Stroking a Dolmar 7900

[hseII]

I was distracted more by the lumps than the haruumphs.

Bless her Heart!


Sent from my iPhone using Jon1212 Pro

 

[Fruecrue]

Case is together now, crank spins smooth.
Bent up some copper wire to space out the oil pump. Figured that’s better than a couple washers because it supports the full face of the pump. Also added slightly thicker wire behind rubber oil hoses to get a good seal on pump.
14 ga sheet cut to size would be better yet as an oil pump spacer.

 

[Fruecrue]

 

[Fruecrue]

Seals installed, flywheel and coil on.
Head knocker for sure. With two base gaskets she’s still barely touching at TDC.
Times at 104, 134, 77 this way.
Hmmmmmm........
Decisions, decisions.

Better hold off, think about it a bit.
Suggestions?

 

[Terry Syd]

Get it running and see how it feels, then go from there.

 

[Fruecrue]

Get it running and see how it feels, then go from there.

Gotta think on it, don’t want to buy more base gaskets as I’ll be looking for more compression to raise the exhaust some.
May just cut the band until I’m at .020” squish with one gasket.
Need a couple more parts anyway, so no rush.
The hard part is over.

 

[mettee]

This is sweet

 

[huskyboy]

Seals installed, flywheel and coil on.
Head knocker for sure. With two base gaskets she’s still barely touching at TDC.
Times at 104, 134, 77 this way.
Hmmmmmm........
Decisions, decisions.

Better hold off, think about it a bit.
Suggestions?

No lathe? Maybe sand the top of the piston on a piece of glass or use a old one to sand the squishband?

 

[Fruecrue]

No lathe? Maybe sand the top of the piston on a piece of glass.

No lathe but I can still cut the band. I’d rather do that than sand the piston because of the compression bump.

 

[andyshine77]

Seals installed, flywheel and coil on.
Head knocker for sure. With two base gaskets she’s still barely touching at TDC.
Times at 104, 134, 77 this way.
Hmmmmmm........
Decisions, decisions.

Better hold off, think about it a bit.
Suggestions?

I would run it first. That said I'd likely raise the exhaust a couple of degrees, and set the transfers to open at 130° and keep the exhaust where it is now, especially if you open it up some, and use a big carb. Ive seen as low as 85 on the exhaust, but that was with the stock carb, but it likely wont kill anything if you lower the intake to say 80 or so. I take it case volume is reduced?

 

[mettee]

I think case volume will be pretty close to what it was. There is crank taking up the area that was clearanced.

I would definitely cut the squish band for .020 so you can retain the stock gasket.

After that, check port timing. Get all your marks for free port, etc. You probably won't have to cut the base since every thing will come out of the squish band. I could be off I'm just running it through my head.

Cant wait to see this run.

 

[Deets066]

Typically a spacer is made for the base from what I’ve heard. Never done one though.
You’d have more than desirable compression if you took it all out of the band.

 

[Fruecrue]

I don’t know if case volume was increased of not.
I plan an exhaust height in the 94-96 range, so that will drop compression a fair amount.
Joey was telling me about a thicker gasket available through Baileys. Called it a big bore gasket if I recall correctly.

Maybe he’ll show up if I play his favorite song.

@Stihlbro

 

[RI Chevy]

Make one out of thin sheet metal, no?

 

[huskihl]

I don’t know if case volume was increased of not.
I plan an exhaust height in the 94-96 range, so that will drop compression a fair amount.
Joey was telling me about a thicker gasket available through Baileys. Called it a big bore gasket if I recall correctly.

Maybe he’ll show up if I play his favorite song.

@Stihlbro

To me, as it sits with the larger bore, case capacity is larger do to the larger diameter cup in the bottom of the piston. But the comparative case capacity is smaller due to the larger piston and stroke sitting on a smaller case

 

[Fruecrue]

To me, as it sits with the larger bore, case capacity is larger do to the larger diameter cup in the bottom of the piston. But the comparative case capacity is smaller due to the larger piston and stroke sitting on a smaller case

Ouch, muh pea brain hurts.

 

[RI Chevy]

You gonna pipe this Solmar Dolsolo saw?

 

[huskihl]

Ouch, muh pea brain hurts.

Exactly

 

[Fruecrue]

You gonna pipe this Solmar Dolsolo saw?

That idea has come a knockin’

 

[Stihlbro]

https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com/ulk/itm/322414572059


I seen them on eBay. 1.5 mm thick. Great seller!