recommendations for THICK head gaskets

[Warpig Racing]

I want to reduce my cr. Its currently 347 probe pistons and pro comp alum heads. Block was zero decked and I believe .020 removed. I am looking to make it more streetable. Guess that might include a locker instead of the spool and less converter but that comes later.

[cgrey8]

Depending on the heads, running thicker head gaskets in an effort to get compression down is often a bad option. Reducing quench by thickening the gaskets can make ping worse. There are people running 10:1 that have too much compression, drop down to 9.5 via your method and wind up with worse ping than when it was 10:1 due to the lost quench.

I suggest a better way to do what you are trying to do is via the cam. More aggressive cams will reduce your dynamic compression ratio which is a far better option. But first, what cam are you running now (all known specs). From that, I can recommend an alternate cam setup that will get your DCR lower.

Next some engine info:

• You said the block was zero-decked. Did you verify that with a mic before putting the heads on?
• Do you know the cc of your heads and pistons?
• What's your current gasket thickness?
• How long are your connecting rods? 347 strokers commonly come with 5.4" or 5.315" rods. Which is yours? And yes, this matters when calculating DCR.

With all that info and your cam specs, I can calculate what your DCR is now, then come up with a cam and setup that will work better for you.

[Warpig Racing]

Stock type felpro gasket
60cc head
5.4 rod

I can't remember if it was zero or negative to compensate for crush thickness.

Cam. I'll have to look up what is in it now. It was a comp custom grind but now I believe it is a comp 268h.

[cgrey8]

Look up what your gasket was and see if you can find the crush thickness and the bore diameter of that gasket. Most gaskets for Windsors are 4.100", but some are slightly smaller in the 4.080" or even 4.060" range specifically for higher compression ratio.

[MalcolmV8]

More aggressive cams come with their own set of headaches though. Depending how much, crappy idle & drive ability, poorer gas mileage.

[cgrey8]

More aggressive cams come with their own set of headaches though. Depending how much, crappy idle & drive ability, poorer gas mileage.

That is unfortunately true. One of the California guys here on the forum, Adam McLaughlin also a fellow DIY tuner, ran a very mild cam (Comp XE258HR) in his 351w years ago. But what he didn't know is the compression the stock E7 heads produced was way too much for the 91 octane premium he has access to. Later he replaced the heads with 58cc AFR185s, but because the 58cc chambers held compression high, they produced more power, but didn't help his ping much. He took the engine apart after running it this way for a few years and every piston ring was cracked due to the years of detonation. In fear of doing this again, he, in my opinion, over reacted and rebuilt the engine with dished-out pistons & a a really aggressive cam...just way overboard getting compression down. I think the cam he went with was a TFS Stage 2...the Stage 1 would've been enough. The stage 2 would've been a better choice for the way the engine used to be setup. I think I estimated his CR around 8.5ish and with that cam, he had a DCR in the high 6s (87 octane is good up to a DCR of 7.9). It was his intention to get back to being able to run 87 octane regular no question. And while he could now do that with his configuration, the cam limited him to an idle somewhere in the 850s and didn't produce nearly as much off-idle torque anymore. But it was a 351w, it probably had some to loose. He said 850 RPMs was as low as he could get it to hold stable. I retuned my computer to get my stock Explorer engine to idle at about 575-600, and it does so without a problem. There are plenty of other aftermarket cams that are mild enough to do this too.

So what my point? The real answer is if you want lower compression, the way to do that is to replace the pistons and/or heads that get the compression to what you want. But when that's just not feasible/practical, the quick-n-dirty way to fix this is to up the aggressiveness of the cam to drop the DCR enough to not ping so much. A 268h cam doesn't tell me much. But it does suggest the cam is a mild street performance cam. A step-up without getting too radical would probably be the Comp XE274HR12. It's in the same realm as the E303 from an idle performance standpoint. It will reduce off-idle torque and like the E303, won't "kick-in" until around 2000-2500, and may force you to run a little higher idle RPM. Anything more aggressive starts getting into the area of "problems" Malcolm is warning against. But I would highly recommend if this is on an EFI, that you get the computer retuned or retune it yourself to compensate for idle issues.

[Warpig Racing]

Here is the cam card

http://m118.photobucket.com/albumview/a ... 0&newest=1

I have been thinking of converting the truck to propane. Propane has higher octane and likes higher compression. I just converted my Camry to propane and it runs great on $1.82 gge fuel. It is saving me a bundle on my 55 mile trip to work.

[cgrey8]

If you can get a clearer pic or just type the Comp PN, that would help. I can make out some of the info, but I can't see it all. But I was able to make out that @.050", the duration is 244/25?ish. And it appears the LSA is 109? That's an EXCESSIVELY aggressive cam. Compression shouldn't be an issue with a cam that aggressive. Although smooth idle and fuel economy would. Unless you are racing this truck and running RPMs up to 7000, that cam is wrong for that engine in the 1st place.

So going to a more aggressive cam to lower compression isn't an option if I'm reading those numbers right.

To advise you better, I would really need more info on your heads and current pistons. But my gut feeling is you are looking at replacing the pistons with dished pistons to drop compression. And unfortunately to do that "right" that means rebalancing the crank for the new pistons. And if those cam specs are right the way I'm making out the fuzzy pic of the cam card, I'd be recommend a MUCH milder cam to get you better driveability and fuel economy. You'd also notice quite a bit better torque off-idle. Although a milder cam better suited to your application would probably max out around 5500-6000, not 7000+.

[Warpig Racing]

It was a custom comp cam grind. I called them and gave them the specs of the engine and truck. This was several years ago. I just have not driven much since I got into motorcycles. Since I last worked on the truck I have acquired 5 bikes and I am currently building a 70 cb750 sohc with 836 pistons, efi off of modern sport bike and a t3/4 Turbo in a after market frame.

Solid lifter
351 firing order
108 lobe separation
Lift I - .553
Lift E- .569
Dur @50 I - 244
Dur @ 50 e - 250

It is in a 347 with probe pistons. There are not many options for 347 pistons so I am not certain that is my best option. Also like you said it would be a complete rebalance.

Heads are pro comp. I would have to dig to find these specs but it was the big ones. I want to say 217cc intake runners. Biggest valves and I don't recall the chamber size.

[Warpig Racing]

Also that can was designed for drag. The truck has a tyranny break and I think a 3800-4000 stall. I know it is all wrong for street. Planning on swapping the came. I think I have a comp 268h can on my shelf. Truck currently has tunnel ram with 2 600 edelbrock. I think I currently have the secondaries unhooked.

I also fear that the intake is not properly seating due to the zero deck. I think it could have a vac leak from the bottom side of the intake???

Like I said, I might convert to efi and install a propane injection like I did on my car.

[cgrey8]

Well, with 217cc heads and your telling them you wanted a race engine, I see why they gave you that cam. But you are right, that is NOT a street cam. If you can dig up the head chamber cc, that will help...but you'll also need to dig up the piston dish cc as well. Even if they are flat-tops, they'll have a negative cc due to the valve lashes.

As for stroker options, I think you'll find your options are much greater today than they once were. In fact, modern forged pistons have gotten so good that they've all but replaced hypereutectic in the Ford stroker market. The hypers are the hard ones to find options in today. But forged stroker pistons can be found in a number of different brands in a number of different configurations for all the various stroker rod lengths.

[cgrey8]

Looking at this further, I wanted to go look at what Pro Comp has to offer and see if I could find your head or at least a close resemblance. And the 1st thing I had to figure out is Pro Comp is actually Pro Comp Electronics. I saw that website and completely ignored it thinking, I'm looking for heads, not electronics.

But once I found the website, I found a flat list of their SBF heads in no particular order and no meaningful titles. But as I clicked on the various listing, this image was consist throughout:


So I'm assuming you have the 227cc heads with 64cc chambers. Yeah those are race heads, not street heads. Street Windsor heads shouldn't have much over ~190cc intake runner even with big engines. Obviously engines with different shape heads will ahve different ranges.
For reference, AFR makes Windsor heads with 165cc, 185cc, 205cc, and 225cc.
The 165s are almost exclusively used on stock & near stock 302 builds (i.e. stock cam, stock intake, stock bottom end, etc). Although I personally would have no problem running these on a 331/347 stroker meant for truck duty since high torque, low RPM could benefit by the smaller intake runners.

The 185s are the most popular & used on anything else built for the street from stock modified 302s, boosted 302s, stroked 302 blocks on up to 351w blocks of various combos. These are the all purpose aftermarket street head that you can't go wrong with. And they do OK on a bone stock 302, although it's usually recommended to at least upgrade the cam if you are doing nothing else to the engine.

The 205s on stroked 302 blocks built for high RPMs, built 351w blocks and used on the street with 408w (stroked 351w).

The 225s are pretty much exclusively racing applications of various flavors. These ports are just too big to maintain adequate port velocity for street duty.

The other brands such as TFS TW has similar ranges with the TFS head being a 170cc runner. I can't remember what Holley, Edelbrock, and RHS common runner sizes are.

But my point is Windsor heads with 227cc intake runners are absolutely excessive for street duty. Can you make them work? Sure. You can put Holley 750cfm carbs on stock engines too. They physically fit and the engine does crank and rev. But I wouldn't venture much more of a description than that.

It's clear what you've got is a purpose-built race engine with straight-up race parts. If what you are wanting is a street-rod kind of engine, you might want to think about getting different parts or selling the entire engine to someone that's looking for what you've got & replacing it with something more reasonable. Granted, that's easier said than done. So if a cam is the best thing this project can hope for, then my off-the-shelf cam recommendation is going to be a Comp XE274HR12. That's about as aggressive of a cam as I would ever recommend for a street application. Using generic ball-park numbers for engine dimensions using those heads, that puts you with a Dynamic Compression Ratio of around 8.0. 87 octane pump gas maxes out at about 7.9. So you'd have to run mid-grade or premium with that cam but I suspect you are doing that anyway. This cam should hold strong to 6000RPMs.

However if you are considering the propane option, you can go with an even more conservative cam such as the Comp XE266HR12 or XE264HR14 to get your compression up a little higher (~8.2 DCR) to take advantage of the propane. And another benefit of the propane is atomization or lack of atomoziation due to the large heads would not be a concern as it would be with gasoline. Your engine with either of these cams and Propane would probably be OK. The stall converter would still might be a negative. Having to rev the engine to 3000+ before it start pulling good at WOT would get annoying. And these cams would tend to nose-dive after about 5500RPMs.

Note the compression ratios I'm referring to are Dynamic Compression Ratios, not the more familiar Static Compression Ratios. I'm guesstimating your engine's static CR right around 10:1. Without knowing whether your pistons are dished and by how much, I'm having to guess...and I'm guessing flat-top with only 6cc for the lashes.

[Warpig Racing]

These heads are the 210cc that had some light porting to get to 217 CC. That makes these the 60 CC chamber.

Probe pistons I believe that they are 4cc http://www.probeindustries.com/Ford_347 ... p3471f.htm

Engine was originally built for drag. I did have 250 shot and removed that some time ago. Basically unwinding some of the mods to make it more street able. I am not going for daily driver but 6-8 MPG on pump gas would be fine by me.

The engine has 5.4 rods with forged crank. Could I swap to the 5.315 rod??? Just ball parking it, that would take the CR down too much... doing research on the phone is a pain.

I have considered selling and replacing the engine with a stock but as we all know, you only get pennies on the $

[Warpig Racing]

5.315 rod might allow me to add a Turbo... I built the engine more than 5 years ago. Back then there were not many options for the 347 pistons...

[cgrey8]

So these are the 210cc heads. That's at least a little better but still extreme for street duty. The fact that they were ported back out to 217cc makes that worse. That just means it won't be getting daily driver fuel economies or off-idle performance. But it doesn't sound like that's what you are expecting.

You said the CR is 60cc??? The list only shows 64cc and 62cc chambers as options. Did you have the heads milled to reduce the chamber volume?

As for what that does to CR, lets see that puts you at 8.42 DCR using that Comp XE274HR12 (hyd roller). That's about as high as you'd want to go on pump gas. Given this configuration, forget about those other milder cams unless you plan to marry this thing to propane or some dedicated high octane rated fuel in which those other cams are back options again. But 8.42 is within the realm of 93 octane premium pump gas using a 160-180 degree Tstat.

If you truly have 60cc chambers, that throws DCR to 8.62. That's pushing the limits of pump gas and would guarantee you have to run a 160 Tstat to be able to run pump gas at all. But it isn't completely outside the realm...just riding the limits hard. The fact that these are aluminum heads will help.

Also do you recall if the pistons are zero-decked? I'm also assuming you'll go back together with FelPro .039" thick gaskets with 4.100" bores. To go any thicker would negate your quench. These heads have a good quench pad and you want to maximize that with this high of compression. Lowering the compression with a thicker head gasket would do more damage than good. The quench is doing more for you than the higher compression is taking away. But you can adjust what thickness gasket you need when you get the heads off and actually measure the piston deck height. Then you'll know for sure what gasket thickness you need.

I WOULD NOT recommend reducing the rod length. That's just a bad idea all the way around. Not to mention new rods would require rebalancing...something you were wanting to avoid.