tearing apart an engine. I have been planning my build up for some time, and I'm not building up a 305.

Aside from the point, my 305 has been rebuilt and is a good learning block to experiment with a few things.

I want to take the L98 350 Heads have them ported, polished, vavle job and decked, I will also have to have my intake shaved as well so it will fit nicely with the new heads.

I've read the facts and opinions on 350 heads on a 305, I know it will lower compression. This is why I am having them shaved a tad bit.

We also know that they will bolt up correctly, but we have all heard about cleance issues. I think this is somethign the machine shop can work out though.

I also have a rather very nice high lift cam for this motor.

My car ran 14.65. All I want to do here is push low 14.2 or so and then I can go find my block for the big toy I want to build.

If I could just get some opinions, and advice about what to look for.

I'm not spending mad cash here, just experimenting. Freebies and Cheapos

 

Umm, you could perform a search on the topic.... (Sorry, dude, but I just HAD to do that!)

Anyway, what valves are you planning to use in the L98 heads? If the valve diameters get too large, you could experience some interference at the valve rim and the bore at the deck. You don't want to go forming the valve face to the deck with that "rather very nice high lift cam".

The machinists could flycut the deck for valve reliefs, but that would open the chambers and drop static compression even more. Even with that, you would likely have some shrouding at the outer edges of the intake valves, reducing intake flows.

It might be best to mock up one of the heads to the case with checking springs installed. Insert a gob of modelling clay in the champer space, then operate the valve to its full planned lift and check the clearance impression in the clay. You could do essentially the same thing without installing the head, as long as you made some carefule measurements.

 

I doubt you'll ever see 14.2 out of an otherwise stock TPI 305 no matter what heads are on it.

There are no clearance issues in anything you're proposing. Don't worry about that.

I would suspect that in this case, the loss of compression will outweigh the gains from any increased flow. 305s belong with 305 heads.

Don't shave relatively valuable heads for a reason like that: don't forget, it is irreversible. Basically, you will have ruined a set of heads for any application other than a mis-applied 305.

Be real careful what sort of cam you put in it. TPI does not support power production above 4500 RPM or so, by design; it deliberately sacrifices high RPM horsepower in favor of torque at around 3600 RPM, by way of the "tuning" of the runner length (the "T" in "TPI"). It is very easy to put too much cam under a TPI, especially in a 305; any cam that promises to improve high-end horsepower above 5000 RPM will slow the car down. "There's no such thing as too much cam, only not enough motor". This truism applies to TPI more than to any other induction system.

Port your 305 heads yourself instead, and your lower intake (base) at the same time. That's where the restriction is in a TPI. Take the money you would have spent paying someone else to do that for you, and use it to buy larger valves for them, and some decent rockers to replace the rubber ones it came with, and some valve springs which you will desperately need if you put a more aggressive cam in it than the stock one. Your car will go much faster for the same or less money.

 

I agree with RB above. A big cam is going to kill a 305 TPI.
Probabily will slow you down. Again just port your 305 heads
with larger 1.94" valves. Sell that killer cam to someone else
and pick up something with moderately high lift and duration
that will enhance the natural "Tuned Port" torque curve of the 305 tpi. You can make improvements especially once you get some headers and port the heads and manifold, with the right cam, but a big cam is going to disappoint you.

Something right around 203 to 214 @.050" and .450"+/-
Try some 1.6 rockers. Ported heads like higher lift.
But keep the duration relatively short. Think about increasing torque, not peak horsepower.

Depending on the available fuel (octane) in your area you can pickup some torque by raising the compression ratio of your 305 above stock, especially if your cam is bigger than stock.
93/94 octane will tolerate a true 10:1 cr. You could measure your
deck height and head cc etc and calculate the machining required
to get the true cr you want.
It's these little enhansments added up that will make your car faster and more enjoyable to drive.
How about a new 3000+ stall lockup torque converter and some sticky tires. That'll get your et down.

As a note: You should mill the intake face of the head to correct alignment after milling the head's decks, not the intake.
A good machinst will help you with the details. The distributor may need an extra gasket too.

 

I suppose I should have been a bit more clear, these heads are off an L98 350 stock Camaro, they are IRON heads and have about 150,000 miles on them. They need to be cleaned.

The Cam is a Crane Cams
Adv. Duration: 270º/276º
Gross Lift: .452''/.465''

it has 3000 miles on it, it also came out of my friends 350. He's moving to something larger.

I just want to experiment. I really don't want to port heads myself for serious lack of knowlegde in my part. I do have access to a hobby shop, but I also have connections to someone willing to do machine work for 50% less then he would normal customers.

What I am trying to research and figure out is, will there been anything benifical that can be done with these heads in applying them to a 305. Otherwise I'll just sell them off to anyone.

Thank you guys

 

I actually have some nice 1.5 rockers too, along with a 52mm throttle body, and a set of headers as well.

 

Ok that cam is 214/220 * @ .050" probabily on 112 or 114 C/l.
I would not go any bigger, thats for sure.
What cam is in your 305 now? "Comp cam"

Consider raising your true compression ratio a bit for the Crane cam. I'd work with your 305 heads as discribed above.
You can port your heads yourself. You won't be able to pay some one to do this as good as you can do your self.
It takes too long.
But you can have a machinst/ buddy
do the machine work for ya after you finish your port job.
The 350 heads would need exessive milling to get a sub 58cc
chamber. You 305 heads are the same as the L-98 heads other than the chamber size and valve size. Work with them.
Use 1.94 intake valves.
You'll get a better result.

If you want to experiment, try the camshaft installed in different
positions. Slightly advanced or retarded from stock to see what the motor likes. Move it 4 deg at a time and no more than 10 deg total. It will tell you what it likes.
I think this cam will work well with some ported 305 heads
and a moderate increase in compression ratio.
I think it will like a much higher rear gear ratio an a high 3000+ stall converter.

Porting 305 heads is not hard or rocket science. It is time consuming and a dirty job. You can find all the info needed
to do a bang up home porting job in a book by David Vizard.
It's called "How to build Chevy small blocks on a budget"
Everthing discribed in there on cylinder head porting is relevent to your 305 heads. Tons of other good stuff in there too.
Best $10 you'll spend on going fast.

Search my past posts on 305 heads. search SittingBull's posts too. Read the article on porting 305 heads in the tech section.
Then get some carbide cutting bits and a die grinder and dive in.
You'll be suprised at how much you can improve these heads.

 

I don't want to even deal with the heads. The 305 Peanut Cam is in there, my other Cam is still in a box. The one listed in sig.

I'll probably just install the cam and say F U C K it and toss the other heads if they can't be used for anythign good. I'm not looking to build this 305 to anything. Just want to beef it up while I'm building my other motor for the IROC.

But if there is no sense in using the 350 heads, then in the garage they go....

 

I really just wanted to here details on using 350 heads, I spent the past two nights reading all the posts and I've read the porting tech before.

It seems the same solution is always presented, and the topic moves back to way you should stick with the 305 heads and what to do with them.

I'd much rather here input on the 350 heads, can we get any real power gains from using them, is it worth the effort, etc.

I know for fact that ***** is running L98 aluminum heads 350 stock on his 305 with stock internals. Why, beucase he needed to lower compression to run that 15lbs of boost for his SC.

Lets assume all we have to work with is 350 heads, and 305 block, and assume we want to run NOS with this setup....

Come on guys. Lets get creative,this is what I'm seeking, I've been digging through forums all day on this subject so I know whether or not to put these in a dumpster or spend some time screwing with them.

Thanx again

 

Physics is not creative. It is fact.

Willie is running boost. The CR needs to be lower for that. You set a motor up entirely differently, from the ground up, to get the best results from using it. Setups that work well with blowers are notoriously weak in a N/A motor.

There's a reason people are telling you what they're telling you. It works. The thing you asked about doesn't. Creativity won't help. Understanding the facts is the key to good results.

Don't put them in the dumpster; sell them to someone whose motor can use them, and use the thing that's the all-around best match for what you have... the heads that came on your motor.

 

Not much point in going on here. Sort of a waste of bandwidth.
You want to somehow rewrite the laws of phisics and put minimum effort into it too.
Like its going to happen by magic... POOF! 400 horsepower.

Just Installing a big cam and lowering the compression in a 305
will SLOW YOU DOWN.

If that sounds creative Hey! knock yourself out guy!

Why not just switch a few of the plug wires around while your at it. he heh hee now thats Creative !!!!:rockon:

 

They are your heads dood. You can do anything you want with them.

 

Ok, if you were to mill the 1083 heads you would need to angle mill them to get enough increase to get you more compression.
Figuring 1.2 cc's per cut that would take 4 cuts to get them to 56cc's, raising your ratio to 9.7 (from 9.3) (angle milling takes more off because the combustion chamber is more to one side than the other) and yes that means doing the intake side to match. Then cleaning up the exhaust side ports for better flow, you would then (according to Dyno 2000) raise your HP to around 250. If that is worth the trouble then go for it.

Don>>>

 

I think the best thing to do here is to not even waste my time and just focus on the motor I'm building.

The 305 will continue to get me to work

 

I'll buy your L98 heads , I missed a whole L98 Vette engine once and I regret it all the time, so let me know what's up.

 

Just as a reference, i have a crane compucam 2030, 420ish lift on both sides, 204/214 i beleive duration, and i am slappin down 235hp and 270 tq at the wheels with just a carb, stock 86 lg4 block, 190k on the bottom end, edlebrock 1 5/8 headers, edlebrock performer intake, holley street avenger 670 carb(i dunno look at the damn sig!)

http://pages.cthome.net/ssoares/webfolder/dynochart.jpg


gotta luv the torque curve! (yes, its above 250 for the whole power band, pretty much)

 

Is that rear wheel hp or on an engine stand? Do you have stock LG4 heads? What year is the engine?

 

86 LG4, those numbers are at the WHEELS.

heads were rebuilt, orginal to the motorheads, with only new guides, seals. there was no milling, no porting, no decking.

i'm still trying to remember the cam specs- i knwo its .423lift, but not 100% on the duration... its somewhere very close to 204-208/210-214- either way, its a very mild cam, and i most de3finately should have went with a bigger cam. There is just about no lope at idle at all. Its only got 1.5 reg stock rockers rockers as well.

the rest of the mods are in my sig, keep in mind, stock heads, with the exception for a rebuild, still stock valves, and an untouched bottom end except for the compucam 2030.

One thing i can confirm is that it was NOT one of the low compression LG4's with the dished pistons. The block is STILL original to the car(numbers matching), but smokes a bit now (rings), i put those numbers down about 2000miles ago, i just turned over 190,000 miles.

This car has ALWAYS been strong for what it was- which is why i ran the engine block codes to see if it was the original block- it sure seemed like it was, and its only been owned by myself and the person before me, who used it as a commuter car for 123k.

I have run the car at the track, and the best to date is 13.8@102, at new england dragway. Car weight was around 3400 with me in it, and full interior and spare tire. i do have a fibrerglass cowl hood which must save quite a bit more than i first thought, needless to say it also pumps in a ton of cold air about 25-30mph.

Also, a fun fact- i yanked the aircleaner off for the run after the chart you see, and i picked up about 2hp, and 3ftlbs... i did a 5th run after that with the air cleaner back on and it went back down those 2 hp.

 

What the car looked like before



What it looks like now, and on the dyno!