Basic Stroker project started

[oletshot]

Probably the biggest difference would be that your intake manifold and head would line up correctly. I read on the Yahoo group that flow #'s aren't as different as most people think.

[gradon]

I'm a big x2 on getting a 7120 head from the JY. Just looking at your head there is no way that those intake ports flow as good as the HOs w/ the renix intake manifold and if those smaller ports don't even match up with the HO manifold then it's the worse case scenario. It'll take you 1-2hrs at the JY and less than $100(for some reason the price list at my JY says $100 for block w/o head and $175 complete w/o accessories, so I guess the head is $75 or less. Take some PB Blaster, socket set w/ small extensions and squigleys if you got em.

[Killman]

I fully agree that 7120 head is correct way to go, but here in Finland where I live junkyards are not filled with Cherokees, yet. I still wonder that this setup was running and at least I did not notice any bad behavior.

With this head and intake manifold odd thing is that head has bigger openings than manifold. Valves are same size as HO head, though. Is it so that 7120 head has actually smaller ports than renix head? Must be. What happens when flow reaches bigger cross section area? Flow speed reduces, is it bad? Turbulence at the transition poit, sure bad. I know from nothing to zero about these flow things, but I am sure somebody from stroker community has real experience what effect this has in practice when operating 1000-3000 rpm, mostly used in trail.

[Shark]

there is a thread here about the porting and head flow. read up.

fwiw, my JY charges $49.99 for heads. plenty of XJs here too. too bad theres no 258's or i would have my crank by now.

[Flash]

Before you get your hart set on that renix head(Note, I'm a Renix fan) pop off a couple valves and take a GOOD look at the bowl area of the ports................If yours is any think like my spare head.....You will find a vary large port "shift" in this area of the casting(when you go to porting it back to stock shape.......You will realize how bad.)

Just something to look at before you decide to buy a porting kit and go to town on it.........Or, buy a better flowing head and call it good...................


Flash.

[Killman]

Day whatever...

I am frustrated with not been able to purchase pistons (Gradon, I sent you e-mail).

Meanwhile, head and intake manifold has received some treating. I made them match as well as possible, anyhow better than before. Lapped valves, changed umbrella seals, painted head, valve cover, oil pan, fitted new blue-top injectors to fuel rail-manifold .... Kind of spent time waiting pistons... and then received mail that pistons did not arrive this week as promised, may come next week

Well, luckily this is not my daily driver, but still I will miss too meny interesting events. And to add some salt in my wound, KB forced pistons seems to come to market these days!! If I did not purchase 4.2 connecting rods, that amount I could spend for KB pistons.!! Damn, I think I fill my wine glass and just don't think about it

[Killman]

Finally things started moving, long waited Fedex arrived with pistons and other goodies... Now I have all components and after machinist shop is done with block, assembly can start. I am slightly worried about compression because I selected standard pistons instead of 667cp, the dish is significantly smaller but I am not going to dish them more. I hope our premium pump gas is good enough, w'll see (or hear). So, few more days with new rear bumper and other not-so-important issues and then assembly can start.

[Flash]

when compression is in question, looking for anything that will cause a detonation and removing it becomes the focus!

Flash

[Killman]

Flash, do you mean sharp edges and that kind places shall be smoothed in combustion chamber? Should I polish piston heads, they look a little rough? Should I round edges of combustion chamber if head gasket allows? I slightly ground chambers smooth, but did not polish them. Other?

If the stock piston dish that I got from Omix Ada is really around 13cc, I think I am on safe side. But I just measured them (area*depth) and I think dish might be smaller smaller than advertised.

However, quench will be near stock with gasket. +/- 0.001 from stock.

[1bolt]

I would go out of my way to replace that renix head with any HO head. People who say the renix head isn't that bad aren't taking into account that your HO intake manifold is not lining up anywhere NEAR correctly and any porting you do to make them match a little more is PROBABALY going to kill your low lift velocity. in other words low RPM torque will disapear. The "dogleg" you create trying to match the renix port to the higher HO intake will kill velocity and probably ruin higher RPM flow as well.

If you don't get an HO head, at least get a renix intake that lines up and adapt the HO throttle body to it.

[Flash]

I would go out of my way to replace that renix head with any HO head. People who say the renix head isn't that bad aren't taking into account that your HO intake manifold is not lining up anywhere NEAR correctly and any porting you do to make them match a little more is PROBABALY going to kill your low lift velocity. in other words low RPM torque will disapear. The "dogleg" you create trying to match the renix port to the higher HO intake will kill velocity and probably ruin higher RPM flow as well.

If you don't get an HO head, at least get a renix intake that lines up and adapt the HO throttle body to it.

Altho this is not the advice that most would give(renix head= renix manifold) I thing it is vary sound advice...........a piece of straight pipe will flow better then one with a jog in it.......and the intake to head is no different.

we all know how well the renix motor runs at vary low rpm, so, even tho the manifold isn't the best design intake........It match well to the renix.

For the longes time, i felt that the rounded manifold was a good choice for my renix when it gets a stroker............but the reason i gave above^^ is why i will keep renix renix and HO, HO early and late additions!!!!!!

Flash

[Killman]

I am deeply aware how right you are right about mismatch between head and manifold. But, here at the side of the world, we do not have fair selection of XJ parts in junk yards. In fact I have send word around that I am willing to buy HO head and late model (curved) manifold but at the moment I must get done with what I have, unfortunatelly. Even if you guys would help me to get them in reasonable price from USA, freight of head to here would be somewhere around 3-400 USD.

[John]

Shipping gets to be a serious matter. Still if you know of a traveler heading your way, I have hand carried some remarkable items in the past to individuals in Europe.
John

[John]

I just recalled a picture of your sailboat, do you know of any of the manufactures or individuals that attend the big shows in the states. I like going to the Annapolis Maryland yearly show and have visited with several that have come from Scandinavia. My wife is of Swedish, Norwegian descent and still keeps in touch with family in Sweden. It wouldn't help just now, but it might be a way to get one to you without destroying your local economy? (Love Bristol Channel Cutters myself)
John

[gradon]

Hey Killman, I ended up buying and using the pistons I was gonna send you because they were the only complete set that were available in order for the build to go down when it was supposed to.