Jason Stine
Well-known member
Does anybody have a good lead on a virgin 948 engine block for a new race motor build?
Thanks,
Jason
Thanks,
Jason
948 Engine Block
- Thread starter Jason Stine
- Start date
Rod Hahnemann
Well-known member
Jason,
I have several.
Rod Hahnemann
SPRIDGETECH, INC.
(810) 229-8639
I have several.
Rod Hahnemann
SPRIDGETECH, INC.
(810) 229-8639
Brian Linn
Well-known member
Since a lot of former 948's have switched over to the LP 1275, I would guess that you could find a fully developed 948 race engine for a fraction of the cost of building a new one. I think my dad sent some 948 blocks to the scrap yard. I will double check.
R. J. Sorensen
Well-known member
Jason,
I too, have a garage full, all in better shape than the cranks I sent you.
B. Linn's comment is so true. Many front running 948 Spridgets had their 948 stuff for sale after the first Run-Offs at Road America. (Dan Collishaw (sp?) comes to mind) Some really good stuff (in their day) was available.
Try advertising for a complete 948 engine. Some market for them in some Vintage classes though.
If building new, better off with 1275.
RJS
I too, have a garage full, all in better shape than the cranks I sent you.
B. Linn's comment is so true. Many front running 948 Spridgets had their 948 stuff for sale after the first Run-Offs at Road America. (Dan Collishaw (sp?) comes to mind) Some really good stuff (in their day) was available.
Try advertising for a complete 948 engine. Some market for them in some Vintage classes though.
If building new, better off with 1275.
RJS
Dayle Frame
Well-known member
Stiner0931":323v3vci said:
C'mon kid.....come to the light.....build an LP motor and it'll last a lot longer and be less hassle. More power, more reliable, wider power range.
I know a guy.....
Dayle
R. J. Sorensen
Well-known member
Jason,
If you insist on rebuilding a 948, a few things to know about these blocks:
*Early blocks did not have insert cam bearings in 2 of 3 bores. CANNOT race without. $200-300 to align bore for bearings, but hard to find a shop with an align bore bar small enough. Hart's Automotive in Cecil, OH one of few shops to do this.
*Check center main bearing web carefully for cracks (Magnaflux). Any excessive load on front of crank (like head on collision, or being rolled across floor) distributes this force on the center web via the thrust bearings. Not uncommon to be cracked. Don't forget to put these bearings back in.
*Seek later block with factory steel sleeves. Per Dave Taber Sr. (original Comptune), these made more power, probably due to better / more consistent ring seal.
*Make sure the slip fit spool that acts as the seat for the oil pressure relief valve, and bypass for the oil filter return line, is present. Not illustrated or part numbered in factory parts manuals (unobtanium), but known to be missing from some blocks. These can be pulled out with 1/4-28 bolt.
*If wet sump, drill & tap for 1275 oil pickup. 65 percent increase in cross sectional area. Easiest solution to oil pressure problems. (I have all necessary tooling)
*Remove ALL flashing/slag from oil return holes between valve lifter galley and crankcase. A lot of this, and ugly.
What exactly is wrong with your current block(s)?
And best of luck with this decision.
RJS
If you insist on rebuilding a 948, a few things to know about these blocks:
*Early blocks did not have insert cam bearings in 2 of 3 bores. CANNOT race without. $200-300 to align bore for bearings, but hard to find a shop with an align bore bar small enough. Hart's Automotive in Cecil, OH one of few shops to do this.
*Check center main bearing web carefully for cracks (Magnaflux). Any excessive load on front of crank (like head on collision, or being rolled across floor) distributes this force on the center web via the thrust bearings. Not uncommon to be cracked. Don't forget to put these bearings back in.
*Seek later block with factory steel sleeves. Per Dave Taber Sr. (original Comptune), these made more power, probably due to better / more consistent ring seal.
*Make sure the slip fit spool that acts as the seat for the oil pressure relief valve, and bypass for the oil filter return line, is present. Not illustrated or part numbered in factory parts manuals (unobtanium), but known to be missing from some blocks. These can be pulled out with 1/4-28 bolt.
*If wet sump, drill & tap for 1275 oil pickup. 65 percent increase in cross sectional area. Easiest solution to oil pressure problems. (I have all necessary tooling)
*Remove ALL flashing/slag from oil return holes between valve lifter galley and crankcase. A lot of this, and ugly.
What exactly is wrong with your current block(s)?
And best of luck with this decision.
RJS
Agree with RJS. Couple things a must... If using a stock crank, lighten, balance and harden. Also, reinforce the center main. Got 2 10,000 rpm engines 15 years old still going strong even with 15.8 cr. Sleeving any of the A blocks is a great way to get long life. Watch the factory sleeved 1275 blocks... getting a good bore to resleeve is tricky.
ADDITIONAL NOTE: Agree that the 1275 is the only way to be competitive in H. Got 2 cars; Jon Stamps Racing's personal/test mule full up national car and a stock suspension style set up for H and Solo 2. The almost LP 1275 in the Solo car ran Sebring only 2 seconds slower than the 98 hp 9,500 rpm, 15.8 to 1 948 Comptune/Stamps engine. That was done with the Solo geared tranny so really had only 3rd and 4th to use on the track. Does that tell you something?
Bob
ADDITIONAL NOTE: Agree that the 1275 is the only way to be competitive in H. Got 2 cars; Jon Stamps Racing's personal/test mule full up national car and a stock suspension style set up for H and Solo 2. The almost LP 1275 in the Solo car ran Sebring only 2 seconds slower than the 98 hp 9,500 rpm, 15.8 to 1 948 Comptune/Stamps engine. That was done with the Solo geared tranny so really had only 3rd and 4th to use on the track. Does that tell you something?
Bob
Acme Speed Shop
Well-known member
Dayle Frame":9etq7vb1 said:
Listen to Dayle, no use throwing good money away building a 948 these days, it took me three months to get rings for 948 vintage racer, who had some Venolia pistons, I had to get Brian Waters to get Mahle tri metal main bearings from the UK, that took two months. Then if you get all the right parts, the 948 has the torque of a wet noodle. There is no good reason to ever build a 948 ever again for SCCA racing, none whatsoever. Once when the 948 was the norm in HP, ok, but that ship has long sailed away. If you build a LP 1275, you will have alot more useable torque, and good 15-20 HP more than the 948, and it will maybe need refreshing after 20 weekends.
Ron Bartell
Well-known member
Jason - I wasn't aware that you hurt the motor so badly so I didn't talk to you about this. I also know that your Dad thinks there is something special about a 948, but I have to agree with the other posts that are trying to steer you towards the 1275 LP motor.
There is a reason why people have moved away from the 948 and that is because in order to get the power out of it that is needed to be at all competitive, you need to overtax the motor to the point where it is seriously challenged from a reliability standpoint. Additionally, the amount of technical knowledge that is needed to keep those motors running may be beyond your and your Dad's capabilities. Not trying to slight you or your Dad, but think of the people that have given up on the 948 because they couldn't keep it together, and then think about whether you are smarter than them.
With a 1275 LP motor you could bolt together any combination of head, block, intake manifold, and carbs and with a good valve job could be within probably 5% of the best 1275 motor out there. If you are lucky enough to find a good head you would be within 2% of the best. Now think about what you would need to be within 2% of Dan and Peter's motor or Bob Weber's 948. Additionally the 948 Spridget runs at a weight (1500 lbs) that you probably can't reach with your car, and is uncompetitive at the Runoffs even at that.
Not mentioned in the posts above is the fact that with a good full-prep 948 you will need a billet crank. Very expensive compared to the 1275. Just think about having a motor that isn't stressed to the max, makes more power, doesn't blow head gaskets, and in general just starts up and runs. Then think about how many sessions you have already not been able to finish because of the motor letting you down. At this stage of your racing life you need seat time and don't need to be missing laps and sessions.
The choice is clear.
There is a reason why people have moved away from the 948 and that is because in order to get the power out of it that is needed to be at all competitive, you need to overtax the motor to the point where it is seriously challenged from a reliability standpoint. Additionally, the amount of technical knowledge that is needed to keep those motors running may be beyond your and your Dad's capabilities. Not trying to slight you or your Dad, but think of the people that have given up on the 948 because they couldn't keep it together, and then think about whether you are smarter than them.
With a 1275 LP motor you could bolt together any combination of head, block, intake manifold, and carbs and with a good valve job could be within probably 5% of the best 1275 motor out there. If you are lucky enough to find a good head you would be within 2% of the best. Now think about what you would need to be within 2% of Dan and Peter's motor or Bob Weber's 948. Additionally the 948 Spridget runs at a weight (1500 lbs) that you probably can't reach with your car, and is uncompetitive at the Runoffs even at that.
Not mentioned in the posts above is the fact that with a good full-prep 948 you will need a billet crank. Very expensive compared to the 1275. Just think about having a motor that isn't stressed to the max, makes more power, doesn't blow head gaskets, and in general just starts up and runs. Then think about how many sessions you have already not been able to finish because of the motor letting you down. At this stage of your racing life you need seat time and don't need to be missing laps and sessions.
The choice is clear.
Jay Lutz
Well-known member
I sold my 948 H engine in around 2007 for exactly that reason. I had one of the best in the country (2nd best ever 948 on Taber's dyno) at 102hp and it was a nightmare to keep running. With oodles of subtle tricks plus obvious ones like a Moldex billet crank, 16:1 CR, dry sump, lifter mods to avoid eating camshafts, head gasket mods, double offset angle hand machined pistons, plug indexing, offset head stud collars to shift the head to a position to maximize valve to block avg clearance, rerouted head water cooling path, Carillo rods........I was able to make it very reliable (after doing H engines since the late 70's...can't tell you how many I broke big time on the dyno and at the track) learning but the head had to come off every 2 weekends for freshening. Just not worth the effort and on top of that they just can't win any more. If a top shoe like Collishaw or Bartell agree on this point, it's a fact.
Jason Stine
Well-known member
Thanks for the input guys. Ron, I don't think the motor was hurt so bad where I'd need to do a whole new block, but I won't know for sure for a few months. I put this feeler out there to weigh options if I do have to go down the route of a new block/head in the near future, I agree that there isn't much sense in building another 948 at this point. But, for now, I'll see what needs to be replaced after I hurt the motor and I do have another good 948 in my garage which I'm going to put together for next year. Once I see how bad the damage bill is going to be from the towing accident, will see what's left in the budget to start accumulating parts for a 1275. Maybe by then, SCCA will knock another 50# off too...