Hey everybody!

I just bought a 225 that got few miles after the rebuild. The cylinder head is also rebuilt so I became very happy when I tore i apart to check the condition. It has very little wear and it is clean inside the block and water jackets.

Before I got the engine I ordered a reground RV10RDP (Grind 2106) from Oregon Cam. So I'm going to run this cam in this engine. I read that it should have compression between 8.4 - 9.0. And when I did the calculation on this engine I ended up on 7.58 in compression.

Pistons are 0.030 and he pistons sits 0.193 down the hole! I checked the cylinder head volume and ended up with 59cc. So with a 0.044 felpro gasket the compression calculator landed on 7.58 then.

I want my compression to be somewhere between 8.4 - 9.0 and by only milling the head I think it would be way to much to remove so I going to mill the deck also. So I going to do the milling at a place that I need to say how much I want to be removed since it's not a machine shop that works on engines.

I guess I can do the most milling at the block, but I also want to mill the head so it becomes flat. So I would appreciate if someone have some suggestion how much to remove so I dont do to much or to little. Since I cant calculate how much the head volume would change from 59cc if I remove 0.060.

will you can take a lot but I would take most of it from the block surface. I had a .060 over bore, cut .140" from the deck but my starting was .187, the head was cut .080" which gave me a 48cc chamber, that was with a polished chamber and a fel-pro gasket, mine was .033 compressed. my ratio was 11.4 / 1. with a 5.40" lift cam I was only 0.079" valve clearance which was close but I never had a issue.

Using the numbers you provided, I calculate that removing .080 from the block will give you a compression ratio of 8.55:1.
Shaving the head is a little more complicated as you have to calculate the new chamber size. I can do it if you can wait.

_________________
-MattMan
LEANED & MEAN

watch the clean up in the chamber the more you grind it smooth helps with detination but lowers comp ratio, also don`t sink valves too far into the seat, it will lower ratio also and hurts performance in the head. I found the larger the comp chamber seem the better the engine runs, so cut most of what you need from the deck. I haven`t done any Dyno work just track tuning.

Thanks for the fast response. I took some measurement on the old felpro gasket I have and it was 0.031" compressed. I looked at the camber and it could be measured quite easy how much volume I remove since it's like a cylinder before hitting the highest spot in the camber, for my head it was approximately 0.100". I'm beeing conservitive and say it would remove 11cc if I mill 0.100". That would give me a chamber volume of 48cc and a compression ratio of 8.62.

This engine is just my spare and is only for have something to drive when I rebuilding my current 225. So because of that I'm only going to mill the head because I rather spend the money to rebuild the original Slant in my Valiant. I know it's a good idea to mill the deck also but I am only going to mill the head this time even if I would love to do it "right".

Today I have done some pocket porting and valve unshrouding on the head like the article here on the forum: http://www.slantsix.org/forum/viewtopic.php?t=41693
I'm doing it pretty much like in the article. Cant wait to put everthing together

Rule up thumb until you hit the wedge or curve of the chamber is .0066 = 1 cc

so

a .100 cut will net you 15.15 cc or thereabouts...

So in SCR terms if you make the .100 cut and the gasket compresses .039 you are up to 8.75 SCR...(with a chanber volume of 45... which is about the limit before the .0066 rule doesn't apply.

If that all holds true, degreeing the cam in at 103-104 will get you about 7.91-7.95:1 dynamic compression ratio, which would be close enough to the 8:1 DCR we try to target...

Thank that was helpful information to know. You guys rock!

How should I proceed when I breaking in my reground cam. I have breaking lube that I'm going to lube the lobes on installation. I will degree the cam before putting the lube on. If it were a V8 I would oil prime the engine with a "priming tool" which I can't do now. How should I do then instead? Because I dont want to crank the engine to much so the lube gets removed from the lobes? Will use oil mineral oil with zinc around 1500 ppm and nothing any higher than 10w-30. Were I live it sucks getting any appropriate oil. Going to pour oil over the rocker arms so they are coated. Will set the timing right and will have a fire extingquisher just in case. Any more helpful tricks that I should do?

when first assembling put a mix of 50/50 gear oil and motor oil on all bearing, if you have cam lube use it on cam and lifter base. if not coat the cam and lifters with the same mix. before installing spark plugs use starter too rotate engine until you have oil pressure. your now ready to fire and run the cam in for 20 minutes at 2000rpms, if timing or fuel mix is off it`s all right to shut the engine off and fix what needs to be checked and start again. better than flooding the engine, running lean or over heating the engine. if you have trouble finding right oil try putting a mix regular 10w-30 3liters with 1 liter of 15w-40, more Zink for flat tapped lifter cams.

Thanks for those advices!

When you say gear oil do you talk about 80W-90 that you use in rear end?

I have found 3 oils that are mineral oil and have almost right amount of zinc.
The first is "regular" 10w-30, tech spec: http://www.biltema.se/BiltemaDocuments/ ... 68_TDS.pdf
The second is turbo diesel oil 15w-40, tech spec: http://www.biltema.se/BiltemaDocuments/ ... 62_TDS.pdf
The third is a universal tractor oil 10w-30 which got very good amount of zinc, tech spec: http://www.biltema.se/BiltemaDocuments/ ... 94_TDS.pdf
What would you choose of those 3? After the cam break in I'm going to change the oil so I'm not want to spend to much on oil that's going to be discarded.

Here are a pic of the unshrouding along the outer edge of the intake valve. And you can also see that the valve pockets are blended. And I also grind the valve guide boss.

yes 80w-90 but only as a pre-lube coating on all bearing and gear surfaces to protect them during start up and run in. I run 0ne litre of 15w-40 in my oil changes for the extra zink . 15w-40 is the only truck diesel oil up here. if you can find lower viscosity oil try it might help protect you cam and lifters, 10w-30 is the heaviest you want too use . I have done cheap oil changes for run in.

what size valves? looks like you could work the bowl and pocket area a lot more!

I have stock size valves. I'm going to do some more work in the bowls thanks for the advice.

Today I got my milled head back . I took off 2.5mm or .098". Now my combustion chamber is 44cc.

When I check the DCR I end up way higher than dusteridiot said I would be with 45cc and 0.039 compressed gasket. Now when my chambers are 44cc and my old felpro gasket measures 0.031" I end up with 9.01 static compression. When I put those numbers in the DCR calculator I end up with 8.65. Even if I put dusteridiot's numbers in the dcr calculator I end up with 8.44.

Would this work or did I type in something wrong in the calculator? From what I have read, Dutra designed this cam profile to run with 8.4 - 9.0 static compression.

Felpro Gaskets when properly torqued should be in the .045-.039 range... I've only gotten .031 after retorqueing it on too many times....my last 3, I pulled before going to Victor Reinz were .043 to .039

So with:
Deck Height: 0.193
Combustion chamber CC=44 CC
Felpro Gasket at .039, 3.5" bore
Bore= 3.43
Stroke=4.125
No piston dish/Flat tops...stock pistons

SCR should be 8.869:1

If the cam is 244/244/108...installed at 103 centerline...

DCR should be 8.02:1 so that is perfect....

If your measurements are a bit off...the results may be higher...

That sounds good then. I ground the small "dots" away to make the chamber a little better so now the heads are 44.75cc. I'm planing running the centerline at 100 for torque and fuel mileage. I seldom run the engine more then 2500rpm and often drive in the city so that's why I want the torque and fuel mileage to be good. I read about having the centerline between 100-104 favor the low rpm torque and fuel mileage. What do you think? I know you say 103 for the DCR to be 8.

So now, if we plug the 44.75 in...that would lower the SCR to about 8.7955:1 and DCR of 7.95

But if we roll the cam phasing to 100 instead.... the DCR becomes 8.06:1...

So no problems there... the thing to really watchout for on heavily advancing the cam is it limits the top end of the engine... so you may get all the torque lower, but you may have an issue if you go out of town and need to run the tach up to 3500 to pass a stubborn truck.... just sayin'...